Why is my truck doing this?

SledPuller21

SledPuller21

Never enough
Joined
Jan 18, 2007
Messages
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Well alittle background info, truck was throwing a code...map sensor circuit voltage low, so I tested the sensor and it was bad truck. Replaced the sensor and it still does this,started doing what it does now around the same time. What its doing is around 5-10 lbs of boost it acts like it defuels, boost gauge goes back to zero then reverses to about 1-2 lbs of vacum or however its measured. It'll do this till you let off and the truck has now power and EGT's slowly creep up to 1200 and past. I have no codes other than the Torque Convertor clutch something or other and thats because I have a TCC lockup switch. I've had it wired up for 5 months which leads me to believe it has nothing to do with the problem. Any suggestions or anything else I could check? Anybody ever had a similar problem?
 
So if I take the comp off the problem should go away? I have another VA chip I can throw on.
 
Well I pulled the comp off and its still doing the same thing. Any other suggestions?
 
I was just about to post this cause I can't figure it out either. You said you had a P0622 code, did you ever get that cleared up?
 
I think so, my one terminal clamp on the drivers side was loose. Check engine light isnt on but I havnt tried to pull any codes in the last 2 days so idk. Thinking I'm just gonna have to take it in to the dealer and let em put it on their computer.
 
VP44? I've seen those cause derate without check engine light. Fault code 368 is the Cummins code that we see alot. I bet the rpm reading on the tach are the same when this happens. Just guessing at around 1700-2000.
Where at in Pa?
 
How did you test the map sensor? If you can clip a DMM on some test leads and read the voltage with the truck running it will tell you if the ECM is sending the required 5VDC to the sensor. You should read approx 1.02 (idle) to 2.44 (20+ psi) volts across the others if I remember right. You may have lost the 5VDC powering the sensor or have a short in the harness.
 
I live in northeast pa, around the meadville area, not sure if it happens at the same rpm I'll check in the morning. But when I pulled codes the other day all I got was P0622 and the TCC lockup code cant remember the number. Also I checked the sensor with my multimeter for resistance and it tested OL, plus when it was bad I had a map sensor circuit voltage input low code or somthing like that, I've had the new sensor in for about a week now. It's really frustrating and I've missed 2 pulls already, and theres another coming up next thrusday I'd like to make it too.
 
Dustin, I'm about to make a trip up there to figure this out.... Snedge, I don't think its a VP, the variation in the symptoms, plus with the MAP sensor going bad before this, something just isn't lining up and I can't figure it out either.
 
Just a thought, but would the ecm need reflashed since I drove the truck around for awhile with a bad map sesor and now it has a good one? Idk I'm just throwing out ideas cause I'm at my wits end.
 
SledPuller21 said:
Snedge I live in Northwest pa, I just now realized I put Northeast pa.
Click to expand...

Yeah, When you said Meadville I figured.
 
I would say it doesn't need reflashed, worth a shot though. What are you using to pull the codes? If you are interested I could plug in with the Cummins puter (no charge). Meadville is about 2 hours north from me. Could you run it down here (Indiana)? I also have a buddy up on I-80 in Barkeyville. Maybe I could have him plug in.
I'll still bet on the pump.
 
My buddy just has one of them cheap actron scanners. But you cant have them reading while the trucks running...I think if I could get hooked up to one of them I could monitor voltages and maybe figure something out. So where at exactlydo you live?
 
The shop is in Shelocta. Bring it on down and lets see if we can put our finger on something.
 
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