Gonna check my KE jetronic manual at home but what is the optimum AFR for running your car and what is the limit for best performance??

Thing is I get my new wideband innovate AFR guage delivered tommorow and need to know what to check for once its installed!

Also I need to sort why on my current narrowband gauge does it trop off way lean when I take my foot off the accelerator under boost?? or normal driving?

 

Oh, that's a huge question. I could write a page and only scratch the subject.
At idle stochiometric ratio is ok, i.e. 14.7:1. For cruise leaner will give you better mileage, but a CVH will start to bog and lose efficiency after 17.0:1. At low boost (~0-10psi) and at off boost WOT a 12-13:1 ratio will be ok. At higher boost you would want to run more fuel than what is optimum for power for safety against melting and for detonation prevention. Anything richer than 10.5:1 and power will go down rapidly after that. It' sprobably needless to say that many parameters affect the wisest ratios like IC, C/R, turbo size, cams, combustion chamber, etc.

Whenever you loft the pedal with revs over ~1800rpm you activate over-run fuel cut. You are essentially braking with the engine and it would be pointless to inject fuel. When the revs drop low enough fuelling is resumed not to stall the engine when clutch is pressed.

 

Yes I read this in the bosch techincal maunal I have.

The electromagnetic pressure actuator stops receiving power on overrun and therefore it will be a lean situation?

So I guess if I look to have 12 -13 for max boost and be as close as to 14.7:1.

Thanks for your help.

 

It doesn't stop the current, but it reverses it to lean out the mixture to the min, effectively cutting the petrol supply completely. The electromagnetic pressure actuator is more for correcting the mixture in most cases and unplugging it completely just sets the mixture to whatever the airflow meter tell to fuel. The car will run quite fine even like that, just doesn't have any mixture corrections for cold engine, transient fuelling, wot, overrun, etc...

 

Thanks for that I have just ordered the Bosch KE Jetronic manual from Bosch so I should hopefully have a better idea of setting it up.

Thanks for your time.

 

do someone knows how much % power will car loose , if have for example 11:1 mixure instead of 12.5:1 ??

is loses about in 5 bhp or more?

I kow that noone knows exactly, depends on 100 things, but rough messured

I have little popings from exhaust when I braking with engine...not bangs but constant poppings...I hope mixure is under 11.5