TB48 rough idle

[Jarrodtorpy]

Hey guys,

So i recently bought a 2002 tb48, it is straight petrol with 150,000km. So when i start up whilst cold the idle is a little rough, now its not that bad, only just noticeable.

It is like the idle just flutters around a bit and feels just a little rough. As i drive and the car warms up this does improve but never really goes away.

I'm not experiencing any power loss or fuel consumption issues either.

I've had the entire intake including throttle body taken off and cleaned and this did nothing.

Any ideas would be appreciated.

[dom14]

I would rule out electrical/electronic issues first.
Spark plugs, ignition leads, ignition coil etc should be tested properly to see if they need replacing.
Use a mulitmeter. Typical rule for ignition leads is 1000ohm per foot, but can be different in EFI performance enhanced ignition systems. Spark plugs are around 5k ohm. I personally prefer testing them properly by taking time on it, but some guys just replace
those things if they suspect it. I bend the leads on every inch of it while testing with the multimeter(I used croc clips).
I guess replacing sensors like MAF etc can help diagnosing problems like the above. After checking electrical stuff, checking for vacuum leaks it the way to go. Either listen for strange hissing noises or spray wd40 or water(spray can) onto suspected areas to
see if the rough idling improves.

I'm thinking 150k is a good number to start checking/replacing things like timing belt etc, but TB engines come with timing chains, so I guess that's not an immediate concern in terms of replacing, but tension should be checked.(not likely to cause the OP mentioned rough idle though).