Gen II System Too Rich Errors

[Alphamacaroon]

Hey all, I have a stock Gen II Coyote crate installed in a FFR coupe. Been getting System Too Rich error codes on both banks, and the exhaust smells like a carbureted firebelcher on a cold morning. Couple questions:

1. Is this "normal" for a crate Coyote that hasn't been tuned to take into account the FFR supplied air intake and exhaust system?
2. Am I generally okay to drive it for a small amount of time until I get it tuned? Or should I absolutely stop driving until it's resolved? A too-lean state would be a no-go for me, but maybe too-rich is okay for some short test drives?

Much appreciated!

[edwardb]

I never saw that with my Gen 2 on the stock tune. In fact I drove it for about 1,000 miles on the stock tune with any DTC's. Many never changed from the stock tune. Mine definitely ran better with the custom tune. Especially at lower RPM's. But never saw that. Mine had the FFR recommended Spectre intake and GP Headers long tube headers. Does yours have the Spectre intake? Positive the MAF is oriented the right direction? Likely wouldn't run if it wasn't, but have to ask. Is the MAF as far from the throttle body as you can get it? Is it on the outside of the curve going into the throttle body? All of these could contribute to it not getting a good signal. I doubt short drives would hurt anything. But don't know how much it would take to build up carbon in the cylinders, valves, plugs, etc. Plus sooty exhaust. In addition to eliminating the codes, you'll be happier with the custom tune just in how it runs and drives.

Now my Gen 3 is another story. It did start throwing too rich DTC's (among other things) with the stock tune and was basically undriveable. After going through this a couple times with Lund, their word is this is all related primarily to MAF calibration. It's tuned to the stock Mustang CAI box. If changed it's going to have issues. Likely not much to do with the different exhaust.

[Alphamacaroon]

I have a Treadstone Performance intake:

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I went with it because it has the honeycomb straightener built-in and doesn't require any size adapters or modifications. Nothing too radically different— can't imagine it'd be much different than what most people are running, right?

I'm fairly certain I installed the MAF sensor in the right direction— haven't had any idle or stalling issues. I assume if it was backwards it would probably tend to run lean, right?

Any thoughts/opinions on the positioning of the MAF sensor? Once thing I noticed is that I definitely took up a lot of "slack" on the MAF tube— maybe I should lengthen the intake run by moving the air filter and elbow further out on the tube?

I will say that my Gen II seems to be acting very similar to your pre-tuned Gen III. Besides the error codes, I find it is extremely skittish at low-speed/RPM (borderline undriveable). The engine seems to run fine, but the throttle response curve makes it almost impossible to keep it at a steady slow speed without surging— it's like it goes from nothing, to "too much" when you press the pedal down a few millimeters. I assumed this could be fixed with a different throttle pedal curve mapping. Makes me wonder— maybe they made some changes in later Gen II PCMs that are shared with Gen IIIs?

[Al_C]

I have the spectre intake on my Gen II. No tune. Yet - may do one early next year.

I have never had a too rich condition, but I did have a too lean condition on one bank. I believe that was a function of how I had driven the car that specific day. Cleared the code and it's been fine ever since. That said, I have one question and one thought consistent with Paul's comments: Is it rich all the time, as in you get the code, clear it and it comes back, or is this a one-off? The comment is that I'd rotate the MAF sensor 180 degrees. That is, assuming that you can rotate the tube. Don't ask me why, but everyone I have talked to about these engines agrees that the MAF has to be on the outside of the curve.

[Railroad]

If your air filter is in the path of the radiator fan wash, it might create a dirty air flow. Correct in orienting maf meter on the outside of the curve line.
Is that fresh air line connected to the valve cover?

[Alphamacaroon]

If you air filter is in the path of the radiator fan wash, it might create a dirty air flow. Correct in orienting maf meter on the outside of the curve line.
Is that fresh air line connected to the valve cover?

The radiator tunnel is mostly sealed off from the engine compartment with aluminum, so I don't think that will be an issue. I'll definitely re-orient the MAF sensor like you say and give that a try.

That fresh air line is connected to the valve cover breather. I assume that's correct? I've heard that others say it's better to use an oil capture can instead?

Al_C: it's consistently rich. I've cleared it twice now.

[Bob Brandle]

Alphamacaroon, it looks to me that you need to rotate the MAF forward about 100 degrees, not 180 degrees. Forward being towards front of the car, as it looks in your photo.

