Intermittent dead pedal and hesitation

[Krlspokane12]

Hey Guys, 

I really need your help on this one.  I have been chasing an intermittent dead pedal and hesitation issue and I'm not sure what could be causing it. It does not happen all of the time, there will be days that i drive the truck and it doesn't happen at all and other days where it happens multiple times.  It doesn't matter if the engine is warm or cold either.  It usually happens under acceleration, but it has happened while cruising.  I will go to accelerate from a light and nothing happens when i push the pedal for about 2 seconds and then it will kinda sputter and then accelerate like normal. I put a new VP on the truck in July and after talking with Mastertech diesel here in Boise, they thought my new pump might be going bad already so i took it back to them on Monday to be tested and it passed, so i know that is not the issue. There are also no codes or check engine light.  All of the following has been done to the truck.  so I'm not sure if I'm chasing an electrical gremlin or the new ECM is beginning to fail.  Any insights or trouble shooting help will be greatly appreciated as i don't just want to start throwing money at random things hoping it fixes the problem

 

New batteries in April

New alternator last year

New battery cables 

New ECM in 2021

New OEM MAP sensor in 2022

New OEM cam sensor in 2021

New VP in July 2024

New Timbo APPS last month

WT wire mod 

Air dog 100 and 14psi of constant fuel pressure

 

 

 

[JAG1]

There are better qualified people on here than I am but, did you get the VP from a certified Bosch rebuilder? In other words, this intermittent may test good at the moment of testing but the PSG board on top of the VP may not have been changed as per Bosch's requirements. just my thoughts here.

[Krlspokane12]

From what I know, Mastertech is a certified Bosch rebuilder. I spoke with them in length about this and they stated they only use genuine Bosch parts for the rebuild. This is the 3rd pump I've got from them and have never had any issues. 

[Tractorman]

22 hours ago, Krlspokane12 said:

There are also no codes or check engine light.

 

Have you used a quality scanner for checking codes? Not all scanners are equal.  Or, have you used the ignition key method to read codes in the odometer?

 

- John

22 hours ago, Krlspokane12 said:

I put a new VP on the truck in July and after talking with Mastertech diesel here in Boise, they thought my new pump might be going bad already so i took it back to them on Monday to be tested and it passed, so i know that is not the issue

 

Since your problem is intermittent, it is possible that the pump could be defective and still pass the test.   Don't dwell on this, but don't disregard it, either.

 

Have you re-checked your work related to the W-T wiring modification?

 

- John

 

 

[Krlspokane12]

A friend of mine has a snapon scanner that we will hook up after we put the pump back in on Monday.  I'm looking over the wiring tomorrow to make sure I don't have bad ground or exposed wire.  I'll check the WT as well, thanks for the reminder.

[Krlspokane12]

So today while I was looking over the wiring, I remembered that a few times since I installed the pump the engine temp reading on the quadzilla would sporadically drop to -40 degrees for a few mins and then jump back to 185. Not sure if this is part of the same problem I'm having. The sensor is less than a year old and I did get it from Cummins, so is this indicative to a bad/ going bad ecm? Not sure if the temp issue and the dead pedal are part of the same issue or 2 separate issues. Just thought I'd mention it while I was thinking about it 

[Tractorman]

To aid in troubleshooting, it may be worth your while to remove the Quadzilla completely from the system for awhile - at least until you get this problem resolved.  The Cummins sensors are very reliable.  In fact, I still have all of the original sensors in operation on my truck.

 

You said that you were going to check for codes with a Snapon scanner after you put the pump back in.  Has that been done?

 

- John

 

Edited September 24 by Tractorman

[Krlspokane12]

I just got the pump back today, so I'll be installing it tomorrow and checking for codes then. I'll remove the quad tomorrow while I install the pump. I'll let yall know my findings.

[Krlspokane12]

So i got the VP installed yesterday and i scanned for codes following installation.  The following codes were present after initial start up. 

 

P0237- MAP sensor low voltage 

P1693

 

I cleared the codes and went for a test drive.  As of this morning, no new codes were present.  I will hook the scanner up when i get home and see if it through any new codes.  During my test drive yesterday and my drive to work this morning, i experienced no issues with dead pedal or hesitation. 

[Tractorman]

Keep us posted....,

 

- John

[JAG1]

On 9/21/2024 at 7:53 AM, Krlspokane12 said:

From what I know, Mastertech is a certified Bosch rebuilder. I spoke with them in length about this and they stated they only use genuine Bosch parts for the rebuild. This is the 3rd pump I've got from them and have never had any issues. 

What's been your average miles gained on these Mastertech VP's before needing another? Should be getting quite a lot of miles for each rebuilt VP. I think I heard something like 250 K miles.