Engine/Transmission (1998.5 - 2002) 02 HO cuts out, smokes, and backfires under load

[dieselluver]

I have an 2002 Ram 2500 4x4 24V HO NV5600 all stock with 103,000 miles which has developed a problem. When you accelerate hard and start building boost it will cut-out (loose power) and smokes and backfires anywhere from 2300 to 3000 rpm depending on the load or how hard that you accelerate. It runs just fine at any rpm if you do not accelerate hard. I have searched the TDR archives and have found information that has helped along the way but I am out of things to check or try. The following is a list of what has been done to diagnose and fix the problem with no avail.



1. Pulled codes. None.



2. Checked fuel pressure at injector pump and it was 10psi at idle and 0 to 3 psi under load. Removed old lift pump from tank and installed new FASS 95gph pump by tank and new fuel filter on engine. Fuel pressure is now 16 psi at idle and 12psi under load. Still runs exactly the same.



3. Replaced the VP44 injector pump and the fuel overflow valve. Old pump was sent back and torn down by local pump shop and metal particles in fuel had damaged and scored the old injector pump. Fuel filter housing and fuel line remove and cleaned out and installed with new fuel filter. Still runs exactly the same.



4. Swapped out the ECM from an 01 HO and calibrated the APPS. Still runs exactly the same.



5. Swapped out the PCM from an 01 HO. Still runs exactly the same.



6. Blocked wastegate closed on turbo. Still runs exactly the same.



7. Removed front gear housing cover and injector pump gear. Inspected key, keyway, dowel pin, gear housing, and pump gear for cracks or nicks/burrs. Everything appeared to be okay and the key was installed properly. Still runs exactly the same.



8. Removed valve cover and inspected valve train. All valves appeared to be operating normal and opening the same as the engine is cranked over. Valve clearances were verified to be in spec. Removed the injectors and had them tested by a local pump shop. Three of them were worn worse than the rest. They were scored and blackened on the inside of the tips. An internal valve must have been leaking to let compression back up inside the tips. The pump shop said that the old injectors were the wrong injectors and they were standard output injectors and not HO injectors. Checked engine compression and it was in the upper 300psi range. Inspected connector tubes and found to be in good shape. Installed new 50hp injectors. Still runs exactly the same.



9. Monitored various sensors with computer when driving. Engine rpm matches crank sensor rpm and VP44 rpm. MAP sensor and IAT sensor seems to be within range and operating properly. Replaced MAP sensor and tested continuity of MAP sensor wire back to ECM connector. Have checked for new fault code all along the way and nothing new. Still runs exactly the same.



Has anyone experienced a similar problem or have any ideas on how to fix this problem? Any help would be appreciated.



Thanks,

Justin

 

[fox]

I would call Chip at Blue Chip diesel and get his advice.

Blue Chip Diesel Performance Specialists

 

[JKinney]

Do you have a slice or cut in a turbo intake sleeve?

 

[JohnBoy5]

sounds like the IP still even though its new... . what color is the smoke?

 

[hcole]

I would unplug the map sensor and try it. From what I understand, it will smoke a lot more but hurts nothing except setting a code. By doing this you may be able to narrow the problem down to a fueling issue and possibly eliminate an electrical one.

 

[dieselluver]

The rubber intake boots appear to be okay. I also put a rubber innertube valve stem over the turbo intake to pressurize the intake system. I increased the air pressure to about 6psi (limited pressure because the unsupported innertube was bulging out too much) and it held pressure for about a minute or so. The air must be leaking through the engine because of valve overlap in certain cylinders. I felt and listened for air escaping from the rubber intake boots and could not find any leaks.

 

[dieselluver]

Upon hard acceleration (WOT) the exhaust smoke is black until it begins to loose power and cut out. Then there is not much smoke for just a split second until it backfires then it is grey smoke turning to white smoke until it begins to regain a little power back, then the smoke turns grey. This all occurs under WOT. The boost pressure (from MAP sensor) drops below absolute atmospheric pressure after this problem occurs when it is slowing down or loosing power. Absolute atmospheric pressure from the MAP sensor is 14psi. It drops to around 7 to 9 psi (absolute) which would indicate a vacuum... . right???



