[Mk2] [Turbo] Running lean in 5th gear??

[MikeMr2]

Hi guys,

i've got a Rev2 with a CT20B mounted with a big Walbro fuelpump, Berk downpipe 3" and a Blitz Nur spec exhaust, standard ECU and standard 440cc injectors..
the car is now running since 2 days, but after putting a wideband sensor on the Berk we've seen something weird.

On idle it seems a nice 14.70 afr, on full throttle 11.50/12.00 so that seems ok i guess.
But when driving in the 5th gear at a speed of about 80miles/hour and than at full throttle, the AFR will have a reading of 16.00 or higher!!
i guess that can damage the engine..

I would love to know if someone knows more about this issue..!
Thank you very much.

[planted1]

injectors maxed out?

[Peter Gidden]

But when driving in the 5th gear at a speed of about 80miles/hour and than at full throttle, the AFR will have a reading of 16.00 or higher!!

What boost?

[alanmr2turbo]

ooops

[Peter Gidden]

A thought: wideband sensors don't like extreme heat which is why they're normally mounted in the bottom of the downpipe - to give time for the exhaust gases to cool by 100 degrees or so.

Is yours in the top of the downpipe by any chance?

I remember a customer having a similar problem - wideband leaned off on WOT. We moved the sensor to the bottom of the downpipe.

[MikeMr2]

The wideband is placed in the Berk, and the turbo is at 0.9bar stock boost.

[Peter Gidden]

The wideband is placed in the Berk.

Top or bottom of downpipe?

[MikeMr2]

Will have to ask my mechanic, sorry don't know yet. I thought there was only one place for it.. but the engine is also shocking a bit when throttle in 5th gear..Doesn't look like a wrong reading to me yet

[Peter Gidden]

but the engine is also shocking a bit when throttle in 5th gear..

Aaaaggghhhh!!! Makes it a lot easier to assist wihen all the important facts are revealed upfront

Cure the "shocking" whatever that is, and it's quite possible the wideband values will correct themselves.

[MikeMr2]

'Cure the "shocking" whatever that is, and it's quite possible the wideband values will correct themselves'

Well that's easy to say mate, that's why i posted this thread. Thanks but that won't help me curing a lean/shocking engine.
The problem is that i only hear things from my mechanic, the car is not at my disposal at the moment and therefor sorry if i can't provide any detailed info directly.
I do my best to be as clear as posible.

Any help i really appreciate a lot!

[ashley]

Any help i really appreciate a lot!

Get a better mechanic??

[toxo]

Mike is in The Netherlands so his technical English might not be that great... I guess shocking could be knocking?

[2mad]

If its not your wideband at fault, I have had similar problems with running lean over the last few months.

The first time was an air metering problem, so well worth checking your air flow meter is not fauly and hoses for leaks.

Second time my fuel pump relay was swithing back to 9v mode under load dropping my fuel pressure from 4.1 bar to 3.1 bar.

Third time was my ecu, there are 2 brown H9325 capasitors in the ecu and both had leaked and the electrolytes had eaten into the circuit board.


Hope its nothing to serious, best of luck sorting it

Kev.

[MikeMr2]

Thanks Kev! Will pass the tips&tricks through

[2mad]

No worries
I should really of added fuel pressue to the list of things to check even though mines been ok so far .
At idle mine sits around 2.1bar, at 0 on my boost gauge fuel pressures around 3bar and full boost 0.95bar fuel pressues 4.1bar.

If you dont have any way of monitoring fuel pressure it may be worh checking the vacuum hose going to the fuel pressure regulator.

Kev.

Edit. . If its the same as this BERK Technology downpipe the wideband bungs at the bottom http://www.japspeed.com/index.php?page=product&info=535 . . looks a nice bit of kit, I want one of these now

[MikeMr2]

Thanks mate, but no, i have the Ceramic version with Wideband, a bit more expensive i believe but it's superb quality mate! I really advice him.

[MikeMr2]

Btw, problem solved! Appears the ignition timing was bad

[2mad]

Glad it's sorted Mike