Looks like we are into an IP

[midnightrumbler]

So after relocating the OPS and installing a relay on this as well as relocating the PMD from the IP to the front bumper and replacing all fuel lines. I am still getting my fishbiting issue and reset a 35.

I just finished getting back in from taking the truck out for a 20 minute run. If anything the truck fishbites worse then before. I can really feel the truck kicking in and out on me more now than before and I am running around 2500rpm at 100km/h. If I put the truck into third gear, I cannot even keep it in this gear as the truck is kicking in and out and rpm's are all over the map sort of like riding a bull. besides looking rediculous driving down the road it is kinda fun.

I checked the codes again when I got back and the 35 is back after removing the code last time. Before I went out I checked the codes after I lassed cleared them to make sure and I was getting 12 which is all clear. Now after getting back, the 35 is there. Looks like we are leading into an IP.

Would the IP cause the truck to pretty much lose third gear like explained?

[rogers]

Have you tried adding oil to your fuel tank to verify that the problems are pump related? Could be the problem is in the electronics.

[midnightrumbler]

I have added a fuel conditioner/injector cleaner and oil to the tank as well as directly into the fuel filter management unit.

[NASFD35]

Did you ever change out the Injector Pump? I’m curious to find out if this resolved you problems.

[midnightrumbler]

I have not yet changed out the IP. I am still not 100% sold that it is the IP causing my problems.

I have the high idle mod installed on the truck and can hold 1100rpms with this activated, I cannot hold any rpm's with the fuel pedal.

Some have said that if I cannot hold RPM's with the fuel pedal, it is the IP. If the IP is bad, would the High Idle Mod not allow the rpm's to be held at 1100?

Also, with the bucking/hesitation I am getting, would the fuel pressure not drop off signifcantly while the problem occurs while driving if it were the IP?

If I had $600.00 to throw at a possible APP, I would do so but I am not 100% sold it is the IP.

[JohnC]

Try removing the filter connected to the optical sensor.

[Robyn]

The code 35 Pulse width time short is pointing the finger at the fuel solenoid
Your issue is very likely the IP.

Ab PMD can cause this but you have already messed with that stuff.

Good bet the IP has gone south.


Hate to be casting bad news BUTTTTT this is looking like the most likely issue at this point.

Robyn

[midnightrumbler]

Some has already removed the filter to the Optical sensor at one point or another. I cannot hold any rpm at idle with the fuel pedal which is leading me to believe it is the fuel pedal.

I am sort of stuck between a fuel pedal or an IP. truck idles great but cannot hold any rpm's with the pedal.

I will have to try and find a guy with a 6.5 and swap out pedals to rule this out.

Should I be able to hold any rpm with the fuel pedal? I can hold a steady 1100rpm's with the high idle mod no problem.

[JohnC]

The pedal will set a code. Robyn is right. DTC 35 points right at the fuel solenoid. The only chance is to give it a heavy dose of a good fuel conditioner and see if you can free it up.

It is very difficult to hold RPM with an EFI setup and an unloaded engine. If the fuel solenoid is sticky it becomes near impossible. Once it gets too far out of hand you'll get (apparently) random stalling.

[midnightrumbler]

I have set a DTC-25 in the past but since I have cleared it, the DTC-35 is the only one coming up at this point. I have also cleared this code and have yet to set it again. The truck will still hiccup/stumble/hesitate but does not set the code.

I have put no more than 60 miles on the truck as I bought this as a project and I am trying to work out all the bugs.

DTC-25 leads toward the pedal and the DTC-35 leads toward the IP. I hope it is not both :eek:

[jerry598]

DTC 35 was the same code being thrown on my truck before the dealer finally agreed that the IP was the problem. I was having no drivability issues except that when the code was thrown the SES light would come on and the cruise control would shut off. The dealer fought me all the way, replacing one glow plug and the ECM/PCM before they agreed it was the pump. It was replaced under warranty and the problem went away.

Forgot to mention. In neutral I was also unable to hold RMPs at any higher level than idle. I almost thought that normal. Now with the new pump and injectors, everything working right, I can idle up to any RPM level and it will hold.

[midnightrumbler]

Ok, the thing I find extremely odd on the truck is I can hold rpm's cruising up to 80km/h and beyond but as soon as I start coming back down and try and hold rpm's around 80km/h, this is when the truck starts bucking.

Another problem is I cannot even put the truck into 3rd gear as the truck will continually buck. There seems to be a dead spot in the Accelerator pedal right at about 1/4 throttle.

I am just not sure why I have not reset the DTC-25 and have gotten a 35.

I am leaning more toward the APP at this point as if it were the IP, I would think the bucking/hesitation issue would occur the same in any gear at any throttle position

Please correct me if I am wrong.....

[Robyn]

If the IP is in reasonably good shape you should be able to run the RPM up from 1000 to 2000 in a nice clean "SLOW" climb without it whizzing around. Once at 2000 you be able to slowly drop it back down.

This is not quite as easy as it is with the old DB 2 but if it gets bouncy and wont hold, then the IP has issues.

When the fuel solenoid gets hinky the ecm can't control is precisely and this is when the codes set (35).


