Jump to content
MattR

Master Fuel question

Recommended Posts

Hi guys, I'm almost ready to start tuning an M54B30 (Vanos disabled, M50B25 intake, standard B30 injectors, M50B25 sensors) running on an E36 G4+ plugin ecu. The base map is sufficient to start the car, though unsurprisingly it's running pretty rich. The B25 base map runs a 177cc/min injector, whereas the B30 injectors are rated to 282cc. Presently the engine is idling at around 11.7 AFR, and seeing 9s at WOT. The Master Fuel is currently set to 20ms, am I on the right track thinking that the value should be closer to 12ms to allow for the 60% +/- extra flow of the B30 injectors? Fuel table numbers look to be about where I'll want them to be if I'm on the right track.

1301115902_fuelmain.PNG.56532e3e2f50d24b6b0aa103546f42b1.PNGfuel.PNG.5ac983de3360a72eef382215dcf1a7db.PNG

 

Thanks in advance

 

Share this post


Link to post
Share on other sites

Yeah about 12 should be approximately correct. Might need to be a few points up or down on that depending on how close the base + current numbers match the real values of the injectors, but your calculations are right.

Share this post


Link to post
Share on other sites
1 minute ago, cj said:

Yeah about 12 should be approximately correct. Might need to be a few points up or down on that depending on how close the base + current numbers match the real values of the injectors, but your calculations are right.

Brilliant, ta.

 

 

Share this post


Link to post
Share on other sites

I would calculate it like this:

If your measured lambda was 0.61(9:1AFR).  Lets say your target was typical NA target of 0.87.  So 0.61/0.87 = 0.70 (i.e need to remove 30%).

New master fuel = 20 x 0.70 = 14ms.

Share this post


Link to post
Share on other sites
3 hours ago, Adamw said:

I would calculate it like this:

If your measured lambda was 0.61(9:1AFR).  Lets say your target was typical NA target of 0.87.  So 0.61/0.87 = 0.70 (i.e need to remove 30%).

New master fuel = 20 x 0.70 = 14ms.

Thanks Adam, much appreciated

Share this post


Link to post
Share on other sites

One last thing - I assume I'll need to change the master fuel value before starting the engine? Have spoken to a couple of people about it and I'm not 100% sure if I should change the value before startup or after the engine is at running temp?

Share this post


Link to post
Share on other sites
1 hour ago, MattR said:

One last thing - I assume I'll need to change the master fuel value before starting the engine? Have spoken to a couple of people about it and I'm not 100% sure if I should change the value before startup or after the engine is at running temp?

You can do either, often easier to change it while it is running - then you can just bump it up or down until it runs best.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×