Hey guys. I have a problem that has been giving me grief for a little while now.. the car runs extremely rich/rough upon startup. Hot or cold, doesn't matter. I bought the car am most 2 years ago and besides a catback, it was none stock and un molested mods wise.. The previous owner did replace a lot of the sensors (Maf, iac,tps,ignition module,o2 sensor) on engine as well as the injectors. This problem is really becoming a pain to deal with. I've checked eveything I can think of. I have even sent out my
Prom to Brian (Tuned Performace) and had the cold start injector tuned out..and I installed a delete kit as well. No luck. I don't wanna give up and go carb but it's tempting.. In open to any help or suggestions.

 

Anyone!???

 

1) Don't expect an immediate response; you didn't even wait a day before bumping your thread. That's a no no on forums imo.

2) Well, first thing I would do is ignore any previous work the owner has done. Start from scratch.

Reset IAC and idle. Checking timing (and clear the code by unplugging the battery). Check o2 sensor output as well as MAF readings. Check for exhaust leaks that'd affect o2 sensor readings, etc.

When you got your chip done did you do any data logging? before/after. Know the BLM counts at idle?

What about vacuum leaks?

 

Thanks for the reply.. I know how to reset IAC and TPS, not sure how to properly check the MAF or O2 output.. Can you run me through that?

No exhaust leaks or vac leaks that I'm aware of..

BLM counts??

I pulled the vac hose off the fuel reg and no raw fuel came out.

No data logging has been done

 

I suggest using the search bar on the front of thirdgen.org (it searches via Google, which seems better than the one on top of this post page), as the 15+ years of posts here can probably explain the nuances of each much better than I could. I'm good at pointing in the right direction, though..

My main suggestion is start from scratch. Don't assume anything the previous owner did helped, or hurt. 100% clean slate.

I will say you should go ahead and have a multi-meter handy, as well as a fuel pressure gauge.

 

I'll do some homework tonight. Thanks

 

you said the injectors were changed. are you sure of the size that was installed? If they put larger injectors than what was stock for that engine it would cause it to run rich.

 

One thing to look at is the coolant temp sensor connector on the front of the intake. They are bad to corrode and send false readings to the ECM and make it run rich.

 

Hmmm. I'll have to looks at he connector closely.. I've changed the sensor but didn't give the connector a good look. Thanks

 

Ok guys, check a few things today.. The connector for the coolant temp sensor is nice and clean.. I traced a number off of one of the fuel injectors (F4SE-A1B) apparently it a 22lb Bosch injector. Makes sence because that's what the previous owner said they were.. I'm thinking the problem may be in the Maf or o2 sensor.... I'll check them tomorrow hopefully.. Also, I'll have to rent a fuel pressure gauge and check that as well..

 

Also check the vac line from the fuel psi regulator for raw fuel.

 

I ran to the parts store today to pick up a new o2 sensor and rented a fuel pressure tester while I was at it... Installed the new o2 and it ran exactly the same. No good.

Here are the pressures
Key on engine off= 36-37 psi
Engine running= 45-46 psi

Also, no fuel in vac hose to fuel pressure regulator.

 

I would suggest investing in a data logger to determine what your engine is doing instead of continuing to throw parts at it at this point. The logger will show you what each sensor is reporting to the ECM and you will be able to troubleshoot much more accurately. The TPI system is a fairly simple system once you learn how it works.

 

I was thinking the same thing.. However I'm not to familiar with what data logger people are using on these cars.. Can you send me a link or point me in the direction of a good unit?

 

What year motor do you have? The 12 pin cable is for OBD1 on 82-92 http://www.aldlcable.com/ Also, do you have any codes?

 

It's the original motor. 1988 l98. No codes currently, but after a 20 min drive I sometimes get 45? It's the "rich exhaust" code.

 

http://support.moates.net/datalogging-with-an-aldu1/

That's what I use.

 

I had a similiar problem, no codes, took to shop that knows TPI
they scanned it, determined MAF issue, replaced MAF relays, burn off and power, then code 33 appeared, new non china brand MAF, car runs amazing now

 

I have my suspicions about the MAF. There's a guy not to far from me that is going to let me swap out my Maf with his.. If that doesn't do the trick, I'm ordering one of those cables and I'll start data logging.. I'll actually end up ordering one anyway just because that stuff interests me..

 

Also note he mentioned he swapped the MAF relays as well. MAF may be good but relays bad, never know!

I used the cable from 1320 electronics. I prefer it because it has dip switches built in for the 10k resistor, and other stuff that the different ECMs require. All in one cable, no messing about. Worked great with all the datalogging apps I tried.

http://www.1320electronics.com/12pinUSBALDL.html

 

Cool, thanks for the info. You guys have been helpful.. I guess most of you are using Tuner Pro software??

 

Hey man, what data logging program is the best for a beginner?? Guys seems to like Tuner Pro. I'll also have to do some homework to find all the stock values/voltages for the sensors so I know what I'm looking for when I start logging... I'm actually kind of excited

 

Tuner pro is what I use, it's pretty user friendly software.

Once you get into it and figure out what it's all doing it does get fun!

 

Update: a local guy to me gave me a MAF for free so I figured why not try it... Well it solved my running issues... It's a happy day today.. Thanks to all of you who helped me trouble shoot and narrow down the issue.. I'm still looking forward to data logging and possibly tuning in the future..