Coils Arcing (glowing In Dark)

HighdesertGMC · September 19, 2009

Just wondering if anyone else has had this problem. I have a 2003 GMC sierra 5.3 L with 78K and changed plugs only at 50k. Also no codes.

Have noticed a misfire at idle lately. Coming back from a long trip last week 400 miles I noticed a small amount of jerking when the cruise would pull back up after going down hill. I pulled over that night and checking under the hood I could see #1 and #5 ignition coils glowing and also #4 plug wire at the plug end arcing.

Funny thing is #4 wire stopped arcing after about 20 seconds but the coils stayed glowing.

Last night I started the engine and the #5 coil was lighting up then stopped after 10 seconds. I went for a drive and warmed it up and never got it to glow or arc again. Even after dumping water on engine. Still notice a misfire and some uneven idling.

Also had a problem with low idle and stalling if I accelerate and let off pedal quickly in gear.

I spent yesterday on a couple things, cleaned MAF (have a K&N filter), cleaned out throttle body, check for intake manifold leaks and fuel pressure regulator plus changed fuel filter. This has fixed the low idle stall problem.

I didn't have the latest info when I changed the plugs at 50k so they are still at .45 not .40 could this be a problem?

Any input before I buy a couple coils, wires and new plugs. Funny I'm not getting any codes. I do run techron fuel system cleaner every 3-5k and do my oil changes with synthetic blend every 5k.

Bob

2COR517 · September 19, 2009

The difference between .045 and .040 shouldn't be a big deal. I would put new wires on (ACD or Napa Premium) and go from there.

jrod332 · September 19, 2009

could it be a bad distributor cap or rotor. In a 98 GMC I had a screw had loosened and fell out of the rotor causing it not spin and spark all the plugs. As a result one of the manifolds would get cherry red.

WilliamBos · September 19, 2009

could it be a bad distributor cap or rotor. In a 98 GMC I had a screw had loosened and fell out of the rotor causing it not spin and spark all the plugs. As a result one of the manifolds would get cherry red.

No cap/rotor on the new trucks. 1 coil per cyl mounted on valve cover.

alwcurlz · September 19, 2009

Just wondering if anyone else has had this problem. I have a 2003 GMC sierra 5.3 L with 78K and changed plugs only at 50k. Also no codes.

Have noticed a misfire at idle lately. Coming back from a long trip last week 400 miles I noticed a small amount of jerking when the cruise would pull back up after going down hill. I pulled over that night and checking under the hood I could see #1 and #5 ignition coils glowing and also #4 plug wire at the plug end arcing.

Funny thing is #4 wire stopped arcing after about 20 seconds but the coils stayed glowing.

Last night I started the engine and the #5 coil was lighting up then stopped after 10 seconds. I went for a drive and warmed it up and never got it to glow or arc again. Even after dumping water on engine. Still notice a misfire and some uneven idling.

Also had a problem with low idle and stalling if I accelerate and let off pedal quickly in gear.

I spent yesterday on a couple things, cleaned MAF (have a K&N filter), cleaned out throttle body, check for intake manifold leaks and fuel pressure regulator plus changed fuel filter. This has fixed the low idle stall problem.

I didn't have the latest info when I changed the plugs at 50k so they are still at .45 not .40 could this be a problem?

Any input before I buy a couple coils, wires and new plugs. Funny I'm not getting any codes. I do run techron fuel system cleaner every 3-5k and do my oil changes with synthetic blend every 5k.

Bob

If there aren't any codes, then it's not electronic it nature but, possibly still an electrical issue. 50k miles is pretty early for a spark plug change. What was the reason for changing them? Also, do you mean the coil was glowing as in the coil itself or the heat sink was glowing consistently or is it a flashing glow? It sounds like you don't have the spark plug boots fully seated at the spark plug(s), causing a misfire. The way I have re-inserted mine was to push them into place till a click is heard/felt at the spark plug first. I've had to pull mine out and re-insert several times before I knew for sure it was making a positive click. It's kinda tricky with those metal spark plug boot shields. It will also help to use some dielectric grease inside the boots. These are pretty high discharge coils and could be shorting into those metal shields and then to the exhaust manifold. Also, if you're using iridium plugs, the gap should be at .040, and if you're using platinum plugs they'll be at the factory .060 setting.

Hope this info helps, good luck!

HighdesertGMC · September 19, 2009

Just wondering if anyone else has had this problem. I have a 2003 GMC sierra 5.3 L with 78K and changed plugs only at 50k. Also no codes.

Have noticed a misfire at idle lately. Coming back from a long trip last week 400 miles I noticed a small amount of jerking when the cruise would pull back up after going down hill. I pulled over that night and checking under the hood I could see #1 and #5 ignition coils glowing and also #4 plug wire at the plug end arcing.

Funny thing is #4 wire stopped arcing after about 20 seconds but the coils stayed glowing.

