Hello,

I have a problem mapping my GSXR tb's on an Omex 600 ecu I can't seem to solve.
If I set the mixture rich around idle the car runs well and I can blip the throttle with no hesitation the problem with this is that the lambda reading is at -25 indicating I need to reduce fuel. If I do reduce the fuel to get the lambda reading around zero and blip the throttle there is a hesitation before it revs.

Can anyone tell me what I'm doing wrong.

Cheers
Stu.

Mine runs best (fastest, smoothest and most responsive) when pretty rich at warm idle
Give the engine what it wants rather than chasing any mythical number using a gizmo that could well be not accurate :-)

The way I see it :
AFR's are only really important when engine is under load

Nothing to worry about as long as plugs aren't sooting up when left idling (could eventually lead to missfires) but doubtful that your engine would run at its best if running plug foulingly rich anyway

Regards
Rob

[Edited on 12/3/10 by robocog]

This is likely to be down to incorrect settings in the acceleration transients leading to a weak stumble. If you are using throttlebodies I assume you are also using TPS for load.
There are five tables to set and the basic options screen.
What engine/state of tune/load sensor are you using?
Can you download your map and send it to me to have a look at. I have the software. I may be able to make changes to the transients and leave you to reduce the idling mixture to more normal levels. Will pm you my email.

Hesitation just off idle is a characteristic of GSXR TB's. On the bike there is an extra set of butterflies which are electrically driven that are used to cure this latent flat spot. Of course, when you fit the TB's to a car, the second set of butterflies are removed and potentially the flat spot comes back.

However, there are ways to eliminate it. The most common is to set the throttle butterfly to a fast idle, say 1250-1300 rpm, so it's open past the point where the flat spot would usually be, then get back to a reasonable idle (and be prepared to accept 900-1000 rpm as an idle) by backing off the ignition.

Don't worry about the AFR number at idle and just off, set it so it runs right.

Thanks for all the pointers chaps. Maybe I am chasing readings when I don't need to be.
My particular TB's didn't have the secondary butterflies to remove, they are from a SRAD model GSXR 750 around 1999 - 2000 model year.

Dusty email sent

Cheers
Stu.