Driver's side header is luke-warm
 

Posted this in PCM & Diag as well..
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I've just noticed this. Pass header is lightning hot-as it should be, & driver's is luke-warm after running.
From initial start-up a few months ago, it ran rich. This might have been extra fuel from driver's side. Also, on start-up, there was some backfire/didn't know which side.
Just had a tune by Frost, and it's still rich/driver's header is cool.
The only codes are for evap.
A noid light shows spark at cylinders on driver's bank. There is some combustion at driver's side as exhaust is slightly warm.
I'm wondering if swapping the O2 sensors might be a good starting point?
Any suggestions are appreciated.

compare spark plugs from one bank to the other.

post pictures if you can please

Just re-checked the situation. While there is plenty of fuel, I think that the spark is either intermitt or missing on the driver's bank. There have been a couple of problems with open wires on this harness, and I think there may be a bad ground.
I will examine the plugs. Thanks.

Two plugs from the driver's side show no combustion whatsoever. They are clean.
A plug from the pass side looks like a functioning plug should....a bit of soot and evidence of combustion.
I'll have to re-check for driver's spark after the weekend.

You can flip the wiring harness going to the coil packs plugging #1 into #7 and #7 into #1 and the same for 3 and 5. This will cause it to backfire and your header will be cool since the spark timing will be way off.

This will cause it to run really rough and backfire alot(ask me how I know). Since you did not say that I am going to suggest that you check key on power on the pink wire at the injectors on the drivers side bank. The LS1 harnesses use 2 fuses for injector power. One for each bank. Check your injector fuses if you do not have power at your injectors. If you had any combustion on that bank of cylinders you would not be able to touch the header. At least not for very long.

Even though you have plugged a noid into the plug and see the injector and see it pulsing, does not mean it is making good connection to the injector.

Selecting the wrong noid can even cause the plug connection to open up and not make connection with the injector pins. I have done this in the past and ended up replacing the connectors in the injector plug.


Regards, John McGraw

Interesting. This makes sense. My other related post in "Diagnostics" gathered a similar answer, except that that reply suggested that the reworked harness may have had the coils wires swapped (reworked harness splicing) by accident, with the same result you have suggested. I don't understand how wires could have been incorrectly spliced as in that example. The harness rework would not have required it.
Your example is possible, but since all four tubes are cold, it would have required all four coil plugs @ driver's cyls to have been swapped, which doesn't seem probable. Anything is possible, so I'll verify your suggestion.
The harness rework changed from the factory designed 2 fuse (1 for each bank), to a 1 fuse system. With the reworked harness (1 fuse), I can see how it would be possible to have power on the pass bank (the HOT header), but none on the driver's bank (COLD).
Maybe they forgot to splice the power in to the driver's bank??
We just arrived home from vac and I'll be checking out all of the possibilities, tomorrow.
Thanks for the help.

John,
As a matter of fact, all of the noid light testing I performed before initial start-up involved only the driver's bank cyls. So, your point does apply to my situation. I'll be checking it out, soon.
Thanks.

When I first started my 5.3 engine my drivers manifold was cool while the passenger was hot. Turned out I had some clogged injectors. They are pretty easy to remove, a couple of mine were visibly clogged.

Good luck

Thanks,
This set was recently resized and flow-matched, so they should be good. It's easy enough to swap a couple.

LSXCESS..thanks to you & edcmat-l1 for this suggestion.

I found that the small, separate harness which joins the coils had been reversed. Similar to what you described, the cable ran 7-5-3-1, instead of the correct 1-3-5-7. It runs like a top, now...no more backfire, and explains why it took so darn long for it to heat up!
Now I have to solve the 'why is the oil pressure so low' issue? 18 lbs hot

Glenn
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fuel in the oil?

Thanks...this could very well be. During the cold header issue, the air (& my clothes) was thick with the smell of unburned fuel. Hope I didn't damage the rings.

Thanks for the simple fix. Sometimes, I need another pair of eyes to properly assess the situation.
I changed the oil & filter. Sure enough, the oil reeked of gas.
Oil pressure went from 18 lbs hot @ idle before the change, to 25-26 lbs after change.
Cold pressure went from 32 before, to 42 afterward.
It also increased from 32 @ 2000, hot, to 42 @ 2000.
The car hasn't seen any acceleration, yet, so I couldn't say whether that has been affected.
With a slightly heavier oil, I can do a bit better.

I know this is an old thread but I wanted to say THANKS! for posting it. I had the coil harness reversed too and was stumped. Turned them 180 degrees and it runs like a champ. I'm sure I reversed them when I took them apart to clean them.

Thanks again.