ECMlink Can't get this thing to idle right! [w/ ECMLink]

[BoostBuddyGSX]

Hi guys, I seem to be having an issue getting this car idling correctly. The car is a 1995 GSX with a 1990 "JDM" 6-bolt in it. I tried messing with the injector deadtime and MAF comp tables, and I either get an idle that is so high that it idle surges, or an idle so low that you have to hold the throttle for it to stay alive. No matter what I do, I can't get a constant, clean idle.

I have already ruled out the major things. I checked for boost leaks, nothing came up. I sent the 1990 throttle body out to throttlebodies.com to get rebuilt/sensors tested, re-installed the TB w/ new gaskets, and I still have the same problem. Removed the TB, checked the IAC & cleaned it, did the 1990 FIAV block off mod where you bottom out the adjustment screw, same problem.

At this point, I'm pulling my hair out because I don't know what to do.

Attached is an ECMLink datalog file of the car idling. PLEASE help??

 

[snowborder714]

Your front o2 sensor looks to be dead since it is not cycling. Replace that and try again.

Make sure to read through this as well.
http://www.dsmtuners.com/forums/ecm...efore-you-ask-ecmlink-dsmlink-log-advice.html

 

[BoostBuddyGSX]

My o2 sensor cycles just fine when the engine idles properly. The problem is, I can't get it to idle properly CONSISTENTLY, it's like this car has a temper!

And yes, I've read that already. Thank you.

 

[snowborder714]

Have you considered that the sensor might be going though? Yes, it'll cycle when it idles properly, but if it's working intermittently, then it won't always cycle which means the idle will be crap. Just curious if you have considered replacing it or not.

Have you tested your ISC? It's reading 0.
http://www.dsmtuners.com/forums/articles-tuning-ecu/386663-dsm-isc-motor-testing-replacement.html

 

[BoostBuddyGSX]

Do you think that could be the problem? I really can't afford to just start throwing parts at it, unfortunately.

Yes, I've pulled/tested/cleaned the ISC.

 

[snowborder714]

A new o2 sensor would be my next try at a fix.

 

[My1GLaser]

I'm with him ^^^ Your STFT is pegged positive and your O2 isn't responding. According to your combinedFT your LTFT Lo is pegged positive also.

If you have the time to wait, you can try oxygensensors.com or sparkplugs.com and get an NGK or Denso O2 for cheaper than a POS auto parts store one. I've even printed out the website with price and had Adv Auto price match it in the past...

Your G/rev is kind of low. Have you checked for a pre-turbo air leak after the MAS?

Your TPS volts needs to be .63 when closed, not .43.

Your global should be -48.9%. [(450/880)-1] If the inj in your profile are correct. You're dumping too much fuel in there, and your fuel trims are still pegged positive!!! Your frt O2 should be stuck at .98 or something, not the exact opposite.

 

[c2ypt1c]

Hmm...you might want to take a look at the ecu and check for any visible signs of damage (leaky capacitors, etc..), this might explain why the isc signal and o2 signal are dead. If it all checks out, I would take the opportunity to buy a wideband and run narrowband simulation, two birds with one stone type deal.

EDIT: just saw you have an AEM wb, but not logging...

 

[BoostBuddyGSX]

A new o2 sensor would be my next try at a fix.

Thanks, Brian! I'll start with that.

I'm with him ^^^ Your STFT is pegged positive and your O2 isn't responding. According to your combinedFT your LTFT Lo is pegged positive also.

Your G/rev is kind of low. Have you checked for a pre-turbo air leak after the MAS?

Your TPS volts needs to be .63 when closed, not .43.

Your global should be -48.9%. [(450/880)-1] If the inj in your profile are correct. You're dumping too much fuel in there, and your fuel trims are still pegged positive!!! Your frt O2 should be stuck at .98 or something, not the exact opposite.

Gotcha. Makes lots of sense. I just didn't know that a bad o2 sensor can cause extremely high idling & idle surge with occasionally extremely low idling.

My G/Rev is low because I was messing around with the MAF Comp tables to get a steady idle.

My TPS is not adjusted yet, I just got finished putting the PITA TB back on!

This car that I'm working on is a different car than the one listed in my profile. This one has PTE780cc injectors in it. Yeah, everything is all out of wack and I don't get it... but I'll start with an o2 sensor first..

Hmm...you might want to take a look at the ecu and check for any visible signs of damage (leaky capacitors, etc..), this might explain why the isc signal and o2 signal are dead. If it all checks out, I would take the opportunity to buy a wideband and run narrowband simulation, two birds with one stone type deal.

EDIT: just saw you have an AEM wb, but not logging...

I would take the time to do that if DSMLink wasn't recently installed.. Yes, I have a functioning AEM wideband, but it's not hooked up to DSMLink yet

 

[Calan]

I would take the time to do that if DSMLink wasn't recently installed.. Yes, I have a functioning AEM wideband, but it's not hooked up to DSMLink yet

Get the WB hooked up. That will let you see whether or not you have a real AFR issue, or just a faulty front O2 sensor (or something related to that).