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stock compression (test results)

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necrotopsy

10+ Year Contributor
719
6
Jun 5, 2010
SW, Michigan
my car is at my mechanics. failed fuel injector and a broken spark plug (the piece of metal that curves over the electrode broke off).

He had said in passing that "you got 125 compression across the board, so looks like the engine is fine"

but after looking it up, it looks like stock compression should be 210?
does that make sense?

i seen that 210 was for a "DIY" compression test, so i was wondering if a compression tester that mechanic would have would display a different reading.(i know this isn't likely, but my mechanic, who i trust, acted like 125 was good. but then again maybe he had the wrong information on what it's supposed to be. or maybe he mean 225. really just grasping at straws here.)

misc info:
180k miles on engine
basic bolt on's (cai, full aftermarket exhaust, msd coilpack and plugs)
 
i'll call him up monday and talk to him again. keep my fingers crossed i heard him wrong, or he said the wrong numbers.
 
Figures should be between 175-220, with no more than 15psi between cylinders. The lower service limit is 100psi.

You are getting down there. Might want to start planning now.

MB
 
let me put it this way...
at first i thought i had a broken valve and piston, so i sent it to him to look at it.
if it had in fact been a broken valve and piston, i would have stripped the car and junked it.

i'm driving this car until it wont drive anymore (smaller repairs not withstanding) then stripping it for parts.
i can't afford to do a rebuild.
 
i would put some lucus in it and sell it while you can man 125 is defintely low

You are obviously a complete douche if you are advising him to cover up the problem and pawn it off on someone else....

Wow dude, just wow :rolleyes:

Karma's a bi***. :nono:


------------------------------------------------------

Yeah, 125 is really low. Just drive it till it won't run.
 
you guys are lame i said lucus so he can actually drive his car longer then a month. did i say hey cover it up and sell it to someone? what he tells someone is not up to me. the lucus was just advice to keep the compression up before he gets so much blow-by and his sensors clog up then he cant get anything for the car. if someone knows what they are doing they could pull the head off and fix the rings or valve seats and have it for a dd. so dont call me a douche
 
So the sell it while you can theory doesn't apply as you stated? Hmm interesting.

Drive it till she goes! You can find a donor engine and swap it out if your mechanically inclined.
 
talked to my mechanic.
125 was the correct number he gave me.
125 across all 4.

100 or below is when it gets too low and you start getting misfires and the like.

i'll drive it untill i can't drive it any longer, then part the SOB.
hate this car...
 
The car is not the "silver avenger" as your profile picture is it? I can't remember, by the way even if it is not, I feel for you man...:cry:
 
i'll drive it untill i can't drive it any longer, then part the SOB.
hate this car...[/QUOTE]

Chuckled when I read this, car is almost 20 years old.. Cant expect it to be perfect, but those low numbers if your giving up, start constructing a part out thread.. :notgood:
 
Lol. why part it.. its not worth much.. we all know the avenger market is dead.. and the only ppl with money in have everything already.. IMO learn and fix it. or get out of cars.. this is the same crap you faced when you purchased the other boosted venge.. or buy a creat motor for it, swapping in and out os not hard, even you can do it. : P
 
Damn it, :ohdamn: That blows, I wish i lived closer. I would not mind giving a hand on it. :thumb: I love that color scheme & body add's! :D I would just pull it & find another (2.0L) and get it running again!
 
A day late and a dollar short but I'm sad no one mentioned checking the timing or allowing fuel-soaked piston rings as being a possible cause for consistently low compression numbers across the board. Granted, the mileage, history and such could be just cause for a rebuild but I was under the impression assistance in coming to a diagnosis should take precedent over blindly throwing a repair idea out there.

Timing that is off one tooth may permit the engine to both run and compression to be low. Performance would suffer and if the cam that is out is the intake but you may not get a check engine light (Crank sensor looks at crank, cam sensor looks at exhaust cam only). If it's the exhaust cam that's out or both then you'd probably get a cam/crank correlation fault code.

Anyways, good luck with the fix.
 
i have the car back, and it runs perfectly fine now.
if a cam gear was off a tooth, wouldn't it idle funny? I don't have any idle issues, and has plenty of power still (as much power as can be expected for this engine anyway)
 
If it were off a tooth and running then the idle may or may not be noticeably different. I've had a 4g63 NT off one tooth and thought it was right until the test drive. Lacked power but I was still able to drive it out of the shop. The vacuum was about 3-5 inches low once I got it back in trying to figure out what I had done wrong.

What was the corrective steps (if any) you've taken to get it back on the road and running better?
 
I know I'm new but for the sake of posting and for adding encourgment. I reccomend you learn to do the rebuild yourself, and save your money for parts. Best of luck with whatever descision you make. :hellyeah:
 
Doug99RS:

Valve cover gasket was replaced. Coilpack was replaced. One spark plug. that's it.
i dont think the coil pack that was on it was bad, it was an MSD coil less than a year old.
I think it was bad gas. I've been running 93 octane for about 2 weeks now, havent had a single issue with it.

but it's also been 105* temps here with very high humidity, i figured it would be safer to run a little higher octane since the intake temps will be so high.


EDIT**
i don't mean to say a mostly stock n/t needs 93 octane. it doesn't. but i was running 93 because i think i had a tank of watered down gas, so i wanted to even it out.
 
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