Hi guys. I'm new to the forum and diesel trucks. Bought an 04 6.0 with 147000 miles to pull a light landscaping trailer (3500 lbs) which I know is overkill, but love the looks and sound of the vehicle. Four days off the lot it started hesitating leaving a stop with with light throttle demand, then started missing on slight downhills with light throttle. No trailer in those situations.

First time with the trailer it bucked for about 5 minutes, again not pushing it hard, in fact, getting on it helped out. Dropped it at a Ford dealership, they said they adjusted BPR. Today it hesitated with the trailer, put it in tow haul mode, behaved all day, 100+ miles.

Operator error? Can BPR be adjusted? Is the trailer heavy enough to require the tow mode on level terrain? I've seen some stuff about bypassing the EGR valve but know absolutely nothing about these engines.

Any help is appreciated.

T

 

Are you stomping on the pedal from a complete stop? If you are the hesitation that i believe your talking about is the turbo building pressure, ease onto the pedal until the turbo gets moving

 

No. Very light touch on the pedal. More aggressive eases the problem, but I don't like jumping from a start. Seems to me though I should be able to take my time up to speed without the engine objecting. I would like to discuss options with the tech, though, without throwing parts at it, but they found no codes.s

 

Consider this:

A) plugged EGR valve / system

B) turbo rust

 

Thanks for the replies. I'll check the EGR valve and the turbo, although previous owner replaced turbo about 15k miles ago.

 

15k is still plenty of "time" to get turbo gummed up again or have the EGR stuck. It would all depend on how he used the truck.

 

what is the BPR?

 

If you are planning on doing work your self which i personally recommend you might want to get a code reader to help trouble shoot. In the long run I will be a good investment.

 

I would second that, however, I would make sure research is done on which code reader you get. Not all are created equal when it comes to reading diesels.

 

I would bet you have a weak injector. When one cylinder misses or doesn't contribute fully, it is felt more at low RPMs. Its usually most noticeable in overdrive when your speed is low, around 45-50. Kicking the RPMs up, like with Tow/Haul mode, usually makes it feel a lot smoother. I have #5 injector out right now and needing to change it out.

 

I said BPR above. I meant back pressure sensor, and i'll probably use wrong terms for a while! I'll get the injectors checked, too. Thanks for all the replies.

 

No problems w/ terminology. That is the EBP, and it really can't be adjusted. If that is what they said they did, I would wonder about their honesty ..... Now the steel tube that leads to the EBP can get plugged and need cleaning. That is always an easy do-it-yourself thing to try (that and cleaning the MAP sensor hose).

Are you seeing any smoke with the hesitation?

If not, either injector or turbo seems likely.

Is it an early year 2004 (ie where is your ICP sensor - under turbo or on passenger valve cover)?

 

ya adjusting the ebp is like adding blinker fluid. I also second the possibility of an icp sensor concern if its an early build unit.

 

Just an observation.

Sensors do not last forever. They wear out.

While non-mechanical sensors in theory have "no moving parts", the reality is that sensors are subject to wear in many different ways even if they don't have a mechanical component.

For example -

Non-mechanical sensors like temperature sensors, or air mass sensors both have wiring that goes to their operating components.

Even if the sensor do not wear (temperature is a thermocouple in many cases), the wiring does --- and as it does so, the signal characteristics degrade over time.

Good ECM/PCM programming understand this, and make allowances for sensor wear --- but even then, there is a point when no amount of software compensation can correct for basically bad input.


Mechanical sensors like the EBP or ICP sensor wear because most often, they involve some sort of a mechanical device moving around that changes resistance / or if it is a digital output, changes either frequency / amplititute.

If it is done with a resistor, they wear. Other ways are using a MEMS strain gauge, which wear, etc.

Again, good software is suppose to fix these things.


Then there are esoteric sensors - like the Oxygen sensor (thankfully not used for us) that have a heater that can fail, and as it does so, trip up.

Now, if the failure were a clear "bad" the software can sense that easily, but often, heaters fail slowly, and then, intermittently, and that always trip the software.


That is why I am a believer that sensors, no matter what Ford / Navistar says, do not last forever and should be all replaced / refreshed periodically.

Problem is, I am about the only one that thinks so.

 

there is truth to that. but is it cost effective to replace things before they break. some of the sensor have continous issues like ebp, icp (03my), etc. some never seem to have issues like iat2.