Idle Problems

[Dagoon]

OK I just bought a 1995 Eagle Talon ESi (FWD no Turbo). Now everything is prefect expect for the idle. At around 1000 and upder rpm it has a very rough idle, almost like a misfire. I checked valve timing, Spark, and I also checked the compression of each cylinder. 1,2,3 were the same, but #4 had a very low compression. Also I smell gas from the exhust pipe when its on idle. As soon as I increase the rpms all is fine. Any Help? Im leaning to maybe a Bent Valve. Any tips or hints to help find the problem? Thanks!!

 

[rstare]

Check all your vacuum lines, my friend just had something that sounds like a similar problem. We thought we had check all of them and it turns out we missed one. So double check all the vacuum lines.

 

[Dagoon]

I checked all the Lines. They are all hooked up and in good condition.

 

[Dagoon]

Update: I removed the valve covers. Everything there looks in brand new condition.

 

[Detective Coating]

How low was your compression in cylinder #4? Have you gapped your plugs correctly? Try cleaning your throttle body or adjust your BISS.

 

[98GSXtreme07]

He's NT. No BISS.

 

[Detective Coating]

D'oh! Well just let us know about the rest, I should have read some more!

 

[Dagoon]

I did the compression test with the engine cold and thottle closed at normal. 3 of them read 120 and #4 came to 60. Im gonna redo the test with engine at operating temp and throttle wide open. As for the gaps on the plug they are brand new and gaped correctly, and I already cleaned the throttle body.

 

[talon96tsi]

I dont know what the compression numbers are supposed to be, but cylindar 4 is sounding pretty terrible. I would definatly get the car up to running temp and do the test again however.

 

[Detective Coating]

Have you checked to see if your piston rings are bad?

 

[Dagoon]

I havent checked anything lower than the valve cover. I dont think its rings because its not burning oil or anything. Just alot of fuel on idle. I thought maybe an injector was bad but that doesnt explain the low compression.

 

[Locke]

Low vacuum will cause excess fuel consumption at idle - poor compression is accompanied by low vacuum. Vacuum should be stronger than -15.

Add a bit of oil to the cylinders and test again, if it brings the compression up, then you are leaking past the rings.

 

[LD25Delta9]

WOAH?!?!? You should be sitting at 175-225 in all cyl. by the 3rd comp. stroke. 120 in three and 60 in the 4th? What stroke were those numbers read at? Do a smoke test to find your vacuum leak. (plug all you vacuum inlets and outlets except your PVC inlet, cover your TB with a balloon, Blow cigar smoke into your PVC inlet)

 

[VelocitàPaola]

I recommend following Locke's advice. If you find that the rings aren't the culprit, research a leakdown test and either perform it yourself, or have a shop do it. The results from the leakdown test will show you exactly what's wrong. You may be smelling oil from your exhaust pipe, not gasoline...

 

[Dagoon]

WOAH?!?!? You should be sitting at 175-225 in all cyl. by the 3rd comp. stroke. 120 in three and 60 in the 4th? What stroke were those numbers read at? Do a smoke test to find your vacuum leak. (plug all you vacuum inlets and outlets except your PVC inlet, cover your TB with a balloon, Blow cigar smoke into your PVC inlet)

Remember I did the compression test with the engine cold and the throttle closed. They were read at the 5th stroke. Im gonna do a re-test tomrrow night.

 

[LD25Delta9]

I'm no ASE certified master tech or anything.....but them numbers sound funny. Velocita' Paola's right. If you can't find any kind of vacuum leak like you thought...do a leak down. Whenever I've done a comp. test, I've done it with the engine warm (not hot or cold) and come up with the proper specs every time. I guess I've only ever done it one way, so the numbers you've got for the way you did it could be proper...except for that #4. That's gotta be off....

 

[Dagoon]

ok so i did the test again.. 125 in #1,2,3, and 60 AGAIN in #4. I put some oil in #4 and it jumped to 70. I did the leak down test and I hear it coming out the exhuast so im leaning to bend valve! O boy... what to do now?

 

[Shadow98]

ok so i did the test again.. 125 in #1,2,3, and 60 AGAIN in #4. I put some oil in #4 and it jumped to 70. I did the leak down test and I hear it coming out the exhuast so im leaning to bend valve! O boy... what to do now?

Time to rebuild yourself a beast!!! Maybe turbo...