118TSI Forged Piston Engine Rebuild

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Originally Posted by rygreen93

Na mine doesn't do it. I have a modified tune so I no longer get the rough idle on starting to heat the Cat. I always get the wining from the compressor which I assume we would all get as it warms up. But I never had the rough idle on start-up. My brother has the 90tsi which does it.

This is more to do with either the fact that the mineral oil is draining of the engine over night as it does not stick as well or my second theory is that while the new pistons are cold there is a lot of blow by and after about 20 seconds that seals up and then she runs smooth. That's my theory anyways.

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Outside of the cat pre-heat (which only occurs if the engine is between 20c and 30c on startup), mine runs ok. It's ever so slightly rougher for the first 20 seconds or so, but i'm only talking slightly - as what you thought, I put this down to the piston's being cold, since they are designed to expand a bit when at operating temperature. Don't recall it being any different on the running in oil, apart from the first startup after rebuild and it being tappety as the tappets needed to refill with oil.

I wouldn't worry about it at this stage - mine wasn't rebored, so didn't have to do hardly any running to get a good ring seal where yours might need a good load of miles on it to get the rings to seal, especially when cold.

When you say the compressor is wining - are you referring to the supercharger during warm-up idle, or the turbo?

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Originally Posted by blower

Outside of the cat pre-heat (which only occurs if the engine is between 20c and 30c on startup), mine runs ok. It's ever so slightly rougher for the first 20 seconds or so, but i'm only talking slightly - as what you thought, I put this down to the piston's being cold, since they are designed to expand a bit when at operating temperature.

When you say the compressor is wining - are you referring to the supercharger during warm-up idle, or the turbo?

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Yeah, it's not a horrible idle but its ever so slightly lumpy and then goes away really quickly. And yeah I am talking about the supercharger warming up at idle.

I wouldn't worry about it at this stage - mine wasn't rebored, so didn't have to do hardly any running to get a good ring seal where yours might need a good load of miles on it to get the rings to seal, especially when cold.

As far as I know, the supercharger shouldn't be running at idle or warmup - the supercharger clutch should be disengaged.....never noticed a whine from it anyway (but I still have the full sound insulation fitted, I know some people remove it for extra whine).

I'm not 100% sure of this though, but I can't see a reason why it would be running at idle or warmup.

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Originally Posted by blower

I wouldn't worry about it at this stage - mine wasn't rebored, so didn't have to do hardly any running to get a good ring seal where yours might need a good load of miles on it to get the rings to seal, especially when cold.

As far as I know, the supercharger shouldn't be running at idle or warmup - the supercharger clutch should be disengaged.....never noticed a whine from it anyway (but I still have the full sound insulation fitted, I know some people remove it for extra whine).

I'm not 100% sure of this though, but I can't see a reason why it would be running at idle or warmup.

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I'll record it for you one of these days. It's always done it. Kinda sounds as if it's just warming up and getting a bit of movement happening. Sounds pretty good to be honest.

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Yeah, you've got me curious now - i'll start mine up later and have a look to see if the supercharger pulley/belt is running.

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Originally Posted by rygreen93

I'll record it for you one of these days. It's always done it. Kinda sounds as if it's just warming up and getting a bit of movement happening. Sounds pretty good to be honest.

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I started mine up from cold earlier - the supercharger is definitely not running at any point, not during the warmup or after the idle has settled. I thought it wouldn't make any sense to have the supercharger clutch engaged and running during idle or warmup.

Maybe its something to do with your tune?

Na my car has done it from when I got it. It's a 2012 model and i know that they changed things, that is why mine doesn't rough start at any temp at all. It's part of the base factory tune not my modified tune. I'll post a video of it for you to have a listen to. You can't miss it.

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Originally Posted by rygreen93

Na my car has done it from when I got it. It's a 2012 model and i know that they changed things, that is why mine doesn't rough start at any temp at all. It's part of the base factory tune not my modified tune. I'll post a video of it for you to have a listen to. You can't miss it.

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Interesting, I wonder why they have done that - maybe it's to get extra air through when it's doing the double fueling for cat pre-heat, and is why it doesn't run rough.

I know 2012 1.4 CAXA (non twinchargers) still have the rough running on start with engine temps btwn 20 and 30c, as my mate owns a march 2012 CAXA. Possibly because they couldn't do what they look to have done on 2012 twinchargers and used the supercharger to increase airflow.

I have a Podi boost gauge on mine so i can see the boost go from an idle vacuum (~ 20 inHg, below 0) when it runs smoothly (~700RPM) through to exactly 0 when it runs rough on startup (~1000-1100 RPM). It's like the induction system is opened up to atmospheric pressure during the warmup (at least where the gauge line connects). I've noticed that mine has only done it above 20 degrees C through the winter here in Sydney.

There is definitely no boost being provided by the supercharger and there is no click of the supercharger clutch engaging or disengaging during the rough idle warmup.

That's on a 2009 ECU running APR, though.

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Originally Posted by Mk R

I have a Podi boost gauge on mine so i can see the boost go from an idle vacuum (~ 20 inHg, below 0) when it runs smoothly (~700RPM) through to exactly 0 when it runs rough on startup (~1000-1100 RPM). It's like the induction system is opened up to atmospheric pressure during the warmup (at least where the gauge line connects). I've noticed that mine has only done it above 20 degrees C through the winter here in Sydney.

There is definitely no boost being provided by the supercharger and there is no click of the supercharger clutch engaging or disengaging during the rough idle warmup.

That's on a 2009 ECU running APR, though.

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Yep the supercharger definitely does nothing during startup/idle on 2009/2010/2011 models, seems only 2012 models run it for some reason, of which i can only hypothesize why above.