Running lean at 5000rpm - FIXED!

AFR's are all good low 11's on boost until I hit about 5000rpm then it just leans out to 17's??

Was thinking fuel pump voltage drop at that point?

Any other ideas before I start checking for problems?

I was going to say fuel pressure. You on standard Reg ?

johnny gtir wrote:I was going to say fuel pressure. You on standard Reg ?

Yes mate still standard reg, got a spare so may swap it over as well.

Cheers

Spark plug spike wrote:AFR's are all good low 11's on boost until I hit about 5000rpm then it just leans out to 17's??

Was thinking fuel pump voltage drop at that point?

Any other ideas before I start checking for problems?

Hey Spike, how do you check afr?
Do you need specialist kit?

Yeah you need a wideband lambda sensor like a AEM wideband or innovate :-) might be worth you getting one

Well thought I would try the easy options first without removing the top mount.

Firstly hard wired from the fuel pump to a multi meter in the front took it to 5000rpm the AFR's dropped to 17's but the voltage didn't drop at all hmmm.

So went back to the garage removed the dump valve and same again AFR's dropped to 17's again over 5000rpm.

So looks like it's time to start checking the fuel reg, any way to test it or do I just change it over to a spare one check the AFR's?

Cosmic73 wrote:

Spark plug spike wrote:AFR's are all good low 11's on boost until I hit about 5000rpm then it just leans out to 17's??

Was thinking fuel pump voltage drop at that point?

Any other ideas before I start checking for problems?

Hey Spike, how do you check afr?
Do you need specialist kit?

As Tom says I use an AEM UEGO wideband which logs the AFR's through the Nistune software, there's a thread in the ECU forum with all the details how to set it all up if that interests you?

For what ill be pushing it wont be worth the trouble, approx 300 target.
I'm making arrangements to have the R passed under Bobs nose now,
Thanks for your reply anyhow,

When did you last change the fuel filter?

During the engine rebuild only a few months ago mate,

pulsarmoley wrote:When did you last change the fuel filter?

Changed it for a new one today still running lean

Does it just run lean? No loss of power or miss fires etc? Could it be drawing air in from somewhere? A split in a pipe perhaps?

PartyPete wrote:Does it just run lean? No loss of power or miss fires etc? Could it be drawing air in from somewhere? A split in a pipe perhaps?

Yes mate hits 5000rpm and the wideband goes straight to lean, took it on the motorway and slowly took it up to 5000rpm in 5th and the same happened, no misfire or loss of boost/power but didn't take it any further as it was leaning out.

Going to remove the top mount and strip the plenum off and check all the hoses for any obvious issues, then go from there

Could you try going back to the stock map and boost and just checking if its not your apexi? dont see why it would be put can you pull the power on it and see if it makes any difference.

shroom wrote:Could you try going back to the stock map and boost and just checking if its not your apexi? dont see why it would be put can you pull the power on it and see if it makes any difference.

Turned the boost down to 0.7 and still the same symptoms?

Was thinking it may be the Apexi so if the basic checks don't reveal anything I will return it all back to stock and go from there.

Was hoping it would be any easy fix, but nothing ever is with a R is it

Sorted, it was the gasket from the turbo to air pipe that was leaking.

Decided to put the freshly painted rocker cover and polished intercooler shroud on.

Glad it's sorted and looks fresh with those on

johnny gtir wrote:Glad it's sorted and looks fresh with those on

Cheers mate, just done a 4th gear run and fuelling is spot on from low 11's to mid 11's.