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iTrader: (12)

I don't know what in the hell is going on here so maybe someone else has an idea.. Cranked the car (408 lsx '98 pcm/harness) and it runs, but runs like total crap. So we checked all the coils.. #4, 5 & 7 there is ZERO Fire.. So we swap all of the coils over to another set of coil brackets with different wiring and still the same thing.. So we swap coils with my '07 silverado and still the same thing.. I get another '98 computer and swap it and still the same freakin thing. So we break out the multi-tester and start checking the wires. Every coil has a HOT wire and every one of them is HOT.. Every coil has a ground wire and they are all grounded. So we check the signal wires from the computer to the coils. The dead coils did nothing when we spun the engine over. The coils that were firing would jump up immediately on the scanner. We checked all of the wires for "continuity" and that checked out great. We then checked the signal wire at the pcm and it was dead as hell just like it is on the other end at the coil itself. So we are pretty sure that the computer, wiring harness and the coils are all in perfect working order.

Could this be the crank sensor?? If the crank sensor is bad would any of the coils fire? I always assumed that when the crank sensor went bad it wouldn't fire any of the coils.

I am also leaning towards it being a problem with the reluctor wheel on the crankshaft. This crank was repaired and the wheel was removed and re-installed after being repaired. Does this sound like the problem? If so then my only choices are pulling the engine out and taking it apart completely to have the wheel fixed or to put a carb/distributor on it and call it a day like I should have done from the beginning.

The only thing I have changed with this setup since it ran a year ago is changed from relocated ls1 coils back to valve cover mounted TRUCK coils and I had the crank repaired which required them removing the reluctor wheel and freshened the engine.

PLEASE somebody with some knowledge in this area help me out here!!! If it could possibly be the crank sensor then I will swap it with an extra that I have. But I just figured that a crank sensor goes bad and doesn't just half *** work. Any and all help is appreciated..

--Matt

socmguy

iTrader: (18)

sounds like you guys did just about every test you can do. I think you may have it narrowed down to that reluctor wheel on the back of the crank. Pull the oil pan and see if any of them are bent or damaged.

SOMbitch

iTrader: (8)

There are people on here a lot more knowledgable than I but I have dealt with CPS problems helping a friend and his car would not run. 99.9% sure it is someting else. Fingers crossed for you it is not reluctor. His car would not fire at all if that helps you.

intense3123

I think this may be a cam position sensor problem. That has more say into when cylinders actually fire than the CKP sensor does, since it knows what stroke the engine's on. So check into that too.

And I don't think the car would fire up if the CKP sensor was bad, unless like you said only certain teeth on the wheel are bad.

Do you have access to a scope so you can see what kind of signals the two sensors are putting out, that would help you out a lot.

1QuickT-A

iTrader: (12)

We are gonna use a TECH II tool on it later this week and see what kind of signal the crank sensor is putting out.. Hopefully that will tell me something..

CalSpeedPerformance

iTrader: (64)

I had a horrible problem on a brand new ls1 conversion I did and had misfires and ran like total crap. After changing everything possible including wiring harnesses and pcm, I ran a "crank relearn" in HPTuners. It would barely even run well enough to do it but as soon as i did *BOOM* instantly ran perfect and fixed all the horrible problems with misfires and dead cylinders and barely running...


Try a crank relearn

1QuickT-A

iTrader: (12)

Thanks that sounds like a good idea, but I don't think I can get it to run long enough to do it.. The only way it will run now is if you hold the rpms up around 2500 or so and I HATE doing that with it running this rough..

1QuickT-A

iTrader: (12)

I'm gonna swap the crank sensor tonight and hope to God that it fixes the problem..

1QuickT-A

iTrader: (12)

I kinda thought I would get a little more help than this from all the techies, but I guess not. I changed the crank sensor and it did nothing different. We did realize that its only the #4 and #7 coil that isn't firing.. All of the other coils work fine. So we are pretty much pointing our fingers at the reluctor wheel..

Obviously thats the only thing left to blame.. Apparently the crankshaft repair specialists have fucked my engine up and now I'm left with a very nice EFI setup that I can't even use due to someone else's screw up. Whats new about that.. This engine has been a nightmare from the beginning. Bought it from a sorry M'Fer that was suppose to be trust worthy on this board and ended up being a worn out piece of **** and after a year of getting it all fixed and straightened out this is what stems from that...

Anybody got a bullet they don't mind me eating??

cablebandit

iTrader: (37)

did you do the crank relearn procedure? since the wheel was moved, the procedure would be needed i would think.

1QuickT-A

iTrader: (12)

Just when I thought my luck was gettin a little better Jerry.. lol

I haven't done that yet, but it is on the agenda before I do anything with the motor.. I don't have anybody local to come to my house and do anything with HP Tuners. As soon as I get somebody over here we are gonna try that, but its gonna be hard to keep the engine running while we do it..

If that doesn't work then I am out of options.. I'll be pulling the computer, harness and the intake/tb setup that I have grown to like so much and trading it all for a distributor and carb and calling it a day..

Z'mnypit

iTrader: (58)

Matt where do you live? Ive got HPtuners for 98's.

Sales2@Texas-speed

iTrader: (5)

We've seen where 1,4,6,and 7 would be the only ones firing (or the opposite cylinders). It ended up being the reluctor wheel installed backwards on the crankshaft. Shoot me a PM if I can help you figure it out!

zman1969

iTrader: (91)

What he said! - you need to see what signals the sensors are putting out and do further t/d in that area if need be. if your crank sensor is putting out a bad signal(bolt old and new and its a square wave signal) it would have to point to the reluctor wheel. looks like youve done a good job diagnosing what cyl are misfiring you just need to track it down further- thats why diagnosticians are your smartest techs (not me) of course it helps to have all the right tools to do further diag

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iTrader: (12)

Vann, I'm in Gardendale... I've got a guy that might be coming to help, but if not I will certainly give you a call. Thanks

JohnPayne

iTrader: (3)

We unplugged the cam sensor and it still fired the other coils. Not sure if they where firing at the correct time with it unplugged but they still fired.

1QuickT-A

iTrader: (12)

Thanks man I'll definitely get with you about this if we can't figure it out this week. my buddy is gonna bring his TechII over tonight or tomorrow hopefully and we are gonna check the cam and crank sensor to see what kinda signal they are putting out.. Appreciate the help..

Z'mnypit

iTrader: (58)

Sounds good, Hope ya get it figured out.

Sales2@Texas-speed

iTrader: (5)

Yea, when we looked at one that had the wheel on wrong, it had strong and steady signal IIRC, but it was the wrong signal all together and the PCM was freaking out.

1QuickT-A

iTrader: (12)

Well I don't think its back wards, but anything is possible.. I called the shop that repaired the crank and he said it was highly unlikely and that their method of removing and re-installing the wheel is basically fool proof..

And I am positive that the only coils not firing is 4 and 7..