Speed density - not working for me

[dynoiasi]

Hello all,

The title is a bit too dramatic because the car runs acceptably in general and there does not seem to be a big inherent problem with my setup. However I am not able to get it to run well at part loads.

The problem is that the MAP signal is somehow not characteristic enough for the load. What I mean is that a value in a cell can sometimes lead to a very rich AFR and other times (like in a different gear) the same value in that cell leads to a lean mixture. And this is not just 1 AFR point difference, but 3 points.

Can this problem be due to my MAP sensor setup (e.g vacuum source, hose length...) or is there something else I might be missing?

My fuel table is divided in 500RPM columns and 10kpa rows, could it be a resolution problem?

Thank you for your input!

Regards,

Florin

[Adamw]

What engine?  Is it just a standard common plenum and single throttle?  Mild camshaft/s?

Do you have any logs showing similar conditions but different AFR?  Is inj PW similar when it does?  

 

2 hours ago, dynoiasi said:

Can this problem be due to my MAP sensor setup (e.g vacuum source, hose length...) or is there something else I might be missing?

Yes incorrect MAP calibration or a source which doesnt represent common plenum pressure well could cause some odd behaviour.

 

2 hours ago, dynoiasi said:

My fuel table is divided in 500RPM columns and 10kpa rows, could it be a resolution problem?

No that would be acceptable for most road car engines.

 

[koracing]

I've had a customer chasing similar issues where a value in a cell would work in the morning, and then require a different value in  the evening.  Turns out his fuel pressure was pulsing and adding a pulse damper dramatically improved his situation.  Having a fuel pressure sensor may also help if your fuel pump acts differently at different times of day and depending on how long it has run combined with stock regulators.