I recently took off the plenum & valve covers to polish them-- looks real nice but the car wont run. High speed is fine but idle is terrible and it always dies as soon as it quits cranking at startup without gas. It will idle fine at 7-800 after driving around, but the damn thing wont hold idle at allafter startup . I checked the TPS and at idle im getting a reading of .62 right now but it will only idle at 5-600 rpm. 7-800 is a smooth idle but it comes at a reading of .72. I was told that if i exceed .68 for idle that it will draw a trouble code. WOT is only a reading of 4.3 when i was told that it should be at least 4.8 .
Im pulling my hair out right now because of this damn thing. I love my car but it can really not be my friend sometimes. Id hate to take it to a shop for somthhing thats probably simple like this because i am on a very low budget right now and hope you can help. The engine was warm at the time of the tests.

 

I was doing some work on mine one day and disconnected the MAF wire connection. I made the mistake of starting it with out reconnecting it and I thought I was in serious trouble it would not idle and ran like ..... well I found out what I did and reconnected it and that helped. However, for awhile after that, 2-3 times, after I would disconnected the battery, don't know it its related, it was like the car forgot totally how to run, wouldn't idle etc. but after I ran it down the highway it was fine after awhile and never had a problem with that since. :crazy:

 

Double check you connections. What kind of vacuum do you have at idle (or there abouts)? A large vacuum leak is what you are describing. You sure you didn't bend a tube flange, or not tighten down enough?

 

I tightentd the plenum with a screwdriver type adapter for the torx bit and got them tight but didnt torque them real tight for fear of stripping the aluminum. How do I check my vacum at idle?

 

Just curious - did your computer set any codes? When mine was doing similar things I got a code 34. I disconnected the MAF sensor, got code 33. It ended up being a faulty $13 relay on the firewall behind the battery - the one closer to the centerline of the car. ~Juliet

 

[I tightentd the plenum with a screwdriver type adapter for the torx bit and got them tight but didnt torque them real tight for fear of stripping the aluminum. How do I check my vacum at idle?]

Did you check your MAP sensor????? It might be bad. Mine did the same thing I bought an after market one and it still did the same thing then I bought one from GM and it worked like a charm. It sounds like your MAP sensor! the connection is bad or the sensor is bad! The diffrence between the after market one and the GM one is that the GM sensor reads the barometric pressure where the aftermarket one dose not.

 

what is the MAP sensor?

 

It is nothing you have on your '87. You have a MAF.