Flea i think your wrong.

When it comes on boost it asks for more fuel pressure which should increase the fuelling to match the increase in boost. Bear in mind by redline rick is fuelling correctly, when the boost is less than 12psi. Whereas most people are worried about fuelling at redline.

Bear in mind i run the gtech2 and have no probem with fuellng what so ever. In fact i have too much at some points. So how can the same map, show totally different results on the rollers, without something else showing an effect?

Ross

Because your car is completely different!!!! Two cars with an identical spec dont fuel the same - this has been proven countless times.

Most people are worried about the fuelling at the redline as it's at the top of the rev range that the engine is most likely to pop if there's a lean spot! The demand for fuel at the top end is going to be higher with an uprated turbo than the standard one - but I very much doubt that the demand for fuel is higher at 3,000 rpm than 6,500 on the standard turbo.

Ross, the fuel pump is not metering the fuel like the injectors it's simply pumping the fuel as required. If the injectors are drawing more fuel than the pump can provide then you have a problem. While the boost pressure may be less at the top end, as the turbo becomes less efficient, this is a product of the greater air volume flowing at higher rpms i.e. it starts to choke. A greater flow of air needs to be compensated with more fuel therefore the pump is under much greater load to meet this demand. In Ricks case the fueling is fine at the top end where it is flowing the most air and therefore requires the most fuel.

In answer to your question Rick, I would ask Graham about a higher fueling chip. The original G-Tec 2 that I tested ran lean coming on boost but it was fine elsewhere. Graham developed a higher fueling chip which sorted the lean spot although I did have to trim the fuel at the top end via the Unichip. You could try an adjustable fuel reg which may just iron out the lean spot albeit with a slightly richer top end which isn't too bad. Alternatively get a live map or Unichip for custom fueling.

I think you would benefit greatly from a custom map Rick, my unichip found me an extra 20bhp, a shed load more torque and more importantly, safe fueling right through the revs.

I had a near identical spec to rickbull when i first got the car, and never had a problem with midrange fuelling from gtech2 chip.

I understand what your saying Flea, but something has to be responsible for the lean spot midrange.

Ross

No two cars are the same Ross, you could put the same chip in 10 different cars all with the same spec and get 10 different results.

All this talk of chips is making me hungry.

HAve you got a unichip fitted Rick or did you just get it on the rollers at extreme, i can't remember??

If not then get a unichip installed.

Group Buy! Matty needs a Unichip and so does Ross (I'm fed up listening to his paranoia). And sounds like Rick needs one and I 'may' be tempted if someone twists my arm sufficiently.

Cheers for the thoughts guys!

I don't actually have a unichip. Just a Gtech 2. I realise that a uni chip/live map would solve the problem but i was saving up for some coilovers to do my new brakes justice and possibly and exhaust. Cash is tight at the moment so will wait for Graham to get back to me with a higher fuelling version combined with a walbro. Hopefully this works better.

I've hardly driven the car in the last few months and to be on the safe side have just put the apexi back to base boost. Is the afr at the moment dangerously lean midrange?

If 11-12.5 is the ideal afr, would I be correct in assuming that if the car was fuelling correctly then it should be roughly this from when it comes on boost to the redline?

As soon as you go wide open throttle the fueling should start dropping to 13s and as the boost climbs you'll go into the 12s where on full boost you should be around 11.8 - 12 all the way to redline.

Agree 100%

Joe

Ditto! Although to add, when at half a bar of boost should be around 12.5!

Ross

I would hold off on this option if possible until you get an uprated turbo, otherwise you'll just have to pay for a re-map when you change it (your standard one wont last forever). See if you can fix the problem with a higher fuelling chip, and installing the walbro and voltage mod will be needed for an uprated turbo anyway - so you may as well do that too!

IMO the best thing you can do for your car right now is a hybird turbo, unichip, and fuel pump + voltage mod. You'll then be running 300bhp and more importantly you'll be running it safely without repeatedly trying different chips and paying for rolling roads (and your time getting it all done).

just like i am now and running very well too, 300bhp at 1.0 bar of boost.

1 bar of boost?

Ross

Thought that would provoke a reaction. yes that's correct. a little bit of development and we are now producing the same boost at 1.0 bar as i was at 1.3 bar.