944 S2 Convertible 1990, Idles rough. - Page 3

Makis · 07-25-2003, 06:36 AM

Power steering should not cause idle problems.
But engine mounts if they are worn would cause the car to vibrate badly giving the impression of bad idle.

Rez 1 · 07-25-2003, 07:46 AM

Thanks, but it's defently not the engine mounts. I am a bit stuck in what to do next so I have booked it into a Porsche dealer for a diagnostic check for next week, but if there is anything that I can try before I take it please let me know

Thanks

Makis · 07-25-2003, 09:10 AM

Well, Rez,
How far are you from West London, Iver.
Every first thursday of the month there is a TIPEC Porshe club
meeting at a Pub in Iver from 8pm onwards. Me and Adrian (RO - Regional Officer) are regulars there, and the place is normally packed with 944s. So if you can hold on your dealer ship visit until then we can go through all possibilities. You will be able to see'/hear other S2 and judge for yourself. Let me know if you are interrested and I send you the details.

Rez 1 · 07-25-2003, 10:14 AM

Thanks for that but I am working nights on 7th Aug, but yeh meetings sounds good I could check it out in Sept 4th, with hopefully a sweat running engine see what the diagnostic tests come up with.
I live in the North London area but know West London very well.
If you can come up with anything that I should check before take the car in on Wednesday 30th please let me know.
Thanks All.

carsontc · 07-25-2003, 02:11 PM

in Iver?....hey my wife used to work in Stockley Park...we were there 6 years...lived at Richmond Bridge, Kew Bridge and originally London Bridge (Hays Galleria)...obviously we liked to pub crawl the Thames tow paths...summer Friday nights were the best!

(took my car to City Porsche in Bow)

wolfrpi · 07-25-2003, 02:19 PM

Your compression is WAAAY to low. That's 951 compression practically and 951s have 8.0-1 pistons. My old 924S had about 180 if I remember correctly. Do a compression check again and make sure that those numbers are correct. If so, you may need a new motor. My Turbo S also has a rough idle and I didn't really think it was a big deal until I performed a compression check. The result is 145-150 on 1,3,4 and 125 on #2. Pulled the head and found deep scoring on #2. Maybe you could get a borescope and see what you find.

Rez 1 · 07-25-2003, 02:58 PM

The compressions are low compared to others we may do them agian, but the car revs move cleaner feels move powerfull after we did the timing again and noticed it was out by 2-3 teeth.
Tom, you have been about thats where I have got my car booked in at Porsche Lancaster Bow.
Cheers

Makis · 07-25-2003, 03:21 PM

Low and/or uneven compression would affect idle, and should also rob some power at the top. But a couple of HP loss at the top would not be really noticable, hence I asked you wheather you have those 211 HP. I am suspecting your low compression reading, if correct, to be caused by valves/seat wear, in which case a cylinder head overhaul will be adviseable. Curius to know what the verdict from Porsche garage will be.

carsontc · 07-27-2003, 06:12 PM

I was reading someplace where a faulty alternator caused voltage spikes that resulted in misfires at idle

proof was to unplug alternator...then start engine and let it idle

ya never know..??

944S Boyeee · 07-28-2003, 08:28 AM

Did anyone mention the Idle Stabilizer Valve yet?

944S Boyeee

carsontc · 07-28-2003, 08:40 AM

well sort of...It was part of the Clarks Garage URL

"If the car experiences a rough idle or idle fluctuates several hundred RPM, this can indicate a sticking idle stabilizer valve. Many people have removed and cleaned them but, this is normally a temporary fix and the valve should be replaced. A faulty O2 sensor can also cause RPM to fluctuate at idle. Unplug the O2 sensor and see if the idle still fluctuates"

but dunno if is was checked

Makis had a list of 12 items to check & I wudda bet my life it was in there..but it ain't

so I think you are the first...

but maybe it was checked and not reported on...

was it?

944S Boyeee · 07-28-2003, 09:03 AM

Also, what about hood insulation?

If you don't have any - there is a warning in the handbook from Porsche that states that the S/S2 is prone to wires arching off the hood, causing all kinds of idle and miss problems.

If you don't have hood insulation, look for lil' burn marks!

944S Boyeee

SoCal Driver · SoCal Driver's Garage

The "S" idle control valve is controled directly by the DME. Actually like a servo.

