Esse Quattro

I finally got around to taking my car to the repair shop for a variety of problems, including having very low power.

Forum members here said my symptoms sounded like a possibly torn TBB and maybe bad BPVs as well. I had my mechanic replace both as good insurance. The TBB was the original and my S4 had 93k miles on it. One or both BPVs had been replaced 50k miles ago, but at $38 each, I deemed them cheap enough to just replace for peace of mind.

After replacement he showed me the original TBB: It had an approximately 3.5" tear above the main clamp and a smaller 0.3" tear on one of the legs leading to the turbos. Think that might have been leaking some boost?

Unfortunately, after replacing those, servicing the car, and replacing my incredibly clogged air filter (no light visible through it), it still had low power. Worse yet, it was then "stuttering" under accelleration and would not go much past 5k RPMs before the power was almost totally gone.

The mechanic thought to replace the fuel filter. It "looked like the original" and was in a tough spot to reach. A quick search here yielded not only a good description of how to change it, but a post with step by step pictures! Wow. I gave my mechanic a quick description and he said "thanks, I was just thinking I might have to drop the gas tank to get to the filter."

After filter replacement, still no dice; same symptoms. Only this time, mechanic changed my APR ECU to "stock mode". It ran to redline. Back to "sport" mode, it would only go to 5k. Time to call APR.

I got Jeremy at APR on the phone and described the problems, how long I had the car and the chip, etc. After a little typing he said that it sounded like the symptoms of a bad MAF (Mass Air Flow sensor).

About two years ago, I had a similar low power problem, and the dealer eventually replaced the MAF and fixed the problem. At that time, APR again had told me that it was definitely the MAF. The dealer ship took four separate visits before they would replace the MAF. I offered to buy it outright, but I deemed it too expensive at ~$300 and kept taking it back until they replaced it under warranty. Score one for APR: They knew the problem in about 3 minutes of description, while the dealer needed four visits.

Knowing this, I asked Jeremy if there was any way to test the MAF, since it was so expensive. He said "sure, just unplug it. The computer will default to some baseline values for mass air flow. You'll get a check engine light, but you should have more power with it disconnected if the MAF is bad."

I had my mechanic do this and he was able to get to redline in both stock and sport modes. He also said it ran better (no stuttering) and had more power. All this with the MAF totally disconnected.

I bought a new MAF at the dealership and ran it down to him (it was late in the day, so they weren't doing any more deliveries). He test drove it while I returned my rental car.

When I got back to the repair shop, he looked up at me and said "That is a different car. I almost got a speeding ticket test driving it." <Grin>

I paid him (GOD Audi parts are expensive!) and drove out of the parking lot. I got to about 2k RPMs and pressed down the gas to go "a little faster". "Holy ****!", was all I could say as it screamed towards redline. I shifted just before 7200 and said "holy ****!" again, as I rocketed up to 7200 again and shifted. This was definitely a different car!

I've now had the car back for a few days and have gotten more used to the power, so it doesn't seem as dramatic as the first two days. That being said, I think the car now has more power than it ever did. I say this because I installed the chip at about 40k miles; at that time the fuel filter had to be somewhat clogged and limiting the total power. My butt dyno says it is faster, so I'm happy.

I think I'll pull out the G-Tech Competition this weekend and do some 0-60 runs. About 10 months ago I was able to get a few runs to 60 in 5.3 seconds. If the car really is faster now, I should be able to clip of a tenth of a second or so. Wish me luck.

I know this for sure: I am one happy S4 owner again, thanks to audiworld and APR.

Thanks guys.

Brian.

TurgutS4

What mods do you have? Just wondering if we have similar setups.

Milpitas2.7T

Very nice write up. Good to see the positives vs all the negatives on this list

mpwolf

and didn't know it. I can just think of all the full throttle runs that were leaking boost. :-\

SLPR S4

Hey TURGUTS4!!!

I just bought a mint condition 2000 S4 (20k miles).

Going to get the APR 1.0 bar chip, bi-pipe, new BOV's installed.

Is the snub mount worth it???

What is the V1?

Thanks a ton!!!

Patrick

Esse Quattro

...causing premature turbo failure. I'm hoping I did no long term damage, but I guess we'll have to see. I *do* notice that I don't hear the turbos whining when the car is cold any more. I had been hearing them more and more over the past few months.

Brian.

Esse Quattro

For performance, I've only got the APR stage one ECU. I have "upgraded" tires, but I suspect pretty much everyone ditches the regular Potenzas that come on the car. I've been using Potenza Pole Positions for the last 50 to 60k miles. I just got my third set installed today, the S03s. I'm axious to see how they ride on the way home.

Otherwise, I've also got a Valentine V1 and love it. I've been thinking about doing exhaust and maybe coilovers, but I haven't made any decisions.

Brian.

S4Patrick

Darn MAF sensors...would you happen to have the link to the fuel filter changeout instructions?

Esse Quattro

Complete with pictures:

https://forums.audiworld.com/s4/msgs/722730.phtml

S4Patrick

some after-market ones such as the Forge or Bailey ones....or as others may suggest, get the TT ones......

Best regards,


Patrick