Can someone explain my dyno results? PICS

**blue_reality** · 01-04-2009, 03:07 PM

I've got a MK4 GTI with a full 2.5" turbo back exhaust, a POD filter and a GFB Hybrid DV Valve (made for the MK4 GTI)

There are no engine mods, so really other than the exhaust and pod its all stock.

Car is always serviced and in good condition - never had any problems with it.

I recently did a chip trial and then dyno'd the car. I did not dyno the car before the retune, though it would have been a good idea.

The car only got 99.6kw (in 3rd gear) and the the Air/Fuel is around 10.6. Boost drops steadily from 12.6 all the way down to 5psi. The guy doing the dyno said that the boost curve didn't look 'right'.

I sent these results to the chip manufacturer and they got back to me and said that the lack of boost is because of the after market blow off valve, even though the valve I'm using is a hybrid system and has no leaks.

Does anyone have any ideas as to why these are the results I'm getting?

(I've attached 2 pics of the dyno results)

Thanks guys.

*EDIT - since been resolved. Page 3 of this post has info*

**velly_16v_cab** · 01-04-2009, 03:43 PM

why does the graph start at 4k????

what sort of result was you looking for?

how does the car drive? does it feel better?
I am asking that because i have a mate with a 2.1 8v mk1 and it NEVER performs on a rolling road but when you drive the car it is silly quick.

**Guy_H** · 01-04-2009, 03:57 PM

Do a stock dyno run & overlay the graphs.

Depending on dyno setup, maybe its a massive gain over stock, or it could also be a massive loss over stock.

**Jarred** · 01-04-2009, 04:15 PM

AF ratio seems a little off to me.... anyone else?

**D3bb4** · 01-04-2009, 11:49 PM

Running lean to me. AFR should be 12 or even a little more for safety. Especially with that little boost, that's messed up.

Maybe whoever did the chip is tryina say that the spring in the BOV is so weak it's opening when it shouldnt? Would be a stupid thing to say though....
I'd stick the stock BOV back on it, do it again, then ask them for some answers...

**blue_reality** · 02-04-2009, 06:42 AM

Originally Posted by D3bb4

Running lean to me. AFR should be 12 or even a little more for safety. Especially with that little boost, that's messed up.

Maybe whoever did the chip is tryina say that the spring in the BOV is so weak it's opening when it shouldnt? Would be a stupid thing to say though....
I'd stick the stock BOV back on it, do it again, then ask them for some answers...

That's exactly what they are saying - but while on the dyno we checked for leaks and also wound the spring up on the BOV so it was only releasing on a very high load.

The chip is one of the big brands and they are confident that it is not their tune as they have done it to heaps of cars. So could there be any other options?

**Jmac** · 02-04-2009, 08:03 AM

Originally Posted by D3bb4

Running lean to me. AFR should be 12 or even a little more for safety. Especially with that little boost, that's messed up.

Maybe whoever did the chip is tryina say that the spring in the BOV is so weak it's opening when it shouldnt? Would be a stupid thing to say though....
I'd stick the stock BOV back on it, do it again, then ask them for some answers...

Think you might be getting a bit mixed up there, 10.6 is richer than 12 mate, head towards Stoich 14.7 and you are lean.
Jmac

**Nafen** · 10-04-2009, 02:53 PM

Have a search of all the dyno sheets round this forum and others, you will see the same thing, they all bleed back boost as the rpm climbs as the pissy little turbo cant keep up.
The AFR's on the other hand as mentioned are more of a concern.

**blue_reality** · 24-04-2009, 08:49 PM

Fixed! Took the car back to Peak who did the original tune and this is what they did:

Replaced leaking hose on the manifold.
Changed blow off valve to an S3 DV Valve
Re-aligned throttle body (had a fault code coming up)
Remapped the revo tune.

One, some, or all of the above could have been the culprit but the car is now feeling amazing.

Pulling hard all the way through the rev range and getting 16psi.

Gotta say a big thanks to Peak Performance because when I wasn't entirely happy with how it turned out they took the car in and spent a considerable amount of time (days!) testing, and trying different options to get the car running right again.

I filmed the whole process and will be uploading a video to the mightycarmods site in the next few days outlining how the tune is done and the dyno run afterwards.

It's good to know everything is working properly as it should and now I can putt to work in the 60 zones knowing that the power that I can't actually realistically (or legally) use is there.

**bujna** · 24-04-2009, 11:51 PM

That's good to hear mate. I got my flash done at peak too.

Could you post your latest dyno graphs? It would be interesting to see where the graphs differ...

I just installed my boost gauge tonight. I'm getting ~16 psi after a quick test, but i'll have to do some more testing tomorrow and see when it drops off...

I'm waiting for a stronger (yellow) DV Spring + the n75 Race valve which i should get on Monday (They got to Sydney yesterday...sigh)...then i'll be ready to jump on the dyno again too.