3.2 needs to try out new ECU please Atlanta area

[Classic11]

Hello all,
I have a 84 3.2 that received pretty much all new parts when it comes to ignition engine and fuel supply. It has good power but not always richens up the mixture on WOT, most of the time is stays above 13, its one out of 10 where it goes well in the 12's and yes you can feel it when it does. It also does not like to idle as smooth as i want it to be, i just replaced the ICV with a new one and it made it much worse. I am out of ideas. Just replaced fuel pump and checked fuel pressure, looks like its in spec also. My last resort now is the ECU and before i spend big money on rebuilding mine, that could be good I would like to see if there is a nice person in the north Atlanta area that could let me try out a confirmed good one? I am willing to pay a fee, or pay in beers.

Thanks in advance!

[76FJ55]

Have you checked to make sure the throttle valve stitch mounted on the throttle body is working correctly? you should have continuity through the idle switch with the throttle closed and contact through the full throttle switch above about 80% throttle. there should be no continuity above idle and below ~80%.

[Classic11]

Thanks for the feedback. Yes I checked both switches. Only possibility would be that the WOT switch is working sometimes and sometimes it's not. Ich am confident I have no vacuum leaks or anything. Fuel pressure regulator holds pressure and moves up when vacuum hose disconnected.
One other symptom i have is that it takes a a couple of cranks to start, never really quick. but again not always the same.

[cabmandone]

Could be a fuel pressure regulator. What is your AFR at idle when it's idling rough? Does it idle better when the engine warms up?

[Classic11]

Hey Nick,
i have idle AFR set to about 14.5. It does fluctuate quite a a bit, not sure how much fluctuation is normal? Cruse is roghly 14.7. only WOT is not rich enough.

[OffCamber00]

i have a perfectly good DME in Charlotte if you get desperate. Car is not being driven so its not a problem.

[cabmandone]

Originally Posted by Classic11

Hey Nick,
i have idle AFR set to about 14.5. It does fluctuate quite a a bit, not sure how much fluctuation is normal? Cruse is roghly 14.7. only WOT is not rich enough.

You did the idle setting after the engine was warmed up, right?

You mention you're running in the low 13's at WOT. I think that's about what a stock chip should do IIRC. I think my chipped DME runs in the mid 12's at WOT. I might have to take it out tomorrow and stomp on it just to verify!

Just looked at the chart I have. Looks like tip in should drop into the 13's with WOT dropping into the low 12's but I'm not sure if that's factory or tuned. I'll go out and run my car tomorrow. It needs to stretch its legs anyhow.

[cabmandone]

I watched a video of my car at 5-6k rpm shifts under WOT. My car has a performance tune. I was hitting 11.9 at WOT. Again, I'll go out and run my car but I think if you're hitting low 13's at WOT, that's pretty much it for a factory tune. I could be wrong. You might want to PM Sal (scarceller) or Steve Wong and get their take.

[Classic11]

Mat, I appreciate you offer, i might come back to you if i cannot find a solution closer by. could be a good excuse to go on a road trip.

Nick,
i am running Fabspeed headers and the appropriate Steve Wong chip for that set up. Not sure what Steve would program it to? I know it needs to be in the 12's because when it goes in the 12's it feels so much stronger. I can tell everytime. Yes i set idle when warm, I have AFR gage in the cabin and watch it closely. Fuel pressure regulator and computer are my only guess.

[GaryR]

If yours is original I would have it tested and rebuilt, I think I sent mine to Ingo Schmidt (sp?) on here but could be (way) off. It wasn't a lot of $$ and I had the piece of mind that the unit was in perfect as-new condition. He will even modify it to take a newer memory module for minimal cost.

[cabmandone]

Originally Posted by Classic11

Mat, I appreciate you offer, i might come back to you if i cannot find a solution closer by. could be a good excuse to go on a road trip.

Nick,
i am running Fabspeed headers and the appropriate Steve Wong chip for that set up. Not sure what Steve would program it to? I know it needs to be in the 12's because when it goes in the 12's it feels so much stronger. I can tell everytime. Yes i set idle when warm, I have AFR gage in the cabin and watch it closely. Fuel pressure regulator and computer are my only guess.

I'd definitely reach out to Steve if you're running his tune. The rough idle is what I'd focus on. Find the cause of the rough idle and I'd guess you've found why you're not dipping into the 12's. Rough idle seems to be caused most often by a vacuum leak. I know you said you've verified no leaks but you might want to go back over it again. Make sure your intake runner nuts are torqued to the proper spec. Seems to have been a lot of guys recently finding bad intake runner gaskets.

