Truck misfiring after sitting for a couple weeks

[ivorton74]

I just got my truck back from the shop after close to 2 months. While driving home it started to misfire. I checked the plug wires and they're all connected properly. Im wondering if its because it sat for so long and its been really cold here in SD lately with below zero temps. The truck was fine before I dropped it off except for the surging which its still doing. After the truck warms up it starts to surge but it doesn't die. I hooked up my obd2 adapter with my torque app and I pulled all o2 sensor codes...p0134, p0135, p0154 and p0155...I did put new o2 sensors in but still doing the same thing. My buddy checked everything but he's stumped. No misfired detected though so I don't know why its missing. Any input appreciated. Im bummed out cuz I missed my truck and now its acting up as soon as I got her back...geez

[Hart_Rod]

Check your plugs. Also sounds like you have a vacuum leak or possible IAC motor going bad.

[RatPoweredTruck]

Check plug gaps, check for spark arcing in complete darkness. Check all ignition components, check fuel delivery and fuel pump pressures. That is the free stuff. Check grounds to body-to frame-to engine.

P0134- circuit insufficient activity bank 1
P135- heater performance bank 1
P0154- circuit insufficient activity bank2
P0155- heater performance bank 2

Poor electrical connections, shorting connections, bad ECM, bad sensors, lean condition, low fuel pressure are some of the things to look at up close before you go throw parts at it.

[aknovaman]

The majority of mis fires are the result of a lean conditions caused by sticking injectors. I would take them out and boil them in eter for 15 minutes and blow dry them with shop air. I use a side burner on my bbq.

[homemade87]

These ls engine are know for fuel injectors sticking or clogging after sitting for a while . Ethanol fuel is mostly the blame . I would remove the injectors and clean them . I made me a injector cleaner from a syringe from the drug store and carb cleaner . Worked really well . Look on YouTube , there is a video showing how to do it . I flushed the injector both ways .

[RatPoweredTruck]

Check O2 wiring(no splicing), continuity, and polarities. Heated sensors need voltage when ignition key on. Stuff like that. Exhaust bolts could use upgraded to stronger hardware. They could eventually break.

[ivorton74]

Im kinda leaning towards the injectors being clogged from sitting. Ive heard about soaking em in seafoam...anyone ever do that? Ill check the plugs but they're about 4 months old so im kinda doubting thats the problem...also has a new maf, iacv, and fuel filter. I think i may try changing the intake manifold gasket too...how do u check to see if that's leaking?

[ivorton74]

here's a video of the truck idling...https://www.youtube.com/watch?v=4mDS...ature=youtu.be

[homemade87]

Originally Posted by ivorton74

Im kinda leaning towards the injectors being clogged from sitting. Ive heard about soaking em in seafoam...anyone ever do that? Ill check the plugs but they're about 4 months old so im kinda doubting thats the problem...also has a new maf, iacv, and fuel filter. I think i may try changing the intake manifold gasket too...how do u check to see if that's leaking?

Soaking them does not do as good as cycling them with carb cleaner . If you soak them how do you get the cleaner inside where the problem is .

[ivorton74]

good point...I have some carb cleaner here so once I can confirm its an injector causing the miss i'll take it out and clean it and see what happens. I may try using the syringe method too

[Five O]

I cleaned mine with PB blaster, compressed air, 2 aligater clips and a booster pack. Probably not the best way but it seemed to work

[Five O]

You can also move the injector and see if the mis follows it

[ivorton74]

Would a leaking intake manifold cause the surge at idle? it only happens when its warm...I need to figure this out because its driving me insane

[Hart_Rod]

Originally Posted by ivorton74

Would a leaking intake manifold cause the surge at idle? it only happens when its warm...I need to figure this out because its driving me insane

Yes

[BR3W CITY]

spray ether on parts of the manifold and near the gasket, see if it changes the surge for the worst. Cracked manifolds will also manifest themselves worse at higher rpm's as the vacuum builds (or boost if it were turbo).

[ivorton74]

Ok ill try that tomorrow and see if I find anything...thing is starting to irritate me for real.

[ivorton74]

So Good News! My truck is no longer misfiring and is running perfect. Cant tell you how happy i am...she has all her power back. Also i went to napa today and i talk to a guy there. He told that my surging issue is probably the throttle position sensor so im going to try changing that out. I thought that the tp sensor was only on engines with dbw and mine is dbc. But he showed me where it was so now i know.

[homemade87]

Originally Posted by ivorton74

So Good News! My truck is no longer misfiring and is running perfect. Cant tell you how happy i am...she has all her power back. Also i went to napa today and i talk to a guy there. He told that my surging issue is probably the throttle position sensor so im going to try changing that out. I thought that the tp sensor was only on engines with dbw and mine is dbc. But he showed me where it was so now i know.

You did not tell us what the problem with the missing was and what the fix you did to correct it .

I assume you still have the surging from you last post.

[ivorton74]

I didnt do anything other than put some Heet fuel injector cleaner in the tank yesterday and drove it around the block by my house a few times. Then I started it this morning and it misfired for about a minute and the while on my way to work it quit misfiring on its own. I drove it around town on my break for about an hour with wot a few times and there was no hiccups at all. I did buy some seafoam...ill put some in the engine and put the rest in the tank and put more gas in. Its still surging though

[homemade87]

Originally Posted by ivorton74

I didnt do anything other than put some Heet fuel injector cleaner in the tank yesterday and drove it around the block by my house a few times. Then I started it this morning and it misfired for about a minute and the while on my way to work it quit misfiring on its own. I drove it around town on my break for about an hour with wot a few times and there was no hiccups at all. I did buy some seafoam...ill put some in the engine and put the rest in the tank and put more gas in. Its still surging though

Glad it work it self out . It was most likely a couple injectors that corrected itself .

Have you thought about your surge being a tuning issue . Has it always done this .

[ivorton74]

We thought it was a tuning issue at first. I just had a simple reflash done by Brendan from LT1swap..didnt do any special tuning since the engine is all stock...its been doing it ever since we finished the swap. My buddy had it at his shop numerous times trying to figure it out...drove around with a scanner monitoring everything and the only thing he could see is that the o2 sensors are not working but cant figure out why. I replaced them both and still nothing. I also replaced the maf sensor, iacv, fpr, and cleaned the throttle body. Has new plugs and wires, the coils are fine and he said he checked for vacuum leaks and there isn't any. Only thing I didn't change is the tps and I'm going to do that next.

[homemade87]

Don't be surprised if you have to get a tuner to straighten it out . There's a lot to getting a idle correct if it has issues . Mail order tunes , some times you win sometimes you don't . Sounds like some one turned the wrong o/2's off ( Just a guess ) . Normally you turn the 2 rears off and leave the fronts on . As for idle , just take look at some off the stuff you have to do to correct idle .

http://www.hptuners.com/forum/showth...-%28w-pictures

[ivorton74]

I have a feeling that might be what it is...maybe he turned off the wrong o2 sensors. I put it on the list i sent to leave the front o2 sensors and get rid of the rear. Ill check out the link u posted

[BR3W CITY]

Curious, are you getting a MAF reading when you monitor the scanner?

[ivorton74]

Im pretty sure my buddy got a reading for that on his scanner. I know its not the maf because the truck stopped running soon after the swap and got a code for the maf so I got a new one and it ran.