i have a 2001 gmc duramax and it is a nightmare the thing keeps shutting down and no one can figure it out it wont go over 2000 rpm and i have a superchips programer and the dtc code that i keep getting is c086b and i cant find what it means at all can anyone help with that

i checked the code c086b on gm's service information and the code does not come up with anything. are you sure that is the code you have. also have you tried to take out the super chips programer to see if that makes any differance.

i think that i read on here the other day that if you have a high idle switch and it is on or the wires are jacked up on it that i will prevent you from going over 2000 rpm. good luck.

it is not as bad with the programer in it . i when it happens i can clear it dtc while i am driving and once it clears it runs fine for a few min . that is the code it gives

fuel filter, fuel filter, fuel filter. that is the first thing to go after when having any sort of fueling or de-fueling issues, or motor will only rev this high issues. fuel filter. i know i sound like an ass, cause i am one, and i see that you are a new member. there is a search button on the top right hand corner, use it. the main reason that people come to these forums, are because they have a problem, and they want to fix it. the duramax is almost 8 years old now. 99% guarantee that the problem has been noted, and addressed. change the fuel filter.

rant off.

Ken

you are what you say you are and i have changed the fuel filter more than once im not an idiot if it was something that easy i wouldnt be on here asking for help i dont think if it was the fuel filter that i could reset the dtc's on the road and it would run ok for a few minutes or only do it when i am pulling a load. so any more wise comments smart guy

You have a dtc that is not related to the pcm, the code if there is one will start with a P, obtain the correct dtc and see if anyone can help.

And fill out your sig and tell us about your truck, type of mods, etc.

Sounds to me like it is going into limp mode.

your right, sorry about that.

a fuel filter could go bad right after you put a new one in. one bad batch of fuel, and its all over. but now that you say you can clear the code while on the road, runs good for a while, then goes bad, im not thinking fuel filter. if you can, try getting a different code reader to get the code, like advance auto or someplace like that that lets you find a code for free. just to get a second opinion.

sparky might be right, engine limp. if it was tranny limp, you would get code P0700 and P070something.(not sure on what the other one is) and it would only go into 4th gear and reverse.

Ken

Mine is doing same thing, first it was with a heavy load, then any load, now just driving, resets after you shut off and restart the motor, GM teck said it was fuel pressure regulator, acts like a throttle position sencer to me, but that's only a guess.

With computer controlled engines and problems like this, you need a real scan tool for diagnostics. You need to be able to read the data stream while driving. With this information, an educated guess can be made. Without the data stream info, pi...ing into the wind. Of the things to look for in the data stream are making sure the computer is sensing rpms, what fuel pressure reading is, throttle position reading etc. They all have to be looked at and usually something will jump out that is out of spec.

I googled the code C086B and found this:
http://www.obd-codes.com/forums/viewtopic.php?f=1&t=2145&view=previous

"who ever has the superchips flashpaq this is a very comon code that will come up. its a nothing code. its a bad program in the tuner. so you have to update it on the web site. then retune to stock then retune to your setting and you'll be ok.."

Don't know if this could be the case but it might.
Hope this helps

Bill