Calling you SBC injection boys

[kylemrushall]

Hi

I was just wondering if i could pinch some data from anyone running injection on a SBC.

1 the pulsewidth you are running on idle?? mine is running way too long and i cant quite get it right. I have 42lb hr injectors.

2 air to fuel ratio at idle mine is running 12.8 to 1 and i want to try and get this nearer to 14.7 to 1????


thanks

ps im sure i will have more questions after today

[GTWayne]

What ECU and hardware are you using?

[kylemrushall]

in milliseconds if you have it please

[kylemrushall]

GTWayne said:

What ECU and hardware are you using?

FAST ecu, world products manifold and fuel rails. It isnt anything like your system Wayne it only runs at 45psi i know yours runs much higher than that.

[GTWayne]

What is the ratio like under load and at various rpm, do you have such data yet?

[kylemrushall]

GTWayne said:

What is the ratio like under load and at various rpm, do you have such data yet?

not got that far yet!! Im just trying to get it to idle and run from cold. I think it is running too rich and flooding as if it stalls when warming up i cant get it to start again till it has cooled a little.

[GTWayne]

Kyle, as you say my system is indeed different from yours and I think you will be very lucky to find someone that can give you some useful information here by way of generalising what settings may be used, but then again, I could be wrong, ( there was such an occasion in 1979 with regard to details pertaining to a street party that was thrown to celebrate the Queens Silver Jubilee two years previous, but nothing was ever proved one way or the other, and I was a LOT younger, and so we will have to chalk that one down to experience! ). I am unable to help in this instance but I am sure that someone will be along soon that may be able to shed some light and if not, you will just have to make the call Stateside tomorrow evening 'eh?, good luck

[CanAm Dave]

Hi Kyle

Don't worry too much mate! I'll see if I can come down and spend a few hours sorting things out for you. If you get a chance mail me your map so I can take a look at it.

Regards Dave

[GreenV8S]

Presumably you've got the ability to adjust the map, can't you simply reduce the fuelling around idle in small steps until you get the AFR you want? I don't know what injectors you're using but if they're high impedance you will probably find it's hard to control them accurately below around 1ms so if you have to go below that it's a clue that you have got the injectors too big or the fuel pressure too high.

By the way if this is only a problem when it's cold, I think you can forget the AFR. It's normal to run massively rich from cold and then gradually lean it out as the engine warms up. You probably need to experiment with the coolant temperature based enrichment settings to get it running well enough to come up to temperature. Try throwing some extra fuel in at the temperature range the problem occurs - if it makes the problem worse, take some away.

Edited by GreenV8S on Monday 24th March 15:20

[canam-phil]

kylemrushall said:

Hi

I was just wondering if i could pinch some data from anyone running injection on a SBC.

1 the pulsewidth you are running on idle?? mine is running way too long and i cant quite get it right. I have 42lb hr injectors.

2 air to fuel ratio at idle mine is running 12.8 to 1 and i want to try and get this nearer to 14.7 to 1????


thanks

ps im sure i will have more questions after today

Hi

Just ratio pulse width you are using now to a first approximation.
Use http://www.bgsoflex.com/pwcomp.html for specific calculated pulse width by entering engine parameters. That will get you in the right ball park. But cold idle is another situation. I would not think you are far off for cold but then I don't know that engine/system too well.

A more comprehensive calculator --- read more complicated http://www.stealth316.com/2-calc-idc.htm

Phil

[eliot]

I'm running 60lb injectors on mine, so apart from stating you should be able to get the 43's working I cant offer too much - I think my idle pulsewidth is around 1.5ms according to megasquirt.
Are you running a wideband ? (please say yes)

[kylemrushall]

eliot said:

I'm running 60lb injectors on mine, so apart from stating you should be able to get the 43's working I cant offer too much - I think my idle pulsewidth is around 1.5ms according to megasquirt.
Are you running a wideband ? (please say yes)

yep im running wideband 9-16 afr.

thanks for all the help guys

[gadgeroonie]

you may get some help here

www.efi101.com

run it rich to get the car warmed up

then adjust the fuel map load site till you get it as lean to 14.7 as it will go - some engines will want to idle nearer 13:1 !

good luck with the mapping - drop me a line if you need any advice

what are you using for load sensing map/maf or tps ?