JurisAg02

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 that's 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
doesn't 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 LS1, since I was told it would work with my 98. is this correct? 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'd hate to foul out a new pair and have to buy another one after tuning. 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? Could it be a broken valvespring even though these have less than 3000 miles on them and I did check em(visually)? The car seems to be down on alot of power and it is VERY frustrating. The fuel economy on it is HORRIBLE aswell now! 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.MODS are as follow from what I can best rememember:
Comp 918's valve springs/Titanium retainers, 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 01MAF, 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

Btchslp

Wow dude, a lot to digest in one post. Anyway, my experience in the past is that the IAT sensor (idle air temp) will cause irratic idle rpms. It can be due to a bad sensor or vacuum leak. The IAT is located on or around the TB somewhere, not sure on an LS1. Seems though that most of the things you have done so far would not cause a car to perform as you have stated. Have you scanned it for error codes, anything? If you don't have a scanner you can go to Autozone, they will scan it for free and tell you if you have any codes.

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99 SS, Dark Metallic Blue, M6
SLP lid, KN, TBB, SLP Y-pipe, loudmouth
ported MAFs, Fernco,......
Currently: 1/4 13.30@114, 0-60 4.85 (w/passenger)

Camaro ChriSS

It would help to check for DTCs with Atap or a scanner for sure to see if a sensor has gone bad. This would narrow things down and should be your first step.

Your '01 maf should work no prob.

Is your PCM reprogrammed? I'd assume so with that serious of a cam. You definitely need a high idle rpm. If improperly programmed, that could be it. Or a faulty PCM (it happens).

I haven't worked on a H/C LS1 yet, so I don't know how important the issue of the drilled hole in the TB is with the size of cam you have. It could be part of it.

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2000 Pewter SS #C161
SLP Dual-Dual, Bilstein suspension, Eibachs, 21mm/35mm swaybars, GMAF
SLP CAI w/lower plate, !EGR, Direct-Flo, SLP STB, Ported TB, ASP Crank pulley
SLP/AAM Differential cover, SLP 2600, Powershot, MSD wires, NGK's,
BMR Boxed LCAs, BMR PHB, G2 DSL, Heavy Lead Foot...
http://community.webshots.com/user/murlynd

JurisAg02

I figured 98 MAF's were calibrated for the 98 large injectors.
I have no tuning but for the few first months it still ran fine and idled at 900 rpms.
All these problems are recent. What exactly are DTC's?
Rick

[This message has been edited by PhatT/A (edited July 24, 2002).]

2002Z28SSConv

diagnostic trouble codes

Camaro ChriSS

I'm not definite on this, but I think the programming of the MAF is liberal enough to handle a variation between the injector difference (is it 25 lbs compared to 28 or so - I can't recall?).

JurisAg02

If that is the case why are you guys telling me the MAF is the culprit? I am gonna get her scanned today and I'l post those results.
Thanks everybody!
Rick

Bill'sWS6

A comment on the low coolant light. These go bad a lot on these cars. There is a level device on them and that is the part that goes bad. Mine was replaced and went bad again within a year. I just leave it the way it is now.

Good luck and let us know what you find out.



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Thanks,
Bill
Click here for my best strip time!
98 WS6, Nitto 315/35/17's,MAC Headders and Off Road Y-Pipe, Flowmaster American Thunder Catback, Vig 3200 Stall, TransGo Shift Kit, MTI Clear Lid, K&N Filter, TR55 NGK's, Taylor 8mm wires, EGR MOD & Other Free Mods. 12.84 @ 104.15 MPH 60ft 1.73.

JurisAg02

Low collant light was just a bad sensor and the problem the whole time was the MAF. I put in a stock one with screen in it and now she drives very smoothly again! It was just a coincidence that the coolant light had gone outwith the MAF.
no more smoke now
Rick