Help engine missing

[Just puttering]

The engine is in the car but is not running correctly.

Its a 347 efi with msd digital 6 plus ignition.

The engine is sputtering and cutting out. It wants to die when you push the clutch to come to a stop. I notice when barely on the throttle it runs the best. When limping home in 5th at 40 to 50 mph? It does not sputter (much) but is not running correctly either.

When rolling down the road if i push in the clutch and rev it a little then engage the clutch it will accelerate for a moment then back to sputtering.

The car a been driven very little for the last four months, so i thought bad gas and added fuel from 1/4 to 3/4 of a tank. I cant say it helped, i drove it about 15 miles after adding fuel. Four months ago it ran good but still wanted to die when stopping.

My first thought is low fuel pressure?

Anybody have any thoughts or experience with these kind of symptoms?

[Gordon Levy]

Check the timing and fuel pressure

[GoDadGo]

We all know that we need fuel and fire, so as Gordon suggested check the timing and fuel pressure since this puppy is already running.

1. Can you hear if the engine is missing or is she popping on all 8 cylinders?
2. What is your idle RPM set and what is your initial timing set at?
3. In addition, is the engine carburated or injected?

Good Luck!

Steve

[frankb]

Agree with Gordon above. After checking those two, if the problem persists, check your TPS and MAP sensor. The MAP is non adjustable, so a failure here means replacement. The TPS is adjustable and should be reset any time you fiddle with the throttle idle stop screw.

Frank B

[Just puttering]

I have to work today so may take some time to check,

It seems to be "popping" on both sides all cylinders when starting from a stop as the rpms come up, poping no power at all, i shift down to keep the rpms down, only way to go.

When at this stage and driving it seems to cut out every so often just for a split second

It has efi and a complete msd ignition75324

[bobl]

Knowing the history of MSD ignitions, that would be high on my list of suspects. But, check all the obvious first.

[first time builder]

Also has Vortec supercharger. My vote is bad MSD box they suck. If you dont need the fancy MSD box the new MSD streetfire is real good.

[Just puttering]

Msd came with the car, i have no preference besides a car that runs !!!

If you could elaborate, msd sucks (i have read some things online stating the same), but then you say another msd box is a good choice? Is it just the digital6 plus that sucks?

[Gordon Levy]

MSD Boxes work or they don't. I vote for fuel delivery or timing

[Just puttering]

This is what i found.

The fuel pressure is bouncing from 30 to 40 psi. I turned it up to see if it would help, about 40 to 50. No change but what should it be and how much bouncing is normal???

Moved the distributor to see if there is any change, i thought it was better but actually no change.

Look at the picture above, the sensor on the top of the throtle body with the orange wire i assume is the throttle position sensor. I moved it and the idle came up the sputtering went away and it would rev just fine. As i continued to try to adjust it the rough idle and sputtering and killing it returned. So after moving it back, i drove down the road a little ran fairly well, maybe a well as it will ( dont know how much cam it has?). I hit the gas and it reved like a ..... I let off because i started going sideways. I think as the throttle opens it is moving the sensor or the sensor is breaking because after that it started sputtering again.

I came back and parked it. Will play with it more maybe tomorrow.

If i need a new sensor, how would i find the part? How would you look it up?

[Gordon Levy]

A new censor for a 1990 5.0 Mustang is what to ask for. It should be set at .97 to .99 volts.

[Just puttering]

Ok, just in case i put a new tps on it, if i set it to 1.11 or so it idles better. It tends to rev ok ,not under a load, just real quick tap of the throttle. When under a load still sputtering, and not as bad in a high gear and low rpms.

I forgot the msd is flashing slowly. Maybe 1 per sec. I need to read up on that error code. It wasnt doing that the other day!

Also reading up on testing the map sensor

What fuel pressure is typical?

[Gordon Levy]

Fuel pressure should be 41psi with the vacuum disconnected. If you rap the throttle and the fuel pressure drops you have a delivery problem.

[Just puttering]

Also has pro billet 8456 distributor which has a stock style pickup, the green wire is cut and using the white wire to the distributor, so i think wireing is ok.

[Just puttering]

I will check the fuel pressure, the other day it jumps about 10 psi maybe once or twice a second. Say going from 35 to 45 psi. I did not notice a drop when reving the engine. Also did not disconect the vacuum maybe that is why the bouncing?

[Gordon Levy]

inconsistent vacuum from a big loapy can can make it bounce.

