BAD2000TA

iTrader: (6)

OK, I'm about ready to shoot this thing! I need some help trying to tackle a massive misfire problem under a load. Here's the rundown: 2001 Trans Am. Original motor exploded due to valve spring failure. Replaced with a 2004 LS6 block, LS6 heads (milled .020), Mahle forged -6cc pistons, SCAT H-Beam rods, SCAT 4" crank, Comp Cam 224/230, .610/.605" 114 LSA cam, stock intake and injectors. G-Force loaded tune, but didn't help.

I am getting P0300 and flashing SES light. I know this means a misfire and fuel dumping into cats.

The question is why. Plugs (NGK TR55's) were black on passenger bank, fairly normal on driver's bank. So, I replaced O2 sensor on the passenger bank this morning - no changes. Previously have switched coil banks, put stock wires back on, put new plugs in (NGK TR55 platinum), still no change.

Read about crank relearn. Possible problem with the crank crankshaft? G-Force said that it would have throw a code if the crank needed a relearn. True? Another thread mentioned crank position sensor. Can engine still runs with a bad one? How about the cam position sensor?

Also, did a compression check yesterday. Results: cylinders 1, 3, 5, & 7 all had around 210 pounds. Cylinders 2 &4 - 200lbs, 6 - 195lbs, 8 - 180lbs. Now, would cylinders 6 & 8 be bad enough to cause a misfire?

Please help! Can't figure this out! If anyone local has a Tech II or other scanning tool, I would be greatful for some help! Thanks!

Brian

OUTLAWZ RACING

iTrader: (9)

Weird man I had the ame issue but it was my crank sensor. I had a burnt wire on it sometimes it works and somtimes it dident . I have since replace the sensor and wire. Oh check the water temp unit on the driver side head make sure it works. I wold have the car running and have somebody wiggle it to see. I had this happen to me befor and the car would just dump fuel an temp guage would go to zero.

Powerhouse

iTrader: (4)

You sure installed the cam right? May be off a tooth

BAD2000TA

iTrader: (6)

Here's the latest: I pulled the valve covers and noticed that all the valves are in the closed position. Only a few look like that have any pressure from the cam/lifters/rocker arm. When cranking over, they seem to pump up, but immediately collapse - like within 2-4 seconds to the closed valve. Should the lifters bleed down that quickly? Could this be my problem? Does it sound feasible that the valves just aren't opening enough and this is causing the misfire? I'm about ready to pull the heads and replace the lifters. Please advise!! Thanks!!

OUTLAWZ RACING

iTrader: (9)

Hows the oil pressure? The lifters shoudent bleed that bad and quick. Does the motor have any odd noise?

BAD2000TA

iTrader: (6)

Oil pressure is very good. 60-70 pounds when started, 40-50 pounds cruising. Odd noise? Well, I'm in paranoid-mode right now so everything sounds bad. I'd say that the lifters are making some noise, but it's a healthy cam and I can't tell the difference between "normal" sewing machine sound and bad lifters.

I guess I'm mainly concerned about the lifters bleeding down that fast. Should that happen? Or should they stay solid longer (do I need to drop a few Viagra's in the oil filler?!?!) I mean, I have pulled valve covers off my Pontiac 455 and the valves are compressed on the lobes showing lift. Shouldn't the LS1 act accordingly?

BAD2000TA

iTrader: (6)

Reading more today, I'm thinking maybe it could be the crank position sensor. Is there a way to test it? Easier to replace than lifters......

BAD2000TA

iTrader: (6)

OK, replaced crank position sensor - no change. I went to G-Force this morning. Mike did the crank re-learn - no change. Swapped a coil pack on the passenger side - no change. The passenger bank is clearly the side that's having a problem. All the plugs are showing black on the passenger side, normal on the driver's side. So, I tried changing the O2 sensor - still no change. So, what else can it be? I'm down to:

Bad PCM?
Bad Lifters?
Dead cylinder?

PCM: Anyway to test if it's bad?

Lifters: I can change, but would they be bad enough to cause the problems?

Dead cylinder: Did a compression check on all cylinders. Driver's bank - all 210 pounds. Passenger bank: 2 &4: 200 pounds, 6: 195 pounds, 8: 180 pounds. OK, 6 & 8 are low, but are they low enough to cause a massive misfire? How can I test??

Need help!!!!

AgFormula02

iTrader: (13)

Check your wiring and also check for a intake leak. May explain why one side is black and the other is OK.

beedo

iTrader: (28)

Have you checked the ignition fuses? Is the pass side banks fireing at all? I have ran across it ONCE, there was no power going to main coil plug that fires all of the coils. Dont know why it popped the fuse but all was good after, the whole drivers side bank was dead.

BAD2000TA

iTrader: (6)

Yep, they are firing. Just have a misfire. I'm trying to determine if the PCM, lifters, or cylinders could be causing. Coils are sending signal to the plugs - all the plugs on the the passenger bank are firing and are black.

AgFormula02

iTrader: (13)

if you have a vac leak in the seal of the intake to the head it will make one bank run like dirt. Check it with a scaner and se where your LTFTs are at. If they are fine, then I am completely wrong.

BAD2000TA

iTrader: (6)

Tuner did look at that, but I don't recall the reads. He felt it was something else.

Anybody else have an opinion on what it could be?

7420NW7TH

iTrader: (8)

On my old GMC Sierra, I had that same problem. Misfires in 6 and 8 on the passenger side. Turned out to be that little fuel pressure regulator on the fuel rail going from the drivers side to the passenger side fuel rail was bad, causing it do dump too much fuel in on the passengers side. Replaced it, and the problem was solved (got better gas mileage too, heh). My f-body has aftermarket rails on, so I don't remember if the stock fuel rails have that regulator?

Tootall

iTrader: (78)

since you pulled the motor . . . are you positive that you reconnected the ground wires? The few on the back, and on the drivers side?

BAD2000TA

iTrader: (6)

I'll check that, too.

BAD2000TA

iTrader: (6)

Yep, triple checked the grounds. All three on the driver's side head, big one on the passenger side block near starter, and body ground from battery.

I wish it was that easy!

BAD2000TA

iTrader: (6)

Well, I finally found out what the problem was: plugged catalytic converter on the passenger side. I pulled the Y-pipe off, fired the car up and there was no flow at all. Remove the cat, gutted the interior, re-installed and fired it up again. Success!!

This was without-a-doubt, the most frustrating problem I've ever had with a car!! I'm just glad I finally could figure it out!!