I have an 04 Cavalier LS Sport with 204,000 miles. I bought it in 06 with 19,500 miles, so i've been doing a lot of driving since i've owned it and a lot of it has been rough miles and high speed driving. So I decided to to a compression test to see how beat up my motor is. I did it two different ways, with the throttle closed and with the throttle wide open. I got different results with the different methods. I counted to 5 missisippi for each reading.
Wide open throttle:
1. 215psi 2. 215psi 3. 210psi 4. 215psi
Closed throttle:
1. 195psi 2.195psi 3.195psi 4. 195psi
The thing about the 5 mississippi count is that if I would have kept cranking the PSI reading would have kept going up, so I'm wondering if I should have kept going until the needle stopped. I know that my catalytic converter is clogged, I'll be fixing that this weekend with a new high flow cat.
I'm just looking for some input as to whether I did the test right or if I should have kept going until the needle stopped. Thanks in advance for any help.
To me numbers look great for the amount of miles on it and I always test the way you did it, but if you say cat is clogging I would fix it right away before burn up internals. My friends old 2002 Grand Am with eco engine got burned up from plugged cat and was not good. Started getting bad gas mileage and was cheaper to drive full size truck than it was to drive the car.
FuzzMASTA9
Pete P wrote:To me numbers look great for the amount of miles on it and I always test the way you did it, but if you say cat is clogging I would fix it right away before burn up internals. My friends old 2002 Grand Am with eco engine got burned up from plugged cat and was not good. Started getting bad gas mileage and was cheaper to drive full size truck than it was to drive the car.
Yup..my high flow cat will be here Thursday, so it'll get done this weekend. The element in the cat is broken free and rattles.
Those numbers are good.
A leak down test is a good test to tell cylinder and valve shape as well.
nice numbers! I guess we got a good batch of engines made in 03
mine just hit 200,000 miles and about 3k miles or less ago i did a compression test. was 200 200 210 200 consistently.
04 Cav. 2dr. 5spd. My DD. 'Nuff said.
