I need help! Ecotec idling/running/tuning issue

[72Pstroke]

I have had the Ecotec in my car since March. I have put about 6,000 miles on it since then and have been fighting a running issue since day one.
The car runs great until you need to stop. If you push in the clutch while at speed, the rpm's fall off way low. Sometimes the IAC will catch it in time, but most of the time it will die.
If you use the engine to slow the car down by downshifting, the car will die every time when you either shift to neutral or push the clutch in.
I have tried three IAC's, all acted the same.
I have a scanner, and all the paramaters look good. I could use some help on the trim parameters.
It has the stock computer reflashed by Tom at Enginewiring.com. He has offered to flash another computer, but I don't think that will help.
All the vacuum lines are capped off and there are no intake leaks.
The check engine light is not on.
Any ideas? I am about to pull the rest of my hair out.
Has anyone else had any problems?
Tim

[Stingray250]

Tim,

Had some of the same issues with my Eco swap... Idle would fall to 500/550 @ idle with an occasional stall while in heavy decel... in gear. I too went round and round with Tom over at Engine Wiring... I was popping a lean code also... if your scanner can check for "pending" codes, I'm sure you'll probably find a po171 pending as well as a po507.

I never really got a straight answer from Tom... I did have another ECU flashed, did the same thing. HP tuners is not the greatest when it comes to the Ecotec... I actually helped them with some R&D... these motors are pretty tight in their programming from GM and thus hard to tune.

My remedy was two part really, first I disconnected the vacuum source from the press reg, capped the reg so I'd have a little more fuel pressure at the injectors at idle... second was to "induce" a little back pressure on the exhaust side of the engine... took off my flowmater and put on a stubby glasspac muffler with a tuneable supertrapp tip on the end of it.

Very rarely do I get any codes and it hasn't died on decel in a long while... sounds pretty cool too. One other item... if you are using one of those Airtex pumps... throw that crap in the trash... buy one of these... WALBRO / ZEX EFI Fuel Pump Chevy LT1 Electric Inline NS6601 255LPH... made a big difference for me.

Also, look into EFI Live for programming... I have a local guy working on a MAP for my particular setup... he's waiting for EFI Live to send him the stock GM file for the 2.2 Eco so he can re-flash my ECU with it and then tweak it from there...

Good luck!

[72Pstroke]

Thanks for the help, Stingray. I am glad that it is not just me!
I have the regulator capped already.
I went through two Airtex pumps from Summit, and they were both crap. Summit warranteed them for me. I picked up a Precision pump locally, opened it up and found the same Airtex pump inside; It was crap, also.
I finally got an Accel from Summit, and it has been fine since.
After driving this thing since March, I just found out last week I had the PCV plumbed wrong. Basically I had 2 PCV valves in it and no vent.
The car runs worse now (since I fixed it) than it did before.
If you get your ECU reflashed and get your problems fixed, let me know. I would send my ECU to you for some new tunes.
Tim

[regnbus]

I 've had similar problems with lean fault codes and stalling after a long decel. I talked to a few Ecotec experts and got some uninspiring responses ranging from "then don't drive that way" to "I have never had that problem with any of my other customers."

Do either of you have a vehicle speed sensor with your installation? Mine doesn't and I think that's at the root of the problem. My computer always thinks vehicle speed is 0 because I don't have a sensor and the speed reading with a scan tool is always zero. My theory is that whenever I take my foot of the gas, the computer wants to control the engine like it's idling and that works fine if the car is actually stopped and the engine is actually idling. But if I'm decelerating with my foot off the gas and the engine speed is above idle, screwy things start to happen with fuel trim and the idle control valve because the computer is trying to idle the engine but it’s not a real idle situation. I suspect a stock Ecotec uses different fuel maps for idling versus deceleration, but my set up and probably yours is using the same fuel map for both idle and deceleration conditions and that doesn’t work. If you watch manifold pressure, which is the basis for fueling, at idle versus under a deceleration, they are significantly different. My theory is under deceleration the wrong map is being used and that throws off fuel trim. So when you finally get to idle, the fuel trim has been tweaked by the deceleration and lean fault is detected. I might try to put a separate sensor in my exhaust and see if it’s really lean when the fault is detected or if the computer just thinks it’s lean because of the a programming issue.

Stingray250, hopefully you can get it to work with EFIlive. I think that’s what was used to program my computer and the programmer hasn’t been able to quite fix it yet assuming it’s a programming issue. I also have a phantom fan problem that hasn't been resolved yet either.

I’ve had to put my project on the back burner for a while. Hopefully, I can get back working on it again and get this worked out. The Ecotec sure is a blast to drive even with these annoying glitches.

[cmiller95]

One word solution: carburetor
Just giving ya crap,
Good luck on it guys!
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[72Pstroke]

R:
I agree with your assessment of what is going on. There are no tranny inputs, no clutch pedal position inputs, no vss inputs.
If I drop off the top of a big hill on the highway (70 mph) and let off the gas pedal, the check engine light will come on for a high idle code.
If I lug the engine way down in gear, I will get a low idle code.
Other than that, I never get a check engine light. Are you getting a lean engine code?
The last issue of Hot Rod magazine has a tech article that shows a universal IAC from Blower Drive Service. It is an inline IAC that goes onto a 3/8 vacuum line. I wonder if it would respond quicker than the stock one? My car just feels like the IAC responds to slow to keep it running. The only catch is that the IAC is $180. It is a lot of $ just to try it. If it would work for sure, I would buy it in a heartbeat.
There were some fan issues earlier with Tom's harnesses and ECU, but I thought that had been cured.
That being said, mine has come on a few times when it shouldn't have.
Tim

[Stingray250]

"I also have a phantom fan problem that hasn't been resolved yet either."

