[Guest]

Since about 3 days I can sometimes feel some kind of hesitation.

It occurs when lets say in 4th or 5th gear accelerating then steady throttle and going on boost again it feels like a short hesitation which has never occured before. Unfortunately it doesn't occur all time. I have also the imagination it feels a bit jerky.
Because even my better half could feel it I'm a bit worried.

What could be the reason? The car has just covered 3000 km and it's an EVO VI TME, bog standard enginewise. Should a get it to the garage to have a diagnostic test carried out?

Any advice appreciated

Cheers

Mike

 

[Guest]

Sounds like the dreaded fuel cut!
Does it happen at about 4000-6000rpm when accelerating hard? Usually it will occur in 3rd, 4th and 5th gear. Does it feel like a hesitation that slams the drivetrain?
If yes then it is a fuel cut.
Basically it is the way the ECU copes with overboosting. Once it detects overboost conditions it will cut the fuel momentarily and that results in the hesitation.
Fuel cuts can seriously damage your engine over a continued period as a fuel cut when on boost puts extreme stress on the con-rods.
Do not live with the problem! You can drive around it in the mean time by staying off boost but get it sorted ASAP.
Fuel cuts can occur due to the following reasons (most common):
If your car has been modified, usually an induction kit and/or sports exhaust can cause fuel cuts due to the increased breathing.
If you have removed/altered the restrictor (often called the 'grommet') in the pipework next to the boost solenoid. Removing the restrictor allows better acceleration by increasing peak boost but it is not a recommended way of increasing performance (unless you know waht you are doing).
If you have removed/altered the restrictor in the pipework next to the turbo wastegate. Altering the restictor diameter alters the held boost level but it is not a recommended way of increasing performance (unless you know waht you are doing).
Your wastegate actuator is faulty. The actuator is situated where water can drop down and can eventually seize the diaphram.

Fuels cuts are more likely to occur when the weather is colder and raining as the air density increases and therefore boost will also improve.

I cannot stress this enough though.....

DON'T LIVE WITH IT, GET IT SORTED!

 

[Guest]

HHsix,

Sounds like experience talking!http://www.ltregister.f9.co.uk/graphics/sad1.gif border|EQU| 0 align|EQU| absmiddle > Is this why you have a new engine in?

I never have figured out why Mitsubishi cuts the fuel and not the ignition.

 

[Guest]

Mike.........I would doubt it is fuel cuts if you have a completely standard car.

However if you mean when you go from power to cruise then the hesitation you refer to is probably ECU related and I believe occurs on all EVO VIs although not all owners seem to notice and it isn't anything to be concerned about.

It's cause is because on WOT (wide open throttle) and above 4500 rpm I believe fuelling is determined by the map programmed into the ECU. On cruise fuelling is determined by readings from the Lambda sensor in the exhaust. The hesitation is simply the point at which control of fuelling swaps for ECU map under power and back to Lambda on cruise. There is no fuel being supplied for a couple of seconds during this moment, hence the hesitation.

This hesitation stopped for me once I had changed to a programmable ECU where fuelling (in my case) is controlled solely by the ECU map.

Steve

 

[Guest]

Get a boost gauge and monitor the boost levels. If its around 1.1 bar
peak / 1.0 sustained under acceleration you should not experience fuel cuts.
Fuel cuts usually kick in at boost levels and amp;gt; 1.3 bar with a std. ecu.

 

[Guest]

Just read your message again. It could be compressor surge, since you say it occurs after accelerating , then backing off the throttle.
If it is ,this is usually accompanied by a very low frequency
noise coming from the exhaust and the associated lag or reduction in acceleration.
Get back on the accleration when this happens and it goes away.

When fuel cuts occur it is a vicious halt to the acceleration as HH6
says. It feels like you have just run into a brick wall and it is no surprise that this could cause engine damage over a period of time

 

[Guest]

Something simpler, it might be your fuel filter is dirty already?

 

[Guest]

I like the WOT abbreviation. What about FOT?

