misfire problems help out please

Posted: Fri Oct 08, 2010 7:30 am Post subject: misfire problems help out please

Okay im gonna lay out the whole story. Cars mods are 2.7 pulley , 20 degrees timing , 42.5 injectors , s3ic from zzp , Johnson pump , stock tb heads and sc . ssac headers with no cat . vs cam and air intake . 180 thermo , I think that's it car ran good 13.06 a few weeks ago at 107

So im on my way to work yesterday doing 70 or 75 on cruise and its raining pretty good like it has been the last two or three days . I move to the slower lane to go around someone , and im still on cruise control no touching the gas and then move back into the fast lane and the car starts to buck like when you hit water and the tcs comes on but misfires. My cel starts flashing and i call up misfires on the aeroforce and have a ton on cylinder 3 and 4 . So i let off and go down to 60 and cruise and its all fine . Go for about another mile and it gets bad so i pull over and check under the hood . Damn 3 and 4 are not the same coil pack , i should have know but was hoping . So everything looks fine and i start it up again or try to and its bad . So i get towed home .

I get home and take the plugs out and they look fine and all consistent .So i go an buy new plugs since its cheap and easy , nope now all the cylinders have misfires .

Next try take the coil packs off my dads gtp and swap them onto my car and try that and the same thing . So i go to the gm dealer and get new wires , also knowing that wires wouldn't help but i gotta try . So while there they said check the ignition control module so i swapped that out of the gtp onto mine and same thing, runs like crap .

I then put the plug wires on and same deal.

So for my next trick i check the fuel pressure on the rail . It checked out the same at my dad gtp . So key on was 50 on both and then 45-50 when running . So i know its getting fuel

What the hell could i check next . The problem is that dezldave961 isn't around anymore to help out . I don't know if the pcm is fucked up or what . And the car is so modded i don't know who to take it to .

I'm in Amsterdam NY Its 20 min from Albany NY and i need someone with a tuner and a spare pcm .But Ive got no ideas

Someone at work suggested bad gas and i guess maybe but i get it from the same place and its no ethanol and the old lady is anal about shit there but shit does happen .

Any ideas people.

Posted: Fri Oct 08, 2010 11:04 pm Post subject:

Bad crank positioning sensor. Take the balancer off and IIRC its right there, just comes off with like two or three nuts and one plug. Not sure on how much the cost or anything but that would be my best guess.
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1998 Monte Carlo Z34 - 12.94@107.71 Street tires (Retired)
1999 Camaro Z28 - LS1 POWA!

Posted: Sat Oct 09, 2010 1:04 pm Post subject:

Had a broken intake valve spring. Awaiting some pbm 110s

Posted: Sat Oct 09, 2010 2:20 pm Post subject:

You were getting misfires on every cylinder with one broken valve spring?

Anyway I would still rather run LS6 springs than any other ones. My stock timing chain setup looked new still after 15k miles with my XP setup. Ask John if you don't believe me.

Posted: Sat Oct 09, 2010 3:34 pm Post subject:

i allready have the pbm ordered and yeah misfires on 3 and 4 first and then changed plugs and then went to all but at least the compression on the others was all 160

Posted: Sat Oct 09, 2010 5:15 pm Post subject:

Good to hear you're going to turn out well. Let me know via text, if you want tips on how to do it/tools that work easiest/methods for quickest job...

Hopefully that freak incident (VS cam with maybe 45k(?) on the springs now, 12k stock, then cammed since) didn't scare you too much. For those who don't know, I'll be highly considering buying that car off Jeff if he ever decides to get rid of it, because it's a mean ride but smooth to drive... and I kinda trust the guy who did the work to it. Cool

- Dave
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2004 Regal GSX - YouTube channel Stattama T67BB, A2W IC, ST5, heads, L32, GMR diff/chain (11.46 w/ Z7 T66, IS3t cam)
2006 Grand Prix GXP - K&N intake and mufflers only, basically stock for me
2012 F-150 EcoBoost SuperCrew 4x4 - stock DD and roadtrip vehicle
1998 Daytona GTP #838 - I/C*d MP112 L26 - Rust in Peace, engine saved

Posted: Sun Oct 10, 2010 4:49 pm Post subject:

Posted: Mon Oct 18, 2010 6:20 am Post subject:

The monte is all back together and running good with no misfires . My brother did the work and did a good job . Im happy as hell with how it turned out .

Posted: Mon Oct 18, 2010 6:00 pm Post subject:

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Posted: Tue Oct 19, 2010 6:14 am Post subject:

okay got another 3800 question, what kind of job is it to change the timing chain tensioner?

Posted: Tue Oct 19, 2010 5:49 pm Post subject:

That's one of those "while you're at it..." jobs (double roller option, etc). Laughing

Basically, you do everything for a cam swap, just short of dropping the cradle & pulling the cam out (and leave the cam/gear bolted in if not changing chain type).

If you haven't done the valvesprings already, it'd be something nice to do together, since relieving chain tension may allow the cam to slightly rotate independent of the crank, until you can re-align the dots. It also will let you rotate the gears for re-alignment easier, if you have the rockers off (no spring pressure transferred to the pushrods/lifters.)

For the front cover work, you'll need a harmonic balancer puller with the proper 3 bolts (pretty small, 1/4-something I believe), a fresh timing cover gasket (~$14 for the whole Felpro kit with many extras), a new crank bolt (~$6 from dealer). ZZP might actually sell everything, but you'll pay probably 50% more in the end.

If your engine wasn't so fresh, I'd say do the chain, but that'd just give you more to re-assemble that you don't have to do. Anything pointing to your need to do a tensioner anyway? I'm pretty sure it was new when I did the cam.

- Dave

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