De-celeration Enleanment

Not sure if that's the right term but on quick decel I always get a rich spike...

The reason for this is explained in the Acceleration enrichment webinar and I understand that but the haltech does not seem to have any function to tune it out? only for acceleration...

Is it something I shouldn't even worry about?

There are two functions in Setup/Advanced which can be enabled to help

"Decel Fuel Cut"

"Transient Throttle Enhance"

New tabs for these functions will appear within Setup/Advanced

New entries will appear in the ECU navigator

(Platinum Pro ECU - I presume other ECU's in the Haltech range have these functions)

Yep both of them are enabled already, But decel cut is more for well actually decelerating not just -ve trainsients and as far as I can tell throttle enhance only adds fuel during accel?

I'm not sure I can give you a workaround on the Haltech platform. Some ECUs do offer a specific 'decel enleanment' function to help correct this while others ignore it. It's less relevant than the requirement for accel enrichment as it doesn't affect the response of the engine - ie you won't feel the engine go rich as you back out of the throttle. Also this will often closely be followed by the ECU moving into over run fuel cut.

It's worth confirming that the fuel table is correctly tuned to achieve your target AFR in the low load cells that you transition through as you back out of the throttle though to ensure this isn't compounding the problem.

Ahh yes I should check my 0% TPS cells and this is likely what the ecu is referencing for the second before it goes into Decel cut.. Thanks :D

one of my biggest reason of moving to the Haltech is with the Nistune, AFM and BOV it was getting alot of rich fueling and the rear of my car was always covered in little black specs of soot. which can be quite hard to remove so want to avoid rich spikes as much as possible.