RS246.com Forum :: The World's #1 Audi R, S and RS Enthusiast Community

Hi guys. I'm new to the forum and thought i'd ask your opinions on a possible boost problem.
I've had a '98 S4 saloon for 6 months now but it just seems to be lacking in power a bit. I understand the tbb is a potential weak point. Is there anything else I should look for while i'm checking this out?

Cheers

Check your DVs as well, I had these replaced the other day and it pretty much transformed the car. I got more miles out of a full tank and the car was much more responsive.

You can replace the DV with the new uprated Bosch ones (N revision) found in the TT, they seem to be much better than the stock ones. I changed mine for piston based one supplied by AMD, may not be as responsive but may be slightly more reliable.

Matt, I've got a new improved TBB plus clips and used but working DV for sale.

You can have both delivered for £12 if you fancy (see my post in the for sale section)

Sounds like that would sort your problem, and you do usually find that one DV fails not both as once one goes the other looses vacuum and so doesn't operate anyway.

Cheers for your comments guys. Car's gonna have to wait for now, off to Norway for a month with work. I'll check these things out when I get back.

Matt,

Where do you live? I live in Aberdeen but frequently visit my folks up in Balitore/Nigg Ross-shire. I could have a quick look and a drive of your car to see if it's anything like the number of flat experiences I had with my last S4. Torn TTB, faulty exhaust temp probes, faulty DV. I also have VAGCOM. However a torn DV/TBB doesn't always register a DTC however you can log the boost to see what the ECU is requesting and actually getting.

Check your air mass meter also G70, this wont bring the check lamp on and should store fault in memory of bank 1 bank 2 lean mixture. You will kill the turbos if you dont sort it soon.
Look in mvb and make sure on full chat it reads over 200g/s for a short while. less than 150 it needs sorting. Dont get any probs with the hitachi type. Bosch ones are crap on even the new stuff. Hey 8P or new A3 has ditched the mass meter.

Morpheus,

Is there a Hitachi direct replacement for the S4 MAF? If so do you know the p/n?

Lately my car has also started to show signs of not much 'stick' , the car feels like its boosting but it also feels like the boost isnt going into the engine! It makes alot of sound but doesnt give me that kick in the arse it used to! i have also fitted 18" rstt alloys since then..

Im going to get my Throttle body, DV and Maf looked at by Audi tomorrow to see if there are any issues here...

Annoying

I thought the pinouts were different ?? Click this link to my gallery for pinouts.... http://www.rs246.com/modules.php?op=mod ... t=0&pos=22

I think the Hitachi was for late 01 US cars, which means Morpheous must be US-based??

Nige.

Well according to that, mine should be a Hitachi as it was built Q2 2001. I'll check.

I don't think Morpheus is a Yank - he seems too clever to be...

I havnt looked into converting mine so would need to research it some more. Dont forget the 2.7 biturbo engine is still in production for the Allroad and A6, although with different power and torque maps. Cant remember any of the new stuff (with these engines) having a Bosch Mass meter.

ECStuning US recomend changing to the Hitachi MAF in their KO4 turbo upgrade kit so it must be possible to convert the Bosch to the Hitachi. As I recall they don't mention any wiring issues...

Would suggest VAGparts as they seem very knowlegable in all things Audi(and cheap).

Got around to checking my MAF. It is a Hitachi part number AFH75-01A. The VAG part is 06C 133 471A.

OK, just checked ETKA out for this MAF info and Dippy's MAF part number appears on the main MAF diagram for chassis range 8D-1-000-001 onwards - whereas the Bosch unit was fitted up to chassis range 8D-Y-300-000 (earlier models than this!) so I bet Dippy's VIN number falls within the later 8D-1-000-001 onwards range.

As you can see from the diagram below, I think the Hitachi MAF will fit MY2000 model cars as long as you fit the associated parts (those being the replaced spring clip and hose - signified again by the 8D-1-000-001 onwards range on the diagram)

Hope this helps.

Actually, mine is 8D-Z-3*****. But then it is a personal import so maybe that explains the difference.