Compression readings

[Stephen Soulsby]

I performed a compression test on my car tonight to check for anything out of whack, but I'm not sure what is normal. My highest reading was in #6 with 150 and the lowest was in #5 with 125. If my math is right that is 16.6% difference. I did the test with the motor hot (burned skin to prove it) and all plugs removed.

My symptoms still are:
Low vacuum (12@idle, 10 in gear)
Erratic idle
Stumbling off idle (almost with rythem like a faulty cylinder)
Way too much detonation (only when warmed up)
Erratic misfire while driving (very noticable with TCC engaged)
Slow cranking most times, sometimes normal. Bat. and alt. good

How is my compression? I'm not confident in doing a cylinder balance test not knowing of any possible damaging effects it may have on the coil and module.

 

[Stephen Soulsby]

TTT

 

[mike85gn]

Check for vaccum leaks. Try the IAC reset if you haven't already. Check plugs, wires. I had a stuble, caused by a bad coil pack. Look in to that as well. Also, wouldn't hurt to change the O2, and do a block tap test on the knock sensor if you have a knock gauge or scantool.

 

[alb84]

Try putting the stock chip back in the computer while trouble shooting. It would be better to do a leak down test rather then a compression test. then you can determine where the air is going. Later...Danny