 

[Guest]

Hi all

thanks very much for all this information. After reading all your comments it's definitely no fuel cut that would much more viceous. Also the car never showed this even when it was 0 degree outside. I think it's what Mr. Mime mentioned with the deep tone because my best half mentioned that (never argue with a woman!). AFAIC the explanation from Steve is the reason for that.
I'll monitor it and if it occurs again we'll see. Maybe my mates were just too slow so I had to cruise more than usualhttp://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >

BTW Steve do you run a MOTEC? I just spoke to the mapper who was responsible for the mapping of Manfred Stohl's GroupN EVO when he became Vice World Champion in 98-99. He would map the car to 350hp and 520NM but with uprated internals. Antilag is mapped with throttle 20 degrees open to not loose engine braking completely. Doesn't sound too bad. What do you guys reckon?

Thanks again for your help

Mike

 

[Guest]

Had the same problem with my car and it was standard. The problem lay with the boost solenoid, it had come rusted on the terminals causing the actuator not to release the pressure. The car was reaching 1.5 bar. The solenoid was cleaned and the cae dosnt cut anymore. Also it feels alot better and the my MPG had improved. The car had been stored over christmas and i didnt notice the fuel cuts for a thousand miles.
Just thought id add mu bit.

 

[Guest]

Mike.........although I have a programmable ECU I don't profess to know a great deal myself about how to tune the engine with it, so your comments about antilag don't mean much to me.

I run the Evolink (as in Possum Link) and expect that it produces circa 430/440Nm torque in its current conservative state of tune, so can well believe the MOTEC figures for competition use.

Steve

 

[Guest]

The Group N cars have a 34 mm turbo inlet restriction, so I would expect a road car without that restrictor to produce more power. Also the mapping will have to be adapted to take this difference into account. Dont let them just put in the Gr N programme.

 

[Guest]

If this was any car apart from an Evo the first thing you would do is put a set of plugs in it. 3000k or not don't overlook the basics guys

 

[Guest]

Hi Steve

so I assume the Link has been done by Bob Rawle who has done loads of Scoobs. Obviously it works also on the EVO. Unfortunately we don't have a Link mapper here in Switzerland.

Claudius,

the mapper wouldn't just put the Group N program in it. . He has done it on EVOs for more than 3 years and has done it before on Cossies. He also uses two different types of dynos to get accurate results.
The 350HP is conservative but I'm more interested in torque. With 520NM it should go like stink!! He said with this setup and restrictor (as on GroupN) I would only achieve 260HP. BTW what torque can you expect from the Ralliart Sports ECU?

Cheers

Mike

PS: No hesitation today everything ok, my mate as a passenger got pale and had sweating hands so performance must still be ok. But you never get enough, don't you!

 

[Guest]

My Evo 6.5 is doing the same thing!
I didnt change anything and now, it stutters when accelerating hard.

I thought that it was the fuel and i tried 100 octane and it still stutters on acceleration.
The result being that acceleration is not smooth and seems slower.

I'll try cleaning the solenoid (wherever that is located...)
Any other ideas ?

Thanks

-ron

 

[Guest]

Would a loose spark plug or spark plug wire cause engine hesitation ?

Thanks

- ron

 

[Guest]

A plug lead might, if the plug is loose inthe head you would probably hear a sound like an exhaust blow because of the gasses escaping passed the plug.
Sean

 

[Guest]

I had this this problem when accelerating hard. I changed the plugs and the problem was solved.I think if the spark is no good it can´t burn the petrol properly making the engine go wrong.(I think this is the reason but I can be wrong)

 

[Guest]

Had same problem which again was fixed by replacing the spark plugs. As the plugs wear, the gap gets larger needing more energy to produce a spark. When the engine is under load, the ignition system again needs more energy to produce the spark.

The bottom line is that worn plugs with an engine under load |EQU| hesitation.

Cheers,

Mark

 

[Guest]

As suggested by someone else the problem may be ignition related. I am in New Zealand and have done work on road and race EVO's. What we have struck a lot of is the spark plugs wear which puts huge strain on the ignition system, and causes the spark to fier a hole right out through the side of the HT lead as it goes down inside the head. ( the non-flexible bit) This usually occours at full boost and low rpm ie 3-4000rpm. Then u put a set of plugs in it and it doesnt fix the problem. The holes are sometimes visable if you look very close but the easiest way to test the is to simply borrow some of another car and try them
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