2000 RD engine stumble

[MACKTRUCKS4]

My tri-axle has a stumble at low RPM's. 2000 RD with a 400. Seems to be worse when the engine is cold. The harder you try to pull out, the worse it is. If it had a carburetor, it would say it is loading up. That's what it feels like. Injectors and turbo have been replaced and it did it with the old one also. No "check engine" light. Could it be an air intake sensor without a check engine light? or something else?

[steeler]

Does the electronic malfunction light work? Any smoke? Does it sounds like a single cylinder misfire, or definitely a stumble?

It runs fine at higher rpm?

Edited August 10, 2016 by steeler

[br549]

Ditto on what steeler said, does the malfunction light come on when the key is turned on and than go off, I' have seen a lot where the bulb has been taken out or the bulb socket fall out of the housing.  Ck your fuel pressure, the fuel supply pumps are bad about fiber gear slipping on the shaft. 

[steeler]

Ya, my first thought is fuel pressure, luckily the etech is almost as easy as it gets to diagnose. Even through the internet.

Some have asked me why I would offer help on the net. These are some of the problems some of us pulled our hair out on 15 years ago, but learned all the ins and outs through it. Why not help somebody else out? 

Sorry I'm rambling.lol

[MACKTRUCKS4]

The light does work, goes out after a couple of seconds. Its a definite stumble. If you pull out and go very easy on the throttle, it won't do it. The same way in between shifts. What should the fuel pressure be? I was told to test it under a load, and while driving. It does smoke at first shift but only a short blast of black.

Edited August 10, 2016 by MACKTRUCKS4

[steeler]

Fuel pressure should be somewhere in the 60-75 lb range. Testing under load would be ideal, but often you'll see it near zero at idle when the gear is slipping on the shaft.

If it's a restriction in the fuel system pressure might be good until you get it under strain.

[Dirtymilkman]

I had this issue years ago, for some reason replacing my fuel check valve cured it. 

[Challenger]

On 8/10/2016 at 10:21 PM, Dirtymilkman said:

I had this issue years ago, for some reason replacing my fuel check valve cured it. 

 

The fuel check valve is what regulates your fuel pressure.   The spring can wear out or something gets stuck in it and holds it open.  

Low power or stumble complaints-- Check for codes and fuel and boost pressures.  Never assume, check them.  

Etech stuttering or stumbling sounds like a fuel pressure problem.  

[Dirtymilkman]

I do injectors every 250,000 miles and I replace the check valve with them. Along with the return line, Jake o-rings, injector lines, thermostat and air filter. I have a 460 with 36,000 hours and 1,000,000 miles and haven't had an issue. 

[1965]

15 minutes ago, Dirtymilkman said:

I do injectors every 250,000 miles and I replace the check valve with them. Along with the return line, Jake o-rings, injector lines, thermostat and air filter. I have a 460 with 36,000 hours and 1,000,000 miles and haven't had an issue. 

You plan to do your mp10 same way?

[Dirtymilkman]

4 hours ago, 1965 said:

You plan to do your mp10 same way?

I think so. The E7's I've always changed oil at 10,000 miles, but they recommend 40,000 on the mp10. I've been doing it at 25,000 so far. It holds almost 15 gallons of oil. Otherwise I'm pretty sure I'll run the overhead and do injectors at 250,000. And when warranty is off, so are the emissions. 

[1965]

10 minutes ago, Dirtymilkman said:

I think so. The E7's I've always changed oil at 10,000 miles, but they recommend 40,000 on the mp10. I've been doing it at 25,000 so far. It holds almost 15 gallons of oil. Otherwise I'm pretty sure I'll run the overhead and do injectors at 250,000. And when warranty is off, so are the emissions. 

Had to change my injectors at 206; they said had to change cups also; mine looked like cups were still good; but changed also

[fjh]

On 8/10/2016 at 9:51 AM, MACKTRUCKS4 said:

My tri-axle has a stumble at low RPM's. 2000 RD with a 400. Seems to be worse when the engine is cold. The harder you try to pull out, the worse it is. If it had a carburetor, it would say it is loading up. That's what it feels like. Injectors and turbo have been replaced and it did it with the old one also. No "check engine" light. Could it be an air intake sensor without a check engine light? or something else?

We once found an issue like this  on a CL the alternator was glitching and voltage spikes were causing issues !The engine would stop in the exaact same spot in the rd on the same haul every several days! Something to think on if your still searching!

Just Sayin  !

[1965]

On August 14, 2016 at 9:32 PM, Dirtymilkman said:

And when warranty is off, so are the emissions. 

So are you saying your going to do a delete?

[Dirtymilkman]

15 hours ago, 1965 said:

So are you saying your going to do a delete?

Pretty sure, I was told I can get an Australian file and eliminate a lot of things. 

[Dirtymilkman]

But I must say, I have had ZERO emissions issues with this truck in 2 years and 175,000 miles. 

[1965]

1 hour ago, Dirtymilkman said:

But I must say, I have had ZERO emissions issues with this truck in 2 years and 175,000 miles. 

Knock on wood mine has been doing good Except had to put injecters in; if it's has problem I would love to do the delete

[Dirtymilkman]

This mp10 is a blast to drive. I gross 91,000 pounds daily, 18spd and 3.73 rears and this thing accelerates effortlessly. I have never drove a loaded E9 but I wonder if it's this good? 

[1965]

11 minutes ago, Dirtymilkman said:

This mp10 is a blast to drive. I gross 91,000 pounds daily, 18spd and 3.73 rears and this thing accelerates effortlessly. I have never drove a loaded E9 but I wonder if it's this good? 

Never driven a E9 either, but I'm impressed with my MP8, I've hauled some heavy stuff & it will stay with the C15 & ISX15, & it's not near as big as they are

[MACKTRUCKS4]

Ok, changed the check valve, no different, changed the lift pump, no different. Could it be a weak eup?  I've changed 2 of them in the past but that was for fuel leaks. Can they be checked in the motor or do they have to be removed to be tested? I also noticed a stumble when the jake first comes on. Could it be connected or 2 different problems?

[br549]

Have seen a couple where the fuel pedal cause it to stumble but usually you can mess with the pedal with foot side to side and make it cut out or stumble while driving it, does it do it with the cruise control? 

[MACKTRUCKS4]

I thought about the pedal maybe being the problem. If I had another pedal around I would swap it to see if that is the problem but every other truck I have is mechanical.  I have not tried the cruise.

[MACKTRUCKS4]

I tried moving the pedal as I drove, no different. Also tried the cruise, no different. Next?

[MACKTRUCKS4]

Got the problem fixed. I took the truck to my local Mack garage. They said Mack had an issue with the computers. They installed an updated program and it took care of the problem.