diablo_911

I've got a service appointment tomorrow, but my paranoia gets the best of me. This afternoon I was sitting at a light and my idle jumped to 1,500. I immediately thought it was due to the AC kicking in, but it wasnt. The idle proceeded to fluctuate between 1500 and 3000 consistently. Back and forth every few seconds. I pulled away from the light, pulled into a parking lot and shut the vehicle off. No warning lights, let the car 'rest' for a bit and restarted. The idle went right back to 1500 and started jumping again. At this point im only a few miles from home so i continued. Above 3500rmp the car loses power. Any thoughts?

1999Porsche911

Is there a model year designation for your car?

diablo_911

02 c4. sorry

Robin 993DX

Interesting problem. 1500-3500 rpm flectuation is really too high to reflect a vacuum leak or DME adjustment due to mixture.

So I would have to say it is probably a throttle body/drive by wire issue. I wouldn't think it is the mass air flow sensor because that will set up the CEL, so......

diablo_911

Thanks. I'll post the prognosis on wednesday when i find out. Its one of the weirdest things ive seen a car do. Systematically 1500rpm to 3000rpm and back. over and over.

Cydog

Same thing happened to my 2002 C2 Cab a few months back, with an Evo Flow intake! Turned the car off and it appeared to reset itself.

photo25

I had the same Idle problem first had the oxygen sensors changed because that was what the code
read out showed. Fixed for a about a month. Then I changed the idle control switch worked for
2 months. Then I changed the throtle control switch. Now its perfect past 4 months. This is a a 99C2
with 77k miles already had a new mass air flow meter. Good luck these codes are not always correct.

diablo_911

saga continues. I went to start the car this morning to drive to my service appointment. The vehicle didnt want to start at first and when it did finally start it would jump to 1500rpm and then immediately stall. I didnt want to push the issue since the vehicle was idling all over the place and the PSM and ABS Failure light where also intermitantly flashing. very weird. needless to say, i missed my appointment and can't get the vehicle in the shop until next week! bummed.

jetskied

Sounds like a ecu problem or vacum leak. Go check under the hood to see if there is any hose disconected or wire that you can reattach. If not you might want to try to reset the computer by disconnecting the battery for 5 minutes. Its not a fix, but it may get you to the shop.

s14roller

Sometimes when a battery is low on juice, it can cause the car to get jumpy and go into limp modes. I don't know if that's the case here but it's worth a thought.

diablo_911

Update. Took the vehicle to a different dealer since they had open appointments. They said there where 7 different fault codes that where retreived and they want to replace the entire "throttle body". unfortunately they werent able to tell me whether or not this is waranteeable under a certified vehicle.

In addition, ive had continuing problems with the vehicle not staying in alignment and the front end pulsing at high speed. This dealer is much more reputable but they are suggesting that i need to rebalance all four wheels and perform another 4 wheel alignment. Thats 2 aligments for me in the last month! I have hardly driven the car! Isnt there some sort of action I can take against dealer #1 for not being able to correct this problem? In the last two months ive Iin order)

1. Balanced all four wheels. (problem still exists)
2. 4wheel alignment (problem still exists, no change)
3. Balanced all four wheels (problem still exists)
4. Repaced 2 front tires with MINIMAL wear! (problem still exists, actually worse!)
5. 4wheel alignment (problem slightly better, car pulls to the right!)

Talk about getting the shaft on this one? Has anyone had any luck correcting the problem at a new dealership and requesting that the existing dealership cover it? Total incompetence!

washington dc porsche

MAF

diablo_911

I just wanted to update this post for future reference if anyone faces similar problems. I got my vehicle back today and the following fault codes were retrieved from the computer. I don't know what they all mean, but heres the list: P1120, P1141, P1151, P1514, P0103, P1121, P1109

The remedy was replacement of the throttle body which was covered under certified warranty. The vehicle was serviced by Paul Miller Porsche in Jersey and the staff was extremely professional and knowledgeable. They also revealed that ALL 4 wheels were out of balance which completely amazes me since they were balanced by another dealership no more than 2 weeks ago! Lastly, Paul Miller Porsche even fixed some annoying interior noises (free of charge) that I brought to their attention.

diablo_911

Update to the Update. PSM and ABS lights are back on, with the same extremely bizarre idling problem. Vehicle goes back to the shop on Monday but this sure does screw up the weekend plans! Soooo pissed.

Ubermensch

Clean the MAF.