boost cut?

[John_Hudson]

Okay so i have developed a problem..

When i floor it in 1st its all fine to 7k RPM i shift to 2nd again pedal to the metal then all of a sudden its if all the boost just dissapears, the power loss is so sudden i get pushed forwards in my seat, at the point it happened i lift straight off the throttle. it has happened 3 times and each time it has happened its been through these conditions.
when the boost has been build gradually it seems fine.  Also ive only had this problem while in 2nd gear. ( so far)  :Grrr

My car has uprated full non sequentil twins, 850 injectors all around, uprated pump, fse pressure reg, power fc, profec b spec 2 BC, apexi gt fmic and apexi filters. Mapped by WGT running 369 RWHP @ 0.9 bar.

commander reads 28 knock(there abouts), 73% duty, 86 water temp, 35 air temp

profec is set to boost cut at 1.2 bar and the boost peak is only 1.07

there is no whistling and ive checked over and tightened IC piping / intake

any insight would be greatly appreciated !

cheers!

John-

[m4drx]

fuel cut not boost cut if that m8

[John_Hudson]

if what..  sorry im finding it hard to understand your statment, have you been on the bottle? :p

[John_Hudson]

just another note, the set limmit thingy on the controller is set to 0% but even though pip set it that way its still not registering enough peak boost to make that event happen so i dunno ... it\'s proper sweeden me !!

[Hayward North]

Sounds like your hitting fuel cut.

[John_Hudson]

would it do that even with an uprated fuel pump + pressure reg and seeing 76.4% peak duty on the PFC?

its been fine for the last month since mapping and the problem as only been occuring since yesterday, nothing has been changed

[Hayward North]

I used to get fuel cut even though my Apexi AVCR was showing 82%.
I did have stock fueling setup and it was before i had the pfc, but it is allaring when it happens, almost shocking as the reduced power makes if feel like you gonna go into the dash haha, made me almost loose control in a straight line in the wet once.

Luckily i dont have issues like that anymore.

Dont take my word for it as it only sounds like the same as fuel cut

[antnicuk]

the stock ecu cuts on boost levels above what it likes, the apexi doesnt fuel cut.

not sure what your problem could be,  i would try and get a fuel pressure gauge and see if your fuel pressure drops when it happens

[Carl]

Apexi does fuel cut at around 0.2 kg per cm3 above what it is set too.
You need to check what the ecu is set to even thou you are running a seperate boost controller because the ecu will still hit boost cut if the levels set in it are not high enough.On your power FC you will need to set it around 1.1bar to be sure.
Regards
Carl

[michaelb]

Apexi does fuel cut at around 0.2 kg per cm3 above what it is set too.
You need to check what the ecu is set to even thou you are running a seperate boost controller because the ecu will still hit boost cut if the levels set in it are not high enough.On your power FC you will need to set it around 1.1bar to be sure.
Regards
Carl

Chaps, sorry to highjack the tread but Carl, how do I find out if the Apexi is set to cut boost at 1.1 bar ?  Where do I go? (I have the commander ) DOes it mean that I do not need a boost contoler?  Will the Apexi act like one and stop high boost spike? I am running twin turbos...

Regards,
Michaelb

[Carl]

Chaps, sorry to highjack the tread but Carl, how do I find out if the Apexi is set to cut boost at 1.1 bar ?  Where do I go? (I have the commander )

Regards,
Michaelb

Just go to the boost settings and see what the level of boost is set too,If you want boost cut to be around 1.1bar then 0.9 should be the setting.
the thing is in you case that if the ECU is controlling the boost,unlike Johns car then you shouldn\'t play with the settings as boost will change and you\'ll likely pop the engine,if your car is hitting boost cut then it needs to be addressed by playing with a number of functions on the ecu.
Regards
Carl

[michaelb]

Just go to the boost settings and see what the level of boost is set too,If you want boost cut to be around 1.1bar then 0.9 should be the setting.
the thing is in you case that if the ECU is controlling the boost,unlike Johns car then you shouldn\'t play with the settings as boost will change and you\'ll likely pop the engine,if your car is hitting boost cut then it needs to be addressed by playing with a number of functions on the ecu.
Regards
Carl

trust me, I am not touching a thing, it would be nice to know that in case of a boost creep engine is protected by a boost cut, My boost is set at 0.94 injector duty at it\'s highest is at 94% but I only hit this for a second a two during hard acceleration...

Where do I go to check the cut off level? by the way I dont think I ever hit a boost cut...would not know what it feels like thou..

So do I need a boost controller?

[Carl]

trust me, I am not touching a thing, it would be nice to know that in case of a boost creep engine is protected by a boost cut, My boost is set at 0.94 injector duty at it\'s highest is at 94% but I only hit this for a second a two during hard acceleration...

Where do I go to check the cut off level? by the way I dont think I ever hit a boost cut...would not know what it feels like thou..

So do I need a boost controller?

You are confusing fuel duty with boost cut.
If the ecu detects a higher boost by around 0.2 of a bar than what it is set too then the ecu will cut fuel to prevent engine over boosting.If boost is set higher than injectors can cope with then they will max out,but keep working with the engine running lean.
However,the injectors should not run in the high 90\'s % of duty for too long as they can stop working,for short burst\'s and occasionally it is ok though.
Regards
Carl

[John_Hudson]

ive checked my power fc and on the boost settings its saying on the primary its 1.1 and on the 2ndary 0.75.  even though im non-seq could this be my problem?

[royston1xx]

Your fuel cut will work at 1.0 kgcm when your target boost is set at 0.75kgcm. Change the secondary boost to 0.85 so that fuel cut will happen at 1.1kgcm but be careful if you have the stock map/boost sensor as if you set the target boost too high you will never hit fuel cut. The sensor cannot read beyond 1.15kgcm if calibrated with the datalogit to read zero and not have a negative vacuum amount with the ignition on. :Thumbs-up