gbbmk

iTrader: (1)

So a few days ago i noticed a rapping in my motor (the 2004 listed in sig) , I took the truck to the shop that rebuilt the motor and they felt it was a stuck lifter due to oil and the build being so new. Fast forward to today. I started to pull away and the truck was hesitating a bit and bucking not bad but enough to notice. Thought it was cold (its snowing here) Put more of a load on it and it started to pop pop pop in the muffler. Like an unburnt fuel. Then it started to rap intermittently. I went to the local parts store and got some Preston Riesling in hopes to free up a possible stuck lifter. The lifters are the original before you ask, i know they should have been replaced but this is what I am dealing with. I also checked for bad plugs and connections, all the injectors are firing from what I can feel. I took it down the road and the noise was gone but under normal load it still shook, when I punched it it would open up but a definite loss of power. Then I noticed my ltft bank one is very lean. Normally I run =/- 2 cruising on both sides. Now at idle in gear i am +18 on bank one and +1 on bank two. My o2's are bouncing fine and I am not reading any codes. Oh I am using the droid app Torq scan. It doesn't appear to be a vacuum leak and my oil pressure is good. I have not pulled the plugs or checked for compression. Id feels like I am down a cylinder but I am not seeing signs of it other then my fuel trims

I am at a loss and I don't want to destroy what I have put into my motor.

I have searched all morning to find something. I can not send you any logs I can only read data.

Thank you in advanced for your help

Chevy_King1500

iTrader: (7)

bad injector? pull the plugs.

use a temp gun on the manifolds to see what cylinder is colder than the others

gbbmk

iTrader: (1)

Don't have a gun but I pulled all the plugs on bank one and did a compression test. All cylinders were at 148-155. The last cylinder on the drivers side up against the fire wall plug was bent down. Swapped it. Fired it up. Let it idle for a min. A few taps to the pedal and the intermittent rap came back. I shut it down and here I sit. Waiting. This motor oy has 4000 miles on it. Three oil changes with oil not synth. Third set of plugs jist for break in and new tunes. I'm at a loss.

gbbmk

iTrader: (1)

Its running now and the knocking is gone for the most part.but its still running like crap. When I rev it runs more lean on bank one. The only thing I have done is fill up yesterday. Could bad gas do this? Could I have a bad injector, how can I tell, what else should i look for or do?


Update:: The trims are now +/- 2 on my long terms and its not popping. Idle and timing at idle are normal. It still is rough not real bad but a vibration under 2000k rpms. The snow makes it hard to go wot but it feels like the power is there i am just worried about the rough driving down low and the idle. It just feels off. Its not a placebo effect either. It almost feels like a bad u joint vibration but from the block.

gbbmk

iTrader: (1)

Well I think, not sure but I think since my combustion chamber is smaller I hit the pkug with the piston. I am running tr5's but the builder said autolite 104 or 103 for nitrous. I guess the ngks are that much longer. That could have been the rapping I heard and why after the new set of plugs I am still getting a vibration similar to a burnt wire. It fires but not well.

Whoever is reading ill update.

gbbmk

iTrader: (1)

Bump I'm still stumped and I swapped a coil. Still runjing rough. Burning fuel and blittle blue smoke. Great oil preassure and oil levels are good.

07vmax1500

Where's your short fuel trims they are more important to find an issue then the longs as the longs are just an avg. I had a 2500 van had a similar problem no codes but ended up being the o2 sensor.

Suburbazine

Keep in mind that "Lean" can be either "Not enough fuel" or "Unburnt Fuel".

If you found a plug bent down then it means someone most likely crossthreaded the plug in the head. You might want to check them all as a crossthreading will cause all sorts of issues and it pretty much requires a competent machine shop to fix. (competent shops don't reuse old lifters, too many risks involved for too small a price)