[Bob Brandle]

Alphamacaroon,
Adding another comment: When you do rotate the MAF forward, (my suggested 100 degrees or there abouts), it looks like the two SS braided hoses may be in the way, as well as what looks like the Coyote's computer may be in the way.
As most if not everyone will likely agree, it's critically important to get the MAF near the far outside of the curved large air induction tube (the silicone rubber one in your case, as I also have on my Coupe with Gen 2 Coyote).

[Alphamacaroon]

Alphamacaroon,
Adding another comment: When you do rotate the MAF forward, (my suggested 100 degrees or there abouts), it looks like the two SS braided hoses may be in the way, as well as what looks like the Coyote's computer may be in the way.
As most if not everyone will likely agree, it's critically important to get the MAF near the far outside of the curved large air induction tube (the silicone rubber one in your case, as I also have on my Coupe with Gen 2 Coyote).

Yeah, I appreciate you noticing that and confirming where it needs to be rotated to. I don't think the computer will be a problem but the hoses probably will be. I have plenty of room on the MAF tube to extend it a bit, so I think I can probably get it to come in below the hoses. Either way, I'll do what it takes to get it rotated around to the long-side of the curve. Thanks again for the advice and ideas!

[edwardb]

Can't add too much. Agree with the multiple comments that the MAF sensor is typically recommended to be at the outside of the intake curve. So in your case basically on the front. Not sure if that will solve anything. But best to put it where most recommend, and leave it there through whatever tuning process you follow. If it were backwards, typical symptom is will start but immediately stop without a proper signal. So doubt that's what you have. But always something to check since it's an easy mistake. If you do use an oil catch can, it's often placed on the RH side. I've had one on both of my Coyote builds (https://www.jlttruecoldair.com/jlt-oil-separator-3-0-passenger-side-11-17-gt-boss-15-gt350/ for the Gen 2) but with the somewhat limited miles we drive compared to a DD, not too much collects. Maybe a teaspoon during the entire driving season. I doubt very much Ford made any changes to the Gen 2 calibration compared to the Gen 3. They are very different. Even the PCM is different. Spectre was the only intake most of used all through Gen 1's and Gen 2's. Only somewhat lately have there been other choices including the Treadstone Performance option. I suspect more than anything else that's what explains the difference.

[Railroad]

If your MAF tube has more length, you might pull some of the alum tube out of the silicone 90. This will add distance from the throttle body. I know I have read where Ford recommends a minimum length for the MAF sensor from the TB.
I am not confident that any of the advise so far is related to a rich condition. I am thinking something like fuel pressure, regulator, O2 sensors, unmetered air entering the system. Might even need to check the engine ground.

[Erik W. Treves]

what is the diameter of the MAF tube from treadstone?

[Alphamacaroon]

If your MAF tube has more length, you might pull some of the alum tube out of the silicone 90. This will add distance from the throttle body. I know I have read where Ford recommends a minimum length for the MAF sensor from the TB.
I am not confident that any of the advise so far is related to a rich condition. I am thinking something like fuel pressure, regulator, O2 sensors, unmetered air entering the system. Might even need to check the engine ground.

All good ideas to check.

1. Fuel pressure regulator is set to 55 PSI when the pump is charged but engine is not running. I think that was what I remember the Coyote install manual calling for. Can you confirm if that is correct?
2. The regulator reference port is connected to the engine vacuum. Is it possible there is a clog or kink in that? My guess (although I could be totally wrong) is that if there is an issue there, it would probably result in a too-lean? But maybe you can confirm.
3. O2 sensors. Both are installed and torqued to spec. I assume the PCM would throw an error if they were not connected properly? Maybe they are on the wrong sides? Orange wire one is connected to passenger side and gray wire one is connected to driver side.
4. Unmetered air. This is an interesting thought. I'm fairly certain the elbow is firmly attached to the throttle body, but there are those two breather connections... Can you see any issues with the way I have those hooked up?

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5. Engine ground. Any thoughts on how to objectively check that? The grounding strap is definitely there, and the starter itself uses the engine ground, right? So I can imagine if the engine ground was bad, that I'd also have starter issues? But maybe I'm wrong.

[Alphamacaroon]

BTW, I take that back on the Treadstone. I forgot I did not use the Treadstone— I ordered one but it was on backorder for so long that I ended up cancelling it. I ended up going with this: https://performancemrp.com/i-30497727-ford-mustang-2005-2018-mass-air-flow-housing-with-air-straightener.html?ref=category:1389188

Not sure if it really makes a difference, but thought I'd correct it.

