100BHp Down on Power

[urquat]

This weekend my dad (04' V8 RS6) and myself (84' Ur quattro) went to the rolling road. I was pleased as punch with a calculated reading of 205 bhp at the flywheel and 245lbft. (when new, 200 and 210lb ft)

However, Dad's RS6 was approx 100bhp and lots of torque down on stock, and on top of that it has a MTM chipped ecu and gearbox so should be putting out closer to 500 flyswheel bhp.

The screen calculated 400 flyweel bhp, but the operator said that as it is an auto that is an exaggerated figure. So it is quite possible there is only 350-380 bhp from what I understand, the car doesnt feel very quick. There was 200bhp at the wheels.

The Mass air flow sensors were replaced when the MTM chip was fitted as it was down on power, that was approx 10 months ago.

The car is going back to the rolling road for a day for a check and probe over to see if they can find any faults. Not sure how sophisticated their fault code reading etc is though.

Can anyone help/share their experiences? are there any particularly suspect areas/mechanical failures to look for.

Haveing searched, it seem diverter valves and the n75 Wastegate controller can fail, are these expensive parts? And does this sound plausible?

My 25 year old technology has triumped for now.....

[JonnyX]

Take it someone who can log it before you start replacing random parts. Anyone with VAG-COM (it's also a worthwhile
investment) should be able to help. Where are you based? MRC are in Banbury, Unit20 (Wirral area I think) also have a
good reputation with 6's.

[Cornishmoocher]

A couple of things, Where did you RR it?
Who applied the MTM chip?.
As above, where are you based? Definately take it to a reputable RS6 specialst, I would only use one of the above mentioned guys'.
Bear in mind, that the car may not have been producing 450bhp to start with, and its not unusual for some less reputable tuners to "guess" at power output and massage figures to suit.........
But all in all, the car should be putting out close to 500bhp as you say, but WHP will be 100hp less. mine is 510bhp and 411whp with MAF's & N75 changed, but only 486bhp and 383whp prior to having them changed.

[urquat]

The car was chipped by QST at Haywards Heath (uk mtm agents) and the car was rolling roded at Engine Advantages in Witham, Essex. (yes we are Essex based) They have a Hofmann Dynatest 112.

The operator seems to be quite an intelligent not full of bullshit bloke, amongst others he used to work for mountune race engines.

I read someehre else on here that you would expect approx 330 Wheel horsepower for a standard car? is that about right? if so the car must be really sick.

It went for a 60k servcie and MTm chip at QST. It was 100bhp down on stock then, but they apparntly cured it with MAF sensors (really struggled to find a fault) their dyno printout says 485 flywheel bhp, so wether that is true, or from another car, or something else has since failed is anyones guess. It didnt feel that much quicker after re map. Perhaps it has never been strong on power...

Just over 200bhp at the wheels is pretty pathetic...!

[Cornishmoocher]

Take it to Grizz or MRC. IMHO Its the way forward if you ask me, these guys are genuine S/RS boys and love the cars more than the money they generate.....So you can trust them.
If the car was not making 450, QST should not have put the MTM chip on if you ask me.

330 at the wheels is about right for a standard car, and it is still bloody quick, you should eb able to see 170ish and 0-60 in about 5 secs, with 500/400 you should be looking at 180+ and sub 4.5 secs 0-60.

[HawkeyeSteve]

Before you do anything drastic or pay a lot of money try this: disconnect the battery and wait one minute. Reconnect the battery and take it out for a spin. You'll find the power is back.

[Cornishmoocher]

Before you do anything drastic or pay a lot of money try this: disconnect the battery and wait one minute. Reconnect the battery and take it out for a spin. You'll find the power is back.

Please explain steve.....

[tweek]

Probably clears the adaptive settings in the ECU, the ECU's learn your driving style and adjust engine settings to suit.

[Cornishmoocher]

Hmm, not sure about that one, the ECU Constantly adapts to your driving style, so surely if you planted it, the ecu would say Ay OOP, ere we go, lets have it!!!!

[tweek]

The Bosch Motronic ECU's do have adaption in them, why Audi bothered on these sort of cars I'll never understand. When I want power I want it all...

There is a thread Think My S4 Is Broken in the B6/7 forum that provides more info.

[HawkeyeSteve]

Pretty much just as I described. By disconnecting the battery cable, you take the power away from the ECU. Reconnecting it effectively hits the "reset" button on the ECU and you'll find the power is back. What I can't explain is why this occurs in the first place but you'll find with VAG-COM is that the ECU is asking for more boost than what it actually gets. I think it has everything to do with the MTM upgrade, as I've never heard of it happening without it. I don't think MTM knows what's happening either.

Try that trick. It doesn't cost anything, takes all of 10 minutes and if it doesn't work, you haven't invested any significant time or money. In addition, you haven't burned any bridges either, you can still take it to someone and have them look at it. After this trick, you'll find the requested turbo boost and the actual turbo boost are the same via VAG-COM.

Let me know how it works.

[Cornishmoocher]

Ah, yup, with a chip I can understand how a re boot could cure the problem.