Something doesn't feel right

[Larrylu]

I could use some opinions or explanations on a newish symptom that has me scratching my head. If I do a WOT burst, when I back off the throttle, the acceleration stops in a normal feeling way but the engine sound stays loud for maybe a second or two longer than I expect...then goes back to normal. I really don't feel like it's right, and I don't think it has always been like this. Otherwise it feels like it's running great. Maybe what I'm describing is normal, and I just haven't noticed before....I doubt that though!

 

[Brucelinc]

Larry, is this happening just as the car is attempting to shift?  If so, it might be normal so that the shift is smoother.  Having a shift happen precisely when the engine RPM is dropping could create a clunky shift so the PCM is doing its job to smooth it out.

Have you tried it in manual mode to eliminate the possibility of a shift occurring at the same time?  If a shift is NOT occurring at the same time, I would say what you describe is not normal.  Could the throttle body be gummed up?  Problem with throttle position sensor? 

 

[SoCalSHO]

I have had this happen a time or two before, but I don't remember the situation that caused it. How about doing a throttle calibration that was posted here (or was it decided here that it did not work). Anyways, it is posted here somewhere, maybe it will work.

 

[Larrylu]

Larry, is this happening just as the car is attempting to shift?  If so, it might be normal so that the shift is smoother.  Having a shift happen precisely when the engine RPM is dropping could create a clunky shift so the PCM is doing its job to smooth it out.

Have you tried it in manual mode to eliminate the possibility of a shift occurring at the same time?  If a shift is NOT occurring at the same time, I would say what you describe is not normal.  Could the throttle body be gummed up?  Problem with throttle position sensor?

Bruce I'm pretty sure it's not shift related. It could likely happen at a midway point between shifts. When shut the throttle acceleration stops so I'm thinking the throttle is not sticking but the engine noise remains at a high level for what seems to me to be a couple of beats too long before quieting. I'm not absolutely sure that this is new....but I think it is.
I'm new to turbos but what if the BOV did not release right away...sticking a bit. Would that scenario present as I'm describing? 

Or maybe it is shift. What if the car waited a bit longer than it should to up shift after closing the throttle. The cars momentum would keep the engine at higher RPM for longer than it should. That actually sounds like it fits pretty well. Thanks for kicking this around with me. Helps to come up with possible causes.

 

[Larrylu]

I have had this happen a time or two before, but I don't remember the situation that caused it. How about doing a throttle calibration that was posted here (or was it decided here that it did not work). Anyways, it is posted here somewhere, maybe it will work.

Easy enough to try and it can't hurt.

 

[SHOdded]

Repeatable phenomenon, Larry?  Does sound like a "smoothing" function to me, allowing for sudden dips in throttle input in between WOTs.  Save the engine a bit of wear and tear/turbo lag.

 

[Larrylu]

Repeatable phenomenon, Larry?  Does sound like a "smoothing" function to me, allowing for sudden dips in throttle input in between WOTs.  Save the engine a bit of wear and tear/turbo lag.

Yes it's repeatable. It's doing it steadily now. If my memory serves, I don't think it used to do it at all but I'm not sure.
Don't think I ever heard of "smoothing" before. I'll do some research on line. Thanks for the lead.

 

[DJE624]

I have had something like this happen. If I let off just before the shift, the motor keeps up the revs for a second or two.  I think, at least in my situation, it was like Bruce described. 

 

[Larrylu]

I have had something like this happen. If I let off just before the shift, the motor keeps up the revs for a second or two.  I think, at least in my situation, it was like Bruce described.

Well Dave now I have a few things to try and that will hopefully throw off some more knowledge. I'll try using the grade assist, and also try the paddles to see if either of those make any difference. Actually if I shut the throttle say at 4K RPM in manual mode and the car held the gear, that would sound and feel exactly like I'm experiencing in D ....only for a couple of seconds though.
The more I'm trying to describe it the more I think it's feeling like a delayed up shift. I suppose I could be closer to the next shift point than I'm realizing. Then I'd be experiencing what you and Bruce have noticed. Must do more research. I should move to Mexico lol. Thanks again guys!

 

[TSS]

I have had something like this happen. If I let off just before the shift, the motor keeps up the revs for a second or two.  I think, at least in my situation, it was like Bruce described. 

Me too especially if I go from hell bent WOT to completely off the accelerator.

 

[BiGMaC]

I have had something like this happen. If I let off just before the shift, the motor keeps up the revs for a second or two.  I think, at least in my situation, it was like Bruce described. 

Me too especially if I go from hell bent WOT to completely off the accelerator.

Good info... The driver can "confuse" the ECM in some maneuvers .... Like this one

 

[crash712us]

I think that's what your seeing here. I know when out on the freeway and doing several brief WOT's darting in and out of traffic will make the car very unhappy and will lose total throttle response momentarily. The wife's 09 escape behaves same way.


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[IHeartGroceries]

I've experienced this, or something similar.

Like, the TCM will have the ATX linger in gear momentarily, after a WOT burst, before it will eventually downshift.

Not sure if it's the same situation, but this is what I have noticed occurs on my SHO.

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