[Erik W. Treves]

what is the diameter - this does make a difference! I am gonna guess 3.25 in which case you are PIG rich!!!

[Alphamacaroon]

what is the diameter - this does make a difference! I am gonna guess 3.25 in which case you are PIG rich!!!

Hahah. How about 3.5"... Does that make me disgustingly rich? :cool: I'm confused— are the Treadstone and Spectre tubes not 3.5"??? I'm pretty sure FFR told me to order the 3.5" Treadstone, and when that was backordered for months, I went with another 3.5" tube. Everything fit right out of the box.

Or maybe you're saying that a smaller diameter would cause a too-rich condition (i.e. smaller diameter = higher velocity = would look like more air entering the system)?

In other news:

1. I pulled out the MAF sensor and confirmed it is pointing in the right direction— hole is pointing forward.
2. Was able to rotate the MAF sensor to align with the long side of the arc. Will see what difference that makes when I take it for a drive here soon.

[edwardb]

I too would be curious what size tube you have at the MAF sensor. The Spectre one that was used almost universally for several years is a 4-inch tube at the MAF sensor with a 3.5-inch calibration tube. These kept the MAF calibration in a range that didn't throw codes. But as I mentioned along with others, ran a lot better with a custom calibration.

Edit: Answered while I was typing this. Both 3.5-inch. Shouldn't be an issue.

For your other questions.

1. That's correct.

2. I doubt very much that vacuum reference line is affecting anything. Most custom tuners (including Lund) will tell you not to use it. Leave the regulator open to atmosphere. And obviously plug the vacuum line on your engine plumbing. I've done a bunch of testing with and without the vacuum reference on both my Gen 2 and Gen 3 setups. Have yet to detect a difference. But I'm leaving it off per Lund's recommendation.

3. Agree the system would be throwing specific O2 sensor codes if something were going on there. Wouldn't detect if they were on the proper sides though. Trusting you on that one.

4. I'm assuming the connection you on the LH side in your picture is from the vent on the LH coil cover. That's the EGR circuit and is correct. What is the connection on the RH side? If that's the vacuum signal for the CMCV circuit that's incorrect. Ford did have a vent line to the intake on early Gen 2 Coyotes. But that was eliminated after the first year and the CMCV vacuum motors vent to atmosphere at the back of the engine. Many mistakenly connect the vacuum line to that spot. Unfortunately instructions don't cover it very well or are just wrong. This has been discussed a bunch with a lot of confusion. I won't add to it here but something you need to check. If plumbed incorrectly, my experience is the PCM will through codes specific to the CMCV system. Not rich codes like you're getting. But still something you want to get right.

5. I doubt grounds are what's causing any issues you're having. As long as you confirm what you have is solid.

[Alphamacaroon]

What is the connection on the RH side? If that's the vacuum signal for the CMCV circuit that's incorrect. Ford did have a vent line to the intake on early Gen 2 Coyotes. But that was eliminated after the first year and the CMCV vacuum motors vent to atmosphere at the back of the engine. Many mistakenly connect the vacuum line to that spot. Unfortunately instructions don't cover it very well or are just wrong. This has been discussed a bunch with a lot of confusion. I won't add to it here but something you need to check. If plumbed incorrectly, my experience is the PCM will through codes specific to the CMCV system. Not rich codes like you're getting. But still something you want to get right.

This is super interesting... I guess this is another case where I sort of had to guess. When the engine came to me, that line was there and not connected to anything. When I put the intake elbow on, there was a port there, and it was a perfect placement and perfect fit for the open line on the engine, so I just connected it :D Actually I take that back— I think it did mention that in the Coyote Fitment manual on page 59 "CMVV Vacuum hose". Is this saying that Mike Forte sold me an early Gen 2 Coyote last year??? Any pointers to threads with more details? Much appreciated!

[Erik W. Treves]

yeah - not so much - the MAF calibration for the ECU is based on I believe is 4+ inch tube - and yes the filter that comes with the kit isn't 4 inches - so you can do what you did but you will need a custom calibration.

