SiPie

This could be complete nonsense but after a complete hairy moment when overtaking last night (felt like complete fuel cut when floored), although no engine warning light appeared a few people on this site suggested it could have been the ECU bug or(my99).
I checked with my local Subaru dealer if they would run a quick diagnostics check just to ensure everything ok as I seriously wouldn't like this to happen again.

His first question was ... Are you using Optimax and if so for how long? This dealer has had 5 occurences of this happening from customers in the last 2 weeks and the common factor is that they all run on Optimax (COMPLETE loss of power and NOT 0.5 bar as the ECU running on limp mode would indicate).

Could be complete fable but he suggested an immediate switch back to normal SUL. I have ran optimax for last 2k with no problems until last night and engine hasn't even had a cough or splutter for the last 10k.

Perhaps just a bad batch of local fuel but thought it best to warn all you just in case.

Cheers

Re-Bitten Hero

Weird?! Not a pleasant thing to happen though...

I've been running purely Optimax (with only one or two exceptions) since it came out, i.e. about a year ago and 10k miles, and I've had no such problems (MY00 PPP).

Someone posted on here a couple of days ago, experiencing the same thing (I think on an older car) and it was suggested the MAF sensor could be contaminated or bust - but the dealer should have been able to check that with the diagnostics .

I'll bear it in mind... thanks for the warning.

Cheers
Richard

dhorwich

Hi,

All this sounds like is overboost.... the optimax has a higher RON number which means the car can advance the timing and enable the car to run more boost when been pushed, then you hit fuel cut...


Just my 2p worth

Dan

LG John

You know Sipie that maybe isn't as dumb as it sounds. Your car pulled just as strongly as mines in 3rd and 4th gears and I was showing 1.1bar at that time. If yours got a good batch of optimax and some nice cold air through that ITG it's not impossible that she overboosted?

johnfelstead

if its total power loss for a split second then i would say this was fuel surge. Had you just come out of a right hand corner and the tank was indicating 1/2 full or less?

SiPie

Cheers Dan... all these suggestions and more have been banded about and I'm keen to go along with that.
I'm only posting exactly what the dealer said... and until now I have had quite a bit of respect for the dealer as they have been only too helpful and even SAVED !!!! me plenty of cash on occasions.

I agree with you but the dealer did say he has had these 5 copmplaints within 2 weeks.

Just passing it on.

Surely it would be in the dealers interest to get your car in so he could prize some dosh from you rather than just suggest a change of fuel ?

Re-Bitten Hero

Good point - how many revs, what gear? Overboost at about 3000rpm in 4th or 5th is possible... I've got within a whisker once or twice when I've seen the boost hit 19.3psi before stabilising at 18.5psi (cold weather, damp conditions, Optimax)...

Richard

SiPie

John

Unfortunately no.... had been sitting in a queue waiting to overtake, therefore revs held quite high (3k ish) and then floored without changing down, so suggests the ECU ??

Edited to say think I was in 2nd or 3rd for maybe a minute holding 3k waiting for overtaking chance..

[Edited by SiPie - 7/18/2002 6:03:38 PM]

Re-Bitten Hero

If it was overboost, I'd expect this to happen more often in Winter than now - it's warm, which reduces the boost slightly...

Richard

johnfelstead

OK, just a posibility that does cause this problem. To be honest, the fuel used causing this makes no sense to me, unless it is causing overboost due to better spool up. If that is the case then the fix is to stop the overboost by modifying the restrictor in the waste gate, not by putting less eficient fuel in.

SiPie

Thanks for all your input... unfortunatley have to leave work just now(no access to net at home) but will keep my eye on it and hold off switching fuels as think the overboost sounds more likely...

