Fuel Cut

[jackerthanjack]

At What Boost is fuel cut supposed to kick in?

Ive had a HKS ebc III fitted and is a bugger to set up dont control boost levels at all just spikes over 1 bar then settles down but when it spikes i hit fuel cut. Ive just put a MBC back in until i buy an avcr black. The boost is not spiking its hitting about 0.78 but fuel cut steps in grrrrrrr and i thought fuel cut was anything over 1 bar?

[Nutter_John]

fuel cut is not boost related as the engine does not know what boost your running , the EBC just needs to be setup correctly with the duty cycle reduced so that your not spiking

[jackerthanjack]

fuel cut is not boost related as the engine does not know what boost your running , the EBC just needs to be setup correctly with the duty cycle reduced so that your not spiking

can you go into a bit more detail john pls what you mean with duty cycle? I did the set up with the three runs same road conditions same gear and that lot

[orionn2o]

The duty cycle is basically the amount of time that the solenoid opens and closes during a second.

So if your duty is 50% then it is open half and closed half.

If its 100% then the solenoid is open the whole time which stops the wastegate opening.

If its 0% then the solenoid is closed which means you're effectively running off of the actuator spring.

Anything in between is well... just that!

[jackerthanjack]

get on gotcha now cheers il give that a go. so i need to lower it then do i?

[Nutter_John]

right in simple terms

Target boost is the point you want to get to
duty cycle is the rate that you get to your target boost

target boost too hight and you will not get it
target boost too low and you will get there quick

Duty cycle too high and you will over shoot the target boost
Duty cycle too low and you will not make the target boost

Start point/cycle is the point at which you start controlling the boost
too high and it will spike
too low means your controlling the boost sooner

[Atik]

right in simple terms

Target boost is the point you want to get to
duty cycle is the rate that you get to your target boost

target boost too hight and you will not get it
target boost too low and you will get there quick

Duty cycle too high and you will over shoot the target boost
Duty cycle too low and you will not make the target boost

Start point/cycle is the point at which you start controlling the boost
too high and it will spike
too low means your controlling the boost sooning
I was following you up to that point :p :upsidedow

[Nutter_John]

yeah yeah spelling corrected

[Nick Mann]

The HKS controllers I've seen learn the cars boosting characteristics by you accelerating in 3rd gear to the red line multiple times. Then theoretically, all you need to do is turn the volume control to the boost setting you require.

If you are getting fuel cut, then your MAF thinks there is too much air flowing - the ECU worries about being able to supply enough fuel, so it stops fuelling altogether rather than risk running lean.

If you are getting fuel cut a .78 bar, then I would guess you either have a very good intercooler, a boost leak or a dodgy pod/cone air filter.

[jackerthanjack]

The HKS controllers I've seen learn the cars boosting characteristics by you accelerating in 3rd gear to the red line multiple times. Then theoretically, all you need to do is turn the volume control to the boost setting you require.

If you are getting fuel cut, then your MAF thinks there is too much air flowing - the ECU worries about being able to supply enough fuel, so it stops fuelling altogether rather than risk running lean.

If you are getting fuel cut a .78 bar, then I would guess you either have a very good intercooler, a boost leak or a dodgy pod/cone air filter.

I changed back to a standard air box as i was warned about cone filters so i could have a dodgey boost hose then hmmmmm investigation is needed

[mattnz]

Are you getting the expected vacuum (-20inHg)?

[ILLEGAL]

hi, new to the site and still trying to find my way around.

best thing to do would be to first find the boost leak.. could be anywhere from the turbo upto the head, this includes the gaskets between the throttle body, and the plenum-injector intake and injector intake-head. it wont be pre-turbo.. if it is it wont cause cut to kick in any lower than standard.

if no leak is present then go to the next step.. upgrade the injectors and fuel pump.. you will also need a s-afc to tune out the extra fuel which in turn raises the cut limit and advances the timming a little.. leave the fuel pressure regulator. this is the best fuel cut defender ever.

[jackerthanjack]

hi, new to the site and still trying to find my way around.

best thing to do would be to first find the boost leak.. could be anywhere from the turbo upto the head, this includes the gaskets between the throttle body, and the plenum-injector intake and injector intake-head. it wont be pre-turbo.. if it is it wont cause cut to kick in any lower than standard.

if no leak is present then go to the next step.. upgrade the injectors and fuel pump.. you will also need a s-afc to tune out the extra fuel which in turn raises the cut limit and advances the timming a little.. leave the fuel pressure regulator. this is the best fuel cut defender ever.

s-afc whats that?

[mattnz]

A different kind of EBC. Let's establish that there is a boost leak first though. What is your vacuum reading?

[keithatport]

An S-AFC is for trimming fueling, nothing to do with boost control.

[ILLEGAL]

correct Keithatport, its fuel trimming device.. but first things first what is a normal maximum boost presure in a 8G galant/leggy before cut kicks in with factory turbos? i thought is was around 13-14psi? are we sure its cutting and not missing or detonating or blowing the spark out?

[keithatport]

Hi ILLEGAL, I was not commenting on your post merely correcting MATTNZ's post #14 - "A different kind of EBC"

[Ryan]

An S-AFC is for trimming fueling, nothing to do with boost control.

Quite right. It intercepts and adjust signals from the MAF which it then feeds to the ECU?

[mattnz]

Whoops, forgot my bad, early morning :o

But yeah, rule out the dump valve, vacuum tubing, and connections before scouring the hard connections, and talking about fuel cut defenders.

[jackerthanjack]

right ive just taken everything off and put all standard pipes on so its all back to standard and the boost is going peaking at 1 bar or 1.2. Is my actuator nackered? im guessing so. Help? if it is where can i get one from?

[ILLEGAL]

if you dont have a boost controller inline and the waste gates are connected correct.. yes the wastegate could be broken/rusted shut? im sure the factory gates a wide open at around 8psi .. not sure what BAR rating that is. but if it dosent cut at 1.2bar id say the problem is in the intercooler or piping.. a leak.

[Nick Mann]

right ive just taken everything off and put all standard pipes on so its all back to standard and the boost is going peaking at 1 bar or 1.2. Is my actuator nackered? im guessing so. Help? if it is where can i get one from?

Are you certain that everything is standard? How are you measuring boost? What is your vacuum reading at idle and also moving, in gear, with your foot off the gas.