[Just puttering]

i have not seen the computer yet but the build thread says its a megasqirt 2, dont know the cam specifics but says its a solid roller.... So i dont know how well it will idle.

[Just puttering]

How is it that the weekend you want run somewhere with the group, your car decides it really wants to stay home!!!

[Just puttering]

Boy how time flys. I have not had time to work on the car, but dont have to work tomorrow.

I can not find a MAP sensor and dont think it has a MAF, the part on the front side of throttle body is for low idle? ( cant find where i read that).

I will look in the AM. I picked up an MSD 6al if all else fails im putting it on!
It has a stock ECU

[Just puttering]

Was just reading it should be a MAF!
Ecu is an A9L.
My pad sent the last before i was done typing

[TexasAviator]

My fox, had an a9l on a 345hp 302. Before I parted the car out, I shorted the computer trying to sort out an electrical problem. My car ran as you described. I scrapped the whole system and bought a race prepped block and built a 347. Point is... the a9l was hundreds of dollars and hard to find. I chunked it and went with Fitech for my cobra.

[Just puttering]

The previous owner used the spaghetti wiring technique, i have one ground wire by the steering column that i can not find what it plugged into! It has a painless harness, i am going to have to clean up all the wiring, i enjoy wiring, so its ok just a pain when you want to be out driving not fixing!

[seagull81]

You said the build info. said you had a Megasquirt 2. If so, you don't have a A9L stock computer. My stock A9L couldn't figure out my 347 with a big cam so I am using a Megasquit2. MS2 has lots of helpful info. on tuning if that is what you have. You will need the software and a laptop to do it. You need to find the computer to be sure what you are dealing with. Can you call the prior owner and talk to him?

[cgundermann]

As Levy stated, your fuel pressure bouncing up/down 10 PSI means you have vacuum issues. Also, most high end distributors come with shutter wheels that are out of spec and bad HALS effect sensors. My new one did; the Ford OEM HALS effect sensor is the best and Pro-M racing sells an exact-spec shutter wheel. Replacing those and resetting my TPS cleared up my similar issues...

Chris

[Just puttering]

The old build thread said MS2 but looking under the dash it is A9L. If it had a MS2, somone wanted to keep it and put in the A9L.
The builder is gone. No way to contact them.

[Boydster]

Whole thing sounds like a vac leak.

[Just puttering]

I have not found a vac leak yet! Any suggestions on carb cleaner or something to hunt leaks?
I found the maf sensor, under the pass fender before the blower.
Read online maf sensor testing, car runs almost the same with it unplugged. The article says that is an indication of a bad maf. Any suggestions on testing it? I dont have a meter with a frequency setting. The signal voltage jumps all over the place from idle to reving. I know this is not the correct way to test but have no other option at this time.

The tps sensor seems like if i could turn it a little further it would run better. I have it cranked all the way clockwise with no more adjustment.

[TexasAviator]

Turning the tps over a volt does nothing. The computer can only read that sensor in a very narrow band. Messing with the tps sensor is doing nothing for you.

[Just puttering]

http://youtu.be/xe1d4D-BqMc

I tried to make a small clip of the fuel pressure guage. First YouTube attempt.

[Itchief]

Just a thought have you considered changing the fuel filter/filters

Rick

[Just puttering]

Havent got to the point of thinking filters but will put it on the list.

[GFX2043mtu]

Not knowing the cars exact history and parts list I second puttering, when having miss firing and bogging issues first make sure the maintenance items are good, distributer cap, rotor, plugs, wires, and fuel filter. All of which can cause misfires and or bogging issues as you have described. Then I would check the TPS for correct closed and open voltages and correct as nessassay. Fuel pressures under load should also be stable. After those checks get some carb cleaner and spray it around the intake and vaccum lines and listen for the engine to idle up. If these don’t locate or fix it he issue then do a leak down check to make sure the motor cylinders and valve train are good as it’s a quick check. You also mention the wiring mess, that would be the next item as messy wiring that is not done correctly soldered, heat shrunk or OEM crimp connectors and harnessed for abrasion resistance. Shorted or broken wires due to poor instillation cause major headaches when they have issues. If all else fails the tune should be checked as a bad tune can put holes in pistons, burn valves and wipe bearings and cause the problem you describe. Also the tuner will quickly know if it’s a bad ecu issue.

