1997 Chevy Cavalier compression

No. The only thing that would affect compression is the rings and pistons and the valves, cracked head, blow head gasket and or warped head and unlikely but possible cracked block. What kind of readings are you getting?

03/10
Know that U are going to think that we are Crazy, BUT the mech.[Who is '1' of them OLD TIME mech.
& he did go back into eng., Just to be sure, Yes Everything was where it was suppose to be [clearances were @ factory spec.S & all valves checked OK 'vacuum] when he did compression test [before was reading from 110 - 100Lbs & yes we know that it takes ATLEAST 90Lbs to crank a cyl.]
Mech. Did find that the EGR valve was STICKING, he 1st tried w/out mounting EGR, won't work w/out the EGR valve, BUT said that he re-mounted EGR valve & [somehow] he was able to blockoff EGR valve [within it's self], Re-bolted EGR valve & Yes the eng. Did run & Re-checked Compression, didn't tell me what he got when did next Compression Test, BUT did tell me that [after blocking off EGR eng. Ran like a top & that is the only thing that he did] NOW, we know that this doesn't make any sense & goes against everything most experts think BUT this mech. Is a can't think of a GOOD word to use , BUT Promise U that if there is a way to make eng. Run [usually against all logics] Phil is the mech.
THANK U
butch @butch's auto & diesel mach shop
318-787-6049[769-1222fax]
gasdieselengine@suddenlinkmail. Com

Good to hear you got it running but it did not have anything to do with the EGR valve affecting compression. What was happening if the EGR valve is stuck open you are continuously recycling exhaust gases into the intake. A EGR valve that is stuck open will kill a vehicle at idle. That is the reason it has a vacuum valve and hose hooked to it which is also hooked to a vacuum solenoid valve that controls the valve allowing it to open under certain conditions. Blocking off the port will prevent the exhaust gasses from entering the system which leans the fuel mixture. So basically he just stopped the exhaust gasses from leaning the mixture which in turn allows the engine to idle and run. However depending on the state you live in (which I think is just about all states) you are taking a risk by bypassing an emission device. It is designed to help burn the raw gas that is left over in the combustion cycle and and to lower the amount of pollution emitted into the atmosphere.

Good Luck.