New DVs

[toasty]

Good luck with the Bosch ones Ian.

They certainly look and feel better made than the older ones. [img]images/graemlins/clap.gif[/img] [img]images/graemlins/clap.gif[/img] [img]images/graemlins/clap.gif[/img]

Which way around are you going to mount them? I was forced due to the length of the vacuum pipes to go for normal orientation, but would have liked to tried the other way.

-Dan

[Joshie]

I'll probably have to mount the with the vaccuum pipe horizontal - I once mounted the forge ones with the vacuum pipe vertical but I could't get the "S4 biturbo" cover with back in place.

[Joules]

Hi Ian /Dan...

Are the OEM Bosch revised and improved DV's over early items?? I was going to try the Forge units but lag question marks have made me think twice??

Joules

[toasty]

I wish I had bought three now and I could have broken the spare open to compare.

...does seem like a waste of £20 though.

I'm told there are improved, and since all of the failures of the early ones seemed to be the diaphram then I assume they've thickened/strengthened these, but I don't know.

I have broken open the damaged one that I removed from my car, the part # was 034 145 710A the ones I replaced them with were #034 145 710B

If anyone has dismantled a B then I'd be happy to compare it with my A.

Cheers
-Dan

[Golich]

Now that's interesting Joshie.

Your experience is identical to mine. I have felt the no boost problem 3 times over the last 6 months just for approx. a min or less. The last time I pumped the throtle and this brought back the boost. What perplexed me was the fact that there was no error codes recorded when I checked my VAGCOM.

My hyperboost DVs went on the car last Nov.

[Joshie]

Yes, I don't get error messages either. I'm looking forward to seeing if the Bosch DV's solve the problem.

Regarding the conditions required to generate the no boost situation I find that at about 70MPH in forth lifting off the throttle and then flooring it and repeating a couple of times gets the no boost response. Gently applying the throttle brings the boost back on. Strange but I am convinecd that the DV's are the problem. We'll see.

[Golich]

I can't remember correctly. But that sounds kind of similar to me. Although once was from the exit of a roundabout. But a couple of times have been while driving at a constant speed probably around 70-80mph then upon accelerating no boost. Hhmm there's an article in DV's in this months Audi driver. I've still to read it. Plus Audi world has a technical article on how to test if these things are sealing correctly.

I had my car on the rolling road at Star performance approx. a month after AMD did the chip work. It was down on boost. Jim at Star tried a number of things i.e. new MAF, solenoid that operates something boost related? And a check around the major components.

On hooking up his VAG tool he noted a low charge pressure error code. But one of the THB hoses had come off earlier in the month, which I replaced.

However, during the rolling road test his VAG tool was telling him the car was requesting boost and not receiving.

He thought it might be collapsed baffles in the centre box as he's seen this before. Strangely enough I do have an odd reverberation from the stock exhaust at certain revs.

The really strange thing was when I left his place the car has fine with the odd exception as we've talked about.

I still have my old Bosh DV's. They were only 7months old. Think I'll give them a try this weekend and try monitoring the boost pressure delivered and requested with VAG com. That’s assuming I can do this.

[Nige_RS4]

Joshie, this is quite common on chipped S4's and referred to as the "3/4 throttle problem" here on AW. Some owners believe it to be due to a boost leak, others swear by this mod. I used to suffer from it, adjusted my N75, banished it completely - wierd [img]images/graemlins/confused.gif[/img]

Nige.

[Joshie]

Golich - when it does occur I get the fault code 17963 - Charge Pressure Upper Limit Exceeded. I fitted the Bosch DV's and this very much improved the situation. Since then Forge Motorsport, who set the benchmark for outstanding customer service, has sent me brand new updated DV's even theough they said that they tested the originals and found them to be OK.

I'd love to get to the bottom if this though.

[Joshie]

Nige - can you explain whet you did to the N75 solenoid exactly? Seems we may be onto something here. [img]images/graemlins/laugh.gif[/img]

[Nige_RS4]

Joshie, sounds like yopu are going into 'limp' mode - had a boost gauge on it? Anyway, after a lot of research on AW, I found out that by adjusting the valve in small amounts(do not turn it more than 1/4 of a full turn in any event)the way the car delivers boost changes. Non-APR chip owners (ABT, MTM) usually turn clockwise to resolve boost spikes (causing surging and limp mode problems).Here is a link to an article on AudiWorld..

Nige.

[Joshie]

I'm just about to read the article. Can you tell me where is the solenoid located within the engine bay and what it looks like?

[Golich]

What exactly is this N75 thingy. I searched the Audiworld site and came up with 1853 hits. I'll be there all night at this rate.

[Nige_RS4]

Joshie, Golich ... et al

Here is an excellent on the subject of the N75 valve posted on AudiWorld.

Enjoy [img]images/graemlins/sleeping_2.gif[/img]

[Nige_RS4]

One more thing ... there is a school that says don't touch the N75 valve, but adjusting it worked for me - no more surging or limp mode since then. Had a boost gauge fitted for a few months to watch what was going on. Noticed that on wet/cold days it would go into limp mode on WOT. Had to come of the loud pedal and go back on slowly to get rid of it. Suspected that the boost was peaking past the upper limit (think it's 1.5bar). Boost would then drop down to 8 psi (on APR chip mode, 5 psi on std mode). Suggest you get a gauge on it or better still log what is going on with a VAG-COM (log block 115).
Nige.