Ur S4/S6 engine Ignition

2.2 I5 20v turbo - 230bhp
4.2 V8 32v Naturally Aspirated - 280bhp
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AndyH-R6S
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Joined: Sun Mar 26, 2006 7:58 pm
Location: Welling

Ur S4/S6 engine Ignition

Post by AndyH-R6S » Mon Feb 26, 2007 10:52 am

Has any body had this particular problem with there standard or modified Ur S6/S4?

While driving on a motorway, and accelerating moderate to hard, the engine hesitates for a few seconds (Max) and then accelerates OK but maybe with a very slight roughish feel to the power, then other times using the exactly the same driving technique the car accelerates off smoothly and with plenty if vigour from the start. (Normal) It tends to only happen in top gear (between 60 to 100mph) but some times I have witnessed the event in the gear below.

The car has been fully checked over by an Audi specialist but nothing can be found. The only potential issue might be that the intercooler is too small for the engine conversion. However, when the external temperature is 4°C externally and exact same driving technique is used and the event does not occur, I would doubt that the intercooler is the issue. My past experience with turbo cars has suggested potential poor ignition/fuel delivery. Possible spark plug/lead or coil pack breakdown may be?

The car has a ‘MTM’ engine conversion so it is running higher boost than normal but this phenomenon occurs as the boost is starting to build up at around ‘0.8 to 1.2 bar’ and the ever so slight. Throttle position tends to make very little difference but I have noticed on the very odd occasions that using a slightly smaller throttle opening works better but there is still a very slight roughish feel to the power.

Lastly and totally not connected, has any body seen more than ‘2.2 to 2.3’ bar indicated on the internal instrument display panel? As mine should indicate more pressure after the MTM conversion but it might be the case that the display is not capable of going any higher? (The engine boost has been seen to go higher on calibrated boost gauge)

Any thoughts out there as when it goes on the rolling road it never does it?

Ba,

Andy H.

JEDIS4
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Joined: Tue Aug 02, 2005 8:28 pm

RE: Ur S4/S6 engine Ignition

Post by JEDIS4 » Sun Apr 29, 2007 10:45 pm

Late relpy but what the hell..........i would check coils for stuttering in preformance and i have 2.5 on the gauge which is running a homefry

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