valter

Went to start a car after it's was parked for an hour and it just starts and dies immediately. If I give it a little gas it runs for a 5 sec, and stalls again. Disconnected MAF - car starts and runs almost normally (speed density, or just pre-programmed A/F ratio mode?)
I guess it's a MAF or some other sensor failing. What is the difference between how and what sensors used in these two modes? Any troubleshooting tips?
Thank you, I appreciate any help!

Dave89IROC

only real diff is the MAF, all other sensors are still used

WS6T3RROR

Might be an o2 sensor causing it to run rich or lean and just flat making it die. Or if your car is modded maybe your target idle vs coolant temps are set too low and the thing just wont idle when it gets 200 deg. Maybe tell us a bit more about the car than the year and the trans.

valter

Thank you, guys. It seems to me I am having problems with MAF. Cleaned it, cleaned IAC valve, cleaned all contacts. It's still doing this even on cold and warmed-up (with disconnected MAF) engine.

Injuneer

Have you scanned it for codes? A faulty coolant temp sensor could cause the PCM to set an excessively rich A/F ratio on cold start.

OBE1 95Z28

O2 sensors aren't used to adjust AFR right after start up; the PCM waits approximately 3 - 5 minutes for the O2's to warm up and the coolant to warm up. Might check the fuel pressure to see if it's within specs. You could also have a leaky fuel injector causing a rich condition.

WS6T3RROR

DOAH! forgot about the timer.

valter

Thank you for all help! No codes (except old evap code I had for a long time and too lazy to fix and code for MAF, when it's unplugged; when it's plugged - engine is not running). This weekend MAF should come in, and I'll check fuel pressure and temp sensor.
One more question: how to check temp. sensor with multimeter? What resistance/voltage to look at? Thank you!

Injuneer

Shoebox has a guide to checking temperature sensors:

http://shbox.com/1/4th_gen_tech2.html#ect

Since you appear to have a scanner, can't you just use it to look at what the CLT sensor is reporting to the PCM?

Dave1980

If it were the maf then unplug it. It should use the map sensor to run speed density. I really doubt this is the maf giving you the problem.

valter

FedEx just brought me a MAF from ebay 5 min ago! Already installed it - and it works!!!!!!! I want to thank everyone for their help

Dave1980

Yeah just read your first post correctly. It must have been tired when I made my comment. It seems if there is a big difference when maf is unplugged, then it has issues. Good deal.

Injuneer

Problem is the first post says it runs better with the MAF disconnected, later post seems to indicate it runs poorly with MAF disconnected.

valter

Sorry for confusion. It wasn't running at all with MAF plugged in. Tried to start, and then immediately dies.
With MAF disconnected it was running "almost ok" with following problems:
- when engine was cold, throttle response was extremely bad
- low on power (very noticably!)
- when cruising on highway, and I let off the gas, RPM drop was so sharp, it felt like I was applying brakes
- I have no idea why, but it was running hotter