Engine/Transmission (1998.5 - 2002) Cummins cannot diagnose engine miss.

[JAlford]

I recently upgraded my '99 by adding some power for towing. Unfortunately, the truck hasn't run right since. Over Easter weekend, I installed 4" exhaust, Piers 35/40 hybrid turbo, DD Jammer 3 injectors, and AFE intake. I had an Edge EZ already. After getting all the parts on the truck, I took the camper for a weekend trip. I immediately noticed a engine miss under load, and the engine misses sporatically when warm. It doesn't miss when cold. After talking with a dozen or so "experts", and replacing a few parts to no avail, I decided to have the local Cummins shop diagnose the problem, before I threw any more money at it. I also have low boost for what was expected (30psi peak), and low EGT's (1200 max), and did not get a dramatic increase in power that I expected.

Cummins had the truck for a few days, and I called and they wanted to put it on their dyno for further test. I agreed, and arranged to be there for the test. After 4 hours on the dyno, they gave up and decided that it was LIKELY to be an injection pump. They also thought I MIGHT have an injector problem and that the Edge EZ COULD be causing some problems. This was due to the reaction they got when the edge was disconnected - no miss on the dyno. The final verdict was a "No Problem Found" on the paperwork and a bill (they did cut part of the cost, since they couldn't give an answer). I have now ordered a pump (Thanks to Rip ), but still do not know if that will solve the problem.



IS THERE ANYONE OUT THERE WHO CAN TRULY DIAGNOSE A VP44!

Jeff

Of note - Dyno reveiled a 40HP increase without the Edge EZ, 59HP with, from bone stock.

 

[Huff N Puff]

First things to check are all the connections to the Edge,all grounds, make sure they are cleaned to bare metal if you have any scotch locks any where get rid of them. Solder your VP44 connection. You need to start with these simple issues before you start looking any where else.

 

[fox]

Is the miss-fire a randon miss or a rythmic miss. ? This will help point you in the right direction.

What is the history of the injectors? Are they used? Did the shop pop test them or check for the spray patern?

What about the connector tubes in the head. They are filters.

 

[JAlford]

Is the miss-fire a randon miss or a rythmic miss. ? This will help point you in the right direction.

What is the history of the injectors? Are they used? Did the shop pop test them or check for the spray patern?

What about the connector tubes in the head. They are filters.

The miss is very random. Doesn't miss at all when cold. When warm, sounds like a cammed gasser for a second, then smooth, then cammed. Under load, feels like I am driving over randomly placed speed bumps.

They did not pull the injectors, since the problem was so sporatic, so there was not a pop test and they did not have the ability to check for pattern. They said only Bosch could check pattern. Where are the filters? When I did the install, the tubes looked straight thru. No wear or marks at the ends. Took great care to tighten everything to correct torque.



There is only one connection for the Edge EZ - at the diagnostic port. No corrosion, and the plug has been in and out multiple times recent. Checked map plug also, same - no corrosion or damage. I had siliconed them initially.



Replaced the crank sensor - no change. APPS - new. The exhaust manifold is cracked at cyl. 4, ATS is on the way (Thanks Piers )



Still waiting on the new pump. Still no codes in the computers.

Jeff

 

[Oil Burner]

I have been chasing a miss when warm also, but I can't feel it at all under load. I had my Jammer's pop tested and some popped 315 bar and some popped as low as 295 bar (305 is ideal). My pump probably can't pop those high pressures (315) but I can't find a local shop to shim these things closer to 305 bar.



I'm not sure this is your problem, just a thought.



Jason

 

[Mark_Kendrick]

The miss is very random. Doesn't miss at all when cold. When warm, sounds like a cammed gasser for a second, then smooth, then cammed. Under load, feels like I am driving over randomly placed speed bumps.

They did not pull the injectors, since the problem was so sporatic, so there was not a pop test and they did not have the ability to check for pattern. They said only Bosch could check pattern. Where are the filters? When I did the install, the tubes looked straight thru. No wear or marks at the ends. Took great care to tighten everything to correct torque.



There is only one connection for the Edge EZ - at the diagnostic port. No corrosion, and the plug has been in and out multiple times recent. Checked map plug also, same - no corrosion or damage. I had siliconed them initially.



Replaced the crank sensor - no change. APPS - new. The exhaust manifold is cracked at cyl. 4, ATS is on the way (Thanks Piers )



Still waiting on the new pump. Still no codes in the computers.

Jeff

Clean and reseat the TPS plug. You can get some real funny results with a bit of condensation inside the TPS connections.



hope it helps,

Mark

 

[gonehuntingagain]

After 4 hours on the dyno, they gave up and decided that it was LIKELY to be an injection pump.

Did they use the tester on the VP-44 that eliminates the factory harness? This would bypass all electrical connections/sensors/Edge and should tell you if it is the pump or not - unless the issue is too intermittent to do this.

 

[Dieseldemon]

Disconnect the edge and see if the problem gos away

 

[JAlford]

Disconnecting the Edge EZ made the problem much less noticable under load, but has no affect on the idle miss. On the dyno, we could not load the truck enough to tell the miss with the Edge disconnected. With full load, the miss still occurs, but with less frequency and severity than with the Edge connected.



They were unable to plug directly into the bosch pump. They are not an authorized Bosch service facility. I haven't found one in my area yet. The only autohorized service facility that I talked with indicated that they had to have the pump off the truck to do any diagnostics.



Jeff

 

[gonehuntingagain]

I would find someone that can plug into the pump before I laid down the cash for a new one.

My VP-44 had a miss, but only at idle and only when it was cold at first. In fact, it just went away for a year, then started happening again. Took it to the dealer since it only had 85,000 miles. First thing they did was test the lift pump, second thing was disconnecting the wire harness and using the tester. The miss still occured = new VP-44.



I am very surprised that the Cummins shop you went to didn't have a tester. I first heard of this tester on this board, and it was a Cummins tool if I remember correctly.

Maybe someone can chime in and confirm this and give a Cummins part number?

 

[Huff N Puff]

The VP is possibly the poblem,but before you do any thing to it,please test the fuel delivery cause the the fuel system was built for 235hp. The fuel modules are very restrictive. Even if you do need the injection pump,The fuel module could be the cause of its demise.