Out of the blue, my '05 TB threw a CEL. Idle was rough in gear but seemed ok other then that. Checked with my scanner and it's P304. The truck was running fine before that. We've had a lot of bad weather lately and the TB was out in rain and ice/snow a lot. Isn't there something about the 4.2 and water on cylinder four? I did a search but couldn't find anything.
Water on #4 cylinder?
- Thread starter thebat
- Start date
Don't know if these will help you, but here you go.
You might check here
https://gmtnation.com/forums/threads/water-sitting-in-sparkplug-holes.3905/
and/ or here
You might check here
https://gmtnation.com/forums/threads/water-sitting-in-sparkplug-holes.3905/
and/ or here
christo829
Member
Some of the older years had hood seal issues, and water could get in and drip on to the
intake, but I thought they had fixed that by 05. You can check down in the plug well and
see, or just spindle a paper towel and stick it in there.
I had a brand new coil go bad on me just going from one stoplight to another. Pulled out
of my driveway, everything was doing fine. Got a few miles down the road, went to stop for
a light, and all of a sudden the truck started bucking, sputtering and CEL flashing. Pulled over,
checked Torque, and #2 was misfiring like crazy.
So, yes, unfortunately, they can fail without warning. And that was an ACDelco coil. Glad I got in the habit
of always having a spare around!
Good Luck!
Chris
intake, but I thought they had fixed that by 05. You can check down in the plug well and
see, or just spindle a paper towel and stick it in there.
I had a brand new coil go bad on me just going from one stoplight to another. Pulled out
of my driveway, everything was doing fine. Got a few miles down the road, went to stop for
a light, and all of a sudden the truck started bucking, sputtering and CEL flashing. Pulled over,
checked Torque, and #2 was misfiring like crazy.
So, yes, unfortunately, they can fail without warning. And that was an ACDelco coil. Glad I got in the habit
of always having a spare around!
Good Luck!
Chris
Mooseman
Moderator
It could just be bad. The usual way to check is to swap the suspect coil with another cylinder (i.e. #4 <> #3), clear the codes and see if the misfire follows the coil. If you do find water in the plug well, it's probably the seal under the coil and #4 is notorious for that since water drips right onto it from the cowl.
YEEET.
I did this mod when I first got the truck and people were first talking about it. Go to a store or junkyard and rip off some firewall weatherstripping from an Audi or some car. Cut it to size, and put it on the firewall above the engine across the length of the truck. WHERE THERE ISN'T ANY FROM THE FACTORY! Make sure it also doesn't drip on a hot exhaust manifold. Can cause that to crack too!
I did this mod when I first got the truck and people were first talking about it. Go to a store or junkyard and rip off some firewall weatherstripping from an Audi or some car. Cut it to size, and put it on the firewall above the engine across the length of the truck. WHERE THERE ISN'T ANY FROM THE FACTORY! Make sure it also doesn't drip on a hot exhaust manifold. Can cause that to crack too!
Thanks everybody. It finally warmed up enough for me to work on the truck. I pulled number 4 coil and sure enough, there was moisture all over the coil and a little puddle around the plug. I dried everything thouroughly, but I decided to replace the coil. I couldn't get into it enough to be confident there was no more moisture.
I didn't bother doing the swap routine because of all the water. I dried the area good, replaced the coil, cleaned spark plug and now the truck is running great.
Since I have the new coil with gasket, do you think the water won't be able to work it's way in again?
I didn't bother doing the swap routine because of all the water. I dried the area good, replaced the coil, cleaned spark plug and now the truck is running great.
Since I have the new coil with gasket, do you think the water won't be able to work it's way in again?
Mooseman
Moderator
Maybe, maybe not. #4 is notorious for water intrusion due to the cowl dripping right on it. If the gasket on the old one was cracked or shrunk, the new one might solve it.
christo829
Member
Did you use any dielectric grease on the new coil boot? Just a light film would probably help keep moisture out.
Some coils came with a small bit in the boot, but never hurts to make sure.
Cheers-
Chris
Some coils came with a small bit in the boot, but never hurts to make sure.
Cheers-
Chris
I did. I forgot to buy it when I picked up the coil. I was halfway home when I remembered. I turned around, went back to Advance Auto and picked up $1.50 worth. I smeared it pretty good on boot and plug. So far so good.