I have a 4" turbo back system. 4" downpipe and 4" pipe and on long trips when my engine gets nice and hot the turbo will start to surge and when I pull off to the side of the road, the turbo is completely shut off and the engine sounds real funny almost like a cummins and this is happening at idle but, when you rev up the engine the turbo spools back up then shuts off when it idles again. So, could this be caused by the exhaust? But I had the exhaust on my truck for about 5 months before it stared doing this.

 

yes this is normal i install lots of exhaust on trucks after hours the ebp changes and pcm just operates like this no actual drivability concerns with it all my customers complained at my work about this issue my boss kind of disliked the fact i installed this when i work at a ford dealer but o well

 

forddr, what you are saying is that the turbo surging is "normal" after putting on larger diameter exhaust? Or should you say that the surging is an expected effect of putting on a larger exhaust?

 

it is an expected effect due to the pcm seeing lower than normal exhaust back pressure

 

Thanks Ford DR, I have been saying this for a while now on this site. I read both the 6.0 Bible and the Ford Service Manual on Powertrain Control and Emissions Diagnosis (PC/ED) section and came to that conclusion.

 

no problem

 

OK, so how much of a gain did you get with the 4" exhaust? Would there still be a problem if the cat back system was installed? Is there much of a difference with either the turbo back or cat back for an '05? I was planning on a turbo back but now am questioning this. If the PCM needs to see a back pressure to run the turbo correctly, did Ford open up and smooth out the exhaust enough that there is less of a need than before to mess with it? Ponderous.

 

will still work fine all my customers ahve turbo back systems largest gain they notices reduced turbo lag on bottom end and better mpg 2-4 mpg increase

 

Ben, its not the exhaust. I have 4inch exhaust on mine with no cat or muffler and don't have that problem like you do. Mine did it to me once where it sounded like the turbo shut off mocking a cummings. Its the solenoid or the VGT sensor on the turbo acting up I was told

 

I went out to start my truck the other morning and the turbo didnt come on after I started it but, when I started backing out of the driveway it came on.

 

Where is the sensor that reads back pressure?, I put 4 inch turbo back on my 03(3.5 down pipe), left cat out with high flow muffler. Isnt turbo outlet 3.5? My exh works fine.

 

I talked to a guy on TDS that was having this problem and he said that they replaced his EBP sensor (left manifold) and the EGR. I'm gonna lean towards the EBP sensor being at fault