[squeakanator]

My 1g eclipse GST (100% stock) idles with a strange lope almost like its cammed, but runs pretty good, still has decent performance, feels like a 15 second car, its only other issue is it takes forever to start when its really cold out. Its got 112k on the odometer, after throwing numerous parts at it without being able to cure the lopey idle i did a compression test. These are my results

#4 - 94 psi
#3 - 96 psi
#2 - 55 psi(went up to 85 psi when i added a dribble of oil into the cylinder)
#1 - 96 psi

I read I am supposed to have 180 psi on all cylinders... I'm thinking the compression gauge isnt reading accurately?( it was a cheap rental from autozone) I'm thinking if i had half the compression i needed on every cylinder the car wouldn't run. I guess I need new rings on piston 2 either way because it wouldnt have jumped up like that without adding the oil. Any thoughts?

 

[96dsmgst]

It sounds like your car is completely out of time. Or it is possible that you have bad lifters or lifters that need compressed. I would check your timeing first off though...

 

[squeakanator]

If it was completely out of time wouldn't it have a dramatic decrease in performance? 90 psi is almost half of the compression it should have, it would make sense that performance would be cut in half, if basic logic works in this situation. But it still has some ass to it when i get on it. Does anyone have a clear answer of how the car would run with this low compression if the gauge were to be correct?

 

[Dsmolition]

How did you do the compression test? Did you have a battery charger hookd up? Was the car at operating temp?. If it did have different cams a compression test would read lower maybe pop off the valve cover and check it out. It could also be a valve in #2 do a cylinder leek down test. Also I would check your fuel pressure.

 

[K_Mans_TSI]

How would fuel pressure have anything to do with a compression test if you're supposed to disconnect your injectors when you do it?

 

[Dsmolition]

How would fuel pressure have anything to do with a compression test if you're supposed to disconnect your injectors when you do it?

The op stated that his car takes forever to start in the winter.....................It could be due to having bad fuel pressure.
Also it could mess with his idle.........

 

[Ambico]

The starting would be from the low compression, in no way would fuel have anything to do with his compression. And I seriously doubt that fuel delivery is an issue at startup. I could check your base timing to make sure it is timed (make sure the crank is TDC an the timing ticks are lined up on the cams).

 

[Rice_Killer]

Could you tell us how you performed the compression test? There could have been an error in the testing method.

Also, I'd be willing to bet the timing is a tooth out.

 

[squeakanator]

No, the car was not at operating temp, but i had someone hold the gas pedal to the floor and crank the starter while i watched the gauge pump up. which was of course screwed into the spark plug hole.

But today i was driving it, got on it a little and my balance shaft belt exploded and the engine died. I pulled over and tried to start it back up but it was like the compression was completely gone. it no longer lopes when the starter cranks, and the car does not fire at all. Headgasket? the timing belt is fine (whew) and so are all the accessory belts. How would a balance shaft belt cause the engine to lose compression completely?

 

[Lazer382]

Lopey idle could be the exhaust cam off a tooth. Use a ruler across the cam gears and double check this because it will still visually appear correct but when you put the ruler across it is much more obvious. Might also be the cause of some of the compression issues but I can't guarantee that.

 

[kp116]

As to answer some of the previous posts a compression test is a test to test the "sealability" of a engine. Cams used or lifters would not affect compression readings. Your timing however would affect it very much so. I would say check your timing and if that is fine then of course proceed to a leak down test.