Hey,



my EMS is Power FC, i can set it up to do a Fuel Cut at deceleration (just like stock ECU) and i can let it inject fuel on decel.

What is safer and what makes more sense?

I have been told, that especially at highspeed driving, it should keep injecting fuel if i go off the throttle, to cool engine internals down etc.

In Motorsports, they often use injecting too.. but mayb for the reason of keep turbo spooling, too.



Have been also told, that many engine blows occure due to F/C at decleration, because engine runs to lean and hot.

Also i read somewhere on another forum (well the people were only up to shooting flames, but no other things..) that the extra injection on decel. wont harm the turbo at all.



Please tell me what you think and what you know https://www.nopistons.com/forums/pub...IR#>/smile.gif



I want my engine to run as safe as possible. Since i am running highspeed runs also, i would like keeping on injecting fuel, if its true that that is a safer way.

its safe to keep injecting fuel on decel, well to a point where the back of the car's on fire...



you might want to set it up, so that in normal driving it does decel fuel cut, it'll save fuel



but if you're really running it hard then the extra fuel on decel will cool it down a bit, which is good

Not sure about running lean and blowing an engine due to fuel cut, if fuel is cut there is nothing to ignite or worse to pre-ignite. The added cooling might be a good argument, but with the small amount of gasoline being injected on decel how much cooling will there really be? I just run with the decel fuel cut on my PFC and have never had a problem with it.

big fireballs are cool

The REPU makes big fireballs, and indeed they are cool!

well, i dont have any backfires, and no fireballs. my Exhaust smokes as hell if fuel is injected LOL but no fire at all.

you sure? maybe its not hot enough?

maybe its not hot enough.. im not pushing the car for constantly.

yeah, ours usually dont shoot fire until its about halfway up the mountain

well, yesterday i got some big flames, too big as i think LOL. at one point i could see the some flames threw the tailgate.

i want to keep injection on deceleration, but does it hurt my engine/turbo if i inject less fuel on decel.?

flames and backfiring ok.. i just dont care, but i am worried i get a melt bumper or even cought on fire!

what AFR should i get MAX. at decel.?

i want bigger flames :(



wonder if i can trick the stock ecu.

i wonder, why it is supposed to cool the engine down.. it should only cool down the engine if injection on decel. is active AND the ignition is turned off, am i right? But you cant just pull out the ignition.. so on deceleration, it fires the mixture.. and i dont know how it is supposed to cool, if there is a full burning process.. does injection on decel. make any sense if the ignition keeps on firing?



or is the benefit of injection, the very short and small "bridge" between going OFF and ON the throttle during WOT to redline or HIghspeed driving? You know, if you have the Fuel Cut and running lets say 140mph, you go OFF the accelerator, and between the full operating of the injectors, and the 0.0% operation (Fuel Cut) there will be some superlean AFR until it gets fully atmospheric air the lambda is reading. and THIS can hurt the engine at highspeed and high dragforces? If you keep injecting when going off the accelerator, you dont have such lean-bridges because it just keeps injecting. i also realised the car makes no "bogs" or something like that, because there is no transition to Fuel/Cut.



the gas mileage gets worse, but the engine runs smoother.. and i HOPE safer! what do you think? does it make any sense if the ignition is still active? or does it the oposit.. not cooling down the engine with injection, but heat it up because of ignite the mixture even during deceleration? does it harm my turbo? and how lean should it be on deceleration? any danger? dont want to blow my engine.



i think its an interesting thing, and i would be very happy if somebody could answer my questions https://www.nopistons.com/forums/pub...IR#>/smile.gif

unless i am missing something ignition doesnt fire on deceleration, thats whay your decelerating... that and your trottle body is almost closed. ignition doesnt come backon until you reach idle or the accelerator is pushed again...i dunno just my 2 cents. i would run methenal injection vs fuel as far as cooling goes...

are you sure there is no ignition on decelaration? In the MAPs of the Power FC, there are also degree numbers in the vac. section, for example -600mmHG and 7000rpm there are 50° BTDC

So far as I know (which isn't far) the ignition fires regardless. On decel, the throttle is closed and you've got either a little or no fuel, so the engine decelerates.



A rich mixture burns cooler than a lean mixture, so any cooling effect will derive from that difference.

well, on deceleration there 0,0% fuel injected (Fuel Cut) So there is NOTHING what could be burned.. In Fact it doesnt matter there is ignition or not, because air cant be burned without fuel anyway.

Ok, but if i eliminate Fuel Cut, and keep injecting fuel, there is a mixture which could be burned.

rich on decel cools things down, because its a lot of fuel, but no load, you're generating 0hp

yea thats right.. but i want to know, how lean i can go at deceleration... because if i stay at the level i have now, or even go richer! i am going to shoot 5-6ft flames on each decelerating towards a corner.. LOL thats was TOO much.



What AFR should i MAX. get on decelerating?

doesnt matter, the widebands not really reading right there anyways.. it shouldnt need much fuel at all though