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Engine/Transmission (1998.5 - 2002) Low boost, high EGT, no repeat codes

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2nd Gen Non-Engine/Transmission Need some guidance, please

Engine/Transmission (1994 - 1998) 1997 Dodge Cummins TSBs

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Hey guys, need a little help,

2002 2500 auto, no problems noted before truck sat for a week or so. noticed upon return that cruise boost in about 2-4 psi lower than normal, and egt, looks a little higher, specially upon shift into overdrive and acceleration to 65 mph or so, Egt can get to well over 1150 empty. I am able to boost up to 25 psi or so (hook), just overall numbers are lower. Only code found earlier was a 0122? the tps low voltage code. Any suggestions as for places to start looking for problems, can't find any apparent boost leak, bought a new Tps from Timbo, have not installed yet, batteries are original. any sensors to look at?

Thanks Pete
 
I'd start by replacing the MAP sensor and then go from there. If the MAP sensor turns out to be fine, then at least you'll have a spare.



John L.
 
Gotta be a small boost leak somewhere. The high egt in cruise means it's getting the fuel, which means the drive energy is getting to the turbo. The lower indicated boost means the air charge is going somewhere other than the engine.

Maybe turbo issues (pull the intake boot, spin the turbo by hand and check for tightness/play - engine off of course), but since the problem happened overnight, I'd lean towards a split in one of the rubber boots along the intake plumbing.

A sticky MAP sensor would prevent fueling, so not only would you have low boost, but egts and power would be down as well.
 
Did some checking today,no boost leaks found at 20 psi. turbo looks clean and moves freely, very little play in the shaft. Did find that the waste gate was stuck in the closed position as far as I could determine, might have been only partially closed. managed to free everything back up, waste gate seems to work fine now, The above mentioned symptoms seem to have lessened, not sure if it is quiet normal yet, but temp seems to have come down some, boost seems still a little low, but not as bad as it was. I presume that a partial closed and stuck waste gate could account for the symptoms, any other suggestions as for where to look next ?
Thanks Pete
 
try taking a look at your air filter, an animal could have crawled up there and died. If it is clogged you will have higher egt and lower boost, and loss of power. hope this helps.
 
Still playing this around with this, I just don't seem to remember the egt's going so high during acceleration, , I can hit 1150 pretty easy unloaded. seem to think it was always between 6-900 during unloaded normal operation. Temps during cruise seem normal in the 7-800 range. Did replace the iat sensor, made no difference, and the one that came out looked normal and clean. Thinking about the map sensor next, wondering if it is failing towards the high side, IAW it is fueling for a higher boost level then there actually is. What are you guy's thinking, any suggestions? Hate to just trow parts at it, still no codes.
PS I am running Smarty at 5, but that is where it's been for 3 years
Pete
 
In a diesel, extra fuel means extra power. If you're not experiencing the boost in acceleration to correlate with the higher egts, then you're not getting the extra fuel. The map tells the ECM to allow extra fuel if it is commanded by the throttle, it doesn't command a fueling increase itself.



If you found a problem with your wastegate hanging up and noticed a change after tinkering with it, I'd look at that a little more closely. A partially open wastegate would give the same symptoms as a boost leak. If the actuator is hanging up it may be time for a new one.
 
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