Idle Issue

[Hairyarse]

Ok, so the S2 arrived yesterday [] http://www.porscheclubgbforum.com/tm.asp?m=606315

Andrew had mentioned there was sometimes an idle problem and there is but not sure where to go with it. The ISV was checked and cleaned not many miles ago, I think Andrew said the O2 sensor was replaced and things generally looked over.

The issue when first collected the car was at times when say idling the revs would go low and it stalls. After a good run yesterday that doesn't happen any more but when you stop the revs drop almost to nothing and 9 times out of 10 it wont stall and revs go back to normal. When driving slow at say 30mph you can feel the engine surging ever so slightly up and down - it's very subtle.

New DME relay is in just to take that out the equation. I looked on line at a test method for the Idle Control Switch - haven't done this yet but my symptoms aren't really the same as described.

Anyone got any other ideas? Vacuum leak?

Cheers
Andy

 

[bertelli_1]

A vacuum leak will generally give a high idle speed. Check the idle throttle switch first (a guide is on clarks garage). Although the idle valve has been cleaned it could still be the culprit.

 

[robwright]

We could do with one to swap out if anyone has a good spare Andy.

 

[Hairyarse]

That would be useful, will check mine when I get a mo anyway

 

[sawood12]

Is the issue just at idle or do you get lumpy running at low speed, for example when you're crawling in traffic do you get the kangaroo effect? When I first got my 944 the idle was erratic - sometimes it would stall or struggle to idle and other times it would jump upto 1500 rpm. Turned out to be the AFM.

 

[Hairyarse]

Ever so slight kangaroo at 30 ish - it's barely noticeable. I don't get an high revving though, it simply drops when you stop then goes back to normal

 

[Alexw]

Could it be running rich? A bad FPR sticky injector?

 

[Hairyarse]

Not sure, but don't know what an FPR is!! [] Looking through all the invoices etc in the history file a lot of stuff was checked June 09 although it was only 8,000 miles ago!

 

[sawood12]

ORIGINAL: Hairyarse Ever so slight kangaroo at 30 ish - it's barely noticeable. I don't get an high revving though, it simply drops when you stop then goes back to normal

Could be speed sensor then if your idle speed is dropping then returns. Had these exact symptoms on my focus where it would sometimes stall as soon as you disengaged the clutch as you approached junctions. The speed and reference sensors are on the top of the bellhousing and can work loose over time. You can easily check this by nipping up the carrier bracket bolt.

 

[Hairyarse]

ORIGINAL: sawood12

ORIGINAL: Hairyarse Ever so slight kangaroo at 30 ish - it's barely noticeable. I don't get an high revving though, it simply drops when you stop then goes back to normal

Could be speed sensor then if your idle speed is dropping then returns. Had these exact symptoms on my focus where it would sometimes stall as soon as you disengaged the clutch as you approached junctions. The speed and reference sensors are on the top of the bellhousing and can work loose over time. You can easily check this by nipping up the carrier bracket bolt.

Where exactly will I find them? Still finding my way around the old gal []

 

[robwright]

ORIGINAL: Hairyarse Not sure, but don't know what an FPR is!! [] Looking through all the invoices etc in the history file a lot of stuff was checked June 09 although it was only 8,000 miles ago!

Fuel Pressure Regulator. Yours has a new one. I noticed on Saturday.

 

[robwright]

I can pop over on my way home from work if you like mate. What time do you get home?

 

[alwigley]

Common and cheap culprit can be the DME temp sensor - caused similar issues to me and an awful lot of head scratching. I believe you can disconnect it with the engine running, and I have an odd feeling that yours' being a later model has a 'get home' mode on the DME that will take over the lack of input and restore normal running. Worth a try and only £15 to fix if it is.......

 

[sawood12]

ORIGINAL: Hairyarse

ORIGINAL: sawood12

ORIGINAL: Hairyarse Ever so slight kangaroo at 30 ish - it's barely noticeable. I don't get an high revving though, it simply drops when you stop then goes back to normal

Could be speed sensor then if your idle speed is dropping then returns. Had these exact symptoms on my focus where it would sometimes stall as soon as you disengaged the clutch as you approached junctions. The speed and reference sensors are on the top of the bellhousing and can work loose over time. You can easily check this by nipping up the carrier bracket bolt.

Where exactly will I find them? Still finding my way around the old gal []

Look at the top of the engine just behind the cam-tower and onto the bellhousing at the 12 o'clock position. There are two sensors with black wires leading to them. One is the reference sensor and one the speed sensor - they are both identical. The sensor itself bolts into a bracket which bolts onto the bellhousing and it is the bolt that bolts the bracket to the bellhousing that can work loose. This happened on mine but with the reference sensor and I was getting intermittent starting, but a nip up with a 6mm socket (If I remember correctly) solved the issue. There is also a resistance test you can carry out on the sensors themselves if you suspect it is them. Might not be this, but worth a check anyway.

 

[Mike_Pollock]

ORIGINAL: Hairyarse

ORIGINAL: sawood12

ORIGINAL: Hairyarse Ever so slight kangaroo at 30 ish - it's barely noticeable. I don't get an high revving though, it simply drops when you stop then goes back to normal

Could be speed sensor then if your idle speed is dropping then returns. Had these exact symptoms on my focus where it would sometimes stall as soon as you disengaged the clutch as you approached junctions. The speed and reference sensors are on the top of the bellhousing and can work loose over time. You can easily check this by nipping up the carrier bracket bolt.

Where exactly will I find them? Still finding my way around the old gal []

Two black armoured cables rear / passenger side of the block heading down to the bellhousing

 

[robwright]

Actually I think the S2 engine only has the speed sensor but still could be a culprit. Should be the same as mine so can swap them over if you want mate.

 

[Hairyarse]

Thanks for the replies guys, found it on Clarks page now with pics! Rob, dunno when home, it varies! but likely to be about 6-7pm I guess?

 

[robwright]

Could pop over Wed then mate. I don't normally run on Wed.

 

[Hairyarse]

No probs Just went out and checked the engine. There's only one sensor on the bell housing and it's securely bolted. Will have to add the resistance check to the list

 

[robwright]

I wouldn't say resistance would be the most reliable way of checking it. It is a magnetic pick up sensor. The best way to test these is an oscilloscope. In the absence of one of those it might be best to swap it []