Looking for Ideas on intermittant miss.

[Wild and Free]

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.

[AH64ID]

My first though is that when its hot and there is no load the fuel required to idle is so low that maybe one of the injectors doesn't pop as low as the others and the VP isn't sending enough fuel to get it to open?But t

[ISX]

My first though is that when its hot and there is no load the fuel required to idle is so low that maybe one of the injectors doesn't pop as low as the others and the VP isn't sending enough fuel to get it to open? But t

That's what I am thinking. Having bigger injectors is letting more fuel in, even at idle, and that's enough fuel to make it rev above normal idle speed, so it is trying to do anything it can to get it back down. A load drags the engine down enough for it to not try and overcompensate, which it seems to be right on the edge of having enough load to not do it. Then you get to AH64ID's idea which is about as right on as I can think of. Maybe it will go away over time as the injectors that are really strong wear out a little.

[Mopar1973Man]

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.

I'm in the same boat... My miss still exist even after cleaning the injectors... But extremely slight and very small miss now. Yes... Its a very random miss that only occurs after hard runs like hauling firewood or climbing the grade to McCall... I can give you this much... It injector caused... If I return back to my stock injectors nothing no miss no problem. Put the RV275's back in and boom! Slight miss while hot. But mine might miss one day and then be several days again till it does again or heavy hauling... Now I've tried cleaners... No good makes it worse... Double dose of 2 cycle oil nearly kill the miss but to expense to keep up... So there is my tidbit of clues maybe you'll find answer from this...

[ISX]

I'm in the same boat... My miss still exist even after cleaning the injectors... But extremely slight and very small miss now. Yes... Its a very random miss that only occurs after hard runs like hauling firewood or climbing the grade to McCall... I can give you this much... It injector caused... If I return back to my stock injectors nothing no miss no problem. Put the RV275's back in and boom! Slight miss while hot. But mine might miss one day and then be several days again till it does again or heavy hauling... Now I've tried cleaners... No good makes it worse... Double dose of 2 cycle oil nearly kill the miss but to expense to keep up... So there is my tidbit of clues maybe you'll find answer from this...

Wouldn't the cleaners make it burn faster and more forcefully, making the injections more potent. So when it is trying to lean out the fuel, the fuel is just burning too instant and increases piston speed since there is no load. 2 stroke I think cures it because it makes each injection less potent but longer lasting. So the cleaner would hurt power with a load because it is just blowing up really fast, but the 2 stroke burns slowly so is not going to make the RPM jump up, though makes each power stroke burn longer lasting. Maybe I am completely full of crap

[Wild and Free]

I read on Blue chips site that the vp44 computer will cause my exact issue when it gets hot and since this is a rebuilt HRVP44 from II, I doubt they install new computers so I am leaning towards that but until it dies or starts acting up and affecting my performance I will live with it as I have for 3 years already.I am thinking of trying a different set of injectors if I find a set and see if it makes a diff or not,or maybe just get mine pressure/pop checked.

[guinnessbrewer]

Just to test the vp44 theory you might get an icepack and set it on the VP44 computer cover when the problem starts and see if it goes away. No I am not suggesting icing your vp everywhere you go, but at least you could narrow down the culprits. GB

I read on Blue chips site that the vp44 computer will cause my exact issue when it gets hot and since this is a rebuilt HRVP44 from II, I doubt they install new computers so I am leaning towards that but until it dies or starts acting up and affecting my performance I will live with it as I have for 3 years already. I am thinking of trying a different set of injectors if I find a set and see if it makes a diff or not,or maybe just get mine pressure/pop checked.

[Mopar1973Man]

Wouldn't the cleaners make it burn faster and more forcefully, making the injections more potent. So when it is trying to lean out the fuel, the fuel is just burning too instant and increases piston speed since there is no load. 2 stroke I think cures it because it makes each injection less potent but longer lasting. So the cleaner would hurt power with a load because it is just blowing up really fast, but the 2 stroke burns slowly so is not going to make the RPM jump up, though makes each power stroke burn longer lasting. Maybe I am completely full of crap

Actually I was thinking along my line of my miss that the cleaners tend to thin the fuel plus the heat makes the fuel so thin its difficult to get it to pop at idle. But now add the 2 cycle oil and drive the cSt up a few more notches making the fuel thicker and now you can reach pop pressure constantly. Like today I drove to Riggins twice in 105*F temps and never have a miss... I even shut the A/C off and let the pyro cool before shutdown and never heard it today... But yesterday after climbing hills in Casade, ID I heard it miss a few but... Now it gone again... A buddy of mine in town tonight gave me a idea of is it possible the pintle is not sealing good and some compression is leaking into the nozzle causing a misfire or slight miss? But you'd see that on a pop test I would assume between pop pressure ad the leak down pressures?