"Flow Area: Keep the cross sectional area of the MAF sensor tube as close as possible to the cross sectional area of the original induction system"

"IMPORTANT NOTE: The calibration of the PCM you have received requires use of this air box/MAF sensor system exactly as
received. Any changes to the air inlet system will result in changes to how the air entering the engine is measured and will
require modification to the PCM's calibration. "

So by making the same MAF sensor sitting in now a smaller tube - the ECU "sees" more air coming across it based on a now mis-matched throttle position - so "more air" sampled = more fuel needed!! but the throttle plate is not really letting that much air in - but since the ECU is using the MAF to do its fuel trims you are getting about 20% too much fuel into the engine based on the MAF curve. This is why everybody need to get a "tune" when they go away from the "stock" setup - The FFR manual used to say to use the SPECTER MAF - it's kinda "Cheap'ish" looking but it had sleeves you can slide in there to make the calibration match stock (note: do not use this setup for boosted applications.... ask me how I know) -

So basically what is going on is that the MAF curve is set to stock but you have a mis-match size MAF tube - the ECU has attempted to make the correction and it is at its limit and you are still rich - so the computer is throwing the rich flag.

It should be lazy in response on throttle stab or if you try and romp on it when you drive it.

It's probably ok to idle it and show friends - but it will stink quite a bit - you will start to get fuel into the oil - which is bad :) . I would recommend getting a tune or changing the MAF to at least match the control pack diameter tube - but you will still need a tune for optimization. LUND can do it for you or any good dyno shop can as well... it really doesn't take that long to do.

for sure you can leave what have installed in there - you just need a tune.

[Alphamacaroon]

Erik— but I'm hearing people like Paul saying they were running just fine on the stock setup with the FFR recommended Spectre system (which is 3.5" right?). I guess I'm not seeing how my system is that much different from the stock setup. Are you saying others used a different MAF sensor?

Edit: Oh wait. Now I see— the Spectre does actually need to neck down to fit on the throttle body. So it's a 4"? So what it seems like FFR doesn't mention is that if you use the 3.5" Treadstone, then you really need a tune? Does that seem about right?

[edwardb]

This is super interesting... I guess this is another case where I sort of had to guess. When the engine came to me, that line was there and not connected to anything. When I put the intake elbow on, there was a port there, and it was a perfect placement and perfect fit for the open line on the engine, so I just connected it :D Actually I take that back— I think it did mention that in the Coyote Fitment manual on page 59 "CMVV Vacuum hose". Is this saying that Mike Forte sold me an early Gen 2 Coyote last year??? Any pointers to threads with more details? Much appreciated!

This is the thread that started a lot of the discussion. Everything you need to know is in the first post. Some of the follow-up posts really confuse the issue. But have at it. https://thefactoryfiveforum.com/showthread.php?22472-Important-Information-Regarding-2015-2016-Coyote-CMCV-Plumbing. The instructions that Factory Five provide for the CMCV connection are incorrect. I sent them a message but no response and no change. Unfortunate.


Erik— but I'm hearing people like Paul saying they were running just fine on the stock setup with the FFR recommended Spectre system (which is 3.5" right?). I guess I'm not seeing how my system is that much different from the stock setup. Are you saying others used a different MAF sensor?

The Spectre is 4-inches. But comes with a 3.5-inch reducer that's installed in the MAF sensor tube. That's what the FFR instructions showed and a whole bunch of us did for a long time. Mentioned it in my previous post. On the surface, what you have would seem to be similar and theoretically work about the same.

[Erik W. Treves]

the 3.5 inch outside diameter tube you have there - based on the site you listed is 3.25 inside diameter. Or did you get the 3.75 inch one? The flow straightener also changes the characteristics of the air - I recently did a test on my own car... presumably the screen would "help" give a more consistent air flow - well with my car all tuned.... all I did was place the straightener from Treadstone in the tube - and..... it ran like complete crap... fuel trims were all over the place. I guess i could have spent the afternoon retuning my car again - in the end I ripped it out and it is running pretty good :) I agree with Paul - that if you run the Specter tube it will "run" pretty good as long as you use the correct insert - what I am seeing here is that the tube you have isn't "exactly" what Paul was describing - so it isn't apples to apples... the MAF transfer curve has some "slop" in it - meaning that the ECU can trim to some inconsistencies - the old A9L computers using narrow bands could only tolerate like 5-10% max - the newer ECU's using wideband like in the Coyote can do upwards of 25%+ fuel trims (out of tune) -

if you have an inside diameter tube of 3.5 inches - then I would get rid of that air straightener or get a tune - would be my .02.

This all assumes that fuel pressure is set to 55 psi as stated above - the O2's are on the correct side and harness isn't swapped from left to right and no vacuum leaks - as paul referenced above.

[Alphamacaroon]

Okay, got it.

