MegaSquirt PNP on EFI 302

[bwwooster]

I'm pretty sure my EEC-IV controlled 302 is running rich and I'd like to do some adjusting with the engine management. Nope, I don't have a wideband O2 sensor in the exhaust, but dang! there's a lot of black stuff at the ends of the sidepipes! Also, the thing tries to gas me into a stupor in slow traffic.

Anyway... I did a search of the EEC-IV tuning aids and since the Moates Quarterhorse requires modification of the existing ECU, and the Tweecer needs a $150 software load, it's not that much of a stretch to go to MegaSquirt's 'Plug-and-Play" ECU for the '87-93 Mustangs.

Has anyone used this unit? How'd it go?

I've got the 340hp SVO crate engine with the E cam, GT40 heads, Cobra intake, 65mm TB and 30# injectors.

Thanks!

[frankeeski]

This is the system I am going for, if the unit is anywhere near as good as the customer service I have received so far I should be very happy. They have spent considerable time with me so far and I haven't even made the purchase yet. Go to the owners manual PDF on the bottom of the page and read it. This system uses plain old english tuning your car, you don't need to be able to write code just to tune your setup. Also go on some of the Mustang forums and check out how many tune with this and the good reviews it gets.
http://www.andersonfordmotorsport.com/efi-systems-series-4-pms-fits-89-93-5-0l-mustang/
Unless something has changed, the Megasquirt system is anything but plug & play

[skullandbones]

I've been looking at systems to further tune my EEC-IV 92 model for months. Doesn't seem to be any easy or quick fix for this process. BTW, what are you running: MAF or speed density? I was wondering why your system is running rich. Also, I agree with frankeeski, I don't think there is any such thing as plug and play with MS. It does look like a piggy back ECU but I haven't seen this one yet. It looks like it plugs into the existing PCM without surgery and allows you to use the systems tuning screen in real time. That could be pretty cool. That's going to be a challenge to find enough space for another computer and associated wiring though. The reason I chimed in is that your engine setup is very close to mine and I would like to see you find a good solution. I could piggy back on your success! Curious about how your system is reading A/F. If MAF what sensor are you running with the 30# injectors?

Thanks, WEK.

[Bob Cowan]

The PNY system is plug and play. There's no other electric or hardware mods needed. It simply plugs in to the stock harness. Unless you're good with building electronics, let them build it for you.

Tuning is pretty simple. Between Tuner Studio and MegaLogViewer, you can get it 90% dialed in fairly easy on your own.

BUT... you need to start by getting a wide band sensor like LM-1 before doing anything else. If you don't know what your mixture is, there's no way to adjust the tuning. Right now you're just guessing. If it is running rich, you need to figure out why. It could be something simple like a failed water temp sensor. If it all checks out well, but you need to adjust the main fuel maps, then you can consider other tuning options.

[seagull81]

You can turn on the fly as well. Either with the built in tuner or make a change and burn while you drive. You don't have to stop and turn the engine off to make an update.

[Mike N]

Been there done that. Sorry to link to the other forum but here is my summary of what I did. http://www.ffcars.com/forums/65-fuel-injection-pit-road/301093-megasquirt-pnp-option-pimp.html I am still very happy with the swap I did and would do it again no question.

[bwwooster]

It's MAF-- can the wide band O2 sensors simply replace the existing HEGOs? Will the system work with those units plugged into the harness in place of the original units?

MegaSquirt's at the top of my list 'cos a couple of friends in the local Lotus club are using it to good effect on Duratec transplants, but that's not the P-n-P unit. I've also got a couple of "next project car" ideas which that system would make possible.

What I'd really like to use it on is my '84 Alfa GTV6, which apparently uses some sort of pre-Motronic version of L-Jetronic, and oh, Alfa never made a wiring diagram for that car, no kidding! I'd have to figure out a way to get it CA smog-legal. Hmmm.

I should probably ask diyautotune, eh?

[skullandbones]

bwwooster,

Is your MAF sensor calibrated to the 30# injectors? It looks like you have a mixture of parts so it's not bone stock. I think yours came with 19# injectors. With your setup, 24# injectors are a better fit according to Ford Racing calculators. If you are using the stock MAF sensor it will not function correctly with 24 or 30 # injectors. I have a graph that shows how the recalibrated MAF sensors "fool" the computer but sending adjusted voltage readings to match the original stock injector readings. The net result is you get a correct A/F ratio for the larger injectors. I will post that when I find it. If you have already matched those components, I apologize but it really sounds like that's the problem with the symptoms you describe.

WEK.

[bwwooster]

I'd been wondering about that-- the stock 5.0 ran 19# injectors and it was recommended to me that with an engine capable of making 50% more oomph that even the 24# injectors might not be enough if I was planning on making passes or laps at Sears Point, etc., and running lean under extended load is not a good thing. I've been figuring that the signals from the HEGOs should cut the injectors back, but is there a limit to how little they'll flow?

[CraigS]

Yes there is a limit to how little the system will flow. Not necessarily the injectors themselves but in the O2 sensing system. In more current systems they started to use a long term adjustment as well as the standard short term adjustment. The O2 sensors have a limited range where they work properly (they are narrow band) so if the mix is off by too much they don't work properly. The idea of the long term adjustment is that, if the ecu sees the O2 signal is always at one end of it's range, it will throw in a semi permanent adjustment to get the O2s back into their proper range. I am not sure if the A9L has this long term adjustment or not but there is also a limit as to how large this long term adjustment can be. Therefore something like oversized injectors can definitely put the system beyond it's capability to correct. On current cars we look at the long term reading as a troubleshooting tool. Anything over 10% tells us there is something wrong somewhere that the system is covering up. Usually it is under 5%.

[Mike N]

I'd been wondering about that-- the stock 5.0 ran 19# injectors and it was recommended to me that with an engine capable of making 50% more oomph that even the 24# injectors might not be enough if I was planning on making passes or laps at Sears Point, etc., and running lean under extended load is not a good thing. I've been figuring that the signals from the HEGOs should cut the injectors back, but is there a limit to how little they'll flow?

I have had 19, 24, 30 and now 42 lb injectors in mine and I can't say that I noticed any real difference in low throttle opening response or drivability between them. Now we are talking about the FFR here so in a more civilized ride you may pick up some nuances but nothing dramatic. I also had numerous MAF's on the car before going to MS2 and there was a real difference between the MAF's. I wouldn't run the 19's in your car on track you will be running much too lean and will hurt parts.

[bwwooster]

Mike-- MS2 does bank injection, not sequential, right? Has that been a problem. One of my goals is to improve low-rpm tractability. The thing does not like small throttle openings and doesn't like load below 2000 rpm.

[Mike N]

My car drives much better now with the bank fire MS2 than it ever did with the sequential EECIV / TwEECer and Pro M Univer meter on the same engine. The WOT performance is pretty much the same if you look at 1/4 mile times but the part throttle drivability is way better. It did take a while for me to get a timing / A/F ratio calibration to give a nice low rpm idle but that is mainly because I wanted to eliminate the IAC.