what could cause this problem

[Spoolin18]

Here is the story, I noticed my car will idle low when you come to a stop, I also noticed a slight miss at idle. The car is completly stock, never seen more than stock boost. It has 95,800 on the clock. I took it to my mechanic, he did a compression test and the results are as follows. #4=145, #3=142, #2=138, #1=110. It holds excellent oil pressure, better than any dsm I've ever seen and i've seen plenty of them. It holds about 18-20 inch HG vaccumm at idle and the needle will slowly snap back when you rev it. But I do have a prosport boost/vac gauge, not sure if that plays a part in it or not. I heard their gauges aren't the best in the world. It has good power. I tried the hill/stomp gas pedal scenario and it didn't smoke. It has sit a long time, probably put 20 miles on it since march. It smokes a little blueish-whiteish color at startup and will do so at idle until it is drove for a few minutes, the smoking goes away. My mechanic has narrowed it down to either a failing headgasket or a valve not sealing all the way on the #1 CYL. Could it be rings? He was going to do a t-belt job, until we found this problem. The timming was off slightly, but when they adjusted it, it was still low. It looks to me to be out of mechanical timming by one tooth, the exhaust looks like its one tooth retarded. I need help and guidance. Should I tell him to pull the head and see for sure what the heck is going on? Anything I should do while the head is off? should the head/block be shaved or something? Could the piston rings be replaced with std. bore rings, and leave the block in the car. I need answers fast. Its been at his shop for a month and our paitence is wearing thin. Thanks.

 

[gsx7707]

have them do a leak down test.when this is done properly it can tell you alot.

 

[95'RS-T]

With the smoking on start up. I would say that's the leaking valve. The compression test is not too bad. The only thing would be cylinder 1 (maybe rings)
But hey if your gonna pull the head you might as well put a new MLS head gasket in there and maybe some arps.

 

[joegamma1]

Sounds like a bad valve guide/seal on no.1, maybe on all 4. But it could be rings. If the timing belt hasn't been changed in the last 60,000 miles or you dont know....change it. If you shave the head it will change the working length of the timing belt, so you should not shave it.
you could do the timing belt and valve guides without pulling the head but it wouldn't hurt to pull the head and do a head gasket while your at it. but thats if you can verify with the leak down test that it is not the rings.
just my .02,hope this helps.

 

[Spoolin18]

seems strange it would be rings with only 95k on it. He did a leakdown test and could only pinpoint it to a couple problems, HG or valve. Any more advice out there.

 

[1990AWD]

well to check valves and headgasket, you have to take the head off so you might as well tell the guy to remove it and then see where your at. the chance of it being piston rings under normal wear is very low.

 

[spartan69x]

always better to be safe than sorry, pull the head check it now so you don't waste a ton of money down the road.