AFR at idle

[Else]

Just installed an AEM wide band lambda meter and wondered what the ideal AFR should be st idle. In fact I could do with a bit of advice for AFR readings for various scenarios for example light cruise, overun, on load at low revs etc.

Thanks all

Andy

[GasMunkey]

What ever your engine likes, some like 12:1 some are happy at 16:1

Trial and error

I'd try 14:1 and see if it likes it

[carsy]

Have a look at the graph on here for some guidance. But like Alex says they all differ depending on state of tune.
http://www.g33.co.uk/fuel_injection.htm

[SILICONEKID340HP]

Mine runs well at 14afr on idle ,low 14afr to stop shunting at low speeds ,15 to 15.5 for low load cruise and max power 12.5 ,every engine is different .



Now running a bit leaner..

Edited by SILICONEKID340HP on Monday 7th January 22:57

[LuckyLucky]

Dazs sounds about right .

[Else]

Excellent, thanks guys.

[Discopotatoes]

Mine likes 13.7 at idle, 15.5 cruise and 12.5 under load then 11.5 to 11 under boost

[Sardonicus]

GasMunkey said:

What ever your engine likes, some like 12:1 some are happy at 16:1

Trial and error

I'd try 14:1 and see if it likes it

My idle gets really splashy any tighter than 14.1 it makes the cam sound more severe than it is and it stinks lean

[blitzracing]

They really dont like Lambda 1, its one of the reasons the TVR tickover is so lumpy on the catalyst map, you are better off a bit richer. Try 13 -13:5 to 1

[450Nick]

You can make it stable at pretty much any AFR, just takes a bit of time balancing all of the variables. It tends to be a lot easier to get a good strong idle when it's warm obviously, and the RV8 doesn't oil its self particularly well below 1k revs, so I tend to have the engine run fast from startup, falling down to 800rpm once its good and warm, around 15 afr to keep the plugs clean

[Sardonicus]

blitzracing said:

They really dont like Lambda 1, its one of the reasons the TVR tickover is so lumpy on the catalyst map, you are better off a bit richer. Try 13 -13:5 to 1

sweet as a bird at at 2% CO idle agree with 450 Nick about the fast idle from cold though

[SILICONEKID340HP]

Sardonicus said:

blitzracing said:

They really dont like Lambda 1, its one of the reasons the TVR tickover is so lumpy on the catalyst map, you are better off a bit richer. Try 13 -13:5 to 1

sweet as a bird at at 2% CO idle agree with 450 Nick about the fast idle from cold though

Ok the bit i can`t work out is how do you get a crude VE table to start with ? there must be a calculation , the injector size must be involved in the equation,thats why the VE numbers get smaller larger the injectors .

Once you have a close enough VE table you can let the Autotune use the lambda feedback to perect the VE table ..


as anyone done this because at some point i will buy the program .Im aware there are s ome settings to change for autotune like EGO correction .

Idle can be closed or open loop!

Wish there were a course on it tunning these things ..

[blitzracing]

Sardonicus said:

sweet as a bird at at 2% CO idle agree with 450 Nick about the fast idle from cold though

The TVR plugs have a bit of a habit of sooting up compared to the projected tip Range Rover ones, so its a ballance between plug heat rating / construction versus mixture. Ive got BP6ES (Range Rover) and I dont have a fouling issue even when driven slowly or with cold starts.

[Sardonicus]

blitzracing said:

Sardonicus said:

sweet as a bird at at 2% CO idle agree with 450 Nick about the fast idle from cold though

The TVR plugs have a bit of a habit of sooting up compared to the projected tip Range Rover ones, so its a ballance between plug heat rating / construction versus mixture. Ive got BP6ES (Range Rover) and I dont have a fouling issue even when driven slowly or with cold starts.

I like the fast ldle cold Mark cos its easier on the camshaft and currenty i am using BCPR7E's never had fouling issues hence why i stick with 7's and use 16mm plugs because of the BB Chevy lead style i currently am using.

[blitzracing]

Just dug out the Des Hammil book and the target AFR's are:

Idle 13.5:1
Full power-constant load 13:1
Light cruise 15.4:1 (and NO leaner)
Acceleration phase 12.5:1

[SILICONEKID340HP]

blitzracing said:

Just dug out the Des Hammil book and the target AFR's are:

Idle 13.5:1
Full power-constant load 13:1
Light cruise 15.4:1 (and NO leaner)
Acceleration phase 12.5:1

Are hose the targets on the 14cux

The lean machine is running 17afr ,don`t know whats gong to break first !

Edited by SILICONEKID340HP on Tuesday 8th January 20:08

[blitzracing]

Those figures are the recommend whatever the fueling system.

Edited by blitzracing on Wednesday 9th January 13:09

[ChimpofDarkness]

blitzracing said:

Just dug out the Des Hammil book and the target AFR's are:

Idle 13.5:1
Full power-constant load 13:1
Light cruise 15.4:1 (and NO leaner)
Acceleration phase 12.5:1

This is exactly what I'm running in all the areas listed.

With the exception the light load cruise figure.

Which I've proved can be 17:1 with no cats, & gives absolutely no ill effects whatsoever.

I just gained another 3-4mpg on a run.

However if I still had cats 15.4:1 would be my light load cruise figure too.