Irratic revving
- Thread starter Guest
- Start date
Does this happen at idle? - if so it could be a faulty air flow meter. The engine tends to hunt up and down between these revs - the exact same thing happened on my brothers 1986 3.2 - the only cure was a new air flow meter.
Hope this helps
Rich
Hope this helps
Rich
Guest
New member
Most likely the AFM - this is the typical symptom of a faulty/worn out AFM. IIRC, new ones are circa £200, but you may be able to find a used one from a 964 (newer and lower miles) for circa £100. Anyone who upgrades to hotfilm, Motec etc would remove the AFM, so some tuners may have known good ones. JAZ had a spare when I needed mine. I had to replace mine after less than 70,000 miles so these don't last forever.
On a slightly related topic, the fact these are the same as on 964s shows the AFM on a 3.2 is more than capable of flowing enough air to make 250+hp.
RB
On a slightly related topic, the fact these are the same as on 964s shows the AFM on a 3.2 is more than capable of flowing enough air to make 250+hp.
RB
Guest
New member
AMolak
Hopefully there is attached to this reply a "copy" from one of my workshop manuals for the procedure to test for a fault in the airflow meter.
Zoom in on the article, and print it - might save you a few quid?
Or you could be just like half the population and throw it away and get a new one?[:-]
Hopefully there is attached to this reply a "copy" from one of my workshop manuals for the procedure to test for a fault in the airflow meter.
Zoom in on the article, and print it - might save you a few quid?
Or you could be just like half the population and throw it away and get a new one?[:-]
IanHighfield
New member
Amolak,
This may be at a complete tangent, but when you mention 'drive', do you actually mean drive, or do you mean when you start the engine form cold ?
I only ask, as when I have started my engine over the last couple of colder mornings, my car automatically revs from 500 to say 1,200 (not accurate figures) until it settles in to a smooth idle.
I understand this is quite normal, but I can get it to stall if I set off too early and let off the throttle at a junction it can stall - another post some while ago explains how I must clean some valve on top of the engine (must did the old article up).
This may be at a complete tangent, but when you mention 'drive', do you actually mean drive, or do you mean when you start the engine form cold ?
I only ask, as when I have started my engine over the last couple of colder mornings, my car automatically revs from 500 to say 1,200 (not accurate figures) until it settles in to a smooth idle.
I understand this is quite normal, but I can get it to stall if I set off too early and let off the throttle at a junction it can stall - another post some while ago explains how I must clean some valve on top of the engine (must did the old article up).
Guest
New member
Hi,
Yes while I am driving, when the car comes to a standstill in traffic the revs bob up and down. This is not normal.
However it happens intermittenty.
The previous owner said it only happend in the rain, where the ECU got wet (bad targa seals).
However I noticed it happend in dry whether too.
I suppose its best to take it to my Porsche mechanic.
Amolak
Yes while I am driving, when the car comes to a standstill in traffic the revs bob up and down. This is not normal.
However it happens intermittenty.
The previous owner said it only happend in the rain, where the ECU got wet (bad targa seals).
However I noticed it happend in dry whether too.
I suppose its best to take it to my Porsche mechanic.
Amolak
Guest
New member
Yes its normal ie., a common or widespread problem but I don't think they are supposed to do it. What you describe sounds like the early symptoms for a worn AFM. Certainly my car doesn't do this with its new AFM (well newish AFM). It just starts and if its cold it idles at 1200rpm before settling to 850rpm. With the old AFM it used to just start, then the idles started surging as described between 500 and 1200rpm. At first just a few surges, say 5-10 - then many surges, and finally all the time at idle. Replacing the AFM cured it for me.
RB
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