88blazin'

First, this is for a buddy/customer of mine. His car is a '70 chevelle, with an '06 LQ4 swapped in. Ill try and be as informative as possible, this car is got my completely stumped. This is the rundown of the swap

'06 LQ4 with 48k, verified before we pulled it
New main/rod bearings
ARP rod bolts
Comp .617/.634 231/234@.050
Comp Double Valve springs to match cam
Rollmaster adjustable timing set-set to 0*
FAST 92mm Intake
Professional Products 90mm TB
SLP MAF
FMS 36lb injectors
MSD coilpacks
Schwanke premade LS swap harness
Schwanke Tuned '99 Camaro ECU
VATS, Emmisions, Trans controls deleted
Tsunami Fuel Pump
Professional products FPR

As the car sits, it will start hard and run rough. It will not stay running without feathering the gas. If you attempt to rev it, it will backfire through the exhaust, and its pouring gas out of the tailpipes. Its setup to run 02s, and both are brand new. We had a local tuner come and take a peek, he said everything seems to be responding. He even swapped his own personal computer in the car, and it did nothing to change. We checked for spark, and all cylinders are firing, but the spark was orange. My experience is that orange spark, means its weak. We tried unplugging MAF, but nothing changed. We tried another set of coilpacks, nothing changed. Fuel pressure was adjusted from 45-75psi, and it did nothing. MAP and crank sensors are brand new. Coolant temp seems to read correctly. Ripped the timing cover off and double checked cam timing, its dead on at 0*.The car is running severely rich, and nothing we try is leaning it out. Nothing we have tried to unplug, or swap out has offered any change in how the car runs. If you attempt to rev it up, it doesnt seem to allow it to rev up more than 1500ish rpms and just hits a wall and hangs and backfires. We double checked continuity from ECU to coils and injectors. Everything seems to be wired correctly. We tried to add some extra grounds, thinking that it might have voltage issues. I feel like im missing something, im in desperate need of opinions and ideas on where to look next. I cant believe that after everything we have tried, that we havent had any progress either better or worse. Any ideas?

CattleAc

iTrader: (7)

What lifters??? What length pushrods???

Sounds like you have valves open when they shouldn't be...

88blazin'

stock lifters, comp 7.400 pushrods. Pushrod length was measured after the cam was put in, and its 1 full turn after setting zero lash. That should be just about .047 preload. The motor has a healthy 180psi compression on all cylinders, no valves are hanging open. Im starting to suspect that the crank and/or cam gear were possibly stamped wrong. Its running like its horribly retarded, but nothing ive seen so far has confirmed my thinking.Id really hate to have to degree the cam, while the motor is in the car. My gut feeling is that im overlooking something stupid and obvious, but my brain hurts trying to think of possibilities.

BanditDave

iTrader: (11)

Stupid question but did you guys play with the tune at all...i.e. check to make sure the injectors were programmed in properly? Also, if you don't get this licked, then you will need to swap the plugs pretty often if it is as rich as you say if you are going to have a prayer of starting this thing. Is that still a 24X reluctor? Or did it switch to 58x?

Thanks,
Dave

Project GatTagO

iTrader: (7)

Double check your wiring. If one of the injector wires got pinched and is being grounded, that injector will stay on constantly.

Andrew

gagliano7

I would say your injectors aren't programmed correctly.Can you post the tune?

Pop N Wood

iTrader: (1)

It does sound like a stuck injector. Maybe a pinched wire like said above or maybe they are just dirty.

For a weak spark make sure you have full system voltage to the coilpacks. Sometimes guys end up chasing their tails and it turns out to be a bad fuse or power connection.

99VetteFRC

Are you useing stock truck injectors. Ls1 Injectors or maybe aftermarket? Is the fuel pressure matched to the injectors being used. Also make sure the O2 sensors are plugged into the correct bank. I swapped mine when I first ran it and it did something like that, one bank went full rich and the other went full lean.

Fahrenschnell

iTrader: (1)

Check to make sure you dont have the harness to the coilpack banks switched backwards....

Paul57

I think Chevelle's are allergic to fuel injection.
https://ls1tech.com/forums/carbureted-lsx-forum-172/

bczee

iTrader: (12)

Nope.. .. nothing wrong with my Chevelle and EFI !.. must be something personal !? LOL

Well. I hope he does find out what is going wrong.. but most likely it will be the wiring or in the tune due to something that is not stock like all of them aftermarket parts.. MAF, TB, etc ... And with everything being changed all at once. You are just going to have to insolate one problem at a time.

BC

krwyellowZ28

iTrader: (10)

I was having a similar issue but it ended up being a bad C5 FPR that was only giving me 12 psi at the rails... obviously not your problem since you can adjust your fuel pressure. I did, however, start removing variables when I was troubleshooting. You might want to go back to stock on critical items such as the throttle body, MAF, and injectors, and then reload a stock tune or one with just MINOR adjustments.

I'm leaning towards a wiring or tuning issue over a mechanical issue, though.

thunderstruck507

iTrader: (18)

Mine had a similar problem, was some kind of short in the coil pack harness. I swapped a whole new rail on and it ran like butter