Idle RPM's

[johnsnow]

I have a 06 987 with 80k miles (recently purchased) and from cold the engine idles at a steady 1100rpm then when warm (after 20 mins of driving or so) drops to a steady 620rpm - is that normal behaviour?

Other niggles I have which maybe or maybe not related are:

Theres a slight judder when settings off unless really really gentle with the clutch release (the clutch doesnt seem worn from a few tests)

1st and 2nd gear are difficult to engage when cold and sometime 1st wont engage - ive read other people with these issues and it seems to be accepted

I guess being a new owner im wondering if the above is normal or not..

[logray]

This all sounds normal to me.

The judder is probably motor mounts or the DMF springs. Also normal, unless your mounts are shot.

The gear problems is somewhat normal, however if you have fresh gear oil which is the CORRECT type it should be less noticable unless it is very cold. Shifting into second and then into first helps. Also pause slightly longer between gears when the gear oil is cold. These things will help.

Welcome to a p-car!

[RFM]

If i were you, i would with a diagnostic tool as PIWIS, the actual values and error codes, if any, checked. It seems to me that the high idle RPM is too high for too long, as well as the difference between both ( 1100 versus 620 RPM ) is too large.

[johnsnow]

Thanks for the suggestions - I will get it tested and let you know (hopefully help others)

Edited May 10, 2012 by johnsnow

[logray]

Good catch RFM on the rpm, I missed that.

I don't think it is abnormally high though, I have read some C4S and 997 cars will idle at or just above 1000 rpm on cold start, and then return to 680ish.

For a 987 I am not sure what the specs are but IIRC the 986 cars might have slightly higher hot and cold idle settings than the 996/997.

I guess it would be good to see what the factory idle set points are for the 987 before jumping to conclusions.

[johnsnow]

I guess it would be good to see what the factory idle set points are for the 987 before jumping to conclusions.

I must have spent days trying to track down that information to no avail - any ideas where I could find that information?

[Loren]

I guess it would be good to see what the factory idle set points are for the 987 before jumping to conclusions.

I must have spent days trying to track down that information to no avail - any ideas where I could find that information?

The idle points are the same as 9x6 series (same engine) -- 700 RPM +- 40 RPM

[johnsnow]

I guess it would be good to see what the factory idle set points are for the 987 before jumping to conclusions.

I must have spent days trying to track down that information to no avail - any ideas where I could find that information?

The idle points are the same as 9x6 series (same engine) -- 700 RPM +- 40 RPM

is it the same engine in a 987?

[Loren]

Yes, 986, 987, 996, 997 all share the same basic engine. Different displacements and some emissions differences but the specs are the same.

[logray]

Interesting.

The original 996 WSM says 680 RPM +/- 20 (3.4L)

Whereas the original 986 WSM says 740 RPM +/- 40

Also where are you getting the 620 and 1100 RPM from, is that from a code scanner such as Durametric which can read the actual RPM? I wouldn't trust to give exact figures by looking at the needle on the gauge, although it is pretty close.

[johnsnow]

Interesting.

The original 996 WSM says 680 RPM +/- 20 (3.4L)

Whereas the original 986 WSM says 740 RPM +/- 40

Also where are you getting the 620 and 1100 RPM from, is that from a code scanner such as Durametric which can read the actual RPM? I wouldn't trust to give exact figures by looking at the needle on the gauge, although it is pretty close.

You guessed correctly - the needle itself. I have bought a Durametric cable so will do some measuring over the weekend its a possibility the MAF could be on its way out as when engine braking it misses rpm's

[johnsnow]

Durametrics show only 2 errors - not sure if either are relevant

PAS:

8004

Versorgungsspannung Klemme 50

(SC+)

CLUSTER:

9152

Unknown DTC: 37202

[RFM]

Clean the throttle body thoroughly to start with, clear the codes, try again and see what it gives is my advice. It is easier to work step by step than to throw everything together. Success.

[johnsnow]

Clean the throttle body thoroughly to start with, clear the codes, try again and see what it gives is my advice. It is easier to work step by step than to throw everything together. Success.

Thanks - I took your advice Ive decided to do a step a time.

Ive started by clearing the codes and installing a new air filter, the first step along the path. Ill give it a few days to see how it drives (so far the judder has minimised and the car seems smoother). Next Ill clean the throttle body. One thing I did notice when the car was idling I could feel a blowing to the right of the throttle body (red arrow in the pic). Is that normal? It made a distinct sucking sound when blipped which is what I would expect but regular idling I could feel a soft blowing