03 lagging rpm

[JSTC]

I have an 03, 6speed 4wd, cc. that has a lagging rpm response when shifting. When I push in the clutch for shifting, the rpm hangs there for a brief time before dropping. had a 91 & 96 manual trans that never did this. Is this an injector issue , or pressure release valve, etc. This is the first HPCR engine I owned. Any suggestions? https://www.turbodieselregister.com/images/smilies/frown.gif

 

[Prairie Dog]

Does it only do it in 1st and 2nd? Is it especially bad if you start out in 2nd and don't give it enough throttle?
If so then it's normal. (Stupid but normal).

Scott

 

[JSTC]

No, it lags there when shifting through all the gears. I also have an 05 with an automatic that doesn't seem like it lags. ( hard to tell with an auto. ) Shifting seems smooth & normal.
Will having an engine scan show anything that may cause this ? Or is that a waste of money? Any ideas?

 

[Bob V]

its normal. Its the first thing I noticed when I went froma1997 to a 2005,

 

[Prairie Dog]

I suspect it has something to do with the eng being programmed for operating with a manual trans and the zero throttle launch capability. That's why the auto's don't try to pull you into the back of the car in front of you.
I've gotten used to it over the years. I just stab the clutch if it's pulling me into the back of some station wagon. Or if it's time to shift and it hangs then I just shift anyway.

 

[cerberusiam]

In neutral, rev the engine to 3000 rpms and let it stabilze for 5 to 10 seconds, then let all the way off the accelerator. Rpms should start dropping within a slow 1 count , no more thna 2, and the rpms should drop evenly. If it hangs for more than a 2 count or the derev is jerky with hangs on the way there is an issue in the fuel system.

The CR engines do not immediately chop fuel to the injectors when you let off the throttle, they ramp th einjection curve down to keep from blow the injectors up with the pressure spikes. Quick on then off the throttle will always have a lag time because the system has to bleed off the built up pressure and stop the fuel flow to the high side of the CP-3 and that takes time. Speed shifting the manuals is a bad idea anyway as it raise total havoc with the synchros if you try to force the shift with power still on. Biggest downfall to the manual trans is the wait time on shift points to get the TQ off before shifting to save the parts, despools the turbo then you have to start over again.

All CR's do it to a varying degree, auto trans also. Don't ever rap the throttle hard in a busy parking lot, it is impossible to get ot the brake and stop the vehicle if somebody walks\drives out suddenly. They will pull right thru the brakes under power. On shift points with an auto, the tran is in fluid coupling which cushions the shift point. You will never feel the throttle hang because it shifts under power. Upside is boost and stays up and it transitions gears much better under power. Downside is the same as trying force a shift on a manual, it eats parts. The TQ rise on the front band and direct clutch pack takes it toll. Those two components take a beating and are generally the first to fail.

The autos defuel on on shift points to address the TQ rise where the manuals don't, operator has to do that manually by letting off the throttle long enough before the shift.

 

[JSTC]

Thanks for everyones input. I was told is was the injectors. I"m glad that's not the case. Save's me some $$$$ & time?By The way what is TQ?

I wish everyone a Merry Christmas & Happy New Year

John

 

[cerberusiam]

Injectors may still be a problem, just not the source of this observed actions. TQ = torque.

 

[Prairie Dog]

TQ=torque.

My buddy has an 06 auto that has never displayed this phenomena. There must be something different.
My truck always wants to spin the back tires in wet weather in tight turns too because it seems like i just can't give it little enough fuel. His never does.

 

[Bob V]

Injectors may still be a problem, just not the source of this observed actions. TQ = torque.

Yes, keep a close eye on the oil level.

 

[sag2]

If it hangs too long the injectors may be hanging open mechanically from dirt/debris.

 

[S.Morris]

I have found that the transmission shifts a lot cleaner and smoother if you make shifts at 2200-2300. (empty).. This transmission is an awkward thing for someone not used to its idiosyncracies. Once you put a good load behind it, it turns into a perfectly matched , nicely geared machine (only adding a 7th would improve it)

 

[dieting]

I was told is was the injectors. I"m glad that's not the case. Save's me some $$$$ & time?By The way what is TQ?