Lean Misfire?

[SMason]

I have the 2006 in my signature that I'm having troubles with. It runs great, never a problem. Well there is a coolant hose that is leaking now that I need to fix at oil change time, but other then that never a problem. I will be going anywhere between 30-50 mph, and I will get on it, usually passing someone or listening to the exhaust in a tunnel, and it will fall on it's face for a split second. Most of the time it will happen faster then I can look at my fuel pressure gauges, I have lift pump and rail pressure. Every once in a while I will catch it, and the pressures never drop below 15psi and 18k ish. So is this just a computer problem not giving enough fuel and lean misfireing or is bad injectors/pump. I am leaning towards computer just not giving it enough fuel. It has done this from the day I bought it when it was bone stock.

 

[nickleinonen]

could be a dead spot on the tps. . could be something with the crank position sensor too [misses a cycle and needs to rotate 1 full cycle to catch where the extra notch is]

 

[Bob4x4]

Diesels can run VERY lean you are not getting a lean misfire.

 

[nickleinonen]

Diesels can run VERY lean you are not getting a lean misfire.

very true...



∞:1 all the way to like 12:1 air fuel ratio's

 

[SMason]

Ya I thought about it being a tps or crank but, I forgot to mention that if I slowly throttle it until about 90% throttle it will run like a champ not a miss or anything. I am just throwing ideas out here now because I really have no idea what it could be.



Would maybe the rail pressure relief get stuck open once I hit the certain pressure, and before my gauge can catch up it has gained pressure back? But I guess if it gets stuck open there it would get stuck open all the time not just when full throttleish is applyied.



The times it does this is only between 30-50 mph and I get on it, if I tried it at 60 it would be fine, if I slowly press the pedal it's fine.

I don't even race this thing or really make it do any work, just on two lane roads trying to get around the slower guy.

 

[JJPage]

Are you throwing any codes?

 

[SMason]

The light isn't on but I have no way of checking for codes, unless I wanna pay the 75 dollar automatic fee for the dealership to hook it up.

 

[Wingate]

Kinda sounds like the turbo is lagging a little, does the boost pressure fall or hesitate before it rises? The boost should instantly rise when you feed it some fuel?

 

[MA2LA]

could it be at a point where the computer is messing with the torque managment and the trans is unsure to ****

 

[SMason]

The manifold pressure seems pretty normal to me before and after, it loses a little boost during the event but for a split second every clyinder cuts out, so I would assume that the boost pressure would drop a little.



Most of the time the transmission will shift down right after the throttle is pressed and right after it shifts it will cut out for the second and then runs fine after that. I'm kinda leaning towards something inside the computer and the torque managment, but I dont wanna buy a smarty or something, for fear I will have too much fun then I will hear lots of noise and no go after awhile.

 

[JWash1]

Sounds like turbo lag to me too. Go ahead and get the Smarty or any other popular downloader. The additional fueling along with some added timing should solve the problem.

 

[SMason]

That's what I was kind of leaning towards, well hoping that is what it was. Thanks for the help guys. I really appreciate it.

 

[JJPage]

The light isn't on but I have no way of checking for codes, unless I wanna pay the 75 dollar automatic fee for the dealership to hook it up.

Turn your ignition key on/off three times without starting, on the third time leave it in the on position, any codes will show up in the odo window.



When it is done displaying codes, it will say "done".

 

[SMason]

Thanks for that information had no Idea. I tried it as soon as I got home, thankfully came up with no codes.

 

[JWadford]

my truck used to do this, when i replaced the injectors it went away, and when i just put these 63litre bfi injectors in , i can make it do the same thing, falls on its face, hesitates, over 20k psi rail and 48 psi inlet, also can keep it doing the same thing if i hold at 26-2700 rpm, popping and blowing white smoke, a little irritating for really expensive injectors that were supposed to be new bodys with 63litre tips, industrial injection will test them and even if one is found bad i still have to pay for the test and any repair to the injectors, now that i think about it, i have had more bad products from ii than ones that really work, they are no longer on the to buy from list