MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: MattC on April 19, 2022, 07:49:15 pm

Title: Slight boost leak?
Post by: MattC on April 19, 2022, 07:49:15 pm

Getting my car tuned tomorrow, thought it would be smart to check for boost leaks the day before. :laugh:

To my eye, it looks like I have a slight boost leak because the actual never meets the specified.
Also not sure how accurate OBDEleven is with it's reading here as the boost pressure looks way too high for stock (I think my car is stock, no evidence of remap).

NOTE: Data recorded with OBDEleven and I have converted mBar to psi myself.
(https://i.imgur.com/5FigBWY.png)
Near the end where the actual is over the specified, could that indicate a sticking DV?

Thanks!

Title: Re: Slight boost leak?
Post by: breeze on April 19, 2022, 08:53:37 pm

You probably need to subtract atmospheric pressure before converting to PSI.

Title: Re: Slight boost leak?
Post by: MattC on April 19, 2022, 09:43:26 pm

Quote from: breeze on April 19, 2022, 08:53:37 pm

You probably need to subtract atmospheric pressure before converting to PSI.

Ah, thanks.

(https://i.imgur.com/JjVV8PA.png)

So definitely looks like I have a boost leak, peaking at ~6.81PSI.

Wouldn't this trigger a code? Car doesn't feel slow, feels the same as it did when I bought it and faster than my Dad's Clubman S.

Title: Re: Slight boost leak?
Post by: mjmallia on April 20, 2022, 08:39:46 am

Check the obvious ones like a split DV (replacement needed), lots of oil leaking from the intercooler joints (new seals) and general condition of hoses etc.

Title: Re: Slight boost leak?
Post by: pudding on April 20, 2022, 11:01:03 am

Yes, ~7psi peak and actual never meeting requested should throw an under boost fault code.....although I don't know how many times that needs to happen before the ECU flags it.

As good as scan tools are, sometimes you can't beat proper analogue gauges.  I've thought about getting the OEM half DIN radio panel and sticking boost and oil pressure gauges in it.  The two essentials for old GTIs!

Title: Re: Slight boost leak?
Post by: MattC on April 20, 2022, 11:08:41 am

It was a torn DV, Stealth racing had a revision D spare that I've bought. I would have replaced myself had I tested earlier!

Graph from changing DV:
(https://i.imgur.com/cwaEwxS.jpeg)
Gained 28hp already. :pomppomp:

Title: Re: Slight boost leak?
Post by: breeze on April 20, 2022, 12:20:42 pm

Glad you got it sorted.

What is the full spec of the car? Do share the after dyno when you get it. I had a car tuned by Vince at Stealth 20 years ago.  :smiley:

Title: Re: Slight boost leak?
Post by: pudding on April 20, 2022, 01:22:42 pm

I've been going there since 2000 :smiley: