Strange power curve
Turbo Mini Forums

Alright chaps,

Haven’t been on here for a while because I mainly mess with minis of the BMW flavour nowadays.

Anyway I know there’s quite a few knowledgable people on here and just wanted to get some ideas for a strange problem I have.

I own a 2013 John Cooper Works (1.6 turbo). Car is fitted with a bigger Intercooler, decat downpipe and induction kit. Car has been flashed with a manic motorsport stage 2 map (bit like revo).

I can run 3 modes which can be changed through the OBD port with a switch module. Mode A B C.

The problem I have is the power curve is all over the place in the 2 higher boost modes.

Stock and mode A look ok and nice and smooth curves, but mode B and mode C are all over the place.

Car seems fine and has no codes showing, it did have a code logged in the history which was a valvetronic issue, but I never have had any check engine lights so not sure if that was under my ownership.

Any ideas what could be causing it would be great, I’m thinking it’s boost related because it only happens in higher boost modes. They run a diverter/recirc valve which I’m thinking might be leaking boost?

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That curve should just go fine not all wavy. only thing i can think it is, is the High pressure fuel pump isnt keeping up.

your not too far from Jason he runs millsys autos http://www.millsysautos.co.uk/

he'll know why.

I reckon its inaccurate rpm measurement and the software trying to draw a line through the points in the wrong place.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

theres a lot of potential reasons for this assuming its not a measurement error as paul suggests.

electric dumpvalve popping open/leaking.
knock being detected and subsequent retard and advance cycles
hpfp on the road out
wastegate getting blown open(back pressures pretty high on these as they sit IIRC)
tbo theres a lot going on with these engines you really need a full datalog of tge run with timing and pre and post hpfp fuel pressures, wg duty and a dump valve blanking kit.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

double post

Edited by evolotion on 5th Feb, 2018.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Will see if I can get the data logs from the run, I know they where recorded but I forgot to ask for them.

Tbh most of what’s been advised I have thought about, I know the diverter valves are a weak spot on them especially when mapped, but mine has the later revised engine and valve but that’s not to say it’s still faulty.

I never thought about a problem with the dyno due to the 2 previous runs being where they should be.

Here are the graphs showing intake pressure and airflow, AFR isn’t in graph form but after looking at the figures with the dyno operator, nothing seems out of place.

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those graphs make me think of this :

https://lh3.googleusercontent.com/-wSkcz2go...3e0d2b5b6_z.jpg

The Airflow on the higher maps is pretty funky looking. but I am not familiar with that particular dyno and what would normally be seen

Sorry, the data i'd like to see would be the ingition timing, and knock retard per cylinder if avaliable or knock events. boost controll duty would be good too, would show if the turbo is having to work in spits and bursts to keep the boost pressure level.

Edited by evolotion on 13th Feb, 2018.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Haha yeh it looks a bit mad, tbh I want to go on a different dyno anyway to see if the figures are any different so will ask for a full data log there.