So to recap:

1. The Spectre tube reduces down to 3.5 ID (according to Paul's comments).
2. I have a 3.5" OD, which is 3.25" ID.
3. The 1/4" difference between the two is enough of a difference where the MAF sensor and computer combo can't compensate.

Is that about right?

My ECU programmer is coming next week, so I'll keep the car caged until then. Thanks all!

Now to look at the CMCV plumbing. I do remember looking at this a while ago, and was utterly and completely confused by it. So I guess it's time to roll up my sleeves...

[Erik W. Treves]

Sounds about right - let us know how it works out and what you find out with your tuner.

[Alphamacaroon]

Paul: sorry to bring up a subject that I'm sure you are completely sick and tired of discussing at this point. ;)

Your description at https://thefactoryfiveforum.com/showthread.php?27422-2017-Coyote-Vacuum-System&p=313458&viewfull=1#post313458 seemed much easier for me to follow. You say "Attach the PS hose to the front vacuum port rather than capping it as some FF instructions say. It's the port right behind the throttle body. I also attached this vacuum source to the vacuum reference port on the fuel regulator. But removed it later at the suggestion of my engine tuner. So you're not missing anything not having one."

Is this still the latest advice for newer Gen IIs? Mine was bought in 2017. If so, I have two ports behind the throttle body— one is capped off as per the instructions and one is being used for the regulator reference. Is it simply a matter of:

1. Disconnecting the PS hose from the intake elbow.
2. Capping the port on the intake elbow.
3. Connecting the PS to one of the ports behind the throttle body? If so, which one? Red or Blue?

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Will that fix my CMCV misconfiguration?

A perfectly fine answer might also be– "it's more complicated than that— go back and read my original post" :cool:. I'm just slightly confused because it seems like the Gen II in your original post is maybe different than my newer Gen II, but maybe I'm completely misunderstanding. Thanks again for all you do!

EDIT: Looking further down in that post, it would appear that the Blue option is the right one? Maybe another dumb question: if we're supposed to connect that PS side hose to a vacuum— wouldn't that port on the intake elbow technically be a vacuum source? Maybe that's why I'm not seeing any error codes.

[edwardb]

Paul: sorry to bring up a subject that I'm sure you are completely sick and tired of discussing at this point. ;)

Your description at https://thefactoryfiveforum.com/showthread.php?27422-2017-Coyote-Vacuum-System&p=313458&viewfull=1#post313458 seemed much easier for me to follow. You say "Attach the PS hose to the front vacuum port rather than capping it as some FF instructions say. It's the port right behind the throttle body. I also attached this vacuum source to the vacuum reference port on the fuel regulator. But removed it later at the suggestion of my engine tuner. So you're not missing anything not having one."

Is this still the latest advice for newer Gen IIs? Mine was bought in 2017. If so, I have two ports behind the throttle body— one is capped off as per the instructions and one is being used for the regulator reference. Is it simply a matter of:

1. Disconnecting the PS hose from the intake elbow.
2. Capping the port on the intake elbow.
3. Connecting the PS to one of the ports behind the throttle body? If so, which one? Red or Blue?

Will that fix my CMCV misconfiguration?

A perfectly fine answer might also be– "it's more complicated than that— go back and read my original post" :cool:. I'm just slightly confused because it seems like the Gen II in your original post is maybe different than my newer Gen II, but maybe I'm completely misunderstanding. Thanks again for all you do!

EDIT: Looking further down in that post, it would appear that the Blue option is the right one? Maybe another dumb question: if we're supposed to connect that PS side hose to a vacuum— wouldn't that port on the intake elbow technically be a vacuum source? Maybe that's why I'm not seeing any error codes.

I'm OK with discussing it. It's confusing and unfortunate the Factory Five instructions aren't correct and the Ford Performance instructions don't address it at all. Plus their own help line doesn't seem to understand it either. I agree the thread you found is easier to follow than the earlier one I linked to. Yes on cap the intake port you're using pictured on the RH side. That port is only needed on the early Gen 2's that vented the CMCV vacuum motors there. Later ones are vented directly to atmosphere at the back of the engine. Whatever vacuum there is on that connection isn't the same as the vacuum using one of the connections behind the throttle body. So no, that doesn't work. Been there done that. I got error codes with it plumbed that way. Can't say why you aren't. Maybe for whatever reason your setup hasn't commanded the CMCV circuit yet. That's when the error code is thrown when it's plumbed wrong, e.g. command sent and CMCV doesn't actuate. And yes, my Gen 2 was an early one. Got it right when they first came out. So mine did have the vent line to the intake. Based on your description, yours doesn't.

