I am a service manager at a dealership here in east texas & we have been playing around with cam & head packages on a few vehicles. I talked a buddy of mine who is also a service manager @ a local dealership to let me do some work on his 06 Z-71 5.3 after he has seen some our recent sucess at the track.
Here is the NIGHTMARE: I decided that we could make a nasty little truck & also was curious to see what it was capable of. So i ordered a comp 212/218 115 lsa, GM cnc ported Z06 heads milled to 61.9 cc with 250cc intake runners, pacesetter headers, 3000 stall, magnaflow cat back exhaust system & some new GM lifters.
after installing the components we now have a horrible backfire. This is what we know so far:

• leakdown test indicate no leakdown on any cylinders at top dead center
• compression is consistant across all cylinders
• injector voltage is normal at injector harness
• injectors have sufficent pulse verified with noid light
• fuel pressure is fine & fuel rail has no restrictions
• all injectors ohm out correctly even replaced them (why not?)
• installed a new pcm
• was not getting cam reference signal so installed a new cam sensor
• passenger side bank runs excessively lean
• the backfire goes away if we unplugged the #6 injector
• have check communication voltage from cam sensor to pcm (all fine)

we have ton a ton of other crap to this thing to no avail. I am hoping that maybe someone could possibly enlighten me....... if not I will be forced to set fire to this bitch in my shop

thanks in advance for any input.....

 

Was the cam installed dot to dot? Sounds like it could be a tooth off or two. Could this be the reason for the cam sensor malfunction?

Go back and pull both rocker arm sets off and retorque using locktite. There was a guy (tarinitup i think) that was having similar issues and he a had some rockers that were loose. I wonder if the #6 exhaust rocker isnt properly torqued thus building up fuel and not being able to vent it. Try that and see what it does.

 

Call TAC & ask the "experts" (heavy sarcasm)

I feel sure you have already done the obvious such as double-checking for pinched wires and stuff, but I just wanted to remind you yet again!

If that thing has any DTC's, you might look up the flow charts in SI and post them up here so we can all scratch our heads.

Haven't accidently created any vacuum leaks have you? When I see a problem with an entire bank and that bank only, my first instinct is to check out intake gaskets & check for exhaust restriction.

Just my .02, hope it might be of some help.

 

Spray some starting fluid around every contact that your intake makes to the heads, tb and you might as well check the intake tube after the MAF. If it leaks, the engine will drop in rpm and possibly die. Just some ideas.

 

we now have a cam signal/ ni vacume leaks. we called TAC & they are on the verge of sending a field engineer out so that is now out of the question. i do know the marks are tooth to tooth. i can manually shhot gas through the vacume on the intake & it goes away. we have had the intake off twice to no avail......

 

Since you installed headers, I would check to make sure the o2 sensors/harnesses are fine. If one of them was damaged/contaminated during the swap it might fool the pcm and make a lean condition on one bank.

Again, we are still fishing in the dark here, but who knows...

 

pinched intake gasket??

 

So, did you burn that bitch down or what??

 

Where are you at now dood? PM me if you'd like, I may have some info for you, depends on where your at.

I would suspect the cam. Maybe a defective grind? Try swapping them out again, just for kicks.

 

Check that your O2 wires are not in contact with the headers. Mine ran like *** until I got into PE mode. Found my O2 wire laying on the header and cooking. It made my truck run so rich it looked like a diesel with a banks kit on it.