Hello everyone, I am new to your web site but i thought i might give it a try. I bougth a 88 IROC-Z about 3 months ago, i had to pull the engine out because of internal damage, so i bought a short block online and rebuilt the engine and put it back in the car. i have the engine running but iam only getting 7-10 in HG at idle and it runs poor and trys to stahl. i found that the TPS sensor was out of specs so i replaced it, and just to make sure i replaced the IAC sensor as well. i was thinking of a vacuum leak, but i taped up the TB and pinched off the vacuum lines and i fed about 15-20 PSI to the intake and i had 3 o-rings for the injectors leaking so i fixed that. it still wasnt solved! i checked the brake booster for a leaky diaphram it was fine, i checked the EGR Valve, it was fine as well. I just dont know now and iam getting tired of redoing work i all ready have done. iam starting to think cracked intake but i know i would have heard that. the valves are adjusted right. compression is good, vavle seal is good. Any ideas people??????? Please help me I have 6 months left in germany and iam trying to fix up this car so i can take it back to the states.

 

Welcome aboard thirdgen.org.

Where in Germany? I assume you're in the service, which branch? I spent '79-'82 in Mainz in the Army, did a V6 swap in a Vega while I was there.

Anyway, some details about your rebuild would be helpful. Is this a 350 or 305? What did the shortblock come from? What cam did you use? What all did you do for the rebuild?

It could be something simple like a slipped gasket. Or, something more involved like a mis-machined mounting surface. Are you sure you have the simple things covered like spark plug wire firing order?

 

Yes iam in the Air Force, station at Spangdahlem. Iam an auto mechanic for the the air force, i guess not a good one if i can figure this out.

Well any ways the details, its a 350 TPI, ordered it from Tbolt.net. they have been around for a while and they were cheap which might be the problem(i hope not). i told them it was a vin 8, i was told by the company that the cam is stock but it was reground. for the rebuild, i rebuilt the heads, took apart cleaned, put new valve seals and reseated the valves. the motor before only had 16000 miles on it so i didnt bother getting the valves reground they looked good even before reseating them. and what i mean by reseating is i used the paste and spun the valves then took a marker and check the contact point and they were good. then used a gasket set and pretty much put it back together. sparkplug wires are on correctly, new plugs new wires, cap and rotor looked good. it runs i can drive it up and down the road but when stop in drive i have to feather the gas to make sure it doesnt stahl. in park it will idle but crapy like i said. now for the lower intake gasket i put a small about of RTV around the ports on the head, used a rubber hammer to tap lightly around the ports to make sure they were sealed and then let it dry a little before i put the intake on, i also used a little RTV on the intake side too, just to make sure everything was sealed. i orgianly thought that mybe the bad tps sensor was causing problems with the IAC and causing a restriction for the vacuum so thats why i repalced both. but iam up for ideas. i have a second intake and i was thinking about ripping off the old one and redoing it and ordering new gaskets again but like you said i think its somthing simple too. but low and steady vacuum means mechical problem or valve timing, I think.

 

Any one?

 

When you say runs crappy, do you mean like a miss? Does it run like crap even going down the road or just at idle? If it's a stock cam, yeah your vacume is pretty weak. Honestly when I hear "reground cam" alarm bells go off in my head. I honestly don't know why anyone does this anymore considering how cheap a stock replacement cam and lifters is. When you first cranked then engine after putting it together did you "burn" the cam in? I'm wondering if the reground cam shaft has a flat lobe. If it sounds like a bad miss, you may pull the valve covers off and turn it over slowly and see if all the valves are opening all the way. Hope you find the problem, I know how frustrating chasing some of this stuff down can be.