[Itchief]

After watching your video I have a question

What happens to your fuel pressure when you shut off the motor

Does it stay at about 40psi or quickly drop to zero

If it drops to zero I would check the pressure regulator and then the pump

Rick

[Just puttering]

I started the car, looked at the pressure gauge, reached around the pass side to turn off the car and by the time I looked back at the gauge, it was at 0. I think the pressure reg may be bad.

I did not have time to do any other checking, so I do not know if this will fix it but thank you all for your help so far and I apologize for not thinking about what the pressure did when shut off before Itchief pointed it out (thank you). Forest for the trees, forest for the trees!

[Itchief]

No problem hope it helps solve your problem

Rick

[CraigS]

On the stock efi there is a vacuum tree under the upper intake. Hard to see but is a junction for 3-4 vac hoses and is a common problem since it is out of sight.

[Just puttering]

I am attaching a video of the car revving for the next post.
https://youtu.be/lvW-646KpVw

[Just puttering]

Ok, I have been putting off working on this problem - but can wait no longer.....

I uncovered the car checked the compression - all cylinders are 140 to 145. put new plugs in and fixed the error code on the 6AL Plus MSD box (put in a new one!)
I cleaned the MAF sensor - Last time the car ran the same with it unplugged or plugged in - I will check again tomorrow, i read that this probably means a bad sensor.
I dont think the idle control valve should be part of the issue.

So at this point I think the megasquirt got pulled out and the a9l put in its place. so I may need to upgrade computers - any suggestions on type and program???

The TPS is new but no difference from the old but when I set it to .97 volts and start the car when I start to move the throttle the rpms drop like its going to stall. or has a dead spot. then at higher throttle it comes back but has a miss to it or a sputter

With the TPS moved to 1.38 volts it runs much better, still not correct but a lot less missing and sputtering. Maybe the a9l is at fault - It probably has bigger injectors and the A9L is set for the smaller ones so the tps turned up makes the computer think more air is flowing .... no I think that is backwards. I am telling the computer there is more air flow than there is when the tps is set higher?

So after all this rambling, comes the questions -
How can I check the size of the injectors??
Does the MAF sensor probably need replaced?
What about cleaning the injectors?
Any good links on pulling the a9l program to see how it is set up?
Any ideas on finding a tuner in my area?

I will put a link up on the car revving (easier to do it from the ipad)

[Joee]

The A9L can run with bigger injectors as long as the MAF is matched to injectors. I see concern in 2 things 1 if the car runs same wit or without maf connected that needs further investigation. Once my maf connection came loose car ran but no mid to top end. 2 if it was a megasquirt setup then it could have a mismatched maf inj combo bc that can be tuned in mega squirt but a9l must have a maf that is tuned for the injector size. If they are Ford oem then what color are they? Should be green, 42lb, for boost or at least red 30lb.

[Just puttering]

They are black

90mm 1l3f-12b579-ab Maf ford number on part

[Joee]

That is prob the 90mm Lightening could be calibrated for 42lb inj. Go here and scroll down to 3rd post great pic of different injectors. Not sure on black ones I only used Ford.
https://www.stangnet.com/mustang-forums/threads/24lb-injectors-tfs-manifold-fitment-issues.854773/

Did the motor run well when you got it?

[Just puttering]

The last time i drove it when it was out of state was in june. It ran fine but might stall on you when you come to a stop. Then it sat for 4 months before i had it brought up to me. The car hauler was a jerk i hope that has nothing to do with this. The car would not run right from the moment he was driving it off the truck. So i can not say exatly when and how it started doing this.

The maf sensor disconnected makes it run worse if you can tell the difference.
It may run better when cold than when wormed up.
At 12 to 1500 rpms the sputtering is mild give it a little more throttle and it seems to jump to 5 to 6000 and a loss of traction
The tps is set to 1.11 volts, it runs better set higher.
At this point it may be throw more parts at it and hope for some change?

[Just puttering]

81210 picture of one of the injectors i will try to look for numbers later

[Just puttering]

Not that it may mean much but it smells like it runs rich.

[Joee]

Was the megasquirt controling in it when you drove it months ago? Your comment that it runs better cold also points to an ECM problem. When engine cold it runs in closed loop, not much ECM feedback.

Before you start throwing money at this can you get it to a good tuner? Perhapse this can all be fixed with a chip being burnt for your setup. It may also reveal what is not right in the system.

