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Random Hiccups

jmack91z28

jmack91z28

Jason
Messages
146
Reaction score
10
Location
Midland, NC
In the past 3 months that i've owned my 6.5 it's hiccuped on me 3 times. It revs up on its own to about 1500 rpm for just a split second. Twice was when I was coming to a stop and I was on the brakes not the gas. Once was today when I put it in reverse and was letting off the brake and again no gas. There was one time when I came to a stop that it shut off but fired right up no problem. It runs great, no SES light or codes thrown. It's got 300,000 miles, IP changed at 175,000, injectors need to be changed but it doesn't smoke or run poorly. IP still runs strong, not sure about the fuel filter when it was last changed, but I wouldn't think that would cause my rare intermittent issue. Wondering if anyone has ever seen this? Maybe optical sensor is dirty? PMD was relocated and replaced too.

Also, just another thought, i've noticed I have two Wait to Start lights in the dash. Is that normal and what is the second one for?
 
My old 1975 Mercedes diesel does that and its a sure sign that the fuel filter needs to be changed, not sure why it happens but I could guess that its trying very hard to suck some fuel or push depending on if its the primary pre filter or secondary filter, it does it on either, anyway the clogging shifts or enough pressure builds up to get the fuel to the IP but almost immediately it dies back to normal pressure and idle and yes it happens in reverse too. Just a guess. Sorta like a lawnmower speeds up right before u run out of gas. But I learned one thing in my short time with Ak n others giving me advice on this site, there are grounds all over these diesels and u better make sure u find them and clean and check them cause bad grounds cause really wierd problems. Ak can direct u to a sticky about grounds, I dont know how to do that yet on here.
 
Just because the pmd was replaced with a new one doesn't mean it can't be bad. Many fail within the first couple months or sooner.Cleaning all the grounds[especially on the rear of the intake] is free. You also didn't say where the pmd was relocated to. It won't hurt to change the fuel filter since you have no idea when it was changed last. You might want to check if the lift pump is working also. No lift pump will cause fishbiting also.
 
I appreciate the responses. It doesn't fishbite even when towing. PMD was relocated to the drivers fender with a heat sync about 8 years ago. I've actually got two more brand new ones that the PO gave to me when I bought the truck.

I'll clean the grounds up and change the filter.

Orrum, what part of NC are you from?
 
The big thriving metropolis of Orrum located about 20 miles from Lumberton, we have the Orrum general store and then there is also the Orrum general store and oh yea a lil bitty post office! LOL U up there where they have that nasty mustard BBQ arent u? LOL Hey I aint a mechanic, just a wore out one legged cowboy better pay attention to these guys they will teach u all kinds of tricks!
 
Gnds & PMD are suspect how many miles on the IP ??? have you done the 2000 rpm test ???

Bring engine to full normal operating temp H2O temp > 170F, then slowly accelerate to 2000 rpm hold for 5 sec and decelerate, do this 3x throttle should allow you to maintain speed as IP ages "innards" wear and can cause the off throttle bumps at idle or when going from park to reverse, if this is happening start saving up pennies for a replacement IP, if you don't have good throttle control and engine "runs away" fuel solenoid armature shaft is worn or broken and sooner is better for getting a replacement IP.

But rule out all other electrical gremlins 1st as IPs don't come cheap.
 
125,000 miles on the IP, I ran the 2000 rpm test on it before I bought it and it operated as it should.

Oh lord, not Lumberton. Everyone I work with is from Florence or Mullins, just below you.

Mustard BBQ, hell no. We make our shoulder and boston butt the correct way.
 
I like it where u cook the whole hog and everybody gets to cut out the part they like. Me I know where the tenderloin is! LOL That and some cold potato salad and pineapple cake!!!!!
 
Do you have a large oil leak in your turbo? If so the oil can be pushed into your air intake and the motor will burn it and try to run away on you even if you turn the key off. Happen to me in a VW Jetta TDI for like 45 seconds just have to wait until it burns all the oil havent seen it in 6.2, 6.5's. In turn check your lower intake man for buld up hope that helps.
 
Just an update, I kinda forgot.

After a month or so of the issue, it finally threw an engine code at me. Crankshaft position sensor. I swapped it out with a good AC Delco replacement, and it's been going on well over a month without anything what so ever.
 
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