Please help, very slow s3!

[brys3]

I need some help badly. I've got an 01 s3 which is ment to have been remapped. It's had a recent service, new stat and cts, green Cotten panel filter. The spark plug gap I think is at 22 thou. I bought a milltek cat back 2 weeks ago. I knackered the lambda while taking my old exhaust off. When driving after about 4000 rpm it looses power badly when I am
heavy on the accelerator. At first I thought it was because of the lambda it was running rich and over fuelling. I replaced the lambda last night and it's still no better. It's like it starts to boost nicely, responsive throttle, then gets to around 4000rpm and doesn't have comparable power to the first 3500 to 4000 rpm. No faults are found so I don't know what to do. Any help will be much appreciated.

 

[fran-s3]

I would log the misfires on (block 062 I think) ... Get a mate to sit next to you log it on VAG-COM while on boost and see if it counts any misfires. (When mine was doing this I had no engine faults come up either but it was misfiring according to the graph... loads!)

 

[Dani_B19]

That could be a miss-fire or poorly MAF, need to get it on vag-com mate.

 

[S3KO4]

the gap on the plugs does not sound right, what make and heat range are they, and did she used to behave the same before the service carried out as it does now?

 

[brys3]

No this is only a recent occuence sinse messing about with the exhaust. However in third gear when I boot it over 4k it does seem slightly like a misfire. I don't know anyone with vag so i'm screwed there. Plug gap has been trial and error. A couple of months ago I had to replace a coil pack. Tried new plugs but would misfire slightly when on boost, closed the plug gaps and was fine but when warm would fluctuate on idle. So I messed about and got to aroud that 22 however after an hours drive it still fluctuates ever ever so slightly. And they are the bosch ones that are recommended in the owners manual

 

[<tuffty/>]

Plugs should be gapped to 0.7mm (27.6 thou)... 22 thou is far too small.. NGK's are the preference and are they iridium?... NGK part number for std plugs is BKR6EIX....

Your car needs to be logged with vagcom before any form of diagnosis can be done I'm afraid...

<tuffty/>

 

[brys3]

just had the s3 hooked upto vagcom thanks to rich @ viper racing the good man. turns out it is mapped, the information was locked for some reason though so he couldnt determine what map it is. on the lack of power, the maf at peak was passing 170 g/s of air, boost in the low rev range was an issue, at most it was asking for 1.3 bar @ 3000 rpm but only delivering 0.8. as the revs continued it evened itself out. he suggests changing the n75 valve and checking hoses for leaks before trying his other software to read map. does all this sound right for a lacking in power? 1st and 2nd gear booting it seem fine but in 3rd the missfire after 4000 rpm is noticeable all the way up to 5500.

 

[sportstractor]

yea boost leaks can hinder performance massively and even throw the car into limp mode, mine was doing this when i got it. Common boost leaks are under the inlet manifold on the breather system, has it not even flagged any fault codes? check for splits on the n75 pipework also.