[Just puttering]

I will try to find a tuner in my area

[Joee]

I will try to find a tuner in my area

Good do some research you want/need a Foxbody raceshop your motor is up there in performance. You may want to become a member on some of the Mustang sites to find the right tuner. https://mustangforums.com/forum/5-0l-1979-1995-mustang/194578-understanding-and-tuning-your-ford-efi-system-sticky.html

Most guys shy away from a chip because it limits future performance up grades, in your case that should be a non issue. A blown 347 with solid lifters and hot cam should be all the hp and torque you need for quite some time.

[Big Blocker]

Quote: " i had it brought up to me. The car hauler was a jerk i hope that has nothing to do with this. The car would not run right from the moment he was driving it off the truck."

FWIW, My son sold his Mustang to a guy in another state. The car hauler (or his employees) liked the idea of a race car to play with and must have (no proof) romped the hell out of it before it was run up on the truck for out-of-state delivery. Never turned on the electric fans for cooling. When the new owner got the car the engine had been over heated and the crank frozen, would not turn over. Car was in perfect condition when it was dropped off at the car haulers site, we drove it there with witnesses. Hauler said they don't start the cars except to drive them on the trailer. New owner took pictures of everything on the car and we stated that the car must have been "abused" by the hauler and he should take it up with them for any claims.

Not saying that your choice of haulers did what happened to me but if the car was running perfect before you dropped it off . . . just sayin'

The stalling when slowing down or stopping might be related to the VSS sensor at the transmission not sending signals to the A9L, letting it know you are slowing down - that is an issue for some other [EFI powered] builders but not 100% of the time.
Any time you adjust the idle screw on your throttle body, you need to reset the TPS sensor so the A9L knows where idle is. Anything over 1.0 volts makes the A9L think you have your foot into the pedal and are accelerating.
"Normal" injectors for a blown engine are; 30 to 42 pounds - not sure what Black ones are rated at.
You need to start from square one by setting timing, idle and then go from there.

Doc

[Just puttering]

Joee, thanks for the info . You are right about the motor ... IF and may I restate IF I need more engine in this car ... No thats wrong, I never will, from what I've noticed so far my biggest problem is traction and the ability at that point to stay pointing straight ahead!!! This car has a very lively top end!

Doc, the car got picked up from infront of a relatives house with pictures of it being loaded and I have pictures and movies of it being unloaded! The story of the transport here was going to be a long post on this forum naming the enclosed covered professional car moving company. I have calmed down abit and have not told that story .... Yet.

I agree with the tps, but at this point it runs better with the voltage set up around 1.11 (as far as it will go that way) not at the .90 or so that is recommended.
I agree with square one, but after I set what I can I get to the tps adjustment before buying more parts to try!
I have been reading about o2 sensors and am going to try to check them next. This is part of a post that I will not try to put on here with this pads screen keyboard! I will add it when I get back from town.

[Joee]

Check your vss on transmission as doc mentioned I kept forgetting to suggest that earlier. You will be chasing your tail if you run it at 1.11 tps. The A9L must see .95 to .98v as base idle. Also the timing must be right on then you need to follow the proper method to set idle. From there the A9L should take over. If it won't run with the proper base setup its not going to run right. Since you seem new, we all were, that is why I suggest a tuner because they will hook your car to a computer which will show the readings of all sensors simultaneously. FWIW I spent about 3 years doing what you are about to do even went as far as obtaining a twEECer to no avail. I had a 6 psi blower, cam, 42lb in etc running through donor harness. Myself and another AutoX competitor threw in the towel on the systems and went with carb setup. The alternative at that time was to get a whole new efi system , prior to carb like efi, for like $2k. A new modern efi may also solve all of your problems.

[Big Blocker]

It runs better at 1.11 because the A9L is adding fuel because it thinks you have your foot on the go pedal . . . as stated above, it needs to be below .99 (recommended is .95 to .97) to idle correctly.
Not knowing your cam specs, I'd try to get it to idle about 900 - 1000 rpm (with the throttle plate screw) to start. Once you get it to that range, re-adjust the TPS to .95 and the A9L should be able to maintain that rpm.
Check advance and adjust as necessary. if the idle falls off, reset to 900-1000 and re-adjust the TPS again. It's a process but you should be able to get it to idle smoothly with the basic settings.

Just as a thought, you might want to remove the SC belt and try to get it running without boost. Get it running smooth and then re-install the belt. It should run without the SC spinning.

Doc

[Just puttering]

Thanks guys for the ideas, it looks like it may be this weekend before I can work on it. I will post what i find.