2001 Surging after coil and plug replacement

JohnRauk

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Collinsville IL
Had to have the car towed after it died on the highway . It was surges and backfires and dies if you put it in gear. I replaced the coils and plugs since it had never been done. No real change. It will start and surge up and down gradually getting worse untill it dies. Gives me a p0102 maf error. Is it worth replacing this sensor?
Thanks John
 
Unplug the MAF and see if it runs better (doesn't stall). If it does, then it could be the MAF, or it could be an intake air leak. You can also try carefully cleaning the MAF. Unfortunately, most aftermarket MAFs aren't very good.
 
Thanks for the reply. Car runs the same when I unplug the maf. Wish it would run long enough to give more codes. I had the battery disconnected so no old codes are available.
 
Just to be clear... It is the same now as it was before the coil and plug change?
Brand of coils?
Plug gap verified to be 1.0 mm?

Will it continue running if you hold the gas pedal part way down?
 
Oh, and the big one. Have the timing chains and tensioners been replaced? If not, next step might be to do a compression test.
 
I checked the codes after it was towed to my dads(his car). It would start and die. The codes were P0133, P1131,and P1151. All o2 sensor related i believe. However, dad said this is the same thing that happened last summer. His mechanic replaced 2 of the 8 original coils and it ran well for a while. I figured it would be worth replacing the coils and plugs. They are an an inexpensive brand Spectrum from rock auto along with NGK plugs gapped to 1mm.
If I push the gas pedal in it will rev up, run for awhile and start to backfire and finally die.
Timing chains have not been changed
2001 v8 with 108k
 
Non-OEM coils are known to damage the PCM, however I would do a compression test first as your symptoms fit well with a jumped or broken secondary chain.
 
Ouch. Would you expect further damage if the chain has jumped/broken? Might be time to retire the old chariot.
 
I'll do a compression check as soon as I can get back over there. Do you have a preferred gauge for the ls? The stem on mine is way too short to reach the spark plug hole.
Thanks again for all you help
 
Finally got the chance to do the compression check.
1-195 psi 2-200 3-200 4-200 5-195 6-200 7-215 8-200.

I reinstalled the original plugs and coils. It ran the same.

Other observations: If spray ether around the intake the idle evens out.

If I let it idle for 5 minutes or so the surge will even out but still backfiring.
Plugs are BLACK.
Does that indicate a leaking intake gasket ?
20190427_181528.jpg
 
It definitely indicates an intake leak. The actual intake gaskets are just one of several possibilities.
 
What other possibilities should I consider? How would you proceed? The chewed wires under the intake( Help plug ID 2001 V8 ) are the CHT. I suppose it is time to pull the intake and replace the gaskets and repair the damaged wiring.
 
... The chewed wires under the intake( Help plug ID 2001 V8 ) are the CHT. I suppose it is time to pull the intake and replace the gaskets and repair the damaged wiring.

There's one CHT, and you have two wiring bundles circled.

There are internal intake gaskets, possible cracked end-cap, o-rings for the air assist injectors, and PCV plumbing. Could be smoke test time...
 
The chewed wires are on the left bundle. I used an endoscope to find that. I think I'll need to learn of this smoke test. I really appreciate all your help. THANK YOU!
 
It's pretty amazing it ran at all. My best guess is a mouse chewed the CHT sensor wire and they shorted and created a fire. The first pic is the remnants of some sort of insulation or heat shield. Will I need to find a replacment for that? Is it even available?
20190503_200332.jpg
20190503_185230.jpg
 
I don't know how critical it is, and if it helps with the knock sensors or not. I don't know of any sources other than junkyards.
 
Finally got the car back together last weekend. I've put a couple hundred miles on it with no issues. It runs great with the exception of the AC. It doesnt seem to blow as cold as I would expect. The car has 108k on it. Would you tear into it and replace the timing chains and tensioners at this point? Thanks for all the help.
 
John, that is some crazy shit. I got traps all over my garage and catch those little bas---ds every few days. I worry about my car and related stuff as I often find evidence of mice in my garage. Wanted to believe in those ultra sonic plug in units but read stuff that says they are a ripoff. I need a cat but the dog says "hell no".

In line with what you're asking, did you find out when these V8 second gen Ls's due for a timing chain and guides?
 
A cheap way to get rid of mice is to fill a shallow tray/pan with used engine coolant mix.

Just keep it out of reach of any animals that you want to live!!!!
 
John, that is some crazy shit. I got traps all over my garage and catch those little bas---ds every few days. I worry about my car and related stuff as I often find evidence of mice in my garage. Wanted to believe in those ultra sonic plug in units but read stuff that says they are a ripoff. I need a cat but the dog says "hell no".

In line with what you're asking, did you find out when these V8 second gen Ls's due for a timing chain and guides?

No, unfortunately, I have not. Car is running well. I guess I'll keep an ear out for any new noise and hope for the best.
 

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