Engine/Transmission (1998.5 - 2002) Looking for Ideas on intermittant miss.

[BILLVO]

I have had an issue with my 02 for about three years now. When it is cold out it runs like a champ. as the temps pass 60-70 degrees and the engine is hot it develops an inconsistant miss. It only does it in warm weather with a hot engine. It developed after I installed the 155 hp BD injectors and an II HRVP44 pump. They were installed about a week apart in the spring while it was still cool out so I never could isolate which caused it.



I Have read that a bad vp44 computer will cause the miss when it gets hot.



The next thing is if It is in gear or has any sort of load on it like head lights on or ac on ect it will run smooth but put it in park with every load sucking option off them it misses. It is not a solid consistant miss either it sounds like morse code and it will miss through the rpm band as it is reved up with no load also.



Seems the hotter it gets or after pulling a heavy load is when it gets the worst.



Any ideas?



It was a fresh II HRVP44 when I installed it about 3 years ago which is where I think the problem lies.

 

[PC12Driver]

I think you're on the right path with the VP44 being the cause. In the world of computers, heat can make electronics that otherwise work just fine start to flake out. Working the engine heats up the VP, and the electronics in the pump get heat soaked. Also, since it's missing when the system voltage is at the lowest (low rpm, high electrical load) and low voltage also will uncover problems with electronics, I think that backs up the VP44 as well.

 

[BILLVO]

Also, since it's missing when the system voltage is at the lowest (low rpm, high electrical load) and low voltage also will uncover problems with electronics, I think that backs up the VP44 as well.

It actually quits missing with any sort of load, electrical or otherwise. Load the electrical system through making it pull the alternator harder or turning on the ac ect makes it miss less or makes the miss stop totally.

 

[Sticks]

Start cracking open injector lines to see where the miss is at. Find out if it is floating around or staying on one cylinder.

Could be an injector that is sticking/worn.

 

[PC12Driver]

It actually quits missing with any sort of load, electrical or otherwise. Load the electrical system through making it pull the alternator harder or turning on the ac ect makes it miss less or makes the miss stop totally.

Sorry about that, I misread your first post.



Yeah, what Sticks said.