Matt O.

Just recently, at idle, the tachometer is showing zero. The engine does not feel bogged down, but every 10 to 15 seconds it bogs just slightly.

The shifts are occurring at approximately 1 to 2000 RPM. That seems really early. To me it seems like the tachometer is just incorrect, has anybody had this issue?

After turning off and restarting the Cayenne, the tach needle shows idle at 450.

Thoughts?

Matt O.

Also, the voltmeter in the instrument cluster is showing about 13. Previously it was pretty much pegged at 14. Should I be looking to the battery, or the alternator? Are these two things possibly combined? I know incorrect voltage issues can cause all sorts of bugs (maybe like an inaccurate tach needle?).

Dan87951

crank position sensor?

Matt O.

I just finally ordered a Durametric.

If I run the Durametric, will it likely tell me the problem even though I am not popping a CEL?

After driving the CS this AM, the voltage showed pegged a hair below 14v, and the RPM at idle was the normal range.

Matt O.

I'm approaching 60k miles. I went ahead and purchased 8 new coils and 8 new plugs. I'm not diagnosing it as the coils/plugs, but figured it was about time for them because they have never been done.

Any help on my original symptoms would be great. Just drove the car again, and it seemed to be normal. But I don't like that issue that I had...

Thanks,
Matt

Matt O.

Well, after another long drive idles shows 0 rpm. Seems to only do this after a lengthy drive and hot engine. I'd like to order the parts ASAP so any input is very helpful. If it was a crank sensor, would I not pop the CEL?

I have Durametric on order, but not here yet.

Thanks.

scottl951

Matt-
Since you said voltmeter was at 13 at one point, my vote goes to battery.

scottl951

Adding on-
When my battery went, the cd changer wouldn't work but everything else was fine. Car wouldn't start a week later.

Matt O.

Scott,

Thanks much. Wish I previously ordered the Durametric. I'll go ahead and pull the battery(ies) and test them. I have a good tester. Going back thru the PO records, there was no mention of a battery replacement, so it is likely well past time. I'll check the date on the batts, and if they are 2006 I am going to be amazed. I can't get 3-4 years out of my F250 with those two batts.

Thanks,
Matt