Ok this isn't on a Camaro, but it is a 2.8L V6 (Model 220 TBI). I am having problems with my 86 4WD Blazer. The idle is all over the place. Sometimes it's way too high (2000rpm), sometimes it will only idle at base idle (500rpm) and will stall all the time.

So far I have changed my IAC Valve, and unhooked the vacum to the EGR because the selnoid was toast, keeping the EGR open at idle. Both helped a bit. I have also been playing around with the TPS. Right now idle is set to 0.37V. Anymore or less and I have serious problems. Also I am only getting a max of 3.9V at WOT. Shouldn't it be around 5.0V? I am gonna try to find a new one on Sunday.

I am sure it is not a vacum leak, because the truck will idle at base idle.

Also the truck always, always stalls the first time you put it in gear. I can rev up the motor alittle and it will still stall, on the second try it's fine. Also every morning I have tried starting it, it will not high idle at all, and will not run. However I can let it sit for four hours while I am work or school, go start it and it will high idle fine. (It's below 0 here every night)

The only trouble code I am getting it 32 for the EGR. However sometimes when the SES light will be on, I will check the codes but only get 12 and no other codes. I'll reset the computer, same thing.

Thanks for any help.
Steve

 

ttt

 

Your tps seems Ok, I think mine Is like .5v to 4v.. Sounds like you have a vaccum line leak or the O2 sensor is toast. When at Idle (engine warmed) check the voltage on O2 wire, Should be 400mv to 700mv. If its around 0v or over 1v it probably gone.

 

I'll check it, won't be untill monday though. I was getting a 45 awhile ago, but it went away. Also doesn't the truck stay in open loop while warming up? So the ECM shouldn't care what the O2 is saying while it's warming up.

Still looking for any more ideas.

Thanks
Steve

 

Your correct about open loop idle when cold, but it goes closed loop at a low coolant temp (could be 60 deg f or lower, not sure for 6 cyl). If idle is eractic then tps is propbly to blame. They have been known to work fine sometimes, and then other times poorly. Could also be wires to the tps.

 

If tps checks out ok then it could be coolant temp sensor. On my truck there is are two cts. One in the head (a thermcouple - not very accurate) and one in the intake manifold (RTD, resistive thermal device - very accurate). The T/C is used for dash temp reading only, and the RTD is used be the computer only. If the RTD was on the way out this could cause the crazy idle too.

 

I was thinking it might be the Coolant sensor too. Especially since it will not high idle when it is really cold, and is fine when only slightly cold. I am gonna try and get out to the wrecker today and grab some sensors. It's just really damn cold here, -20C today with a minus -30C wind chill.

Thanks
Steve

 

I just now noticed you were from edmonton, Yeah is damm cold in these parts. The last time I was at the pick-a-part in edmonton I loaded up on sensors and relays (always handy). The sensor you want will have two wires going to it (redundancy). The thermocouple will only have one going to it.

 

Changed temp sensor (2 wire), no effect. I grabbed 2 from the wrecker, all three had the same resistance at room temp and then in boiling water. So I assume they are all good.

I got a new TPS. The TV cable was holding the throtte alittle closed so I was only getting 3.9V at WOT. Now I am getting 4.4V. There was no difference with the new TPS.

I pulled the computer out. It doesn't look like it was grounded very well. So I am deffinetley gonna fix that with a hard wire from the ECM case to the (-) side of the battery.

I am gonna hook up a wire to the O2 sensor and see what I get for numbers tonight.

Thanks for all the Help
Steve