Do the 5.3 in my 2005 suburban have individual coil packs or plugs and distributor on it? I notice when I am plowing and snow dust gets in around the engine I get a bad misfire and poor running. I am thinking its one of the wires that's on its way south and water is shorting it out. Any thoughts on where I should look for issues?
5.3L misfire diagnosis
- Thread starter kojackJKU
- Start date
ZMagic97
Explorer
+1 on coil packs
Check the knock sensor harness: I was getting a P0172 and P0175 at random for a few weeks starting back in October. I would reset it with success for a day and sometimes a few weeks. Sometimes it even cleared itself. Then while washing it and the underside one day I got a P0327, knock sensor #1 low voltage. I found out from the factory there is a small gap without a seal between the block valley and the intake manifold, allowing water come weep in over time and not leave. This degrades the knock sensor (factory has no rubber seals or caps) and corrodes it. In my case, it was little enough at first to not let the ECM recognize a bad knock sensor, but instead used the data from knock sensor 1 to add more fuel, thus causing a running rich condition.
While my situation let to some different results, I would still check the harness for the knock sensors, the plug wires, plugs, and coils. connects are always a quick, cheap, easy fix.
I'm curious what your scanner will come in for a code. If you get a single cylinder, I would swap one component at a time and see if it follows.
Hope this helps,
Chris
Check the knock sensor harness: I was getting a P0172 and P0175 at random for a few weeks starting back in October. I would reset it with success for a day and sometimes a few weeks. Sometimes it even cleared itself. Then while washing it and the underside one day I got a P0327, knock sensor #1 low voltage. I found out from the factory there is a small gap without a seal between the block valley and the intake manifold, allowing water come weep in over time and not leave. This degrades the knock sensor (factory has no rubber seals or caps) and corrodes it. In my case, it was little enough at first to not let the ECM recognize a bad knock sensor, but instead used the data from knock sensor 1 to add more fuel, thus causing a running rich condition.
While my situation let to some different results, I would still check the harness for the knock sensors, the plug wires, plugs, and coils. connects are always a quick, cheap, easy fix.
I'm curious what your scanner will come in for a code. If you get a single cylinder, I would swap one component at a time and see if it follows.
Hope this helps,
Chris
Northern_Touch
New member
If I had a vehicle come into the shop with these symptoms i would perform a wet test (literally spray coil and wires with the engine running one by one until you get a misfire or stumble). You will often actually see a spark from the bad wire or coil. If that doesn't work right away and you have access to a scanner you can swap coils or wires from one cylinder to another and see if the problem follows the suspect coil(s) or wire(s). Thats where i'd start personally.
Jaymes_Raye
New member
Had a similar issuein my old '05 Sierra. The area around the knock sensors usually gets wet and the mounting surface will rust and the knock sensors will give a bad signal causing the engine to misfire.
Once you pull the intake manifold off you'll see a flat plate filling the valley between the cylinder heads. The two knock sensors sit recessed in this plate. Tape over the intake of the cylinder heads, and take a wire brush or coarse sandpaper and hit the holes (once sensors are removed) until back to bare metal. Coat with some self etching primer or a few good coats of paint, then make a lip of silicone at the top of the holes. Once everything's dry re-install the knock sensors, install new intake gaskets and re-install intake manifold.
Once you pull the intake manifold off you'll see a flat plate filling the valley between the cylinder heads. The two knock sensors sit recessed in this plate. Tape over the intake of the cylinder heads, and take a wire brush or coarse sandpaper and hit the holes (once sensors are removed) until back to bare metal. Coat with some self etching primer or a few good coats of paint, then make a lip of silicone at the top of the holes. Once everything's dry re-install the knock sensors, install new intake gaskets and re-install intake manifold.
rayra
Expedition Leader
Your ODB scan ought to tell you which individual coil pack is misfiring. If that's what the problem is.
If you've never changed your plug wires you may be due, and might be the source of your trouble when things are getting wet. Certainly a cheaper place to start than coil packs.
I'd also be looking for rat-chewed wires in the splash areas as well as inspecting all the wiring ground locations I could find. Battery, block, main and secondary fuse blocks.
If you've never changed your plug wires you may be due, and might be the source of your trouble when things are getting wet. Certainly a cheaper place to start than coil packs.
I'd also be looking for rat-chewed wires in the splash areas as well as inspecting all the wiring ground locations I could find. Battery, block, main and secondary fuse blocks.
1stDeuce
Explorer
I've not heard that knock sensors going bad can lead to misfire, but raising the hood in the dark and misting in some water with a spray bottle will quickly reveal if you've got any bad plug wires. If it's been 100k miles and they've never been replaced, it can't hurt. The coils themselves also have some potting on them. If it cracks, water can short them out internally, so a good inspection may be the best thing. Since it's not a Ford, you can actually see all the coils and easily inspect them. 
Let us know what you find!!
Let us know what you find!!
ZMagic97
Explorer
Yes it should. P0327 and P0322 are for the knock sensors.
awesome, I will see what comes out of it. I have a atv in the shop now I am working on, so that was taking up my time. But I am waiting on parts for it so I will be able to fire up the burb today to see what comes out of it. When it was misfiring the check engine light (chevy logo) was flashing wildly at me. ha ha.
I call the CEL the chevy logo because every chev I have owned it has been on constantly. THey need to like make it less sensitive or something. It has been on on my dads avalanche for ages but no codes. weird.
I call the CEL the chevy logo because every chev I have owned it has been on constantly. THey need to like make it less sensitive or something. It has been on on my dads avalanche for ages but no codes. weird.
02TahoeMD
Explorer
If you do end up finding that it is a knock sensor issue, it is a half day do-it-yourself repair, you have to remove the entire intake plenum to replace them. Don't want to guess what a shop would charge to replace two small parts like that. I hope it is just a plug/wire/coilpack issue as they are considerably easier and quicker to tackle. Good luck.