HI To everyone,just got an 1989 Iroc conv.It runs terrible the idle goes up and
down for about 5 mins then dies.Car won't start again.Have to let it sit,starts up and does the same thing.The previous owner replaced the following Egr,iac,
ignition module,fuel pump,maf,tps,all relays,coil,fuel cap,thermostat,and o2 sensor.I was going to get a new ecm,injectors and distributor.Just don't want
to keep throwing parts at it.I have read allot of the posts on here and they are very help full.Tps is set right and i played with it to see if any thing helps no luck.I think its the ecm but not sure.Thanks please help

 

Get a fuel pressure tester, it should be 36-42psi while running, & hold psi when engine is off.
Disable the egr valve, it might be getting vacuum at idle, which it shouldn't.

 

I just check ed fuel pressure and it's 42.Disconnected egr nothing changed.
Did get code 42"the est signal did not change when the ecm applied bypass voltage to the ignition module.
The previous owner said he replaced the module.I am leaning towards the
ecm is bad.Any thoughts

 

Check the ecm grounds carefully, usually at the backof the heads or near the t stat. or do a continuty test at the ecm connector to ground.

 

How do i do continuity test at the ecm?Thanks for your help.i am pulling my hair out

 

You can get a volt meter, set it to ohms, put one end on a good ground (battery is best) & the other probe the ecm connector. You'll need a good repair manual the shows the ecm connector view & what each pin does, while your there check the proper voltages too.

 

I'll try that.When the car is running i am getting water coming out the tail pipes.
Is this common?

 

Alittle water is common, condensation. Is it coolant?

 

I don't think its coolant.I have a Chilton repair manual and it doesn't have much info
on the ecm or what each wire does.Is there a source on the internet that i could get info
on?Again thanks

 

The car will run fine when first started up,then in about 5 mins or so the idle jumps around and eventually dies.It's kind of weird and it smells like its running rich.When it
dies it almost acts like its flooded,becaues it wouldn't start back until it sites awhile

 

Any one else have suggestions,it driving me crazy.Thanks

 

Well i replaced the ecm and car runs better doesn't seem to want to die.Still
the idle isn't right it searches up and down about 200 rpm.Anyone have
any ides.And car smells very rich out the tailpipes.Thanks

 

Clean the maf sensor.
Do a resistence check on the coolant temp sensor, google "GM cts resistence ohms" for the values/temps. You'll need that volt/ohm meter though.

 

Thank you

 

check for a cracked magnet on distributor under rotor. Could keep contact until it warms up and then it expands and separates causing open. Saw this on a 94 chevy truck. Don't know if it applies here.