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Discussion Starter · #1 ·
At what rpm does fuel cut typically occur? I think I am getting it (at about 5k rpm or thereabouts), feels like an unseen hand is suddenly pulling you back witht the engine cutting back all of a sudden. Not sure why this is happening seeing as I do not have any performance mods, not even a cone filter. Boost gauge is not showing excessive boost (0.7-0.8 bar)

What can I do to stop fuel cut? Could it be due to the engine running lean at higher rpms? Might an AFC device help? At lower rpm, the engine is fine and performs normally.

Please help!
 
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Discussion Starter · #3 ·
alexbaby,

if you are confident that your boost gauge shows the right pressure you may have a problem
with your fuel pump. In any case I would advise to visit a Mitsubishi dealer.
 
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Discussion Starter · #4 ·
While ur on this subject, I dont wanna jump your thread - But when I got my new exhaust fitted, on about 3 or 4 occasions ive been accelerating or have dropped it down a peg and then the engine has sort of 'cut', almost making me leap forward! Is this a fuel cut then or something more worrying? :(
 
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Discussion Starter · #5 ·
Duffman, that's fuel cut. I never got it until I changed my zorst and filter. Now on cold mornings I can get it cutting on full chat. Just really got to watch it and change earlier, say about 6900rpm :D It's like you say you get chucked forward as if you've hit a wall, then you think WTF, please be okay...please be okay. It's amazing as you have to try it again to make sure.

...John
 
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Discussion Starter · #7 ·
Eric, if my limited knowledge serve me well, the fuel cut is there to stop det, from overboosting as the ecu sees it. I'm sure someone will give a more meaningful explanation than me.

...John
 
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Discussion Starter · #9 ·
Craze

Sorry if this is an asinine question, but how does a leaky actuator contribute to fuel cut?

Fuel pump theory: Ok I think I understand this one ie the pump may not be supplying enough fuel at higher revs causing the engine to run lean?

Detonation - ignition timing, bad fuel, what else?

This fuel cut thingy is getting rather bothersome and I want to fix it asap! Esp when I haven't done any mods!

Thanks again for the replies!
 
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Discussion Starter · #10 ·
This topic of fuel cut has been covered many times on the forum. Here is the detailed post from the very knowledgable HH6, I'm sure he wont mind me repeating it here.

Fuel Cuts

Cars affected:
Evo 4-7 (possibly earlier Evo's)
Symptom:
A very sudden de-acceleration due to the fuel being cut to the injectors, similar to your foot slipping off the accelerator except it will recover almost immediately. It occurs when coming on maximum boost i.e. while accelerating hard (common at roughly 4000rpm in 2nd, 3rd or 4th gear but possible at other rpm). Also it is more common if the outside air temperature is cold.
Problem and cure:
Fuel Cuts are the Engine Management's way of stopping over boost. Instead of detecting the actual boost pressure the ECU (Electronic Control Unit) uses information from the Air Flow meter and the Outside Air Pressure sensor to work out the boost pressure. The ECU will cut the fuel at a minimum of roughly 1.3 bar boost pressure (18.8 PSI) on the Evo 6 but the actual cut point is dependant on air pressure and air density at the time.
Fuel cuts can occur after fitting an upgraded aftermarket induction kit and/or exhaust. The increased airflow created by these parts is enough for boost levels to increase. It is also possible for fuel cuts to occur due to a faulty Wastegate Actuator (see elsewhere).
The cure for fuel cuts depends on what is causing it. If you have just fitted any upgraded parts then the boost level can be dropped fairly easily by a manual alteration to the Boost Control system. This procedure will not be covered here as it is open to abuse that could result in engine failure and should not even be considered without suitable measurement of Boost levels and knowledge of the system. If you are having problems with fuel cuts then consult a qualified garage/mechanic that knows about Evos.
Approximate cost of repair:
Depends on the fault.
A new Wastegate Actuator is approximately £200 inclusive (plus fitting approx. 1 hour).
Adjusting the boost level will take 30 minutes with no parts required.
 
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Discussion Starter · #11 ·
My E6 is completely standard, I had the actuator checked by MADevelopments and I had a leaky actuator causing overboost. I had this changed under warranty and now runs fine - no cuts - although the car seems alot slower now its running standard boost again(!).........
 
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