You want the blue connection in your pic plumbed to the fitting on the back of the manifold. The one the existing hose to your intake is attached to. In my origional link I explained how on my Gen 2 I ditched the Ford vacuum line and made up my own. Partly by accident and partly because I didn't have to try to use their connectors. If you're planning to stay with the vacuum reference signal to the fuel pressure regulator, then you need a "Y" in this vacuum line. Once you sort it out, you'll see it isn't that complicated. Just seems so at first.

[Alphamacaroon]

You want the blue connection in your pic plumbed to the fitting on the back of the manifold. The one the existing hose to your intake is attached to. In my origional link I explained how on my Gen 2 I ditched the Ford vacuum line and made up my own. Partly by accident and partly because I didn't have to try to use their connectors. If you're planning to stay with the vacuum reference signal to the fuel pressure regulator, then you need a "Y" in this vacuum line. Once you sort it out, you'll see it isn't that complicated. Just seems so at first.

Okay great, so here's how I'm understanding it now:

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I guess the part I don't understand now is— what happens with the line outlined in yellow? Does that get cut and capped off as well?

[Alphamacaroon]

Wait: re-reading again. I guess maybe I misunderstood again, and had it right the first time.

1. I'm going to disconnect the blue line I have running to my fuel regulator.
2. I'm going to disconnect the line outlined in yellow and cap the elbow.
3. I'm going to plug the yellow outlined line into the place I just disconnected the blue line from.
4. Optionally add a y connector for my fuel regulator.

Basically following this diagram:

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Is that right?

[edwardb]

Wait: re-reading again. I guess maybe I misunderstood again, and had it right the first time.

1. I'm going to disconnect the blue line I have running to my fuel regulator.
2. I'm going to disconnect the line outlined in yellow and cap the elbow.
3. I'm going to plug the yellow outlined line into the place I just disconnected the blue line from.
4. Optionally add a y connector for my fuel regulator.

Basically following this diagram:

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Is that right?

I'm not quite following your color codes and explanations. But the diagram you marked up is correct. That hose from the back of the manifold goes to your vacuum source at the throttle body. Just like you show. If you want vacuum reference to your regulator, you'll need a "T" off that hose. Then cap the unused connection on the intake. It's that simple.

[Alphamacaroon]

Okay makes sense. I'll give it a shot. I'm still not clear how that vacuum behind the throttle body is any different than the vacuum that is created in the intake elbow, but I'll take your word for it. Thanks!

[edwardb]

Okay makes sense. I'll give it a shot. I'm still not clear how that vacuum behind the throttle body is any different than the vacuum that is created in the intake elbow, but I'll take your word for it. Thanks!

Put a vacuum gauge on it if you like. They're different. And as I mentioned, I originally had my Gen 2 plumbed to the intake just like yours. Didn't work and threw codes. That started the investigation and string of posts.

[Snowman]

Okay makes sense. I'll give it a shot. I'm still not clear how that vacuum behind the throttle body is any different than the vacuum that is created in the intake elbow, but I'll take your word for it. Thanks!

The throttle plate in the throttle body is the what makes the difference. It creates a massive restriction to airflow while closed (idle), thus as the pistons are drawing air in on the intake stroke they create low pressure on the downstream side of the throttle body, which we read as vacuum. Where as your air filter and intake plumbing upstream of that should definitely not be creating nearly that much of a restriction. In the case of the CMCV actuators the amount of vacuum produced upstream of the throttle body is negligible and I'm sure is not enough to move them. I would hazard a guess that is why Paul experienced codes being thrown with CMCV connected to what is essentially a non-vacuum source.

Interestingly enough (or not if the subject bores you:rolleyes:) this is why most modern turbo-diesel engines do not have a "normal" vacuum source. They have no throttle bodies. Many diesel powered vehicles have hydro-boost brakes for that reason. If for some reason the vehicle does have a demand for a vacuum source then you'll find a dedicated vacuum pump, typically engine driven or electric. I believe some of the Ford Diesels had an electric vacuum pump. I have a small diesel Chevy Cruze with vacuum boosted brakes and it has a dedicated engine driven vacuum pump.

Apologies if this is boring, not trying to hijack the thread. I just enjoy the physics and science behind it all.

Cheers,
Patrick

[edwardb]

...I would hazard a guess that is why Paul experienced codes being thrown with CMCV connected to what is essentially a non-vacuum source...

