Porsche Enthusiasts Club Forum

Hello, new to this site. I have a 944 S2 purchased in May last year. It's been an expensive learning year, and still having some running niggles. As the title says, uneven tick-over and "lumpy" on gentle throttle and over-run - which makes smooth slow driving difficult. Just done a home service and changed the plugs. Cleaned out the throttle valve - which wasn't bad. Any opinions on changing the throttle control switch? It's heavy on the fuel - about 22 mpg, but doesn't appear to be running rich. Any idea folks?

Assuming everything else is OK & that means check VERY carefully for airleaks on all the hoses. Check the throttle position switch is A.set correctly & B. actually making & breaking the contacts. If it is then it's probably the airflow meter AFM. They're around £220ish might be worth borrowing one to prove it because they're fiddly to check out.

with that mpg could it be O2 sensor ?

Thanks gents - I have a good local parts supplier "Frazerpart", but haven't asked to borrow any spares. Yes, these bits are in a tight confine. I have a "Hometune" man calling on Tuesday, who reckons he has knowledge of these old systems, but if a component is faulty, it will be another visit to re-check and set things. Well I'm in the right area - but more money again - the paint job on hold again! Thanks for your comments, I'll keep you advised.

If you have a good quality multimeter and a bit of time, this is good test procedure, i used it on my 2.5 n/a AFM.

http://www.frwilk.com/944dme/

Let me know if you need any help

cheers

If you havn't replace all the vacuum lines yet I would do that anyway. You can get silicon vacuum hose kits for around £20 & it looks good too. Mine was much better behaved after doing that. But with only 20mpg must be another fault as well.

hi. pull pipe off vacuum reservoir, next to bonnet strut lh side if no vac you,ve got a leak!

Update on my problem following the visit from Hometune. We couldn't detect a leak on the intake side, nor on the exhaust, but the exhaust reading was showing oxygen level too high - 1.03% ? - which could be marginal for the MOT. Throttle valve was checked and throttle valve switch re-adjusted and checked if working. The uneven tick-over sometimes felt like a mis-fire, but the ignition checking machine didn't verify that. Occasionally the revs dipped low enough to sound like it was going to stall, but then re-caught again. The recommendation was to clean the injectors, firstly with an additive into the petrol, or removing the fuel rail and taking to specialist to clean and check/recalibrate? Next could be to swop the Air Control Valve. Does anyone know if this is a standard Bosch numbered part, or a specific one for the car - with a Porsche price tag of £120+ ? Bought a bottle of STP Injection cleaner which I will wait until the tank is 1/2 empty. Will replace the vacume pipes as that looks a good Saturday afternoon play! Keep you posted ..... Thanks to all who have contributed.
Al
After a couple of runs, looks like the Hometune man has adjusted out the uneven tickover. Put the STP Injector Cleaner in about 7/8ths of the fuel - couldn't wait any longer! BIG improvement in overall running, smoother and less abrupt on lifting off the throttle.
I also had an electrical problem which I thought was linked to this rough running. It manifested itself by loosing all the radio station pre-sets when I used the driving-lights flasher. Some bright fellow suggested checking the battery, which proved to be the culprit! I enjoyed the runs to Three Sisters and Aintree for the sprint events, just need to sort out the gearbox howl and crashy rear suspension ...... Another tale for another topic!! Cheers to All - Al

Hi, have alook on pelican parts they list various idle control valves for 944 models, it is a bosch part but i don,t know if its available elsewhere, if you put a long screwdriver on the solonoid body and to your ear whilst engine running you should be able to hear the solonoid working. best of luck with it. could be o2 sensor, test via multimeter, look on clarks garage for info.