Cayenne 2009 GTS hesitation on light acceleration

Matrixxxx · 8 Oct 2019

Well, to add to my list of problems, after changing the thermostat and a new set of plugs, and fixing the vacuum leak, the hesitation is still there.
But!! If I switch off the "PSM" it runs perfect!??, runs as if in sport mode holds the gears longer but no hesitation and pulls a lot more when accelerating,

when you switch it back on the revs drop and it become sluggish and hesitates.

just wonder if it is related to the faulty signal from the front acceleration sensor?

Matrixxxx · 13 Oct 2019

Now realise that psm keeps the revs above 2k , the hesitation seems to be below 2k rpm.

CarraraWhite · 14 Oct 2019

What garage are you using ?

did they plug in the diagnostics machine

crash7 · 14 Oct 2019

When were the coils last changed?

Are you getting a CEL?

Billy Bumpsteer · 14 Oct 2019

Coil packs would be my guess

Matrixxxx · 14 Oct 2019

I bought an icarsoft scanner, just put a new acceleration sensor in, still hesitating, I do all my own work.
Im sure the coils have been changed at some point, it is looking like they may need changing.

crash7 · 14 Oct 2019

I had a similar problem on my 58 GTS.

Intermittent hesitation under light throttle, no CEL.

I lived with it and eventually the car through up a CEL, which would reset everytime you turned the car off and not come up every journey, I carried my scanner in the car and eventually caught it, codes indicated a coil fault on cylinder 2.

Changed the coil(s), problem solved.

Good luck.

Matrixxxx · 14 Oct 2019

Did the bad coil look ok? I didn't see any cracks when changing the plugs, I would assume that they all are not failing. May buy one and swap it around.

crash7 · 14 Oct 2019

No, no visible signs of any wear or damage.

I only had a fault with one, but given they were all the same age and original to the car I replaced them all as a matter of course, however as you say it may not be necessary.

Billy Bumpsteer · 14 Oct 2019

A Durametric will certainly pick up the faults even if it hasnt thrown a full CEL, I take it the icarsoft didnt show up anything?

Matrixxxx · 14 Oct 2019

It hasn't thrown any faults, but can see a lot of variables, I guess it should be possible to see something not running as the rest. How long do they normally last?

Billy Bumpsteer · 14 Oct 2019

They can last 10 years or 6 months. I changed all mine and 6 months later the exact symptoms you have showed again, Durametric showed cylinder 5 missing, just changed that one that time and all ok 12 months on, get it plugged into a decent machine and it will tell you the cylinder/cylinders missing

Matrixxxx · 15 Oct 2019

ordered a full set.

Matrixxxx · 15 Oct 2019

Old and new sensor

Matrixxxx · 24 Oct 2019

fitted the coils, it drives differently, more torque, quieter and smoother, while playing with the scanner after 10minuites or so there was a noise like the cd player loading a disk over and over, turned the head unit of but it was still going, now I think it was the throttle recalibrating its self.
it now holds the higher gears , if you accelerate slowly it will pull along in top gear, before it would not do anything then jump down 2 gears, there is still slight juddering but it doesn't feel like a misfire. will leave if for a few weeks for everything to settle down.
got all the coil packs for under £180 off eBay.

I am also wondering if the ignition module was in the water that was trapped in the bulkhead/firewall.

Cayenne 2009 GTS hesitation on light acceleration

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