RPM jump with light touch on throttle.

[kojo]

BPDN is for 4l80E

 

[buddy]

Maybe my manual is messed up but it infers that DTC67 is unique to the 4L60E. I'll have to dig out the big book. Or maybe the shorted 5V system is causing the glitch.

Well, your shorted 5V could be to the Accelerator (APP) or the Optical Sensor (OS).

Just pop off the connector to the pedal and test the lines to ground with the truck off, none should have continuity to ground. With the IGN on you should have 5V across specific lines you can see in the attached. Along with the 5V line to the OS on top of the IP.

 

[Holyoak]

When my IP started going bad I couldn't get the truck to hold a steady rpm above idle while in park. The RPM would run away uncontrolled with the smallest throttle movement.

In addition the cruise control also couldn't hold a steady speed on the highway. As I understood it this was due to the computer requesting a set fuel flow rate to match the requested throttle position but since the pump was worn internally it was providing more fuel then requested causing the truck to over accelerate. The computer would try to back off the fuel flow to adjust and the truck would start to slow to much. The computer would try to compensate again, the truck would speed up to much and the process would start over again.

I don't know if this helps but this is what happened when my IP started going bad/went bad.

 

[buddy]

Yeah, but his computer is telling you its internal reference voltage is shorted

 

[jimloycom]

Made sure the eprom was seated well, removed it reseated it. I tested the fuel pressure and it was about 5psi before the IP. I changed it with one I have that was getting 10psi. tested and really did not notice any difference. Then changed oil and filter. Cleared codes and it ran perfect. Weird, have not really done anything. No RPM issue. Normal power.

So pulled new codes:
51 PROM Error (Faulty or Incorrect PROM)
53 System Voltage High
66 3-2 Control Solenoid Circuit Fault
67 Torque Converter Clutch (TCC) Solenoid Circuit Fault
78 Wastegate Solenoid Fault

On this drive I came to a full stop. Went FOT, black smoke, good power, seen better. Did this a couple times. The amount of smoke you should normally see from a diesel pulling. I don't think it was excessive. When I get the scan tool I will have a ton more info and probably get it where it should be.

 

[NVW]

I was probably a bad connection with the eprom, things went back to normal after the codes were cleared

 

[buddy]

If you are getting the 78 then the black smoke is because the turbo isnt spooling.

What is the IGN voltage? Is your alternator outputting too much voltage?

Strange is tells you there is an EPROM error, I believe you said the PCM had been swapped before right? Did you do that, or is original back in?

Your EPROM or PCM could be malfunctioning causing your issues. I have some extra if you want to try send me a PM. And now it has recognized the fault. Or you have moved a wire that was previously shorted and isnt shorting at the moment.

 

[jimloycom]

I'm not sure how to check he IGN voltage. I can verify the altenator tomorrow. I tried a different PCM with no luck. Now that I'm thinking about it I think you are right. I don't think the turbo is working. That would match the power loss feeling.

 

[Turbine Doc]

GND's clean ? all of them ??? that is where I go 1st when you get codes that defy conventional logic or are intermittent http://www.thetruckstop.us/forum/showthread.php?t=14596 link to this & other good to know info can be found in the technical reference area http://www.thetruckstop.us/forum/forumdisplay.php?f=218

One way to rule out APP as culprit, run in cruise control the APP is taken out of the loop, if it happens in cruise control as well then you don't need to spend time with the APP.

 

[jimloycom]

Replaced the coolant temp switch. That fixed the high idle and long glow plug issue.

Checked the vacuum pump. It was not providing vacuum.
Replaced that and eliminated 78 Wastegate Solenoid Fault.
Also dumped the burnt trans oil and changed filter/oil.

Cleared codes and test run out good. I think the original issue may be related to the trans not shifting to top gear. That seems better now.

The good news is I'm down to 1 code:
21 Accelerator Pedal Position (APP) 1 Circuit High.
I agree if the APP or cruise control can not manage the issue an the APP is OK. And this is true for my case. It appears if it gets stuck in a lower gear it is basically rpm on off. Like being in a low gear, the APP will be very touchy at high RPMs. I'm hoping the new trans fluid and filter and new vacuum pump will assist if that is what is happening.

I also verified operation of the wastegate vacuum system, and checked replaced bad lines. So the vacuum system should be good. Is there any line that run to the trans that I need to inspect?

I did not get to looking at the grounds. I plan on it.

Any suggestions or thoughts is greatly appreciated.

Thanks
Jim

 

[buddy]

Sounds like you had a plethora of issues that has been causing a plethora of confusing codes.

That code means the PCM is getting 5V back to itself when it only sent out a 5V reference voltage that was supposed to go through some resistors.

You need to test the APP wires in the diagram I posted earlier, one of your pedal sensor may be bad, or one of the wires is shorted. With the truck off make sure there is no continuity between any of the 3 wires going to APP1, which is G, F, and A. Then make sure there is no continuity to chassis ground on each. Then check to make sure there is resistance between the pins of the sensor itself. With IGN on verify there is 5V across A and G.

 

[buddy]

I checked mine and there is a few hundred thousands ohms between wires and to ground, so thats not continuity, but you will get some reading when checking.

On the sensor, there should be 2-4 kOhms between pins.

 

[jimloycom]

Current status

Been a while. Installed a new IP per KR services. He said there was an issue with the pump because of the rpm management was out of control and it blew black smoke on acceleration. Well that was it. It is running much better. I got in the GMTD scan. And it appears I might have done something wrong somewhere. I don't think the turbo is working. I manually operated the waste gate at different rpm's and had no reported difference with the scan tool or audibly. Any thoughts? Thanks Jim

 

[96 OILBURNER]

"I manually operated the waste gate at different rpm's and had no reported difference with the scan tool or audibly."

Turbo won't do much of anything, if you are in Park. It needs to have a load on it to make boost.

 

[buddy]

You replaced an IP off the advice of a mechanic because you had black smoke? Usually not good to trust mechanics.

What problem were you trying to resolve? Thought most things were cleared up and you had a code for an electronic sensor in the pedal. Did you check out the pedal?

Have you verified you have boost when accelerating? GMTDScan can show it in the dashboard while driving or you have a boost gauge?

You mentioned verifying the vacuum system, did you verify the vacuum at the turbo actuator?

 

[ak diesel driver]

If it runs better after an IP change you might have had 2 issues. The one you have left sounds like an inop turbo system. Start by checking vacuum at turbo at idle should be around 20"

 

[matuva]

optic bump ?

 

[jimloycom]

KR Services is the guy I bought the original IP from. The IP had a one year warranty. He identified a part in the IP that caused this issue. Sorry I don't remember what it was called. It did correct the issue.

There is no vacuum at the gate at idle. There is vacuum coming from the pump, and the lines are good, so either the solenoid is bad or the signal to it? Will check them more today.

I do not have any boost when accelerating. It is driving like a non-turbo.

If I bypass the solenoid and hold the gate open will that test to see if the turbo is working?

I'll look into this today.

Thanks
Jim

 

[ak diesel driver]

yes

 

[buddy]

Yes, just bypass the solenoid.

And realize that lack of vacuum to the actuator will cause incredible smoke on acceleration, and low power, and you should still get the DTC78.