No guesses. That's exactly what I experienced (along with a number of others) and have been trying to explain.

[Alphamacaroon]

Snowman: not hijacking the thread at all! I always like to understand why something happens, and it makes sense now. I guess for some reason I thought the CMCV needed vacuum at open throttle (meaning the difference between the two was less), but I guess I'm understanding now that the CMCV requires vacuum power at idle to activate, rather than vacuum power at open throttle to de-activate (assuming it's not bi-stable).

Paul: how does this look now? I'll clean it up a bit before I'm done, but just wanted to make sure it was plumbed correctly first. Put a T there in case I want to end up connecting the vacuum line to the regulator, but I think you ended up not connecting it (on your Gen II), and keeping it that way, right?

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[edwardb]

Snowman: not hijacking the thread at all! I always like to understand why something happens, and it makes sense now. I guess for some reason I thought the CMCV needed vacuum when the throttle body was more open (meaning the difference between the two was less), but I guess I'm understanding now that the CMCV actually needs vacuum to activate when at idle?

Paul: how does this look now? I'll clean it up a bit before I'm done, but just wanted to make sure it was plumbed correctly first. Put a T there in case I want to end up connecting the vacuum line to the regulator, but I think you ended up not connecting it (on your Gen II), and keeping it that way, right?

Should work. Right, I settled on both my Gen 2 and Gen 3 running the regulator without the vacuum reference signal. But I have the line there in case something changes.

Final comment on vacuum source. Keep in mind that vacuum line is charging the reservoir in the intake shown on the diagram in post #29. It's not directly attached to the CMCV actuators. So whatever variation there is in vacuum isn't seen by the CMCV system as long as the reservoir is kept at the minimum operating level. For anybody following along, FYI the Gen 3 requires the same approach. Slightly simpler though because the reservoir connection is on the front of the intake vs. the back.

[Alphamacaroon]

Excellent! Thanks again for all the help. Working with the tuner now and we'll see if we can get these MAF issues ironed out.

[Snowman]

Snowman: not hijacking the thread at all! I always like to understand why something happens, and it makes sense now. I guess for some reason I thought the CMCV needed vacuum at open throttle (meaning the difference between the two was less), but I guess I'm understanding now that the CMCV requires vacuum power at idle to activate, rather than vacuum power at open throttle to de-activate (assuming it's not bi-stable).

Not that I'm trying to take a mile with an inch given..."vacuum power at open throttle" is kindof not a thing. Aside from unavoidable restrictions in the intake tract, when at wide open throttle (WOT) there should be little to no vacuum on a naturally aspirated engine. Vacuum is really just a measure of intake manifold pressure. So at WOT this pressure should be very close to atmospheric pressure, again with minor variations due to intake tract restrictions and air velocities through said intake tract. There is an entire industry dedicated to reducing these variations/restrictions (every cold air intake manufacturer out there).

To provide a real world example let's look at aircraft piston engines (carbureted in this example, they are the most prevalent even today). In flight they are operated at power levels that fall closer to WOT than idle. What this means is that they produce little to no vacuum in the intake manifold for the large majority of engine operations. There are a number of aircraft instruments (on analog style systems, which still make up the majority) that require vacuum to operate. These are things like turn coordinators, artificial horizons and horizontal situation indicators, all of which require a gyro that is spun using vacuum. To provide that vacuum most piston engine aircraft have not one, but two vacuum pumps installed in the accessory drive on the back of the engine.

For the times that carbureted aircraft engines DO produce vacuum they have a special feature to deal with one of the down sides of lower intake manifold pressures. This is carb heat, which routes air heated by baffles over the muffler into the carb for the purpose of preventing carburetor ice. Lower pressures cause temperatures to lower which can cause ice to form in the carb...this is bad since that causes a restriction in air flow. Believe it or not carb ice is not a winter phenomenon, it happens more in humid climates and can happen in the middle of the summer heat when the air is close to saturation with moisture. Temp, pressure and moisture...it's all just physics.

OK, I promise not to post any more about vacuum :o

Cheers,
Patrick

[Alphamacaroon]

No keep posting! It's an interesting discussion, and I'm always excited to learn something new!

My line of reasoning was that an air intake is one giant vacuum for all intents and purposes. And as a vacuum, it's going to try to suck air from any hole with a pressure differential (whether it be the air filter, or the tube on the side of the elbow). And if we take that to the extreme: if my air filter was the size of a thimble (or completely clogged), then I'd most certainly measure high vacuum on the port in the elbow, right? And I would certainly measure higher vacuum rate at WOT vs. idle, right?

