You can change the style the forum displays by selecting your preferred style at the bottom left of the site.
We have made an enhancement so that old threads should now link from search results to the correct thread. This is not yet in place for single post links
Hi guys! I've had an ongoing problem with my S4 for some time now. Started with what I thought was a missfire but now believe may be overboost protection. I've recently replaced the Lambda and Altitude corrector as well as the leaking intercooler but have now noticed that the max boost pressure is down according to the digital reading on the dash. I made up a pressure test kit including bungs for the throttle hose (AAN engine) and oil breather but when I tried testing it I seemed to lose pressure almost as fast as I could pump it in. I could hear air escaping from somewhere around the turbo but couldn't feel anything with my hand. The turbo also appears to be whistling more than it used to, so could the problem be that this is on it's way out, or is it more likely a hose. Think I may need a trip to Yeovil to finally get this ******* car sorted!! Are you reading this Tom?
'93 S4 Avant now back on the road complete with new shiny go faster bits.
sounds like you have a big leak somewhere if you can here the air rushing out and it doesn't hold any relative pressure....whats the max it will retain?
I have quite a noisy turbo, especially on hard spool ups but its been doing it for over a year and no major issues/smoke/pulls like a train so noise may point to some wear but hopefully nothing too problematic.
No it hardly holds any pressure at all. I got it up to around 10psi at one stage but that took some time and it disappeared extremely quickly! When driving I can get a spike of around 1.2bar but it drops down to a max of 0.9-1bar immediately. I have an MRC remap by the way so should see around 1.3-1.4 max. I was just concerned that it may be possible for the air to escape through the turbo somewhere as I couldn't feel air escaping but it looks as if I maybe just need a bit more investigation!
'93 S4 Avant now back on the road complete with new shiny go faster bits.
Yep, that's where I was trying to inflate the system from and I blocked the small hose from this to the rocker cover as well as the hose at the inlet manifold. I may well have done something else wrong so I'm probably better off leaving it to the experts!
'93 S4 Avant now back on the road complete with new shiny go faster bits.
someone like Paul N, Tom or a load of the others who have traced boostleaks this way shouldgive you som egood pointers once they log in, most of mine have been through 1 split pipe and then air bleeding off via jubilee clips which work loose.
To be honest if you can here it then it shouldn't be too difficult to spot with a bit of help, the worst ones are those which linger on with no audible/visible signs of a problem.
We process personal data about users of our site, through the use of cookies and other technologies, to deliver our services, personalize advertising, and to analyze site activity. We may share certain information about our users with our advertising and analytics partners. For additional details, refer to our Privacy Policy.
By clicking "I AGREE" below, you agree to our Privacy Policy and our personal data processing and cookie practices as described therein. You also acknowledge that this forum may be hosted outside your country and you consent to the collection, storage, and processing of your data in the country where this forum is hosted.
Hi guys! I've had an ongoing problem with my S4 for some time now. Started with what I thought was a missfire but now believe may be overboost protection. I've recently replaced the Lambda and Altitude corrector as well as the leaking intercooler but have now noticed that the max boost pressure is down according to the digital reading on the dash. I made up a pressure test kit including bungs for the throttle hose (AAN engine) and oil breather but when I tried testing it I seemed to lose pressure almost as fast as I could pump it in. I could hear air escaping from somewhere around the turbo but couldn't feel anything with my hand. The turbo also appears to be whistling more than it used to, so could the problem be that this is on it's way out, or is it more likely a hose. Think I may need a trip to Yeovil to finally get this ******* car sorted!! Are you reading this Tom? 
Comment