Power loss when warm?

[ashmo]

Had my S3 for about 3 months now, the first month it was spot on then I noticed some power loss at first I thought it was all the time but tonight drove it cold and I know you shouldn't but I put my foot down and it pulled like a train??? Recently serviced with new coils and new a MAF but its made no difference, there is a muffled whistle sound when the turbo kicks in, not sure if its the turbo its self or coming from the exhaust? Scanned with VCDS nothing comes up, any ideas what it could be?

 

[Bazzle]

1st thing I try if I can find nothing wrong is to remove neg batt lead for 20mins.
Get in reset windows and go for a drive.

 

[sliced]

Cars are generally faster when colder, hence cold air intakes, inter coolers that keep temps down etc. Sure someone will be able to explain it better.

In terms of it feeling slower, have you done all the usual checks such as the diverter valve?

 

[nluk100]

Very common with intercooled cars. Not a lot you can do about it (except drive at night). Even a bigger intercooler won't help that much as the ambient temp will still be high. My car got dyno'd at 29deg C and it was down on power because of the temps.

 

[smurfworth]

Very common with intercooled cars. Not a lot you can do about it (except drive at night). Even a bigger intercooler won't help that much as the ambient temp will still be high. My car got dyno'd at 29deg C and it was down on power because of the temps.

Except WMI which lowers the intake temps

 

[S3Alex]

A more efficient intercooler will help by keeping intake temps closer to ambient,and as an example,the ProAlloy on mine will keep temps to within 7-10C of ambient under load,so it will minimise the effects of a hot day,or hard driving,but cannot remove it altogether.

WMI is a huge help in addition to a good intercooler,as not only will it reduce intake temps to below ambient,but by using up to 50% methanol,you also increase the effective RON of the fuel you're using.

 

[ashmo]

This isn't just a little power loss its more like day and night, ulls like a train at first then foot down after warming up and bam limp mode, with hesitation and an odd muffled sound, could it be the CAT? the first month I had it it was pulling like a train 247 night, day, warm....

 

[S3Alex]

OK...what you're describing is something completely different.

You need someone to log the car properly,and find out why it's pulling back like that.
It could be fuelling,boost levels,and a host of other things that you won't know until it's been logged and looked at.

 

[ashmo]

OK...what you're describing is something completely different.

You need someone to log the car properly,and find out why it's pulling back like that.
It could be fuelling,boost levels,and a host of other things that you won't know until it's been logged and looked at.

Dropped it off at a "German Specialist" today they said they checked the CAT and they said there is nothing wrong with it and they can't find any issues with the car??? I know my car and I know there is something wrong, what should I do next?

 

[s3_trev]

Post some more information mate, is the car mapped etc etc? What mods does it have?

 

[Compkiler]

Where do you live?

 

[ashmo]

Post some more information mate, is the car mapped etc etc? What mods does it have?

Its totally stock.

When I first had the car it was spot on everything running sweet, then it started driving a but lumpy with some boost lost, first I thought it was the fuel, was running Tesco 97 switched to VPower since done at least 5k miles.

New Sparks
New Coils
New MAF
New DV

CAT checked no issues, checked for boost leaks nothing found, VCDS nothing found, put some of that CATClean stuff in and its a little better but still something is not 100% under load there a muffled stuttering around coming from the exhaust or somewhere which wasn't there before and the turbo hesitates

 

[ashmo]

Where do you live?

North Wales

 

[s3_trev]

Have you tried replacing the fuel filter

 

[TorqueTerrorist]

My friend had this. It was the cat

 

[ashmo]

My friend had this. It was the cat

That's what I still think but the specialists did a full system test checking all the mixture levels and said it was fine, when they did a test drive they used the wording "performs very well" to be honest it is driving a bit better since I put that CAT Clean stuff in last week so I may wait a bit longer and put another bottle in a week or 2.

 

[nluk100]

North Wales

How far away are you from Unit20.com in the Wirral as they are S and RS specialists and know their stuff.

 

[David de los Reyes]

Very common with intercooled cars. Not a lot you can do about it (except drive at night). Even a bigger intercooler won't help that much as the ambient temp will still be high. My car got dyno'd at 29deg C and it was down on power because of the temps.

Same issue on my car (2002 S3 bam225). Replaced dv, plugs , coil packs, o2 sensor and still getting power loss . This happens as soon as the temp gauge is on or slightly before the half way mark . Anything before that the car pulls hard. No CEL, no codes. There is a noticeable back fire during idle without the AC on . Don't know why since coil packs are only a day old, had that issue with my old coils as well .

 

[nluk100]

Same issue on my car (2002 S3 bam225). Replaced dv, plugs , coil packs, o2 sensor and still getting power loss . This happens as soon as the temp gauge is on or slightly before the half way mark . Anything before that the car pulls hard. No CEL, no codes. There is a noticeable back fire during idle without the AC on . Don't know why since coil packs are only a day old, had that issue with my old coils as well .

You need to get your car scanned to see if there are any error codes. If not then logging EGT, MAF and boost should help identify what may be going on. You may have a boost leak that only shows itself when the pipes get hot. Check the VCDS page to see if a local member can help.

 

[A3Powa]

That's what I still think but the specialists did a full system test checking all the mixture levels and said it was fine, when they did a test drive they used the wording "performs very well" to be honest it is driving a bit better since I put that CAT Clean stuff in last week so I may wait a bit longer and put another bottle in a week or 2.

Hey man! I know this was 7 years ago but I hope you reply... I got the same problem with my car and I've either replaced or checked everything but the CAT. So I just need to know, did your car end up working like it did before after working on the CAT???