The post 85.5's valve is contolled by the DME too but with a single pulsed signal (current) against a return spring.

The idle adjustment for the "S" cars requires jumpering accross two of the terminals on the test plug in the engine compartment to null out the emmission sensor feed back.

ronin · 07-28-2003, 01:37 PM

Quote:

Originally posted by 944S Boyeee
Also, what about hood insulation?

If you don't have any - there is a warning in the handbook from Porsche that states that the S/S2 is prone to wires arching off the hood, causing all kinds of idle and miss problems.

If you don't have hood insulation, look for lil' burn marks!

944S Boyeee

that would hold true for non S models as well such as my turbo. I noticed that the wires at the front from the distributor come quite close to the hood so I looked up and noticed impressions from the wires in the insulation! need to make sure that doesn't wear through.

Rez 1 · 07-31-2003, 10:14 AM

Hello all,
944S Boyeee, The car has not got any wires lose or arching on the hood as the problem occures when the hood is up. The idle stabilizer valve was taken off and cleaned,
The hood has a foam protection where it would meet the dustrubitor.
Carsontc, Does not seem to be anything wrong with the alterantor.
O2 sensor was replaced with a spare one I had made no difference.
SoCal Driver, The DME has been replaced.
Just got the car out of the main dealer, they state that the plugs had to be adjusted? (we went by the book).
The O2 sensor has a low reading of 0.44 and can not be adjusted and this could be due to a faulty engine management unit.
I have ordered another ECU (under the drivers foot well) second hand from the porsche breakers and sould recive it soon.
The car idles worse since the main dealers checked it?? and they did not check to see why the ABS and warning light comes on together every now and then. They say it needs to be booked in again? what a waste of time.
Sorry I did not get back to you guys sooner as I was waiting for this check to be over with. Hope it is what they state,
what do any of you think!
Thanks

Makis · 07-31-2003, 10:42 AM

Rez,
Remeber next Thursday, Iver, Porsche Club meeting we can have a look at your car and you can have a look at ours.
Dealer did not sound like they done a proper diagnosis. 02 sensor
reading of 0.44 does not mean anything, if anything 0.44(0.45) is
the correct average value it should be registering once warmed up.
Unlikely that a new ECU will sort out things of. Did the dealer check your CAT? Is the exhaust system in good order?

carsontc · 07-31-2003, 11:08 AM

Quote:

Originally posted by Rez 1
what do any of you think!

I think Henry's Pub by Richmond Bridge would be a good place on a summer's thursday evening to think this all over one more time...I'm heading to Capt. Ben's on Woodcleft Canel (Long Island) myself and that's where I'll be doing some heavy 'thinking'

944S Boyeee · 07-31-2003, 12:37 PM

Rez1 - I had my Idle Stabilzer Valve "cleaned" also. It doesn't help much if it's faulty.

Have you re-done/re-tracked the AFM???

944S Boyeee

Rez 1 · 08-02-2003, 07:31 AM

Well I have replaced the ECU, and Yes, Makis you were spot on, it did not sort out things? Thanks for the invite but I am working nights maybe another time.
I will try sending the ECU back and getting a Idle stabilizer valve stated by 944S Boyeee, and a flywheel sensor, these are the only 2 things that I could think of that I have not replaced yet!
Tom, nice pint of Guinness.
944S Boyeee, I have replaced the airflow meter which made it run a little worse but because it was newer and only done 11,000 miles I left it on.
Any more suggestions as I am now seriously confussed.
Thanks
Let me tell you about few other problems that may or may not have someting to do with my Idle problem.
The ABS light come on every now and then?
I Have had to remove the G7 relay (window motor) due to after removing the ignition key the heaters stay on and the wipers and windows can work without the key in, so I have removed the relay and it has stoped the problem and strangly the everthing still works as normal. I know this is another problem but I am just mentioning it as it may have somthing to do with the Idle.
Thanks all,

Martin T · 08-02-2003, 04:06 PM

Sounds like your drivers door switch isn't working (that relay holds up untill the door switch tells the circuit you are gettign out of the car.
Have you checked the engine grounding with an ammeter? this solved the rough idle on mine, the fault could only be detected by connecting an ammeter from the battery negative to the engine block, any reading is a fault.