Boost issue

[scott_s4]

Hello,, i have just bought an s4 b5, seemed to be running fine, it had developed a problem with previous owner, he put it on Vagcom and it showed a faulty n75 and oxygen sensors, aparently he replaced them but never reset codes, now the car has a problem again,,it seems to boost fine in lower gears, eg hard accelaration in 1st/2nd gear but once in higher gears with more load it seems to die,,just seems to stop boosting?
im totally lost due to this being first audi,,and being more used to old fords!

any help/advice would be greatly appreciated!

[HEKTOR]

Do you have access to Vag Com?

Once it dies does it recover and go back to normal quickly or does it stay flat with no boost?

If you have Vag Com then check for codes, clear them and see if they come back.

I am thinking its going into limp mode. If so then it should have codes for you to see.

[scott_s4]

hello, no i dont have acces to Vag Com which is a downer!

no it dosent recover,well not if i was to try keep going,, just seems to hit a wall and thats it,

but as i said when in low gears and accelerate hard it seems to be fine then hits a "wall", but if i was to stop again and accelerate hard again it would seem fine low down,, should there be any lights on dash that would indicate limp mode?

[HEKTOR]

You will have to have the car scanned by someone who has Vag Com, or if you have the funds buy the genuine ross-tech cable and download the program from ross-tech.

It seems like limp mode to me. It could be a whole hose of things, MAF, EGT's, boost leak causing problems etc etc

I have never had any light on the dash when my rs4 went into limp mode, just no boost. I think its something like 7psi. You certainly know the car is in limp mode.

My suggestion is definetly get Vag Com and then take things from there. Shame you are not in glasgow.

[scott_s4]

yea getting it scanned seems like the way to go!

was going to ask where i could download software so cheers for the info!

but looking at ross techs site im unsure of which VCDS software package i should get also which cable?....complete newbie

[grizz]

Get a pressure test done ....

Get a hex can lead ...The best ££ you'll ever spend ..

[scott_s4]

yea im goning to try and get a pressure test done today,

is there any common leak areas? pipes which are common to split etc?

and also hex-can is the lead im going to get i think, but still unsure of what software to get!

cheers for replys guys, seems like a helpful site!!

[HEKTOR]

download the software from the ross-tech site.

On the s4 the throttle body boot split so worth checking that.

No worries fella

[scott_s4]

well,, purchased a pressure tester kit, fitted it and it was instantly worth it, almost as quick as i could put air in it was leaking out very quickly from what sounded beneath/behind inlet,

spent ages trying to find a split hose with no avail, also due to having no previous experiance with this engine i was running on minimal knowledge so i presumed taking inlet off would let me see more clearly,,didnt enjoy taking it off to much (far to much pipes and plugs for me)

started testing the small hoses at back with airline,, took a hose off of what i belive is a boost control solenoid which splits on a y-piece then heads to turbo actuators, drivers side actuator funtioning fine,passenger side is dead! air is massivly leaking from where the rod comes out of rear of actuator,

now its time to attempt to change actuator with engine in situ? is it possible?

[HEKTOR]

Give Johnny at jjb motors, grizz at unit 20, doug at mrc a call, they will be able to help you alot better than anyone else.

[scott_s4]

Hello hektor,,
yea mate thinking thats what im going to do,, once ive fitted new actuator and sorted out boost prob itll prob be going to mrc for a check and a remap!

[HEKTOR]

Sorry i couldnt help you more. Last thing i want to do is give you wrong advice.

MRC will sort you out not problem. I have a funny feeling you will want k04's soon

[scott_s4]

Thats cool mate, youve been more than helpful,
i had a look at actuator, should be able to change it with not to many issues! (hopefully)

Haha yea i can see ko4s in the near future, trying to source some rs4 intercoolers just now, but not having much luck!

[HEKTOR]

Happy to help mate, drop me a line anytime.

try jimbo on here for the intercoolers. He is breaking an rs4 soon and may still have the intercoolers. If you cant get hold of him let me know and i will fire him a text and get him to message you.

K04's will make a huge difference to your car and you will love them. With the right mods you will clear 450bhp no problem. Well worth going the extra mile and getting a few special parts like 3"dp's, etc

[scott_s4]

Will do mate!
Ahh i saw an rs4 on ebay being broken, email addy was jimbo123.. I mailed him but no reply,
Maybe i typed the address incorrectly!

And yea, ive got 3" down pipes but look cheap, but will prob get milltek ones to match rest of system