The operation of the fuel solenoid is not a static thing, it is very dynamic. The solenoid works many many times a second and when the thing either gets sticky due to galling of the parts or an electrical problem, then the problems arise .

As John suggested, try some super duty fuel conditioner and see if it helps. If not, no harm done but if it does help then maybe you can get some more miles out of the IP.

How many miles on the IP now ??


Missy

[JohnC]

DTC 35 explains everything. The pump cannot accurately control the fuel rate and at lower rates the errors are more significant, hence more noticeable. If the problem were the APP, you'd be getting APP codes, not pump codes.

[midnightrumbler]

As previously satated, I have gotten APP codes, DTC-25. Also, I have heard that a DTC 35 can be a misinterpreted code and does not directly lead to a faulty IP like everyone likes to think. I am not saying it might not be the IP but I am thinking I am having issues with the APP as well as part of the problem or directed on it's own. I am hoping it is just the APP and not both. I have heard that a faulty PMD could also cause a DTC-35 or poor lubricity of the IP.


I recently did some tests of the APP and came up with some interesting figures


Terminals G and A have 5.03 Volts and do not fluctuate at all when pedal is at WOT

Terminals D and B have 5.03 Volts and do not fluctuate at all when pedal is at WOT

Terminals E and J have 4.90 Volts and can drop down in volts to 0.64 when pedal is at WOT



Between terminals F and A (Sensor Circuit 1) have 0.66 volts and increase to 3.44 volts

Between terminals C and B (Sensor Circuit 2) have 4.40 volts and decrease to 1.72 volts

Between terminals K and J (Sensor Circuit 3) have 3.38 volts and decrease to 0.62 volts



I think this is pointing to a bad APP for sure. I would like to try another APP in place of mine and see what happens before I spend over $400.00 for a new one or jump into an IP.

I seem to be getting a higher voltage than what is required through terminals G and A and D and B which is what could be setting my DTC-25

I am getting a continuous 5.03 volts through these terminals which is either a short somehere along the lines or a bad PCM as it is sending the wrong signals. Not sure if .03 volts over reference would make a difference or not.

So we know that the APP has 3 sensors, my readings throughout APP sensor 1 appear to be correct, it is APP sensors 2 and 3 where the problem seems to be but I am not sure if it is the pedal or the wiring

Incase you are wondering what signal wirings are what

G, F and A are all in Sensor circuit 1

D, B and C are all in Sensor circuit 2

E, J and K are all in Sensor circuit 3


I found some other info on the APP and it is as follows


APP Sensor Circuit 1 produces a varying voltage of between 0.35volts-0.95volts dc at idle and 4.0 volts dc at WOT

APP Sensor Circuit 2 produces a varying voltage of between 4.5 volts dc at idle and 1.0volts dc at WOT

APP Sensor Circuit 3 produces a varying voltage of between 4.1 volts dc at idle and 2.5 volts dc WOT


If I compare the information based on the above readings to what I have recorded, I think we have diagnosed a faulty APP as the readings in APP Sensor Circuit 3 are way out. APP Sensor Circuit 1 and 2 are within specs....

Please confirm this if you believe what I am reading is correct.....

[DmaxMaverick]

Your APP values are well within the acceptable range, and appears to be working correctly. The system line voltage, among other factors, effect these values. Not the problem. Your DTC 25 was either a glitch, ghost, or a connector/ground issue. In any case, the APP will not cause the symptoms you are seeing, absent a persistent related DTC. Fuel quality can cause a DTC 35, but only after the fuel has caused enough damage to condemn the pump. The PMD could possibly contribute to a DTC 35, but it won't be the only contributing factor. The APP can never cause a DTC 35. DTC 35 can be misinterpreted by individuals, but code itself is not vague. If it is present, there is a problem with the fuel solenoid, its circuitry, or the PCM. Chase the APP if you wish, but it's a wild goose.

[midnightrumbler]

I am not suggesting that the APP is throwing a DTC-35, I was simply making it known the code is present.

Correct me if I am wrong here, but in Sensor Circuit 3, my readings are far below the acceptable 2.5 volts WOT and I should not be able to have volts fluctuate through terminals K and J as these are reference signals

I know people are suggesting these pedals very rarely fail, but my results compared with the results I have gotten from professionals seem awefully far off



In reference to my numbers, here is accurate numbers taken from another users APP with do driveability issues.

With the Key on: Between terminals G and A, D and B, E and J should all have 5 volts.

Between terminals F and A should have 0.5 volts and should increase and decrease as the pedal is pressed and released.

Between terminals C and B should have 4.5 volts and should decrease and increase as the pedal is pressed and released.

Between terminals K and J should have 4.0 volts and should decrease and increase as the pedal is pressed and released.

[midnightrumbler]

Well, I must say guys that it is not the IP that was acting up, I went with my gut on this one and ended up finding a used APP to test on my truck as there was no way in hell I was digging into an IP without knowing for sure my APP was not at fault.

After purchasing a used APP for an excellent price, I went ahead and installed this and my numbers are now within spec and the truck is running great. Can hold rpm's at idle and can now hold 3rd and second gears.

Appreciate the responses but here is living proof that the APP is a unit to be a culprit. The DTC-25 was not just a ghost but a major factor.

These units are definately reliable but not to be left out of the equasion