compression on a 2003 Chevy cavilier
Asked by racerx80p Oct 29, 2018 at 05:04 PM about the 2003 Chevrolet Cavalier LS Coupe FWD
Question type: Maintenance & Repair
I have a 03 Chevy cavalier and I'm getting a po300
code I was told it might have low compression I
checked it cylinder 1 has 190 cylinder 2has 155
cylinder 3 has195 cyl 4 had180 is these number in
range I can't find any reference numbers to go by
8 Answers
Cylinder 2 is weak. Usually compression numbers should not vary by more then 10 to 15%. Did you block the throttle open while testing and crank the engine for a similar amounts of compression strokes for each cylinder? Did you follow the dry compression test with a wet test by squirting a small amount of oil in the cylinder and retesting? Does this vehicle consume oil?
no that was a dry compressor test I did not hold the throttle open I'll do that and check the numbers also I'll do the wet compression test thank you for you're Input
it dosent use any oil I just replaced timing chain head gasket and bolts spark plugs plug wires and control module
update after retesting the compression with throttle wide open numbers flex little cyl1 190 cyl 2 145 cyl 3 190 cyl 4 175 with the wet test cyl 1 195 cyl 2 140 cyl 3 190 cyl 4 185 it dont use oil
#2 is still a little low, but it should run okay. There might be a small piece of carbon on one of the valves or the valve isn't quite sealing. I really have no way of knowing if the #2 cylinder is low enough to cause a P0300. Do some reading at the link for more info on P0300 code. https://www.autocodes.com/p0300_chevrolet.html
is there a better valve cleaner I can use maybe in the fuel system
BG 44-k is one of the best fuel system cleaners out there. It is somewhat expensive, but may help with deposits or cleaning the fuel system. BG is the company name and 44-k is the product. It may not help in your situation cause we are speculating as to the cause of the low compression of the number 2 cylinder.
