llorracs93s10

iTrader: (5)

I had one of my wires that was meant to be on a bolt that is hot only with the key "on" and I had it on a constant hot and when the motor ran, it ran.....than with the ignition off, it still ran....So he straightened it out for us within a few days.

busta9876

iTrader: (3)

Not knowing how its programmed can be troublesome. Different applications had different injectors, flex fuel, non flex, and either one of which will allow engine to rev, but won't idle very well. I get a lot of PCM's from people that don't match the engine they have, so, when your PCM was programmed hopefully you had a list of questions to answer as to what you wanted, or what you had. Just blindly programming the computer assuming as it came in matches your customers engine is a lot of the times incorrect. Questions must be asked.

The fact that throttle works, it revs up, and stays running with throttle input leads me to believe the programming for throttle, and security should at least be correct. The drive by wire system is NOT very forgiving, get something wrong, it lets you know and shuts things down.

as I stated above, check your plugs (to get it running again), clean the throttle body. I have had many 2003 pickups with drive by wire that wont idle after a re-flash. The PCM can slowly adapt for gunk buildup around the throttle blade as it slowly accumulates..however, if you reset the PCM back to factory, its as if engine was brand new with perfectly clean throttle body. PCM won't adapt to the dirty throttle body quick enough, and then you get the low idle.

busta9876

iTrader: (3)

In the video you have camera pointed at the throttle blade, Is the Mass Air Flow sensor plugged in? (the electrical connector)

Kingblazer84

Yes plugged in it won't even idle or change when in speed density mode

busta9876

iTrader: (3)

well best leave the electrical plug unhooked all together until you get it figured out...or hook air tube back up to throttle body.... Because with the MAF electrically plugged in, and NOT in the air stream going into the engine, it will do exactly what the video shows.....

what is the 8 digit injector part# located on side of your fuel injectors, call your tuner, find out what injector the PCM was setup for. If the tuner has no record of what he put on your PCM, that's bad record keeping, shame on them.

what is the fuel pressure, hook up a guage, read the pressure. Rule this out completely. I have a basic troubleshooting approach.

K.I.S.S

keep it simple stupid

it is way too easy to over complicate things...

mountainman

Fuel pressure is 54 psi
Throttlebody is hospital clean

I plugged in the stock computer that came with the motor, still wouldnt start, so I guess thats a good thing? It should start up and run for at least two seconds before VATS kick in....right?

busta9876

iTrader: (3)

Start, run, die...usually just a second, or just long enough to make some noise...but it will usually get up to regular idle speed....

BigEd_72455

iTrader: (7)

did you check to see if the coils were firing? Pull a wire off a plug and hang it close to the manifold.

You are going the wrong direction with this thing man. I think you have something else wrong..

Kingblazer84

coil packs are firing , im going to bring my noid light set to him so he can watch each plug fire.

busta9876

iTrader: (3)

Have you checked to make sure all injectors are actually flowing fuel? If engine sat for a while in junkyard, injectors can gum up, won't flow any fuel. If you have 3 or 4 cylinders down, it might still rev when you give it gas, but won't be able to hold an idle. I've seen engines run on 3 cylinders, but would not idle.

If you have headers, its easy to check, run it, give it some throttle, try keep it running 15 seconds or so, shut it off, and feel all the header tubes...see if any are still cold.

just something to check I don't remember it being mentioned.

mountainman

Good one Busta I will try that one
But I have swaped intakes and injectors, but still worth a try.

mountainman

ok... Just tried it...they all get HOT! ouch!

All cylinders firing

busta9876

iTrader: (3)

What is the 8 digit number on the side of the injectors?

25317628

25326903

12580426

-???

mountainman

25317628

BigEd_72455

iTrader: (7)

you could have checked the headers with a thermometer or lazer temp reader instead of your hand...

busta9876

iTrader: (3)

check with whoever tuned it, make sure its programmed for standard gasoline injectors.

Hotrodnova66

I'm curious to know what the solution will be. I have a 6.0 in my car and have the opposite issue as you, my car will idle but at 1400rpm and sometimes it comes down to idle normal and sometimes it doesn't. I have tried replacing everything you have tried. Only way I can make mine idle is taking the maf loose and moving it up and down (I have the ls7 card style maf) and finally it will come down and idle but if I just leave the maf alone it won't idle. I have replaced it with two different ones and no change, also when unplugged the motor does not respond as well but unplugging the map sensor will shut the car off and throw a code. Could be similar to yours, been driving me nuts for a while now.

Try moving the maf or blocking some of the air going to the maf and see what it does.

Hotrodnova66

I just watched the video you posted trying to get it to run. Mine with no cold air intake on it will not run unless you hold the maf right in front of the throttle body and even then it will not idle very well, wants to stall but if you kind of cup your hands around it you can make it idle. Still trying to fix my issue but I ran into that with mine, worth a try for you.

mountainman

Yeah, Ive got the MAF right mounted to the TB, with tubing in front of it. Ive heard it can cause disruption of the MAF performance, but it also didnt work with a cone filter in front of it either.
Here is a live data shot of it not running (as it wont idle!)
stft b1 0.0
ltft b1 25.0
stft b2 %0
ltft b2 %25.0
MAP 29.2
RPM 0
IAT 54
MAF .0
TPS %17.6 (but drops to seven)

o2s b1 s1 v .445
stft b1 s1 %0
o2s b1 s2 .445
stft b1 s2 %99.2
o2s b2 s1 %0
o2s b2 s2 v .445
stft b2 s2 %99.2

busta9876

iTrader: (3)

LTFT 25% That is a problem. LEAN. The computer has MAXED out trying to add more fuel. Now, either it really is lean, and computer has maxed out fuel trying to richen it up, OR, you have oxygen sensors mounted close to exit of exhaust pipe, and computer has corrected for a 'false lean' condition, to point that it won't run.

to rule out the first, you need to verify your injectors are programmed correctly. If its programmed for FLEX fuel injectors, and you have the standard NORMAL injectors, you would get similar results as you have shown.

To rule out second, let us know where oxygen sensors are installed, and if close to exit of exhaust. Also, you will need to reset long term fuel trim. Some scan tools can do this, if not, unplug PCM for a few hours and it should reset. Once you get long term fuel trim (LTFT) reset back to 0, unplug the oxygen sensors to keep the computer from trying to adjust fuel. Only try this paragraph if you have verified correct injector programming.