AFR under boost

[mike 850]

Looking at my chart it looks very lean, above 4500rpm its upper 13's, chat is the optimum AFR under boost for our cars?

[M-R-P]

12.5 (ish) iirc

[Jamest5r]

You really want it in the 11 to 12 range defiantly not in the high 13's you will start melting stuff

[oblark]

If you are running a RICA 304 or a HLM 304 (which are written for a 16T and whites)

With anything other than what it was written for you are asking for trouble with lean/rich readings.

[S70T5Chris]

You really want it in the 11 to 12 range defiantly not in the high 13's you will start melting stuff

This :biggrin:

[MoleT-5R]

If you are running a RICA 304 or a HLM 304 (which are written for a 16T and whites)

With anything other than what it was written for you are asking for trouble with lean/rich readings.

I'd better get me a wideband soonish then....

[oblark]

I'd better get me a wideband soonish then....

And your 4.4 ECU

[mike 850]

My aem wideband is here now...

[MoleT-5R]

And your 4.4 ECU

yep.... draggin me heels a bit at the moment...:buttkick: point taken....lol

[no1tosh]

If you are running a RICA 304 or a HLM 304 (which are written for a 16T and whites)

With anything other than what it was written for you are asking for trouble with lean/rich readings.

so what would happen if you run a rica 304 on a standard 855 t5?

[Jamest5r]

so what would happen if you run a rica 304 on a standard 855 t5?

Nothing usual as it's mapped for that

[no1tosh]

ahh right, just wondering as im having fueling problems, when i read that about the 16t turbo and white's, i thought the 304 was wrong for mine.

[Jamest5r]

What sort of fueling problems?

[no1tosh]

its low fuel pressure at the rail 30-35 psi, and jerking everytime you let off the throttle.

with that was said above i just thought the rica 304 wasn't ment for a t5 an it only does the throttle thing with the map.

theres a thread titled at the end of my teather from lastweek with what i have been doing.

[Jamest5r]

You changed the pump and filter?

[no1tosh]

ive changed the filter, rail and regulartor. the next on my list is the pump. not sure witch one to go for though as money is a bit tight at the min. ive heard about walbro's and duechte 300's. ive probably only got about £50 max to play with though.

any other pump sugestions??

[Wobbly Dave]

14.7:1 AKA Stoich - is the optimum AFR for the best burn - however it needs to be richened up. The modern ST/RS ford versions of the t5 run Stoich even under full boost. I don't think you want to go much under 12 at WOT. It really depends on what pressures you're running.

[960kg]

Just my 2 pence worth!!......first of all if your fuel pump is supplying the correct pressure then how can it be the map!, if you have problems...look at the fuel pump

AFR`s , yes i know they are important as above but only on WOT and for how long? .......i have the HLM304 map and was told it was designed for an 18t with whites but who knows what!

All i know is that i have used the map for 2yrs with no probs. and on checking the colour of my plugs it runs in line with the map being on the weaker side but not dangerously weak.

Our ECU`s are Adaptive ones and will learn what is happening, yes i know there is a limit but as an example my `98 T4 was on 19psi of boost which is 8 psi over the standard and the AFR`s were spot on so why should the 4.4 not do the same?, and adapt to the performance.

I think there is a lot of scaremongering and nonsense about maps.........however if i were on a racetrack instead of the normal road then i would of course take steps to ensure my map was correct but then i would have enough money to ensure all this!

[no1tosh]

ok cool no problems, my heads just up my arse with trying to get to the bottom of this problem and ive only just found out about the fuel pressure. im a painter, i can fix stuff but diagnosing mecanical problems is my downfall :(

[mike 850]

hooked up my afr gauge, under boost its in the 11's on the road, different from the rolling road for some reason? also is it normal for the gauge to "swing" between rich and lean and maintaining a consistent speed? its stays at about 14 at idle and is steady under boost but just normal cruising it fluctuates alot