gtdreirs

Hi folks,

Greetings from Sydney Australia. Finally got my hands on a silver 996 GT3 CS after dreaming about them for eternity it seems. Owned way too many cars to list them all...Evo 9, e46 M3, Golf R to list a few.
I have one question at this stage, noticed the car is a bit rough at idle. It basically has a miss but seems perfectly fine on throttle. It has been suggested I replace the MAF and O2 sensors to start with. Anyone else experience this?

Cheers

serickson

First thing I would suggest is to clean the throttle body. I used MAF cleaner, I recall a good article on renntech. Pretty easy job need to remove air cleaner housing, MAF connector, remove large hose clamps around throttle body and remove. Spray inside with cleaner and clean with cotton cloth.

gtdreirs

Thanks for that, will give it a go.

aussie jimmy

welcome to rennlist, my friend!

onelove

Depending on mileage swap the plugs and check the coilpacks, these earlier 996s were notorious for bad coilpacks (both GT3 and Turbos).

AudiOn19s

This was discussed in another thread, GT3's have a rough idle so you may just be chasing nothing really.

When I had my engine out for the coolant fitting repair @ 20k miles I changed the plugs, cleaned the throttle body, cleaned the MAF all as preventative maintenance and it didn't change the idle any. It's a characteristic of the car. Unless it's running really rough I'd say don't sweat it too much.

996FLT6

At idle it's lumpy on mine. Always been like that since day one. Now if depressing go pedal and it misses that's not normal. Mike

911SLOW

Welcome.

Is it a mk1 or 2?

gtdreirs

It is a mk 2 '04 model. I can understand a rough idle just a bit surprised by the odd miss. Would be good to compare to another GT3 here, for now I only have 1 mate with a GT2 and I am guessing that would be like comparing apples to oranges? On the porsche diagnostic tool it doesn't come up with any faults.

jpeytonii

Welcome.

If you truly had a misfire it would show as an ECU fault. As others have mentioned a rough idle is a characteristic of the car. Does your CS have the LWF? (I can never keep straight if the factory CS cars had it or not, seen it listed both ways.) Anyway, if you do have the LWF it will accentuate the lumpiness of the idle also. I know it does on mine.

Cheers.

gtdreirs

Hi, it has a dual mass flywheel from factory. It will be replaced very soon with a LWFW as the original clutch is near the end of its life.

gtdreirs

OK, so 1 piece of interesting info..speaking with my mechanic who did a service on the car not long ago it seems like the 2 x oxygen sensors after the cats were removed at some point. I can clearly see the plugs in the engine bay where these would normally plug in. Just wondering if this could be a potential contributor..

996FLT6

Anyway u can record/video the miss at idle? Mike

jpeytonii

I would say it "shouldn't". The downstream oxygen sensors are there just to verify that the cats are doing their job. That being said the fact that they are completely missing and you are not having a CEL makes me think someone has messed with the ECU. Do you know if the cats are even in there? Only reason I can think of to remove the downstream oxygen sensors is if the cats failed or were removed. Do have emissions testing down in Oz?

Cheers.

Mikelly

I asked the same question a few weeks back when I got my car. It does indeed have a rougher idle, but I've heard it now on two of them, and all the guys here say the cam makes it have a little but of lump to it, making the idle not quite smooth.

Mike