But I gather what you are saying is that the intake and filter should be able to supply more than enough airflow to the engine at anything between idle and WOT because there is very little restriction, and as such, very little vacuum generated in the intake tube. Is that right?

I guess I just assumed that there was more restriction to the intake system than there is in reality. But like you say, there is an entire industry dedicated to making sure there is as little restriction as possible. So that makes sense now (assuming I'm not mischaracterizing what you are saying).

But it does beg the question: maybe this is precisely why there is a difference between what Edwardb experienced with his CMCV codes and what I'm seeing (no codes)? I think we both agree that there is some amount of restriction in any intake system (even if it is very small), and if there is any amount of restriction, then there has to be at least a small amount of vacuum generated.

If I'm understanding EdwardB correctly in his description of how the CMCV works, it charges a reservoir, so even a small amount of vacuum would eventually charge the reservoir enough to do the work required— just at a slower rate. Maybe that 1/4" difference in diameter between his intake and my intake is enough of a difference in restriction to make a difference? Maybe mine, with the smaller intake tube, charges at a slightly faster rate and is working by the time the computer decides to complain? I've driven it almost 80 miles now at various speeds and RPMs, so I can't imagine it hasn't tried to activate the CMCV yet.

I still think it was a good idea to plumb it the right way (no argument there because it might have been on the precipice of failure), but I'm always curious to understand the root cause of a discrepancy like this.

[Snowman]

Two your first two points, correct on both. If you had an extremely restrictive intake tract (to the point of being nearly, if not the same, as the restriction created by the closed throttle plate) then yes, a higher engine RPM would create a larger vacuum. Since we try for very free flowing filters, tubing, etc. what we actually experience is a decrease in vacuum. This video explains it and you can see it on the vacuum gauge he installed: https://www.youtube.com/watch?v=RVDK9jyq6UE

This is where my specific Coyote experience/knowledge completely drops off, lol. I do severely doubt that the 1/4" difference in MAF tube size will create any noticeable vacuum differences. The only thing I could speculate is that your too rich trouble codes are either preventing or masking the codes induced by CMCV plumbing like what Edwardb experienced. I'm afraid I lost the bubble on your initial problem, do you still have the too rich condition and codes or has that been resolved?

As far as having a small amount of vacuum "charging the reservoir"...first we need to talk about what vacuum really is. Which is to say it is a measure of pressure and in terms of automotive engines this is normally expressed in inches of mercury. Atmospheric pressure on a standard day (59 F) at sea level is 29.92 inches of mercury, you may recognize this number if you study or pay close attention to weather. So if we assume that the current atmospheric pressure wherever we're at is 30 inHg (easier for the sake of discussion) that means no matter how efficient, what RPM, or what amount of restriction your engine has, the greatest vacuum it can produce is 30 inHg. Once you hit total vacuum, that's it, the same pressure that is effectively what is in outer space. Atmospheric pressure is created by the weight of the mass of air that sits on top of us. Weight being a measure of the force gravity applied to the mass of air. This is why when you go up in altitude the atmospheric pressure decreases and why when we fly on airlines at 30K + feet that the cabin must be pressurized for us to have dense enough air to breath.

OK, that was really long winded and hopefully I didn't lose or confuse you. Back to vacuum...

A vacuum gauge that's installed on an engine is referenced to atmospheric pressure so that when the engine is off the gauge always reads zero not atmospheric pressure (those devices are called barometers :)) This is a good thing since it always shows the difference between whatever our current atmospheric pressure is and what the engine is doing. So if you connect the vacuum reservoir to the port upstream of the throttle plate and instal a vacuum gauge on that you'll find that whatever that maximum vacuum level is on the gauge, this will be the maximum vacuum pressure the reservoir can achieve. This is because pressure is just normalizing between the reservoir and what ever vacuum source it is connecting to. For sake of argument if the port in front of the throttle plate maxes out at 5 inHg (this would be a very restrictive/clogged filter) then that is as high at it gets. If the CMCV valves require a minimum of 10 inHg then they will never move no matter how long they are exposed to 5 inHg. If they only require 4 inHg then they would move, but probably slowly since there isn't much pressure differential there to create a lot of air movement, but they would move eventually.

Again, as far as codes go, I have no idea why you are having different experiences than what Edwardb had. I know the physics, but not the math Ford programmed into their computer.

I have certainly enjoyed the discussion, made me dig back through some of my old notes :D