Eagle7

One thing that troubles me with my car (UK MY00) sometimes is when accelerating hard if you change gear and then reapply the power, the car accelerates again for a short time (half a second or so) then there is no power for about half a second. Then it continues to accelerate as normal.

What do you think is causing this as it is a very strange sensation? A bit like when you **** up a gear change

tweenierob

Have you got an after market dump valve??
Rob
Probably turbo lag...

teddykiller

hi dude check out my thread m8, sound familiar????http://www.scoobynet.co.uk/bbs/thread.asp?threadid=114963



[Edited by teddykiller - 7/21/2002 4:01:09 AM]

Pavlo

Overboost...

You are getting a spike in te boost, ECU cuts fuel for while then you are off again.

If it is overboost, more likely to happen in the higher gears.

I am sure John banks will reply, and I thnk he pobably has some threads on here you can look at.

Easily fixed, don't panic.

Paul

fubar

Actually, on a standard car, I believe this is normal.

Many new drviers have commented on a similar thing, and whilst on modified cars, some of the above comments may be true, on a standard car it is a 'feature'.

The ECU has a feature built in where it tries to save over-stressing the transmission/diffs. SO if you try to really push it though the cars, the ECU will momentarily reduce power during shifts.

My car does the same. (MY99)

I find I can avoid it by not backing of the accelarator as much when changing - which is obviously not good for the car.

It does feel exactly as you say - as if you've missed the gear. That's just how its meant to work - unless like I said, you really change quick.

Edited to say: Do a search for the word HESITATION. The topic has come up lots of times, and various answers.


[Edited by fubar - 7/21/2002 9:13:51 AM]

john banks

Lag, overboost, emissions half boost, fuel cut, fuel surge are all possibilities, and without a boost gauge at least it is difficult to say.

Eagle7

ok some more info on my car. I have the boost increased to peak at 1.2 bar(properly tuned APEXi S-AFC & AVC-R), I have a HKS SSQBOV vent to atmos dump valve. I also have a Blitz induction Kit. I have looked at the Boost guage and it never peaks over 1.2.

However, this is the only problem I ever have with the car, this hesitation after changing gear while under acceleration.

If it is one of the things mentioned, what can be done to improve it?

it doesnt sound like turbo lag to me because the acceleration is constant, even after i have changed gear for half a second or so and there is no power whatsoever for about half a second then. Also I havent seen any blue smoke and it is only a momentary loss of power. Sounds like some kind of fuel cut is likely, whether due to overboost, fuel surge or the ECU 'feature' or something else.

thanks

Dale

[Edited by Eagle7 - 7/21/2002 1:31:40 PM]

peppermint scoob

My car has the same power loss, I also have a blitz induction kit and I am told the air filter sucks air in to fast for the E C U to get petrol to the engine dont know if this is right. I have also got full pro drive kit any advice would be gratefull

peppermint scoob

My car has the same power loss, I also have a blitz induction kit and I am told the air filter sucks air in to fast for the E C U to get petrol to the engine dont know if this is right. I have also got full pro drive kit any advice would be gratefull

mutant_matt

I suspect you are hitting the fuel cut. To see, try this out. Drive along a long straight (empty) bit of road in 3rd at about 4000rpm. Take you foot off the throttle and immediately, floor it again and let the revs build. If you look at the boost gauge, you will probably find it's right on 1.2bar. After about 2 seconds, if it's the fuel cut, this will happen. If it doesn't happen (and even if it does), try the same in 4th and if possible, 5th (as it'e more likely to happen in 4th and 5th).

If this is taking place without the gear change then you know you are overboosting and the fuel cut is kicking in (something like if held for 2 seconds at 1.2bar or more.....). Turn down the boost a fraction should sort it.

Matt

GeeDee

iTrader: (2)

Sounds exactly like mine. Fuel surge.

Does it happen on a full tank?

It can happen to me whenever my tank gets to around quarter full or less. At around mid revs in second I sometimes lose all power momentarily with a hell of a jolt. Thereafter no problems 'til next time.

Graham (MY99 WRX - A proper one)

mutant_matt

You don't get fuel surge in a straight line though do you? (and not in a straight line just after a bend )

Matt

MorayMackenzie

yes, you do get it in straight lines too.

The lower the fuel level, the worse the problem... I try to keep it filled above the last quarter level. Low fuel levels will also mean higher fuel temperature, as the smaller amount of fuel is recirculated through the engine bay and back... this also doesn't help.

DemonDave

iTrader: (13)

Had the same problem ... swapped to a MY98 ecu (Or tek1) and the problem went away !

mutant_matt

Didn't know that Moray, as I've only ever experienced it coming out of corners on the track (and never in my car for some reason).

Matt

GeeDee

iTrader: (2)

The effect in a staight line also depends on the acceleration as well as tank level.

I imagine a WRX has a touch more acceleration than a UK car!

Graham (MY99 WRX - a proper one)

Eagle7

not than my UK car, it aint normal!

Moles Dad

gdavey, what a load of 8ollock$ !!!

harvey

iTrader: (48)

With less than 20/25litres I can get fuel surge on hard acceleration. This is also evident particularly on right hand coners pulling lots of g.
In a straight line it is obviously dependant on how much acceleration you have too and to a certain extent the level of mods affecting fuel use.
On track I can average less than 8mpg.

GeeDee

iTrader: (2)

Moles Dad - Why?