RPM's jump up

[superdutylariat08]

anyone else truck rpms jump up when they put it back in park from driving around.. i know it has the regen mode when it gets too hot.. but its still does it even when its only 60 dg's outside and does it everytime. normal ? take it in ? thanks

[DavidPhillips]

Regeneration is not from being hot, it's from soot building up in the DPF.

It's hard to say if it's just driving habits or actually a problem with some trucks programming or sensors. Seems some do it a lot more than others.

Some people a saying 30 minutes to an hour of regeneration at a time. That has to be considered excessive. I would consider it a problem unless your driving is really abnormal. For instance towing an extremely heavy load around town.

I think periodically it would be normal but it would be nice to have a good idea of what's normal.

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Last edited by DavidPhillips : 07-11-2007 at 08:13 PM.

[bleedsblue]

This is the way I see it if your vehicle takes 30 minutes to get through regen when it gets to that point and you cut it off at 10 minutes then the next time you put it in park it's going to go back into regen mode till it sees the correct back pressure.

My regen usually only last a few minutes tops but I think that me cruising on the freeway at 65-70 MPH helps with burning off the soot in the DPF, which may be why mine only does it for a short amount of time.

Bill

[TwinTurboStroker]

Originally Posted by superdutylariat08

anyone else truck rpms jump up when they put it back in park from driving around.. i know it has the regen mode when it gets too hot.. but its still does it even when its only 60 dg's outside and does it everytime. normal ? take it in ? thanks

Yeah I would say that the truck is just going into regen, but my next question is, is this happening every time or just every once and a while?

[superdutylariat08]

it does it everytime i drive it...

[TwinTurboStroker]

Originally Posted by superdutylariat08

it does it everytime i drive it...

I would take that sucker back to the dealer and have them check it out with the quickness

[pierre3737]

Mine did that but then I let it idle in regen (1200 rpm) in the driveway and it took 1 1/2 hour to come back down It did this at 500 miles and hasn't done it since but my DPF is busted as I can blow soot on acceleration easily.

[DavidPhillips]

Well, your truck is not working right apparently. The regen is excessive which has resulted in the DPF being burned out.

Soot particles cannot pass through the DPF because it has small holes in it that will not let soot pass through them. When it burns off the soot that's been trapped it puts raw fuel into the exhaust which ignites and burns the carbon that has built up. There will never be much soot built up unless somehow your driving puts out more soot than could possibly be burnt off. Normal driving should remove the soot from the heat of the Cat alone. In the event of a burn off it should not take that long to remove soot that has built up since the previous burn off.

If the DPF is letting soot through there would be no restriction and should not need a regen.

I think the sensors are defective or the reprogramming recall was not done on your truck to correct the flame thrower problem which has resulted in the damage to the DPF.

It would seem that if it does not do it anymore then the DPF is opened up and that would indicate the sensors working properly.


It would be interesting to see what would happen if the DPF were gutted and the Cat left in place. If everything else works right there should never be a regeneration cycle.

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Last edited by DavidPhillips : 07-20-2007 at 08:21 PM.

[TwinTurboStroker]

Originally Posted by DavidPhillips

It would be interesting to see what would happen if the DPF were gutted and the Cat left in place. If everything else works right there should never be a regeneration cycle.

I've been toying with that idea myself, but $1236 is alot of money to fork over for a cat.....