Bouncing idle, little hestitant at low speeds

[sid86]

I used to just throw new parts at a problem, but Porsche parts are a little bit more expensive So:

1) My 987.1 S has a rough idle. It bounces up/down 50rpm when everything is up to temperature. No shaking, no vibration, just a bouncing rpm needle.
2) The car doesn't feel 'smooth' at low speeds. It's a manual, and I know how to drive one, but it just needs that extra 'touch'. It hesitates a bit. Also, when the engine is cold the gearshifts take a little more attention (releasing the clutch, feeding in the power) to make it all go 100% smooth. She doesn't seem the be running 100% (and this is a dangerous statement, as I'm sure most other drivers wouldn't feel it).

The rough idle is like this (although the video isn't from a 987):
https://www.youtube.com/watch?v=cRRKoAUirBo

The car has:
- a new MAF sensor
- the throttle body is original
- new sparkplugs
- the ignition coils are original

It does not throw any codes.

My feelings says it's either the throttle body, or the ignition coils. Any ideas or similar experiences?

[M. Murphy]

One thing to check are the connections to the coil packs, especially #6 , right rear. Last year I had a similar issue and thats what it was.

[sid86]

Originally Posted by M. Murphy

One thing to check are the connections to the coil packs, especially #6 , right rear. Last year I had a similar issue and thats what it was.

What symptons were you experiencing?

[BYprodriver]

[QUOTE=sid86;10415435]I used to just throw new parts at a problem, but Porsche parts are a little bit more expensive So:

1) My 987.1 S has a rough idle. It bounces up/down 50rpm when everything is up to temperature. No shaking, no vibration, just a bouncing rpm needle.
2) The car doesn't feel 'smooth' at low speeds. It's a manual, and I know how to drive one, but it just needs that extra 'touch'. It hesitates a bit. Also, when the engine is cold the gearshifts take a little more attention (releasing the clutch, feeding in the power) to make it all go 100% smooth. She doesn't seem the be running 100% (and this is a dangerous statement, as I'm sure most other drivers wouldn't feel it).

The rough idle is like this (although the video isn't from a 987):
https://www.youtube.com/watch?v=cRRKoAUirBo

The car has:
- a new MAF sensor
- the throttle body is original
- new sparkplugs
- the ignition coils are original

It does not throw any codes.

My feelings says it's either the throttle body, or the ignition coils. Any ideas or similar experiences?[/QUOTE


Clean the throttle body with brake cleaner spray.

[sid86]

Yeah, so.... I talked to some more 'experts' and all pointed towards the throttle body. A new OEM part was only 150 euros, so I got one and installed it. The drive seems to be smoother, but time will tell. The bouncing idle needle however remains unchanged. This is with a warmed up engine:

[stealthn]

Got a Durametric?

[sid86]

Originally Posted by stealthn

Got a Durametric?

No. I have a iCarsoft Porsche II which says there are no codes.

[stealthn]

It should have some real time graphs for things like AF mixture, timing, etc. I haven’t used in on the POR II but watched things on my durametric to troubleshoot issues. I will hookup my carsoft and have a look.

[sid86]

Originally Posted by stealthn

It should have some real time graphs for things like AF mixture, timing, etc. I haven’t used in on the POR II but watched things on my durametric to troubleshoot issues. I will hookup my carsoft and have a look.

Thanks.

[stealthn]

OK hooked up my POR ii and can really see the difference between it and the Durametric. I really like the Durametric graph of real time data especially the cam shaft deviation so I can see if/when the IMS bearing is going.
The POR ii has some realtime data in ODB mode but they are limited fuel and o2 sensors, timing but only at cylinder 1, etc.

I knew it would be limited but I do like the quick and easy stuff its' good for rather than getting out a laptop.

Sorry I couldn't be more help, I would be looking at MAF, Vacuum, O2 sensor, and Gas, you have changed out the MAF and plugs, so I would run some techron through the system.