It has been a few months since I had the heads and cam done on my car. The car is a 98 M6 T/A. Just recently it has been having ALOT of problems that I just can't seem to figure out! It all started with the temp gauge not reading right and the idle acting all screwy. It would rev by itself during idle from 700rpms to 2 grand and then drop and die. I changed the coolant temp sensor in the driver side head since it was broken and that fixed the problem of the gauge which now reads proper temp again. I also changed the throttle position sensor to see if thats what had happened to my idle. Now the car has started to missfire very violently after a warm restart and while cruising at NON WOT speeds it buckles and jerks like if I was a newbie at shifting a six speed. It also backfires if I shift normally at NON WOT between gears, it does it especially bad under 3 grand.It also still idles crazy and randomly starts to rev and hold an idle at 2 grand right before a missfiring fit. I changed the plugs recently and that didnt help. I checked the wires and fuses and all look ok. Eveything is back on tight and snug. The number one and number three cylinder plugs however are white(lean) while the rest are fine or slightly rich. Those two cylinder plugs are also slightly coated with oil, making me suspect that I had two bad valve seals. Jason99T/A had told me that it coulda been the fact that I had forgotten to red loctite the intake rocker bolts. I have gone ahead and done that now. I need to check to see if that solved the problem. I am also thinking that the lean condition coulda been the bad coolant temp sensor since the manual says it can cause improper fuction of the fuel injection system. If not I am gonna pull the injectors and clean em out to see if they are clogged. It also now starts real rough sometimes and I have to keep cranking it to the point that I think I'm gonna toast my starter. When it does start it'll smoke for just a second(white thin fume like smoke, smells like fuel) but only after a rough start. When it starts ok, like after a cold start, it doesnt smoke. Last weekend it started to have the low coolant light come on after missfires and now it stays on all the time. The car's coolant level is fine and doesnt over heat according to my gauges. I still have the stock tb hole size, only mods to it is porting and JB welding the trap. I also have a ported MAF out of an 01, since I was told it would work with my 98. I have had these on there for months after my H/C work and they didn't seem to cause any problems. I haven't changed out the 02 sensors, just cleaned em out since I haven't had any tuning done yet. I have no idea what to check next. Some one told me to see if my water pump was still working, I don't see why not since the car doesn't over heat but why else a low coolant light? Could it be air in the system? Aren't LS1's self bleeding though??? Could it be a Vacuum leak? The car seems to be down on power some and it is VERY frustrating. The fuel economy on it is Horrible aswell! Please help me since this little BS has slowed me down on getting the car tuned and focusing on getting a new nine inch with some gears installed/paid for.
Thanks in advance!
Rick
ps. 918's/Ti ret's, comp hardened pushrods, GTP "PIG" cam[591/591 226/226 112], S2 heads, LS6 intake, Hooker Long tubes, Dr. gas true three inch dual exhaust, whisper lid, fernco coupler, 160 stat, ported 01 MAF, ported Tb, TR55/MSD 8.5mm, B&M Ripper, BMR strut tower brace, waiting install on nine inch with 4.56's, IRS terminator lower control arms/relocation brackets
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<small>[ July 24, 2002, 11:35 AM: Message edited by: PhatT/A ]</small>

 

Check for broken valve springs. I know you were just in there, but check some recent threads on this at ls1tech.com and ls1.com.

 

clean your mass air, my car did all that jerking, really bad, and i couldnt figure out what it was, untill i cleaned my mass air and that fixed my idle and jerking problems, hope it helps.

 

Rick,

I'd be happy to help you diagnose your issues over the phone. There are too many ideas to post here and it would be much easier to just talk you though a few things. If you'd like, give me a call here at the shop at your convenience.

Thanks,
Shane

 

Damn, gotta love the guys at Thunder

 

Done reading right there...take it back to the shop that did the work.

 

i've seen a cam position sensor do this on a saturn, or something like a saturn, but i dont know...

The sensors leads were reversed though so...

 

Werd !

Rob (Bad30th)

 

sounds like O2's or injectors. Could also be FPR, AIR. Theres so many things that come to mind.

 

I'd give Shane a call at Thunder, smart guy - very helpful