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Annoying holding revs issue AGAIN

cobalt911

cobalt911

New member
Hello all,

I had the engine revs 'holding' late last year and into Spring and despite their best efforts Northway could not find the issue. It disappeared completely over the Summer (did not happen once) but is back now we are in cold/damp weather. It varies in severity but is annoying as you lose engine breaking and you get some lurching when changing up. The only way I can describe it is that it seems like something is 'sticking'.

Northway and Tognola have found nothing through diagnostics and I have cleaned the ISV to within an inch of its life and it has a new oxygen sensor.

When the engine is hot the problem still exists so I am thinking outside of that area but the throttle on/off switch passed diags ok. Ambient temperature and/or dampness in the air seems to figure...

Have put a youtube clip on to help you guys in helping me! This clip is actually a 'mild' form of the problem but you will notice hesitation from 3000rpm down. It can be roughly twice this bad which is maddening and spoils an otherwise faultless drive.

http://www.youtube.com/watch?v=L98gD515YzY

Any thoughts?

Cheers,

Mark
 
I had this on a couple of cars - replacing the air flow meter solved it in both cases. Not sure if the same rule will apply with the 993 though...
 
Did cleaning the ISV help at all as it sounds like an ISV or MAF prob. I clean the ISV on mine each year when I do the Oil & filters change however it could be a faulty ISV in which case cleaning it would not have any effect - just a thought.
 
well, gave it another clean today and we shall see! I would have a go at the MAF as well but that looks a job and a half!!
 
Different car, same issue. I had this on an S3 which turned out to be a sensor under the clutch pedal. Designed to cut the throttle when you depress the clutch. Not sure if there's something similar on a 993 but worth checking.
 
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