Hey all. First off I'd like to say it feels good to be back in the Third Gen world. I had a 90 GTA, put a lot of time and money into it and sold it, moved to a 95 TA and did the same. After that I bought a brand new truck, then my first home, then switched trucks about 4 times, and finally got to a comfortable financial point where I felt I deserved a toy. And now I'm back... anyways, on with the show.

I recently bought a 1989 IROC Z with a 350 TPI. The car is completely stock and original with only 70 000 miles on the clock. She's clean. Anyways, I noticed the oil pressure gage is erratic. It'll be at 30 then dance around and max out then jump around for a while and then max out. Just curious, on the 89 5.7 TPI is the sending unit for the gage going to be on the rear of the intake or on the block above the filter? I found the one above the filter but haven't had a chance to look for the other one. Any help would be greatly appreciated. And I'll have pics of the car up this week hopefully.

Also, I noticed at idle in gear at a stop light the car jumps between 500 - 750 RPM. Is this normal or do I have an IAC problem?

 

IAC TPS MAF or vac leak.

 

There might be a sensor beside the distributor for the gauge. If there is indeed one there, just replace it. They are pretty notorious for going bad. (and giving the symptoms you have....)

 

Replace sender unit. It's likely gone bad,

 

Thanks guys. I have to say it feels good to be back in these forums. Missed the third gen world

 

UPDATE: I replaced the sending unit near the oil filter and the gauge works now, and the idle is approx. 700 RPM and holds there, so all is good again.