click

Where did the 4000 rpm "jump to life" go ??????? Although I have read that many of you report that the torque kick is felt at around 3000 rpm, my engine has this occurring around 4000. It is now getting worse, in that often I do not feel a kick at all. The acceleration, albeit smooth, feels like a normally aspirated engine.

The car starts fine, idles and accelerates smoothly, but no "kick". The max. boost does get reached (.7) but it appears to reach this point much later in the acceleration curve than in the past. I am at around 5500 rpm when the .7 is reached.

In reading Andre's troubleshooting, he notes that the CBV can be the culprit. His driving "test" involves releasing the throttle once in 3rd gear 3-4000 rpm and a psssst should be heard. I don't hear this sound and so this is likely one possibility. BUT, I do not recall hearing such a sound in the past

Before I remove the CBV to test it by blowing through it, I thought I would find out if you guys actually hear such a "pssssst" (not doubting Andre for a second, just wondering whether this is a very audible sound).

Any alternate thoughts appreciated. Many thanks.

Nick

SonnyV

I have the all original exhaust system back on my car now and I don't remember hearing CBV sound when let go of the throttle. My CBV was replaced with a billet one a long time ago.

With a G pipe I am sure I did not hear it.

You might have a small boost leak. Your car should start pulling hard around 3500rpm. I don't have a lot of mechanical experience so I can't help much. Other guys will sure coming along soon. Good luck

Sonny

Francisco Martinez

No psst here either, our metering plate and air box mutes just about anything going on in there. If you hear an increasing hiss along with boost increase, then you have a boost leak, our don't hiss either like subarus...etc...not that there is anything wrong with thant.

click

thanks for your replys

this is what I was wondering ..... my Audi A4 hissed noticeably ... not quite as much as Subarus, though.

I will be checking the CBV tonight (manual blow test) since the weekend inspection of all lines and seals did not reveal any looseness or obvious leak causes.

cobalt

The CBV is very hard to hear in these cars. It is easy enough to remove and test. I recommend replacing it with a billet unit (picture with arrow) which don't have the same tendency to fail as the factory plastic ones.

The gauge on the dash only reads up to .7 even if you are using a 1 bar spring it will max out at .7. You might check your WG and verify you don't have a slight leak there. Here is an old chart of my boost as you can see you should be feeling power sooner than 4000 rpms. This is using both a stock and 1 bar spring. Stock boost for these cars vary between 3.3 and 3.6 motors but are still higher than .7 bar. now that I have redone my exhaust it comes on sooner.

Kevin

I recommend the new Bosch design.. The 710N. It is more durable and does have a major edge over the billet valves. Frequency in bypass. It is not sluggish due to the lack of a piston. The other issue with aluminum valves is leakage after install. The seals and valve seat must be cleaned to maintain the seal. I have been testing the 710N for three years at 1.6 bars.

cobalt

I have not had any issues with mine needing cleaning so far, but this new bosch unit sounds interesting. Any more info on it?

Kevin

Tony you can Google the Bosch 710N.. The Audi boys are pushing 2 bars with it.

I have "dumped" all my piston style valves in favor of the 710N.

Francisco Martinez

Found this on the 710N

http://exaltmotorsports.com/i-154053...t-engines.html

My aluminum one is leaking by a simple blow test, but I have to admit, I ordered a cheap one out of ebay, got what I paid for. I think I am going to go with the 710N, it is not the first time I hear about this one.

click

Excellent comments, thankyou. I did the blow test and there did not appear to be any leakage. So in the end I took of all lines and intercooler to ensure all were crackless, etc. and replaced ...... VOILA ..... everything back to normal! Whether it was a poorly mounted intercooler or loose hose, who knows , but I got the KICK back Thanks again for the comments.

Motilev

I order two 710 for me and my fried. Will try it in 10 days.