6.0 tuning/limiters

Figured some of you may be able to save us some time if you have seen this before...

2003 F350.

Wont fuel up to its potential, mostly high RPM issues.

Currently running 225/100 and an S371 with a DieselSite high flow HPOP. This truck does have a 4r100 with a stand alone as well, which I am wondering if this could be part of the issue. Nothing from the factory transmission harness is plugged in expect for the transfer case.

We are still running tunes that require the MAF sensor.

-4.8v+ of ICP
- 63psi of fuel pressure at all times
- 48-50psi of boost shown through an edge sending unit
- Idles great, spools amazing, launches very hard

The bad
- MAP only shows 20-22psi maxium
a. Has a brand new Motorcraft sensor, did not change
b. No boost leaks
- We can only log 2.2ms of PW through the OBDII port, which quickly falls to 1.8 during a run
- Back pressure monitored on the Edge CTS2 is at 0. We cannot get a reading and never have been able to get a reading on back pressure, even with a brand new sensor. It just will not provide a signal to the OBDII port.


When the truck has 190s and a stage 3 it would trap out at about 110mph consistently. Felt strong throughout the run and honestly ran about how I would expect from that setup.

With current setup... Still runs strong and as you would expect, there is just not the gain in power that we should have seen. In fact going by the numbers, we lost power going to the 225s and 371.

This would totally make sense if ICP or fuel pressure were suffering now with the larger injectors, but they certainly aren't. We have verified this numerous times.

We have tried Gearhead straight PCM tuning and then we also tried PHP's PCM/FICM programming. Almost an identical result from both tuners taking very different approaches to it.

Anyone with some tuning knowledge have a suggestion as to where a guy should start from here. It has to either be a limiter in the tuning tables or a mixed signal from a sensor/lack there of on the truck.

Dont believe that EBP-A (actual) is a valid pid on the 03/04 trucks. Doesnt work in my 04 either.

stroke6.0 said:

Dont believe that EBP-A (actual) is a valid pid on the 03/04 trucks. Doesnt work in my 04 either.

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Okay so that would explain the 0 reading at all times, no issue there we can verify that pressure mechanically. That eliminates that from a potential issue

It still is used for boost refrencing/fueling thought. Just last week the day before I did an oil cooler in mine, i had a weird boosting pulling off a light, like there was no turbo. Pulled the codes had a p0470 for ebp issue. replaced the sensor while i did the oil cooler and hasnt happened since. Doesnt make sense why you would lose power if you have the ICP and boost. If the log shows that commanded pulse is dropping on a hard run, it would have to be a tuning issue or PCM issue i would think. But youv tried two different tuners so not sure there.

Yes exactly... Unless the OBDII port does not show accurate PW. I know the ICP pressure is not accurate and the voltage is required to truly understand the reading. Could it be similar with the pulse width?

ill add my truck to ebp... i have an 04.5- reads zero all times on the ebp pid. Supposed to from what i have read.

i have gearhead tuning as well with my setup and i believe my tuning does not look at the maf sensor, unplugging the sensor does not effect the truck. I just recently tried warren tunes and not sure if he uses the maf or not.

Perfect, I guess I should have known the 03-04 trucks did not read that PID correctly. One less thing to worry about

The only reason you have to look at icp voltage is because it's an actual reading from a sensor. The pulse width is a commanded value from the pcm so it should be accurate.

I saw this thread earlier today... but did not respond... so I had all day to wonder about it. So sorry for the long post.

What is your max engine load at WOT?
What is your max fuel desired at WOT?

You might not be reaching maximum fueling parameters for some reason... probably like you mentioned it has something to do with the MAP sensor being bad? Or i have seen issues with the diesel fuel parameters of the tuning section. There are some weird portions that randomly happen with some strategies that limit fuel parameters based on things like oil temp, boost, elevation etc... I would make sure your tuner has removed ALL fueling parameters in the diesel fuel section.

What all did you change? Just the turbo/injectors? Does not make sense why the map sensor would read right for one turbo and not the other? Did you try plugging in the vgt solenoid and just let it dangle in the engine bay? I have heard of some strategies that will cause issues if it is not plugged in, but I don't think it is common.


I know you said you have no boost leaks? But did you pressure test? I see cracked map sensor lines all the time that will only leak under WOT so you don't feel your typical idling boost leak.

Possibly a PCM/wiring issues that is causing the MAP sensor to read funny.

Possibly a bad BARO sensor that is causing a weird boost reading or altitude reading.

That's is definitely odd and way short of what those injectors and turbo should be capable of. Maybe KC is onto something with the VGT no longer being used, maybe the PCM is seeing something from the VGT that's telling it to pull fuel

KCTurbos said:

I saw this thread earlier today... but did not respond... so I had all day to wonder about it. So sorry for the long post.

What is your max engine load at WOT?
What is your max fuel desired at WOT?

