LLY: Need help with 05 lly

[86dmax]

Man I need some help.I got a 05 lly with 240K.I have been fighting a problem
with a rough idle/miss for a year already.When the truck is cold it idles fine smooth as silk.When the the trk gets hot it will ack up at idle.If you turn the ac on or put it in gear it goes away and idles fine.If i have my scanner on it when it acts up all balace rates go to 0 and when the miss starts to fade away all the rates wil start reading.I have already changed head gaskets,all 8 injectors,cp3 pump,rail pressure sensor,all 8 injector pigtails.I have also tryed a ECM and injector control module off my buddys 05 lly truck and it does the same thing.Sometimes if you let the trk idle for a 15 minutes or so the miss/rough idle will go away but as soon as you drive it again it starts all over.Do any of you guys have any sugestions im about to blow this thing up.

 

[Dan@PPE]

Have you checked the Ficm harness? It comes out of the ficm and rests on a aluminum bracket to the left of the alternator. There is a know issue on the 04.5-05 LLYs with the ficm harness wearing through the protective tape and shorting on the bracket. Find the support bracket cut the zip tie and inspect the harness for chafing, usually black streaks on the wires and you will see pitting in the aluminum. If found tape up each wire individually and then tape up the main harness, install some rubber under the harness and reinstall a zip tie.

 

[86dmax]

I have had the zip tie cut since i had the truck and the harness looks good.Its funny all this started the day i put a LBZ intake on it,but that should not have anything to do with it.It almost acts like it is someting with the voltage to the injectors due to all the injector balance rates go crazy when it acts up but other than that the truck runs great.Do you think it could possibly be air bubbles in the fuel?

 

[dc3]

bump

 

[cdprayor]

Lbz intake? Wouldn't there need to be some reprogramming with the maf sensor?

 

[Cknight199]

Lbz intake? Wouldn't there need to be some reprogramming with the maf sensor?

Shouldn't need to be adjusted unless it's a different size intake pipe where the maf sits. (4" to 5")

 

[cdprayor]

Shouldn't need to be adjusted unless it's a different size intake pipe where the maf sits. (4" to 5")

That's what I was thinking. Going from an lly intake to an lbz and the different size would cause an issue

 

[Cknight199]

That's what I was thinking. Going from an lly intake to an lbz and the different size would cause an issue

No because the maf doesn't need to be rescaled because where the maf sits, the pipe size stays 4".

 

[hopkins_fam]

Man I need some help.I got a 05 lly with 240K.I have been fighting a problem
with a rough idle/miss for a year already.When the truck is cold it idles fine smooth as silk.When the the trk gets hot it will ack up at idle.If you turn the ac on or put it in gear it goes away and idles fine.If i have my scanner on it when it acts up all balace rates go to 0 and when the miss starts to fade away all the rates wil start reading.I have already changed head gaskets,all 8 injectors,cp3 pump,rail pressure sensor,all 8 injector pigtails.I have also tryed a ECM and injector control module off my buddys 05 lly truck and it does the same thing.Sometimes if you let the trk idle for a 15 minutes or so the miss/rough idle will go away but as soon as you drive it again it starts all over.Do any of you guys have any sugestions im about to blow this thing up.

Good luck. Im dealing with same prob, already done new harness FICM, FPR, HG's & Studs, Filter Head, Lift Pump, replaced a Injector cause of spray pattern, MAP Sensor, every fuel line.

I've even checked crank sensor for play. Everything looks good on my Solus as far as sensors go. Im out of ideas and options. Trying to get into a dealer now to see what they say.

If you have any luck please post. Ive been thing about the Neutral Safety Switch. Had a 96 7.3 that'd lope at idle and ended up being it.

 

[02greysixer]

I have a buddies truck that started doing the same thing. He has a drive it till it quits mentality so we haven't worried about it but I am still curious. It's an 05 lly with 275k miles, knn intake, exhaust, and a mild efi milage/tow tune. He's had the truck for years and short of never getting over 15 mpg it's been great. But recently he had a gooseneck with a 5 ton mud truck on it and it went into derate for high fuel pressure, p0088 I believe. It also had a maf circuit code. Cleared code and on the 3-4 shift it came back. Since we had to get the truck and trailer home and I don't have a ball in the bed I went in and disabled the p0088 derate and engine light. But the miss is still there and balance rates do all go to 0. We were going to swap maf sensors just to see what happens but once it was drivable and useable he didn't care to mess with it. His truck did just recently go from driving/towing several hundred miles a week to less than 50 miles and sitting all week. First time he'd towed in months.

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