I have a GSR engine that I got ripped off on... It has bad compression on one of the cylinders. When the engine is on, I pulled the spark plug wires off on each cylinder and all cylinders made the car go rough idle except the one with the bad compression. Also, the spark plug is black on that cylinder. I do not get blue smoke. Anyone know the problem? I am looking to rebuild my engine.

 

id pull the oil pan off and pull that piston out and replace the rings on it unless u wanna do a full rebuild then pull the whole motor out and redue everything (bearings, rings, hone, resurface, head gasket and a few other things) that would probably only run u about 500ish with machine shop work. up to u. the black spark plug just means its running rich

 

it could be just valves... but i hear knocking noise when I rev or run so I think it might be piston rod knock

 

you can rent a compression tester with the gauge, pull the plug on that cylinder crank the motor until you get a steady reading.. pour a drop or 2 of oil straight into that cylinder then do the test again.. if the compression results are better you have bad piston rings

 

doesn't have to be bad comp - could be injector, spark plug, or your ECU. happened to me too. i was pissed, but luckily a friend had an extra P72 USDM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EgSick6 &raquo;</TD></TR><TR><TD CLASS="quote">id pull the oil pan off and pull that piston out and replace the rings on it unless u wanna do a full rebuild then pull the whole motor out and redue everything (bearings, rings, hone, resurface, head gasket and a few other things) that would probably only run u about 500ish with machine shop work. up to u. the black spark plug just means its running rich</TD></TR></TABLE>

what a retard. you need to pull the head off to get the piston out

 

I did a compression test. Thats how I know one cylinder is low.

 

so what else did you do so far? did you try the wet test? is that injector clogged?