well as for those that dontknow its a big rig engine. i need some help if its even available in here. my dad has had problems with it. it acts like its an injectorproblem. black smoke will comeout the pipe till it jus fixes it self(rpms at 1500 or 1600 but in gear, not while in idel cuz it doesnt do it.). i mean that if he sits on the pedel at that engine speed it will just stop after a while. but it only happens when he is in gear (8th 9th and10th). it doesnt do it in any gear. he'll run the engine up to 1500 or 1600rpm in any gear up to 7th with no problem. he's already changed out 2 injectors and hooked it up to the computer but nothing comes out. they'v also changed out timing sensor but the prob persits. hooked it up to the computer while its running but no code shots up.
any suggestions? i know the engine might be different but i just wanted to give this site a shot cuz i know there are some smart old people in here..j/k.
thanks in advanced.

 

Is there a missfire? How's the power escpecially when it acts up? The n14s had problems with the injector harness at the pass thru connectors but I would think that would cause a fault. Have you checked fuel pressure, that'd be where I would start. If it only does it under load (when needing lots o fuel) you might be getting some air in there. There is a screen on top of the fuel pump (slotted screw driver I believe) pull it out and clean it. I've seen a lot of those plugged causing problems.

 

power is healthy allgears up to 8th and so on. if it was the fuelpressure wouldnt it act up in all gears? it only does it like i discribed before. he'll check on the filter and fuel pressure tommorow.

ok...my dad says that he'll have it 1800rpm for about 10-15mins and it wont missfire. he says that when he shifts to 8 or 9th gear and it will start to misfire, black smoke will come out..then he'll let off for a sec...then blue smoke will come out...then he'll ease on the pedel again and the engine will will shake a bit and then it will fix itself. once he goes into lower gears and works his way up to 8th and so on it starts again.
he says that it all started with him pumping fuel at well known truck stop. he noticed that the fuel was dark yellow...like a pinaple drink. would that have any effect on it?
thanks.

 

If it was bad fuel it would cause it all the time. I would start with that screen and go from there.

 

thanks man. i'll let him know.

 

problem still persits. its starange. the shop even gave my dad 4injectors to try(all injectors have been changed out to brand new ones). need more ideas

 

i work on them here and there as i am a level 4 heavy equipment mechanic apprentice. Sounds like maybe turbo is weak. Do simple things first. Check air filter for dirtiness, Pull air intake off of turbo and check turbo wheel. Is it worn out broken fins etc... Is tehre too much end play in turbine wheel..Then id say make sure fuel filters are changed . Then id say maybe check unit injectors by doing a cut out test. If you cant do this via laptop then do it by letting engine idle and pull out pass thru connectors one at a time listening to engine idle. If cconnector makes a difference then that injector is usually good. if u remove the connector and nothing happens then replace that injector or check its setting. Also wouldnt hurt to do a vakve set.

 

but if the turbo was weak then it would do it in all gears. 30psi in 1st gear is 30psi in 8th gear. but the problem only comes around when he is in 8th or 9th and 10th gear. its wierd. all the injectors are new. computer has been checked. all fittings and lines, fuel pump screen have been checked. filter is new with like 1month of use. valve set is next..since the shop wasnt open today or monday.. so now we wait.

 

make sure injectors are set right. i believe you use a dial indicator gauge with magnetic base to set it. with engine running unplug injector at pass thru connector 1 at a time and see which ones DONT make a difference.

 

thats all been done with a whole set of injectors. ill let ya now wat it is thats gona be done next. they werent open today.