Did this rough idle just occur or has it been that way for you? My thought is that you could have masked a problem by adjusting the base idle mixture. Did you send the DME into Steve to have it chipped?

I'm curious too about how you set the base idle. When I did my base idle mixture, I fully seated the adjustment screw and then backed it off about 2 turns which got me really close. When I set my base idle after verifying the injectors, fuel pressure regulator, switches and vacuum system were in working order, I found someone had turned the screw 5 full turns out from fully seated.

[jons911]

I've got a DME available in Jacksonville, although that's a fair bit further than Charlotte. I've also got a MAF, ICV, TPS, and fuel pressure regulator/damper if those are something you end up trying as well.

[Charlesm3]

I’m in Atlanta. Just got my ECU back from Steve Wong yesterday. I had to send it to him to resocket it for his 28 pin chip. I’ve got an 89 that the PO at some point put an earlier ECU in it. I’m out of pocket until tomorrow afternoon but I’m happy to help if I can. PM me.

...BTW, here is the part of my post where I tell everyone that Steve Wong is one of the most helpful and responsive people I’ve ever come across in the car world. He turned my ECU around in a matter of hours so I could have it back for the weekend. (Thanks Steve!)

-Charles

[mysocal911]

Originally Posted by Classic11

Hello all,
I have a 84 3.2 that received pretty much all new parts when it comes to ignition engine and fuel supply. It has good power but not always richens up the mixture on WOT, most of the time is stays above 13, its one out of 10 where it goes well in the 12's and yes you can feel it when it does. It also does not like to idle as smooth as i want it to be, i just replaced the ICV with a new one and it made it much worse. I am out of ideas. Just replaced fuel pump and checked fuel pressure, looks like its in spec also. My last resort now is the ECU and before i spend big money on rebuilding mine, that could be good I would like to see if there is a nice person in the north Atlanta area that could let me try out a confirmed good one? I am willing to pay a fee, or pay in beers.

Thanks in advance!

It's extremely rare that your ECU is causing the problem you describe. Avoid wasting your money on "rebuilding"!

[Classic11]

I tried a different ECU (was just recently rebuilt) from some member on Pelican. Big thanks to him and all the people here offering help. Good to see there are still nice people left in this world.
The ECU did not fix my problem not getting in the 12's, it leaned out my idle mixture a good bit, had to readjust everything but in the end did not make the car run better. It caused a weird idle popping (sounded like a header leak), was gone when I put my ECU back in. I did a lot of driving and testing (perfect weather in Georgia at the moment). One other symptom that i noticed is that when i park the car hot for 10 minutes and get back in it, it acts like its cold and i see idle and part throttle numbers of 11 and 12, after 5 minutes of driving it goes back to normal. Dont think it can be CHT sensor related though. When i WOT it during this time it actually leans the mixture to the low 13's again, which shows the WOT switch is working correctly. I emails Steve W on the issue, maybe he has some ideas. I am getting ready to replace fuel pump and regulator next.

[GaryR]

Originally Posted by Classic11

I tried a different ECU (was just recently rebuilt) from some member on Pelican. Big thanks to him and all the people here offering help. Good to see there are still nice people left in this world.
The ECU did not fix my problem not getting in the 12's, it leaned out my idle mixture a good bit, had to readjust everything but in the end did not make the car run better. It caused a weird idle popping (sounded like a header leak), was gone when I put my ECU back in. I did a lot of driving and testing (perfect weather in Georgia at the moment). One other symptom that i noticed is that when i park the car hot for 10 minutes and get back in it, it acts like its cold and i see idle and part throttle numbers of 11 and 12, after 5 minutes of driving it goes back to normal. Dont think it can be CHT sensor related though. When i WOT it during this time it actually leans the mixture to the low 13's again, which shows the WOT switch is working correctly. I emails Steve W on the issue, maybe he has some ideas. I am getting ready to replace fuel pump and regulator next.

Did you use your chip or his? If you used your Wong chip I would say the changes are possibly due to issues in your current Motronic box that have been adjusted for and now are out of whack with a perfect unit. If you used his chip all bets are off, who knows..

[Classic11]

Its been a few weeks but some update on my issue. I sent my unit to Steve and he tested and rebuilt it for me. It turned out that my running rich after every start (cold or warm) was caused by a mismatch of ECU and chip. For some reason i have a ROW ECU with no O2 sensor circuit and used Steve's US chip. He added the circuit and rebuilt the unit and now this issue is gone. The only problem i still have is that the AFR values go up (leaner) after 5K rpms. I get almost in the 14s which is too lean. they are good all the way to 5k right around 13. I know the ECU is good and all sensors, tried a different AFM with no change. I don't think the amount of fuel is soo much more between 5k and 6k so i doubt the fuel pump can cause this. I am leaning towards fuel pressure regulator and damper.