You might not be reaching maximum fueling parameters for some reason... probably like you mentioned it has something to do with the MAP sensor being bad? Or i have seen issues with the diesel fuel parameters of the tuning section. There are some weird portions that randomly happen with some strategies that limit fuel parameters based on things like oil temp, boost, elevation etc... I would make sure your tuner has removed ALL fueling parameters in the diesel fuel section.

What all did you change? Just the turbo/injectors? Does not make sense why the map sensor would read right for one turbo and not the other? Did you try plugging in the vgt solenoid and just let it dangle in the engine bay? I have heard of some strategies that will cause issues if it is not plugged in, but I don't think it is common.


I know you said you have no boost leaks? But did you pressure test? I see cracked map sensor lines all the time that will only leak under WOT so you don't feel your typical idling boost leak.

Possibly a PCM/wiring issues that is causing the MAP sensor to read funny.

Possibly a bad BARO sensor that is causing a weird boost reading or altitude reading.

Click to expand...

I will go plug in a VGT solenoid just to try.

MAP sensor and MAP line are both brand new since we noticed the issue. We even installed a boost fooler on it set to 22psi just to see if it would regulate it correctly and allow it to read right up to 22psi. In the data logs it goes up to 22psi and hold steady there the entire time, so I believe the MAP is reading up to that point correctly. We have worm drive hose clamps at either end of this line to make sure no leaks develop.

We have pressure tested the system. Actual boost is right around 50psi on all WOT runs and EGT's stay nice and cool (never over 1550*).... so I am ruling out boost leak.

MAP was probably reading this same way with the last turbo and potentially the last setup was not performing up to par either, it just became much more obvious when we added a good amount of potential and lost power.

Where is the BARO sensor? I would like to replace all air related sensors just to verify. Going to a new MAF this morning.

Thanks for the info!

I have an early 04...has everything an '03 truck has. I can read ebp with my edge insight.

strokin6L said:

I have an early 04...has everything an '03 truck has. I can read ebp with my edge insight.

Click to expand...

Interesting! Most of the population has issues reading EBP. I checked signal voltage and ground yesterday at the harness and all seems well. Has a brand new tube and sensor on it also, still reads 0 at all times.

Does your tuning have the inferred or non inferred ebp reading? The rollback strategies are inferred and don't use the ebp sensor and that's why it would read 0

Quite possibly could be a rollback, I don't know what strategy it is being tuned off of. Can a guy read the current strat of the PCM to find this out or will that always show you the original strat?

I would assume it is inferred then and always has been, never has it show BP

You can read the current strategy when tuned. Then when you turn it to stock it'll read a different one. This is the way to find out if it has a rollback strategy.

If your VGT turbo was working at all... then I don't think EBP is your issue. If you did not have an inferred strategy and your EBP sensor was not working... then the vgt turbo would never run well.


Did you try plugging in your VGT solenoid yet?

Have you tried running a stock or canned tune? Just to check and see if it is the tunes?


BARO is under the dash. Just check it with your monitor. It should be reading the correct barometric pressure (around 14.0-14.7 depending on your altitude). MAP - Baro = Boost. So if you baro is reading super high then it would limit your max boost. I dont see many bad Baro sensors... but it does happen.


There are lots of "fuel desired limiters" in the tuning software. They can limit fuel based on oil temp, barometric pressure, boost, and a few others. If you are only reaching 22psi of boost then it is very possible that you are not able to reach max fuel desired. You can turn those limits off but it will just be masking the underlying issue.

There are also parts of the software that can mess up your MAP readings. You can make them read higher/lower. I don't think tuners usually mess with that though. But if you run a canned tune and your MAP jumps up to 28-32psi then you know it is your tuning that is limiting your MAP.



If you do have an inferred strategy... then the computer relies heavily on the MAF sensor to run properly (at least with vgt turbos). So if your maf sensor is bad/dirty/disconnected then that could be messing with the fuel tables also.

We install E-fans, a new motorcraft MAF sensor, and are going to re-test this evening if we get any time.

I will check the Baro reading of course. I believe I checked the MAP reading and Boost reading on the CTS and the MAP was about 14psi above turbo boost, which would mean the baro is reading as it should, but regardless I will check!

As KC said above the Baro sensor is separate from the map and is located under the dash on the drivers side.

Have you tried back probing the signal wire on the MAP sensor and reading it's voltage output? I would be curious to see if it correlates with the pid reading of 22psi.

You could also get a handheld pressure/vacuum pump hook it to the map sensor and increase pressure while back probing the signal wire on the map sensor. Then you could reference a voltage/pressure chart to see if the sensor is functioning properly.

Kc and I where just talking about SCT tuning last night... about how the tuning is so tight lipped on these 6.0's. I would love to get my hands on the software and check it out, but using efi live on the "other" brands might have spoiled me.

As kc also stated there are a lot of limiters built into the pcm's and can be hard to find out which one your hitting. elevation, iat, eot, ect, map, ect......

Good luck!
Awesome build by the way