Last night I started the engine and the #5 coil was lighting up then stopped after 10 seconds. I went for a drive and warmed it up and never got it to glow or arc again. Even after dumping water on engine. Still notice a misfire and some uneven idling.

Also had a problem with low idle and stalling if I accelerate and let off pedal quickly in gear.

I spent yesterday on a couple things, cleaned MAF (have a K&N filter), cleaned out throttle body, check for intake manifold leaks and fuel pressure regulator plus changed fuel filter. This has fixed the low idle stall problem.

I didn't have the latest info when I changed the plugs at 50k so they are still at .45 not .40 could this be a problem?

Any input before I buy a couple coils, wires and new plugs. Funny I'm not getting any codes. I do run techron fuel system cleaner every 3-5k and do my oil changes with synthetic blend every 5k.

Bob

If there aren't any codes, then it's not electronic it nature but, possibly still an electrical issue. 50k miles is pretty early for a spark plug change. What was the reason for changing them? Also, do you mean the coil was glowing as in the coil itself or the heat sink was glowing consistently or is it a flashing glow? It sounds like you don't have the spark plug boots fully seated at the spark plug(s), causing a misfire. The way I have re-inserted mine was to push them into place till a click is heard/felt at the spark plug first. I've had to pull mine out and re-insert several times before I knew for sure it was making a positive click. It's kinda tricky with those metal spark plug boot shields. It will also help to use some dielectric grease inside the boots. These are pretty high discharge coils and could be shorting into those metal shields and then to the exhaust manifold. Also, if you're using iridium plugs, the gap should be at .040, and if you're using platinum plugs they'll be at the factory .060 setting.

Hope this info helps, good luck!

HighdesertGMC · September 19, 2009

Just wondering if anyone else has had this problem. I have a 2003 GMC sierra 5.3 L with 78K and changed plugs only at 50k. Also no codes.

Have noticed a misfire at idle lately. Coming back from a long trip last week 400 miles I noticed a small amount of jerking when the cruise would pull back up after going down hill. I pulled over that night and checking under the hood I could see #1 and #5 ignition coils glowing and also #4 plug wire at the plug end arcing.

Funny thing is #4 wire stopped arcing after about 20 seconds but the coils stayed glowing.

Last night I started the engine and the #5 coil was lighting up then stopped after 10 seconds. I went for a drive and warmed it up and never got it to glow or arc again. Even after dumping water on engine. Still notice a misfire and some uneven idling.

Also had a problem with low idle and stalling if I accelerate and let off pedal quickly in gear.

I spent yesterday on a couple things, cleaned MAF (have a K&N filter), cleaned out throttle body, check for intake manifold leaks and fuel pressure regulator plus changed fuel filter. This has fixed the low idle stall problem.

I didn't have the latest info when I changed the plugs at 50k so they are still at .45 not .40 could this be a problem?

Any input before I buy a couple coils, wires and new plugs. Funny I'm not getting any codes. I do run techron fuel system cleaner every 3-5k and do my oil changes with synthetic blend every 5k.

Bob

If there aren't any codes, then it's not electronic it nature but, possibly still an electrical issue. 50k miles is pretty early for a spark plug change. What was the reason for changing them? Also, do you mean the coil was glowing as in the coil itself or the heat sink was glowing consistently or is it a flashing glow? It sounds like you don't have the spark plug boots fully seated at the spark plug(s), causing a misfire. The way I have re-inserted mine was to push them into place till a click is heard/felt at the spark plug first. I've had to pull mine out and re-insert several times before I knew for sure it was making a positive click. It's kinda tricky with those metal spark plug boot shields. It will also help to use some dielectric grease inside the boots. These are pretty high discharge coils and could be shorting into those metal shields and then to the exhaust manifold. Also, if you're using iridium plugs, the gap should be at .040, and if you're using platinum plugs they'll be at the factory .060 setting.

Hope this info helps, good luck!

Your right, platinum, iridium different gaps!

I'm almost positive the manual showed to change plugs at 50k.

Don't remember if stock plugs were platinum etc. Been awhile.

They seem to be glowing on the side of the coil at least on #1. On #5 coil it's more of a flashing on the side of the coil. No arc jumping from coils to mounting plate or valve cover.

I'll look at it tomorrow a little more and check the plug wire ends. Yes I put some

dielectric grease on the end when I changes the plugs at 50k.

Another thing is now my idle is good but when in gear idle (off the pedal) likes to go up to around 1000 rpm and have to hold the brake to keep from going about 25-30 mph. If I put it back in neutral or park it drops back to around 600 rpm a/c off.

Been so long that i can't remember if this was normal?

Thanks

Bob

jerseymike68 · September 19, 2009

Thank You!

HighdesertGMC · September 19, 2009

I double checked triple checked what I can. Also checked everything I could with my Diablosport tuner I'll see if I can snag my tech II from work and take another look.

Guess I changed the plugs early ( guess I didn't like then a couple years ago?)

Going to order 2 ignition coil and a set of plug wires.

Found a good price a AC-Direct reasonable shipping.

Bob