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Discussion Starter · #1 ·
OK, here's one that has me stumped. Very occasionally I will get a fairly hard stumble on moderate to hard acceleration. Only occurs that odd time but it is a hard one and it might happen twice in rapid succession. Once it happens, it clears and the car runs fine thereafter. It seems the circumstances around these occasions are that the car is turning and/or is not on a level stance such as being on an incline then pulling out onto a level road. It also seems to occur after the car has set for a few days in a high humidity or heavy rain. Although due to other situations, I have replaced over the last 6 months or so the PEM, fuel filter, alternator and battery. It feels to me like a bit of water sitting in the bottom of the tank but I've run gas treatment through it a few times with no apparent result.

Anyway, looking for some ideas. Thanks in advance.

Cheers,

Bill
 

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Fuel pressure sensor on the fuel rail? Mine went a few months ago and would stumble pretty solidly. $35 and ten minutes cleared it right up


2007 V70R Ti Grey Nordkap GT, 2008 C30R-Design Black M66
 

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Is your car a M66? Grasping at straws, but a failing clutch position sensor will cause a stumble like that. Typically at about 3500 rpms on acceleration. No codes until it starts bucking pretty bad. Our cars use the cps (potentiometer) help smooth out the throttle when letting the clutch out. On my car, the master was leaking fluid onto the sensor. Went through a couple sensors before figuring it out. There a test in vida for the cps, somewhere.

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2006 V70R M66, Titanium/Atacama
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Is your car a M66? Grasping at straws, but a failing clutch position sensor will cause a stumble like that. Typically at about 3500 rpms on acceleration. No codes until it starts bucking pretty bad. Our cars use the cps (potentiometer) help smooth out the throttle when letting the clutch out. On my car, the master was leaking fluid onto the sensor. Went through a couple sensors before figuring it out. There a test in vida for the cps, somewhere.

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How would one diagnose a clutch position sensor?
 

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Discussion Starter · #6 ·
Is your car a M66? Grasping at straws, but a failing clutch position sensor will cause a stumble like that. Typically at about 3500 rpms on acceleration. No codes until it starts bucking pretty bad. Our cars use the cps (potentiometer) help smooth out the throttle when letting the clutch out. On my car, the master was leaking fluid onto the sensor. Went through a couple sensors before figuring it out. There a test in vida for the cps, somewhere.

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Astro-R:

No, its a GT. The stumble has occurred in both a steady state throttle and when the car is accelerating from a stop.

Thanks,

Bill
 

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Discussion Starter · #7 ·
I can't remember how to access the test in Vida. But you can pull the sensor and test it on the bench, if you have a DVOM (multimeter basically). See article below for directions.

https://www.pelicanparts.com/techar...LEC-Clutch_Switch_Testing_and_Replacement.htm



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I thought about that, but the problem is so occasional, at least so far, that it would be almost pure dumb luck if it occurred with VIDA hooked up. Took the thing out this morning since yesterday here was nice and damp and the car drove fine. I just hate tracking down **** like this! Arggghhhh!

Thanks for the suggestions

Bill
 
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