[GaryR]

Originally Posted by Classic11

Its been a few weeks but some update on my issue. I sent my unit to Steve and he tested and rebuilt it for me. It turned out that my running rich after every start (cold or warm) was caused by a mismatch of ECU and chip. For some reason i have a ROW ECU with no O2 sensor circuit and used Steve's US chip. He added the circuit and rebuilt the unit and now this issue is gone. The only problem i still have is that the AFR values go up (leaner) after 5K rpms. I get almost in the 14s which is too lean. they are good all the way to 5k right around 13. I know the ECU is good and all sensors, tried a different AFM with no change. I don't think the amount of fuel is soo much more between 5k and 6k so i doubt the fuel pump can cause this. I am leaning towards fuel pressure regulator and damper.

Just a guess but when I built my 3.2 the tuner required me to get 944 Turbo injectors because they flow more but you may be able to adjust for it. Assume your injectors have all been cleaned and flow tested (or new)?

[mysocal911]

Initially you posted this;

Originally Posted by Classic11

I have a 84 3.2 that received pretty much all new parts when it comes to ignition engine and fuel supply. It has good power but not always richens up the mixture on WOT, most of the time is stays above 13, its one out of 10 where it goes well in the 12's and yes you can feel it when it does. It also does not like to idle as smooth as i want it to be,

So the problems were JUST related to AFRs @ WOT, and no smooth idle, right?

And then you posted this;

Originally Posted by Classic11

I tried a different ECU (was just recently rebuilt) from some member on Pelican. The ECU did not fix my problem not getting in the 12's, it leaned out my idle mixture a good bit, had to readjust everything but in the end did not make the car run better.

So it really wasn't an ECU problem, but most likely a performance chip (you bought) problem, right?

Originally Posted by Classic11

For some reason i have a ROW ECU with no O2 sensor circuit

If you had posted what the Bosch ECU number was of your ECU, the forum could have informed you that your ECU was NOT a U.S.,
i.e. providing you insights on how that would affect your issues.

Remember, once the ECU "sees" the wide open throttle switch, the O2 sensor has no more effect.

Now you post this;

Originally Posted by Classic11

The only problem i still have is that the AFR values go up (leaner) after 5K rpms. I get almost in the 14s which is too lean. they are good all the way to 5k right around 13.

So it appears, having the ECU "rebuilt" was potentially a waste of time and "big money"!
Additionally, some 911 3.2 owners with engine mods, prefer to use the EURO ECU.

Start by finding a KNOWN good late 911 3.2 DME (082) with a stock chip, testing the WOT switch,
and then testing the fuel pressure at WOT.

[Classic11]

Gary,
yes i had my injectors cleaned with before and after reports when i rebuilt the engine and they are all to spec. Thanks for the feedback.

Hey Dave,
I had 2 initial issues.

#1 was car was running rich every time it was started, hot or cold for a few minutes and running rich (in the 11's AFR) when driving for a few minutes at times.

#2 was not getting in the 12's when WOT, the higher the rpm the leaner the mixture, all the way to 14AFR.

I tried a different ECU from a member but it turned out after i tried it that this ECU was chipped for a 3.4 engine and my car did not like it. I sent my ECU to Steve, he confirmed my running rich every time the car was started. this was caused by the Euro ECU and US chip. He converted my ECU to US specs and the problem is gone. It idles good now. Only Idle issue i have is when I start it cold it wants to be left alone for a minute before i tough the throttle or it has a tendency to stall. It could point to the issue i still have, not sure but i can live with it.
The Euro ECU's have no O2 circuit but besides that what would make people want to use one in a modded engine? If you unplug the O2 sensor in a US ECU it that not the same? When the ECU sees no O2 feedback it acts like a Euro ECU I thought?

Steve confirmed that my ECU was working, and during WOT adjusting AFR values in his car to 12.8 to 13.2 , this makes me rule out the ECU as the reason for problem #2.
I would not say the rebuild of my ECU was a waste of money, it fixed my occasional rich running, now takes O2 sensor feedback while cruising (i konw its not really necessary with headers and all) and going forward I don't have to worry about the 35 year old computer under my seat ;-)

Thank you for the hint to test fuel pressure at WOT, Steve also recommended that and I have an idea to measure and record FP while driving. I will report back when i have the data. What kind of values should i be seeing?
Thank you.