MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: jakex181 on May 29, 2015, 04:20:20 pm

Title: vcds vacuum leak help
Post by: jakex181 on May 29, 2015, 04:20:20 pm
Have done some testing today using VCDS, here is what i have found:

I first cleared fault codes, and set vcds to measure blocks 32 and 33, i then started the engine.

After about a minute of nothing happening the values begin to change, block 33 (lambda control) shoots up to 27% and then steadily reduces as block 33 (Lambda regulation) increases until eventually block 33 is at 0.8% and block 32 is at 4.5%. Im guessing this means i have a vacuum leak somewhere? What is the reason for the initially lag?
Title: Re: vcds vacuum leak help
Post by: pudding on May 29, 2015, 04:54:59 pm
Block 32 is the long term trims for idle and part throttle.   33 must be the live adjustment.   You need to look at 32 after say, a week's worth of driving.  Mine are 0.8% and 2% respectively.  4.5 is kinda high, but if you cleared it before the test, then the initial entries will be, hence it should be treated as a rolling average only.

Did you start it from cold, or hot?   The wideband lambda takes about 60 seconds to heat up, hence the lag.

A leaking brake servo is common on the MK5.  Any hissing noises from the pedal area, which goes when you press the brake pedal?
Title: Re: vcds vacuum leak help
Post by: jakex181 on May 29, 2015, 05:41:57 pm
SOLVED: it was the break servo feed

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fs21.postimg.org%2F5o6bqopeb%2FIMG_0046.jpg&hash=b8ea2962a0740c102cfa10868882b6ca45595925) (http://postimg.org/image/5o6bqopeb/)

split at both ends, i replaced it with some flexible rubber pipe as its all i had so will get an order the rigid vacuum pipe. Also tested again with VCDS and block 32 showed no fuel trims so no other leaks.
Title: Re: vcds vacuum leak help
Post by: da_ansa on June 28, 2015, 09:43:58 pm
SOLVED: it was the break servo feed

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fs21.postimg.org%2F5o6bqopeb%2FIMG_0046.jpg&hash=b8ea2962a0740c102cfa10868882b6ca45595925) (http://postimg.org/image/5o6bqopeb/)

split at both ends, i replaced it with some flexible rubber pipe as its all i had so will get an order the rigid vacuum pipe. Also tested again with VCDS and block 32 showed no fuel trims so no other leaks.

was it a hard job to change out the brake servo feed?