Lemme guess... after exactly... and I do mean exactly... 6:40 of run time @ idle... the fan cycles on but wont cycle back off regardless of actual engine temp... unless you cycle the ignition switch off and then back on?

If you have used a automatic trans ECU for your build, you will find out that after 6:40 seconds of run time by default the ECU is looking for a nominal trans temp signal... When it see's a high voltage because there is no return signal input, it thinks the trans is overheating there by cycling the fan to cool the trans cooler and radiator.

I about lost my freakin mind dealin with my fan issue... I ended up finding the signal and return wire and popped a resistor in between them at the connector to the ECU... can't remember what size but you can experiment with different resistors while wathing the live data on your scan tool... the temp reading will fluctuate with differnt size resistors... I set mine at like 120* F.

I think the pin number is 60 on the C2 (large one) connector..
YEL/BLK
Circuit number 1227
Trans Fluid Temp Sensor Signal

My fans operate normally now.

As far as the "tune" issue... I've learned to drive the car the way it likes to be driven... if there is such a thing... I was popping the lean code along with the low idle code for a while due to hard decel comin to a stop... my back pressure mod and a quality fuel pump made a world of difference... hadn't had a MIL come on in over 600 miles now. According to my tuner guy... who used to tune GM 800hp+ Vette's for Hennessy... he claims because GM made the tuning values/parameters so tight because of EPA reg's, it really is a pain to fine tune these little motors. Most people who do these swaps run the shit out of these things offroad and never have an issue with MIL comin on... for those of us that run these swaps on the street also, well it is what it is. I figure if it really does get popular as an alternative... someone will step in and fill the need for a finely tuned stand alone ECU for the Eco.

[Mr. Unpopular]

I'm running an auto ecm flashed with hp tuners and I dont have the fan issue or the idle issue. My swap has stalled twice while coasting in gear, once when only running for about 30 seconds (coolant temp low) and once after a long coast in gear. I personally think the problem is it running rich rather than lean, since I read that using dfco (decel f:uel cutoff, requires a vss) is actually worth a few mpg.

The difference may be that a friend flashed a file from hp tuners forum. It seems both of you are running a flash from tom. Maybe he has a bum file?
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[MURZI]

Could you not drill a tiny hole in the throttle plate?
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[72Pstroke]

What is the idle RPM on your cars? Mine idles around 600 RPM. That seems to be a bit too low, and that may be part of my problem.
Tim

[Mr. Unpopular]

mine's at about 900. I could see where 600 may cause problems. Maybe you can bump up the idle some with the screw on the TB?
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[72Pstroke]

Stingray, I sent you a PM.
Regnbus, I think you are right about the VSS. I have switched to a local tuner, and he recommended that I install a VSS. I am going to make a tone ring and mount it to the CV next to the tranny. He says without a VSS, the ecu does not know which map to use.
I did bump the idle to 750, and that made a world of difference.
If anyone is interested in a tone ring, let me know.
Tim

[BajaBug222]

I may be interested in the tone right soon. I'm going to be starting my swap last this year is my guess. Want to get all my parts collected before I start
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[72Pstroke]

222, what kind of axles and cv's are you running?
Tim

[BajaBug222]

In the process of putting my 002 in right now I haven't ordered axles yet. Gonna be running 930 cvs
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[shmoe2k]

we need to have more info. Fuel trim numbers, i think you posted the IAC counts i'm not worried about them. what are the O2's doing and are they a wide band O2. Injector pulse width at idle and cruz. MAP sensor and/or MAF sensor. I'm not sure what set up you have there. There is a lot more info we need to have. you might even think about getting a Mega Squirt and set up your own parameters. Keep us posted.
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[regnbus]

[72Pstroke]

Regnbus,
I am waiting on some info from Chad, to see what parameters I need to be within before I move any farther forward on the tone ring. Most OEM's are calibrated in pulses per mile. Ford uses 8000 ppm, I think, but I am not sure about GM. Once I get that information, I will be able to calculate the number of teeth on the tone ring. After that, it is up to the tuner to calibrate it for your tire size.
It is tight at the axle/framehorn location. It could be mounted outboard on the outer CV, it would just be more prone to damage.
Does anyone have a tranny out? It woud be interesting to see if the tranny case could be drilled in a location that would allow the VSS to pick up ring gear teeth. Or even mainshaft teeth?
Schmoe,
From what I can find out, this is an isue with nearly all the Ecotec swaps that use the stock ecu. There are different fuel maps it uses, depending on several different issues. The Mega squirt would also be a fix, as it uses simpler programming.
I drive mine every day. If I drop off the top of a big hill on the highway, take my foot off the gas and leave it in gear, it will set a check engine light for high idle every time. Without knowing vehicle speed, the ecu just does not have enough input to perform correctly.
Tim

[BajaBug222]

PIcked up a 2.2 ecotec lastnight and it has an electronic throttle body on it. I have noticed there are a couple different cable one depending on the application. Will any cable style throttle body work?
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[72Pstroke]

How hard would it be to mount the drive-by-wire throttle pedal in your car and use it that way? It may be easier than using a throttle cable.
Just thinking out loud.
Tim