Also I can easily accelerate past 3000 rpm with no problem if I don't push it too hard.

 

[dieselluver]

I just unplugged the MAP sensor and ran it. It has less power but it does not cut out or backfire. So does that mean it is a fueling issue or a wiring issue? Where do I go from here?

 

[RAJohnson]

Not positive but it sounds like you need a MAP sensor.

 

[dieselluver]

I had already installed a new MAP sensor.



So without a MAP sensor signal because I unplugged it, what does the injector pump do? It must de-fuel and not advance the timing without this signal... ??? Would this be a safety feature for when a sensor goes out? Does this lead me to a IP problem even though it is new and has the same exact problem as the old pump that I took off? What are the chances? Any thoughts on this?

 

[hcole]

Well, in the absence of a map sensor, (unplugged) the ecm has a default value that will get you home. Probably with a little less power. I'd try another map sensor and see what happens. Maybe borrow your buddy's with the 01.

 

[dieselluver]

I swapped the MAP sensor from an 01 HO. It still has the same problem.



I then plugged in the extra MAP sensor into the harness and just left it dangle beside the engine. This is so the ECM could read the atmospheric pressure signal without being unplugged and throwing a code. It ran good except it didn't have full power because of not sensing any boost. What does this tell us?

 

[Sticks]

The truck you are talking about is not in your sig. Any performance chips/tuners? If so, remove them and try again.

If you had metal shavings/debris in the old pump, then I'd start looking into having the injectors tested.

Compression and leakage test while they are out.

Is this all on the same tank of fuel?

Try to get a hold of the trouble shooting trees for all the MAP sensor codes (3 of them IIRC) and run through them.

Might want to look at the IAT sensor.

Best course of action is to get a scanner hooked up to see what your down stream readings for the various sensors are doing.

 

[JohnBoy5]

you map sensor pressure should start out higher then 7 psia, normal absolute pressure is about 14. 223 to 14. 696 maybe you have another bad sensor or the wire was cut or damaged causing the computer to read pressure lower...

and yes 7 to 9 psi absolute would be a vacuum, i am not sure but i dont thing you sounds be able to draw it down that low, i will monitor mine today and get back to you on this


edit, i just looked at mine with the engine off and it was 28 psia... that seems high but i do have a boost fooler also, i would have thought it would make the reading low... .

 

[hcole]

This is a shot in the dark but the threaded boss that the map is screwed into, you reckon its stopped up with carbon on the inside of the intake? I have had to clean my map sensor and ait sensor because it would fill with carbon. Just unscrew the map and stick a screwdriver in the hole and twist it around. Maybe that will break it up.

 

[bromano676]

You said that the boost pressure goes into a vac after this starts. But what is the boost before it starts? You put the pedal to the floor, it starts to pull, smoke increases, boost does what? then it starts to smoke real bad, boost drops off and back fires?

 

[hcole]

Mouse or bird nest in air cleaner or air intake? You say it only occurs on heavy acceleration when the turbo needs LOTS of air quickly?

 

[BEnglish]

dirty air filter?

 

[dieselluver]

No chips or tuners installed. The injectors have been tested and replaced. The compression was test and was good. The MAP sensor always starts out at 14psia. It has been run with 3 different MAP sensors and all with the same results. The original MAP sensor was realitively clean. With a mirror I checked the MAP port in the intake and it was clear and no blockage.



I am thinking that I purchased a defective injector pump due to the white smoke and backfiring. It seems to be a timing and fueling issue inside the injector pump.



JohnBoy5 - Out of curiousity, does your boost fooler hold a constant 28 psia no matter what? Or does it offset your boost pressure a certain amount higher than whatever your absolute boost pressure is?

 

[dieselluver]

It has a brand new BHAF.