Spiers

Last summer I parked my cam only car to do alot of modifications and go max effort cam only. Here is what I changed:

Moroso windage tray
Patriot Gold dual extremes
Scorpion 1.7 rockers 7/16 ARP studs
LS7 lifters
Trickflow guideplates
Trickflow chromoly pushrods
No AC, PS, AIR, EGR, ABS
Wire tuck, have extended most wires and rerouted to hide them
Battery relocation
SJM ABS delete
CSR electric water pump
MSD cap & rotor
SVO 30# injectors
Professional Products 58mm TB (ported intake inlets)
All vaccum lines/ MAP sensor relocated to the rear of the intake
Fuel line relocate
PCV deleted just running breathers on the VCs
Ebay longtubes & ypipe
Relocated coil/ICM with longer coil wire
Mail order tune from Ion (Madtuner)


It's a rebuilt bottom end (15k) with stock heads (milled), a Comp Cam 230/236 .510/.555 112, Cloyes timing set, Trickflow 7.2 chromoly pushrods, NGK V-power plugs gapped at .040, and Taylor Spiro Pro wires. It ran perfect before I parked it. Got it started back up a few weeks ago... It has a backfiring problem at idle and is misfiring. If I let it run long enough/hold the RPM's up, the #3 and #5 header primaries begin to glow orange. Also #4 and #1 primaries are still very shiny and chrome while the rest have discolored/turned gold as new stainless headers do. But I checked for spark at #1 and it is getting spark. I have triple checked all the plug wires. They are all in good condition, on correctly, and tied away from the header. I have checked for any arcing in the dark.

My fuel pressure runs right around 50psi, I have checked the regulator, I am positive the timing gear dots are lined up correctly, I have re-adjusted the rocker arms 3 different times using three different methods. I have a brand new coil wire custom made from Taylor, I have the tune file for anyone who would want to see it (will need LT1 edit to read it). I checked the pushrod length when I put the motor together and the valve sweep pattern was dead on as far as I could tell. I tried switching the injectors around to see if the temperature of the primaries would follow but nothing changed. Sometimes when I start the car I have to give it a little gas for a few seconds to start and before it will idle by itself.

Also I am not throwing any codes, except for P0122 for low TPS voltage, which is a whole nother problem with the PP throttle body. Didn't want to idle, I have the stock TB on for now until I figure out this misfire.

Im pretty much stuck right now, don't know what else to try. The only things I can think of now are to check the opti harness and the injector wires. Can anyone tell me how? Earlier today I got an idle vid. The car is backfiring in the video. This is a warm start and I didnt have to give the car any gas on this one.

Guest47904

Identify any dead cylinders.

BlackbirdWS6

First, 50psi of fuel is too high. Get that to 43 with the vacuum line off the regulator. Next, I would confirm you did not accidentally swapped injector wires as you mentioned you did some work to the harness.

As for the headers getting hot, I had this issue with my build and it turned out to be too lean. The tuner corrected the issue on the dyno when he was able to get the wideband on it. Only my center cylinders would glow a little which makes a little sense since they are closer together.

Did you double check the spark plug gap?

bw_hunter

So, to clarify, you did the cam change before you parked it and it ran fine but after the above changes it no longer does?

Did you tell ion that the pressure was set to 50 psi? It doesn't matter what the pressure is if it's tuned for it.

Valve timing would be the first thing that comes to mind.....

Spiers

The regulator is stock I havent messed with the fuel pressure... my electronic gauge is just showing around ~50psi little less. I pulled all the plugs and they are all black. I double checked gap at .040-.045.

And yes the car ran just fine when I parked it to begin my work and after first startup I have had this misfire/backfiring problem.

I know the cylinders are different temperatures. It's weird. The #1 and #4 primaries are not running very hot. I know this because they are still shinier compared to the rest and even after cooling off for just a few minutes I can literally rest my hand on them. #2,6,8,and 7 seem to be normal and have turned a goldish color. Its only #3 and 5 that are glowing hot and have turned blue/purple because of it. If I got an infared temp gun would that help??

Spiers

Would a bad ground somewhere cause this?? I also did battery relocation at the same time and I am having problems with my starter clicking. The car will usually only start if I have a charger on to jump it. Or else it will just click. I have been assuming that the two issues arent related though.

Spiers

I found a cracket plug boot and replaced both the plugs and wires. It no longer backfires but still is not running right and the cyl are still different temps (3&5 glowing). Here is a vid of what its doing now

wtf!!!!!

Spiers

I also had the ICM tested and it failed, replaced the ICM and it made no difference at all.........