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5.3L Motor - Misfire Cyl 2

dhcomp

dhcomp

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Ok, so our 2001 tahoe, I do a full tuneup (Plugs, wire, fuel filter), injector cleaner added to tank, sea foam ran though vac line, cleaned out throttle butterfly. No issues, Ran like a champ during test drive, and the day after.

2 days later.....started stalling out in chain controls going up the mtn with my parents driving.
Towed off of summit in full chain controls (2:30am = happy parents :doah:), dumped in the driveway at our tahoe place.

Went to trouble shoot the next day.
Started up the next day, would start every time, but wouldn't' run above idle, and not smoothly at idle. Would stall out in gear.
Added some 2 bottles of HEET to almost empty tank to eliminate possible water in the gas. Pump didn't sound right priming.

Bought a scanner and fuel pressure gauge to verify my hunch that it was a fuel pump (hoping it was some bad sensor). General misfire code, lean bank 1, lean bank 2, and 10-30psi of fuel. I was right :doah:

150k, oh well. Got teh fuel pump/filter replaced.

That tuneup we did was the first major service service besides trans fluid a time or 2. Oil changed regularly, but at walmart.


Now for the kicker: It runs rough, stumbles off of idle, and throws a check engine light.

Code is misfire on cyl 2.

First, How does it know what cylinder is misfiring?

Second, in my head, cyl 2 has the following things that could go wrong.
Air - its got to be getting air, or the rest of the cylinders wouldnt' work.
Plug - need to inspect
Wire - resistance must be tested, but "new".
Coil - resistance must be tested per service manual
Injector - must be cleaned somehow?

Am i on the right track for this? Anything simple i'm missing.

My parents are getting frustrated, and we (myself included), are regretting touching the thing at all. If its not broke, don't fix it....right?:doah:
 
There are 8 coils on that engine, one for each cylinder that the ECM fires. I don't know exactly how the ECM knows which cylinder but i'm sure it has something to do with the coil for each cylinder and or the crank sensor.
 
4X4HIGH said:
There are 8 coils on that engine, one for each cylinder that the ECM fires. I don't know exactly how the ECM knows which cylinder but i'm sure it has something to do with the coil for each cylinder and or the crank sensor.
Click to expand...


Got it. And for the record, I'm an idiot. Was too tired when i looked up cyl 2 to check teh plug wires. Looked it up again, realized i was checking the wrong cylinder. Has my dad verify the plug wire was secure..and no more misfire.

Took me longer to type this thread than for him to fix it.:doah:

Guess that is the type of logic you have when you are sick and spend most of the day in bed.:haha:
 
also big thing on newer stuff.

stick with oem brand and # plugs.

can cause big problems and chasing around for ever and then figure out its the plugs. :doah:
 
sweetk30 said:
also big thing on newer stuff.

stick with oem brand and # plugs.

can cause big problems and chasing around for ever and then figure out its the plugs. :doah:
Click to expand...


Yep, definitely took that warning. Replaced with delco's. But IIRC, the stock ones that came out had the NGK and delco name on them....or just NGK.

Maybe the original owner did a premature plug change. Really, before the tuneup, it ran fine....just a touch rougher than it should.

Who knows....but it runs now.

Wierd thing on wires though, the repair manual SPECIFICALLY states there are 2 styles/types of coil/wire setups, and that you HAVE to use teh right ones together. Well, kragen only carries one style, that really, it too long. But we made them work.....actually looped/ziptied the rear passenger side to keep it out of a firewall pinch weld.

Good thing these are 100k tuneup trucks, changing that rear plug sucked :doah:


Haha, but then again, my parents 90 burb they bought new made it to about 180k on the original plugs w/o a tuneup....and only got changed cause the new owner got it tuned up. Ran like a champ :)
 
sweetk30 said:
3" body lift makes it super easy. :haha:
Click to expand...

Bastard :haha:

To get it off, i used a plug socket to small spinner adapter that converted 3/8 drive to some allen socket, to an allen wrench, to a nut driver that i could put some leverage on the allen key with.

Haha. It was quite the contraption, but worked. God, even getting the plug wire on/off was a pain. And WTF is up with those plug wire cover things? That heat shield should have been built into the exhaust manifold or something, those were dumb.
 
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