Thumper#1

I installed the GMPP LS3 480hp C&C package into a '57 Chevrolet.
At this time, the project is finished but the engine runs real ragged.
It's real rich at idle, and very rough weak idle. I removed the spark plugs and they are all black.
I have installed every sensor connection, earths exactly as required, the O2 sensors are connected into the 2-1/2" MaxiFlow head pipes from the Hooker cast iron exhaust manifolds about 18" from the manifold flange and inclined upward.
I have checked the efi running fuel pressure which is 60 psi.
The MAF pipe is 4" U shaped, the MAF sensor is 11" from the throttle body and is midway between a 8" straight pipe which flat turns to a dry filter. All of this was a GMPP kit.
I contacted a local EFILive tuner who has a good rep. he came and reviewed the ECM file, noticed a few concerns with the fuel map and the idle ignition advance. However he was unsure if his laptop would have enough battery to upload an edit, so he saved the ECM file, and as far as I know has sent it to EFILive for review and comment.
Before he left, he said to change all of the plugs to a non iridium type so he could start with some fresh plugs.
I'm so frustrated with this deal, so much for plug and play!!!
I must also comment that the front drive kit, also GMPP contained an alternator which when first started, voltage spiked to 18v, it had a faulty voltage regulator. Would that damage the ECM and/or O2 sensors?
Any feed back would b appreciated, Cheers.

85LSXTRUCK

iTrader: (2)

Those packages are really expensive and if you want it to be top notch you need to get it on the dyno for a real tune. It will never run to its full potential unless you do so.

Michael Yount

iTrader: (1)

Seems like this story repeats itself with the GM "run and drive like crap" kits over and over, even with the 430HP "stock" engines. I stayed away from it after hearing so many similar stories. Good luck getting it going.

Thumper#1

Yes, I agree, but the car is not even able to make it to the dyno yet unless I flatbed it.

Michael Yount

iTrader: (1)

Too sick to go to the Doctor. I hate when that happens.

Is there any kind of GM help-line that's of any actual, uh, help?

kwhizz

Did 4 LS3 480hp connect and cruise swaps..........Never had a Issue

Ken

G Atsma

While it would not be running absolutely optimum, a Connect & Cruise pkge. should run well enough to use. Something is REALLY wrong here.

Thumper#1

I have to agree, I am going to hire a auto electrician next week to audit every connection I have made.
I guess I'm suffering from "I did it so it must be right!" syndrome.
He will audit all power connections, earths & sensor connections.

DT69cam

I know many guys with LS swaps using the GMPP and it runs perfect. I'm in the middle of mine now. Something is wrong and I'm going to bet you its not the tune. Keep us posted. Double check your GROUNDS, very important, make sure 12 volts to ECM. How did you run your wiring to ECM and alternator and battery ?? Do you have a MIL present ??

LLLosingit

iTrader: (4)

Edit: Disregard. I found the instructions online and it says use non referenced fuel regulator set at 60psi


Double check your instructions, I know some efi systems you have to set fuel pressure when the car if not running.
If the fuel pressure regulator needs a vacuum source they are set without the engine running or you'll be putting to much fuel in the engine. At Idle fuel pressure would be considerably lower than at WOT.

jimmyg

I would check all the grounds , fuel pressure is not vacuum referenced. Needs to be 60psi at idle . Put fresh plugs in it and give it a shot. Are you using MAF that came with kit? I would try putting MAF right before the filter

vannatta20

iTrader: (4)

I bet the MAF needs tuned. A 4 inch tube will read much differently than a 3.5 incher.
Looked at the Long term fuel trims on a scanner. They might be off to much.