2000 Rpm Miss / Surging ?

[96ccdd]

I have a issue with my 6.5 having a miss or surging at 2000 rpm under light load or no load. Any ideas ? I'm thinking it maybe the TPS ?

Thanks
Mark

[Robyn]

TPS generally wont cause that.
The TPS actually has three TPS's in the one pedal unit. The PCM must see agreement with all three or it has a fit. If one does not agree with the other two then it will set a code. If two are out of whack it shuts off. This is done because these are fly by wire engines and if you were to lose control it could be a runaway.
A miss can be many things????? Do you have any codes showing??
How about white or blue smoke from the tail pipe??
lets dig deeper.
Robyn

[N9Phil]

I would check Fuel filter, OPS and fuel pump.

N9Phil

[96ccdd]

Thanks for the response back. I have no codes and no smoke. I just seems weird that it only does it around 2000rpm, above or below that and all is well.

Mark

[Hubert]

2000 rpm is near the sweet spot on the power band. Torque peak is 1760 rpm +/- a little but the turbo (when under load) and HP feel much better for drivability at around 2000 rpm.

Cruise speed very light throttle at around 2000 rpm I think the pcm goes into some type of fuel savings cruise mode and optimizes several things (like boost and torque converter lock / unlock maybe too to prevent compression braking - I don't know what else). Any changes in load or fuel delivery are much more noticable there. I can feel ac compressor cycling on/off when on defrost easiest there its not that is it? Note the ac button will not light its just when vent selector is set for defrost it automatically cycles the compressor.

Describe surge a little more. Is it a fishbite feeling, miss, or other?

[96ccdd]

Hubert,
As you described I do notice the ac comp cycling, I wish that was it. This is a rather odd way, but it does feel kind of like a fish bite. If I increase or decrease rpm it does go away or have the truck loaded such as towing my flat bed trailer it does not exist. I'm going to change the fuel filter today and see what happens.

Thanks
Mark

[Hubert]

I think you have a common complaint.

IMHO its like I commented on its a sweet spot and has to do with electronic PCM controls and precise fuel delivery. Sorry to not be specific but I don't know exactly or how or what all gets optimized timing, fuel rate, boost, torque converter lock unlock etc??? With age or some deterioating subsystem its not as smooth as new.

Have heard some have fixed it replacing the 1: optic filter harness, FSD, and improving connectivity/voltage issues or 2: fixing fuel delivery (ops, filter, or LP). Some seem never get rid of it until IP replacement. I get it sometimes and I think I can corelate it is fuel quality sensitive too. A good heavy dose of cetane improver and rich Stanadyne additive helps me some.

Filter and fuel delivery is always a good place to start. All the stuff in group 1 above you are not really able to test.

Keep us posted.