Alright first I will start out with my mod list- My lightning has a built short block, comp stage 2 cams, springs, ported eaton(13psi),long tubes, high flow cats, cat-back, e-fan, accufab, JDM tuned SCT 9100, 55lb injectors, 92 mm Pro M, NGK tr6 plugs.

My symtoms are as follows: Trucks seems to have a missfire(breaking up) when lightly on the gas parked or under load. Also if you let off the gas you can feel it breaking up slightly(shaking kinda). This does not happen when the truck is accelerating at all. It has very smooth acceleration

The truck was throwing a code for Bank 2 Rich, I changed in a brand new O2 sensor and now it does not throw any code.

I took the truck to school my tech school today. Hooked it up to an NGS scanner and found out the following.
Short term fuel trims +-3% jumps around like normal at idle same under cruising conditions
Long term trims Bank 1 -3% Bank 2 -7%
Injector pulse width 2.1 ms @idle
Pulled plugs all looked lean and very clean(NGK TR6) (My Instructor told me i should be running Motorcraft plugs ONLY....Ha Ha he basicly told me that was my problem.)
Hooked up to a 5 gas- 1500ppm HC's 3.5-4.5%oxygen , High CO(DEFINATELY NOT PASSING EMISSIONS)
Also vacuum is a steady 15in at idle in park 11-10 in gear
Also no missfire data on the NGS
NO CODES at all!!!

I hope someone is more creative than me at figuring out this problem!!!!!!!!!!! Any ideas????????
I just want a truck that runs right.

Zach

 

what are your plugs gapped at?

 

They are gapped at .040 but I have had them at .035 also.

Zach

 

I hate to say it, but I wouldn't rule out plugs either. Put a set of ford Copper 12C's in there and gap them to about .38. I'm not saying that the NGS plugs are the problem, but sometimes you can't see any defects with spark plugs but they still don't fire right.

The fuel trims look good, that's a confirmation that it's not missing from a lean or rich condition. Based on that, I think you still need to be checking ignition. How did the truck do on a dyno? Make good power?

and heck, if you go thru the PITA to pull and change the plugs, might as well do a compression check just so you can rule that out too.

Brian

 

I ran a 12.0 @115.54 with it like this a while back didnt get it dynoed and with a JLP setup i put down 470Hp and 540tq.

 

and you have checked all of the plugs recently to make sure you have all your electrodes?

 

You also might try cleaning The idle air control unit on the drivers side of the plenum. The PCV tube hooks up to it.
Just remove it hold the open end up like a cup spray some light weight cleaner in it and take a pincel and move the plunger in ther back and forth so as to free it up. Then turn it upside down and shake out all the dirty cleaner. Then spay a little WD-40 in it and shake out the excess. Wipe the face off and reinstall.

Suavy

 

Yes i have all of my electrodes and i do not think that a sticky iac will cause my problems and or my symptoms.

Zach

 

ttt

 

I'd look at the Pro M 92mm MAF, it's calibration & the tune working with it. Just to cove the bases.

 

I have had my IAC get gummed up and the truck not beable to go to boost and spit and sputter. Another time it would start but stall.

I see your gonna be a tech what does your instructor say?

Good Luck


Suavy
"Chief Lightning Racing"