Duramax surging at hwy speeds.. NEED HELP!!

[SDA88]

The regulator is new came with the cp3 and the truck does not have a tune, I could live with a pulse but this a 100-300rpm surge and only at 100km/h and above

 

[adeso]

Don't drive it dumping fuel in like that, it might be electrical if it is commanding something strange like that. I would check all the grounds, I have had a bad ground do strange things to me

 

[SDA88]

It's parked right now, I've ran ground cables directly off both batteries to the block and still the same issue, and no codes what so ever, no trans codes, no engine codes and I know it will flip a code if a fault is found.. It's got me beating my head against the wall

 

[Aaron@LDS]

Did you reinstall the return lines with the bolts in, holding the washers or did you install one bolt at a time holding the line and washers in place? Odds are you have a return line washer that isnt right. And fuel is spraying out of it. It doesnt take much to mess that up.

 

[SDA88]

I put all the bolts in first then put the line on

 

[Aaron@LDS]

You will need to remove the cover and run it. Look for the leak. If you cant find it easily remove the wires from the FPR and run it while you look. That will put the fuel pressure to 100%. If you still cant find it you may need to use fuel dye and a blacklight.

 

[adeso]

Just be very careful messing around with it while running, don't ever put your hands down there to feel for it. high pressure fluid can really mess you up

 

[SDA88]

Found the leak, looks like a cracked injector body, time to replace all 8

 

[TheBac]

Sorry to hear. At least you know what that issue was now. Hopefully the new injectors will cure the surge, too.

 

[jkholder09]

Air in the fuel could cause you to have inconsistent power.

Incorrect MAF sensor readings could also cause power loss. Have you changed the air filter lately? How about the fuel filter?

Try driving it with the maf unplugged, if it goes away fix the source of unmetered air, or replace maf

Allot of diy guys don't get the air inlet to turbo sealed up properly and suck air right there

 

[SDA88]

I'll keep ya guys posted thanks for the help

 

[SDA88]

Got the fuel leak issue solved with new injectors but still have the surge at the same speed, anymore ideas?!?!

 

[jkholder09]

Try driving it with the maf unplugged, if it goes away fix the source of unmetered air, or replace maf



Allot of diy guys don't get the air inlet to turbo sealed up properly and suck air right there

try this yet?

 

[SDA88]

not yet

 

[SDA88]

wouldnt it run worst with it unplugged under load

 

[WVRigrat05]

Mine surges from 14-1700 rpm in all gears, about 300 rpm surge as well, its worse then its on flat ground or at low speed with no load on the engine. I put a gasket in between my mouthpiece and turbo, pulled injectors, cleaned plug ins, maf, everything, the only thing I haven done yet is change the FPR, Im wanting one out of an LBZ so I guess Ill try that next. Also my actual vs. desired is close too.

 

[SDA88]

ive put a pump and FPR on mine and still the same problem, that was the first thing i did

 

[SDA88]

Another update, unplugged the MAF sensor same surge same speed, pulled the air filter, same surge same speed, just out of curiosity at this point could the fan clutch be locking up at this certain speed, im running out of thoughts and ideas!!!!!!

 

[jkholder09]

could it be a torque converter?
like a locked up one way clutch in the stator. that will cause surging if its locked after the converter couples, but no tcc

 

[Aaron@LDS]

I didnt re-read everything but do you have any way to monitor rail pressure? I suggest watching your rail pressure durring the surge to see if it's a spike or drop in fuel pressure causing the "surge".