Thanks again

Attu

You wernt in 2nd were you ??? Ive read some where that the ECU can cut the fuel if youve been in 2nd for a while and then boot it,it does this to save the drive train.
The only time Ive had this happen is when ive wound the Dawes up to much and I run Optimax all the time

TonyBurns

iTrader: (3)

Agree with John here,
Ive been running optimax since its come out so ive covered a good 8k miles with it, never had one hicup and my car is an MY00 PPP'd with Scoobymania D/P and a modified restrictor (drilled out by another .1mm).
I think this is the ECU IMHO and not the fuel or else there would be many more people complaining about it

Tony

Scott J Davies

This sounds like a MAF sensor about to go to me what filter are you using?

Bob Rawle

This is nothing more than boost cut, you were at 3000 or so revs and then floored it, in a low gear you caught the turbos sweet spot and the ecu couldn't catch it.

There's nothing more to it than that, Optimax encourages the ecu to run a bit more aggresively, hence if you switch back it goes away, not the fuels fault just the way the car is set up.

So lets not panic about Optimax, it was doing exactly what it was developed for, enhancing your cars performnce, the ecu was not able to keep up though.

Solution is to open out the restrictor slightly, std size is 1.2mm, try it at 1.3mm.

bob

Pitch Black

I've done about 45,000 miles using nothing but Optimax since it came out, and have had no problems. Mines a MY95 WRX, imported from Japan, if that makes a difference?

Paul

[Edited by Pitch Black - 7/18/2002 6:37:32 PM]

Trout...

Optimax - done over ten thousand miles on road and track - nothing but

Trout

Langy

Hmmm, mine did a similar thing to that coming home from t in the park on Sunday night. I've only had the car a couple of weeks but use optimax and having had other turbo'd cars i would def say it was overboost, happened when accelerating in 3rd/4th/5th, very cold night, 2 up full tank of petrol. However, it's never did it since. Strange one that, i'll keep you posted for the future

Scoty

What about fuel surge, could it be that?

TonyBurns

iTrader: (3)

Nope, this definately sounds like the emissions thing kicking in, the trick is to blip the throttle before you go or keep it in a higher gear then down it
Its something that you have to get use to driving around

Tony

LG John

For whoever asked Sipie has an ITG panel filter and a swana back box but that's it......until the modifying bug really sets in

EvilBevel

If it was 2nd gear, then yes, definately emmission thing, as first aired by Pete Croney on here.

Still think it's a crime BTW to build something like that into an ECU. It caught me out a few times as well. Safe overtaking anyone ?

john banks

It is not that slow when it runs lower boost and by the time you get over 5000 RPM it flies up to full boost again - if you are relying on the extra boost to complete your manoevre safely then perhaps it should not have been made at all? Same with a fuel cut whilst overtaking a bus or tractor, it is not that astonishing really?

T-uk

It is not that slow

it is when you are chasing an evo out the hairpin on track.can't you ecutek dudes sort it out by taking it out the map.

SiPie

Thanks again for all responses.

I'm going to hope it was just a 'one off' occurence/ECU/overboost and carry on with optimax and blip the throttle or change up then down after holding high revs prior to any overtaking maneouvre.

But if this continues (even occasionally) I would rather sell the car rather than play russian roulette on the wrong side of the road..... !

LG John

Harsh John! I've tried accelerating through the gears without the turbo spooling up and it's not quick enough for good/safe overtaking. If you want to pass something you need boost and usually a healthy amount of it, IMO of course

SiPie

That is the grey area that confuses me a little.....

John says 150lb of torque still available and 0.5bar boost in but there was nothing like it at all available. This was a tractor travelling at around 30mph and for a good few seconds it would have whipped my *** on a 1/4 mile...!!!

Who knows..!!

Mo

SiPie,

re-read Bobs comments. I used to get the exact same thing if I was sat for a while at 4500k waiting to overtake and then floor it.

MRK

I have occasionally had this problem, with different types of fuel.

And Evilbevel has suggested that its built in to the ecu for emissions.

Can someone please clarify further, as its very disconcerting when it happens, and it only ever happens in 2nd gear!!


M

SiPie

Mo..

Thanks, sure Bob is spot on and just glad nothing too serious (it would appear) wrong with the car.

Thanks again