Richard Fogg

I just confirmed my "butt dyno" with some G Tech readings, and my S4 occasionally fails to generate full boost, but with no discernable pattern. A 2nd gear flooring at 20mph usually gave a .46g to .48g reading, but I also got a .33g and a .34g (5200', full tank and about 440 pounds of driver and passenger). 3rd gear at 50mph was usually .34g or .35g but every now and then it dropped to .24g. It isn't a heat soak problem because it would give a good run several times in a row, then a bad run, followed immediately by another good run, etc. Very perplexing. It has done it on every tank of gas, all premium and different brands. The check engine light came on last week, but the readout at the dealer just showed "misfire", and the problem with the boost has been around well before the light came on and is still occuring after the light was reset. I have an appointment for a car physical on 12/8, but I am sore afraid.
This is the sort of gremlin that could be very difficult to track down. I know a few of you have reported similar problems. Any solutions yet? As you other S4 owners know, these are fantastic
cars, but it sure takes a lot of the fun out of it when you don't know what to expect when you put the pedal to the metal. (I guess that expression is still valid with a fly-by-wire throttle). And on top of everything else I'm a Broncos fan. Sigh.

Alan

This a problem that has plagued this car from the very start.
Here in England, the first cars delivered (I got mine in October '98) had this problem really bad, also the ECU would just "crash", and go into safety mode, not at all embarassing, 25mph in a brand-new $67,000 car!
Audi's fix (and there were MANY cars with this problem) was a change of ECU (same type, just new software). Whilst this solved the "crashing" business, certainly with my car, and some others I know of, this seemed to make the inconsistent boost drop-off more regular (my case-drive for an hour and it would happen 2/3 times).
Audi NEVER solved this.
I had my car chipped (after 3 ECU changes and a major re-call in which virtually every hose on the car was changed) and whilst this virtually eradicated the problem, it would still occur occasionally, mainly when the engine was very hot. Of course I then had much better performance, too!
I'm fairly sure there are still many owners driving around with this problem occuring on a regular basis, but it is so unpredictable (and not that frequent) and almost impossible to reproduce, most people just live with it.

Mark S

verify the boost reading when this low power condition occurs?

Neil

I noticed this tonight, too... Hadn't before now. Hopefully my new TAP Stage II will fix it.

N