truck has been great but just recent it has started surging on the highway with constant speeds and then another thing is it has been "poping" through the exhaust while at an idle im thinking maybe its an injector problem truck just hit 200,000 miles it also dosnt really sound as strong while driving but i might just be hearing things oh and no codes

Have you noticed any white smoke after it is warm at idle?

How many miles are on you current injectors?

You could have the injector balance rates checked, along with the fuel rail desired vs. actual pressure tested to confirm bad injectors.

To be honest I dont know that they have ever been replaced bought the truck at 140k. I have noticed no smoke after its warmed up alittle black smoke at idle. Does this sound like it could be an injector problem? My fuel mileage has gone down hill a bit when all mods were done I could limp around and get about 22-24 now its about 17mpg

I am sorry I just seen you have a 6.5
I thought you had a Duramax.

I am not familiar with the 6.5 engines. Sorry.

Hope someone else can chime in.

problem getting worse at an idle it surged and wanted to drive away without me pushing the accealerator

Sounds like your ip is failed.

How long ago did you put the PMD on the intake? Reason I ask, there are a few cases of PMD causing surging. It even happens with new PMD. Unfortunately, the intake location for PMD is probably worst than the IP.

It can also be caused by bad IP?

Have you done a Lift Pump test? There is a diagnosis procedure in the FAQ.

Another possibility is the Accelerator Pedal Potentiometer (APP). There is a diagnosis procedure in the FAQ.

from what I understand surging and racing engine can be caused by the governor In the
IP somehow. I have a 6.2 and that was one of the symptoms when my flex ring on the together failed and out started wearing the governor rivets down. Trading could also be caused by a sticking metering valve In the ip.

put pmd on 5 months ago also noticed while at highway speeds truck will jump to full throttle then kick back

Which brand of PMD ?, did you buy it new ?

Could it be the optic sensor filter harness that is going bad?

ill check the harness but the weird thing is that it will act fine for 50 miles then act up or act up when i start it then go away for a while

Also check the Accelerator Pedal Potentiometer?

Matuva asked some question also.

I am having the same problem with mine, you step on the throttle and the engine wants to rev to 2100 rpm and stay there, while I am driving if I hit the brakes it will stop, but it keeps doing it and surging when I try to slow down.

I have swapped out the PMD, IP, and the Pedal, still doing it to me.

To expand on it, I am getting codes 13, 29, 34, 35, 36, 88

I called Pensacola Diesel, it sounds like what the problem is that my timing chain is getting stretched and thus throwing off the timing between the crank and the pump confusing the computer.

oh sorry yes bought pmd was bought new and is a ssdiesel remote mounted to my bumper

I would check to see if the OS filter is still there. If it is I would take it out and see if things change. It is about 5" long and is connected to the OS. You would have to take the top half of the intake off to get to the other end of the harness. Just plug the other end back into the OS leaving the filter part of the harness off for now. It might not be there either if someone has already taken it off.

I would then put in a clear hose at the IP and sight glass it. Start the engine up and look for any bubbles in the line.

It wouldn't hurt to put a gauage on the end of a longer piece of tubing and put the hose on the t-valve and run the gauage up and under the windshield wiper and drive it and see where your fuel pressures are while driving it.

My 1999 Suburban had similar symptoms: When starting in the morning, and driving the first few miles, the engine speed would increase and decrease by itself. At first it would go away when the truck warmed up. Then it was constantly surging up and down. The test I was told to try was to see if I could hold the pedal at one place and keep the engine speed from running away. If I tried to hold it at 1800 rpm it would just rev up on it's own. My fuel filter showed a lot of silver particals, which I thought was the IP breaking down. It turned out that the lining had flaked off the inside of the tank, due to water getting in around the metal lines in the sender (They were loose and wobbly). I removed the injector pump, and even found silver particals under the fuel shutoff solenoid! How did they get past the filter? I bought a rebuilt injector pump, changed the tank and lift pump. I used the old PMD and relocated it. I have put 400 miles on the truck so far, and it seems fine.