Engine/Transmission (1998.5 - 2002) hesitation with no codes

[WadePatton]

Originally posted by ThrottleJockey

Slight, temporary flooding of the combustion chamber due to.....



You got it, timing advance. Not enough to damage anything, mind you.

Then why did the problem not appear until many months AFTER the installation of bigger injectors? And it started in frigid air temps only, now air temp doesn't seem to be as important.

 

[Gary - K7GLD]

... and on the several cold morning occasions MY truck has been affected. I was pulling a load, and don't have aftermarket injectors...

 

[kdw75]

I have been living with this for about 8 months, ever since the dealer replaced my Crankshaft Pos. Sensor and Boost sensor. I got the truck back and had the bucking. I have also noticed that the box doesn't add fuel until about 5 lbs of boost. Before it added it before then. So far chasing the problem I have replaced the following: ECT, IAT, Boost, Crank Sensors and also the ECM. Today in the warmer weather though the problem vanished!! Then this evening when it dropped down below about 75-80 the problem came back and is there again.



Another thing is that ever since the problem started the truck has idled kinda rough. Today when I started it and it was about 84 out the truck was doing it's usual slight shaking at idle running rough. Then like someone flipped a switch it cleared up and started running just as smooth as ever.



Keith

 

[DavidC]

kdw75

Have you tried running without the fueling box?. Checked and cleaned the Elect. connection on the VP44?. It sounds as though you could have a wire or connection that could be marginal somewhere. The symptoms could show up that the voltage needs to overcome the resistance of the marginal wire/connection before normal operation can happen. This connection could be a ground, the fueling box, connection at ECM, connection at Vp44 or any connection for the fueling or sensor system. I would check all of this before seriously getting into the VP44 replacement ( it could be).



Dave

 

[kdw75]

Yeah, I have tried running without the box, what I did was just plugged the factory Boost plug directly into the sensor bypassing the boxe's harness. Yeah, now that you mention it that is what it seems like. I put in an old Boost sensor and at idle it has less resistance so now instead of adding fuel at 5 psi it does it at about 1 psi of boos. But there is still smooth power fluctuation and when accelerating you can let of slightly and hear the timing change and the engine get alot louder. I also tried cleaning the Boxes ground and even added another ground to it directly to the batter as a backup. The engine block seems to be well grounded also. I have cleaned all the electrical connectors I could see but don't know where all of them are and the manual I got at the auto store doesn't show where they are on the truck.



Keith

 

[DavidC]

kdw75

The service manual is still available even on cd



https://techauthority.gltghosting.c...rHome?langId=-1&storeId=10051&catalogId=10051



Dave

 

[kdw75]

Thanks for the link. I ordered one so I am anxious to see what I can figure out.

 

[jaybigboy34]

I am having the same surging problems as everyone else on here. I live about 5 miles from the highway so I keep my foot off of the pedal until the temps warm up. By the time I get the highway, everything is warmed up. It surges on me when I start to get on it on the highway. It doesn't matter how many times I floor it, it surges everytime while going to work. When I am ready to leave work, and start to drive home I can floor it as many times as I want, and it doesn't miss a beat the whole way home. I am not sure about the cold weahter theory, because it has been 60 degrees here in the morning. That doesn't seem too cold to me? What else could it be?

 

[kdw75]

Well, as you can see I have replaced just about everything you could think of. I am leaning towards it being a fuel pump problem. Maybe I am just paranoid since my pump is a Reman. from Dodge.