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sketchmyster
 Post subject: high octaine fuel
PostPosted: Mon Feb 18, 2013 2:04 pm 
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Hi i have a 1992 jdm jap import gt4 st185 very rare edition (has (r) on vin plate at teh end) with this in mind i was told to run it on high octaine fuel first time i did this the afm jammed causing serious overfueling went back to standard unleaded car got sorted and has been running great forced to put in high octaine due to no normal unleaded at the garage driving home pop and again the car is no overfulling again the only diffrence is fuel the main qustion is does anybody know why this might happen plus anybody know how to un jam a afm

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two_OH_five
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 2:33 pm 
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Location: drinking devil fuel
Car Model: ST205
Do you have electric windows?

Also, what's you definition of high octane fuel?
Mine would be 105RON+ but that only comes out of drums, not fuel pumps

If you mean Optimax, BP Ultimate level of high octane then you should always be running this quality of fuel
JDM import cars are programmed to run on the higher octane fuels available in Japan. Typically 100RON which is still higher than we have in the UK but at least closer on our 98/99 quality stuff

Using low grade Tesco value horse petrol risks poor running as the ecu slaughters the ignition map in an attempt to prevent the engine from grenading

As to why the AFM sticks on good fuel, I would hazard that the engine is running better and consuming more air and hence taking the AFM into areas that don't get used when running cheapo Dobbin juice:-)
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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 2:40 pm 
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high octaine as in the bpultramax and things like that dont think the previous owner ever ran it on anything other than bog standard unleaded getting a new afm as it is the second time its jammed would you consider getting anything else as would prefer to use the higher grade unleaded

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jgtcracer
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 5:27 pm 
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Location: Chirnside, Scottish Borders
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anything that comes out of a pump at the petrol station should work without problems, at two_oh_five said, you would be far better off using highter octane, quality fuel such as shell vpower though (for engine safety if nothing else).

If I ever get caught at a petrol station without a high octane alternative I just put a tenner in to get me to the nearest/most conveniant shell to be honest. Did you add an additive to 95ron fuel?

Are you still using original AFM

cheers :D

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Gary ST165
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 5:51 pm 
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Location: South Wiltshire
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sketchmyster wrote:
Hi i have a 1992 jdm jap import gt4 st185 very rare edition (has (r) on vin plate at teh end)



http://www.turbocelica.nl/st185models.htm#gt-four-rally

Quote:
GT-Four Rally

The GT-Four Rally was introduced as a competition-based version of the normal GT-Four, which meant is was lighter and quicker. To achieve this, electric items such as electric windows and mirrors were changed with manual parts. ABS was not available and the narrow body model had no sunroof, fog lights or rear windscreen wiper. Even hubcaps and mudguards were left off to reduce the weight. These changes made the GT-Four Rally 40 kg lighter than the normal Four. Also, the first four gears got shorter ratios to allow the car to accelerate even faster. All Rally models had steel wheels as standard. The price of an early narrow body Rally was 2,385,000 JPY. The (heavier) widebody version with yellow fog lights as standard was available at 2,686,000 JPY plus taxes.


Model code E-ST185-BLMVZR (narrow body) or E-ST185H-BLMVZR (widebody)
Production September 6, 1989 ~ August 1991 (narrow body) or August 1991 ~ May 1993 (widebody)



Nice. It is likely to be a rare "lightweight" Rally 8)




Best advice is to use the Super Unleaded fuels, and either inspect and strip down / clean the AFM or pick up a replacement from www.tcbparts.co.uk

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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 5:56 pm 
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it is a rare lightweight rally and am picking up a replacement afm on thursday but again with the fuel on high octaine no addative it makes the car overfuel and jams the afm

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two_OH_five
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 6:15 pm 
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A change of fuel can't jam the AFM as fuel goes nowhere near it

What it can do is make the engine perform better which could in turn make a gammy AFM move into areas where it doesn't normally go causing it to get stuck

What are the symptoms exactly?
- you fill it up, start the car and the AFM is immediately stuck and the car is over fuelling
- you fill it up, start it and everything is OK. After a blat the AFM is stuck and the car is over fuelling
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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 6:18 pm 
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A change of fuel can't jam the AFM as fuel goes nowhere near it

What it can do is make the engine perform better which could in turn make a gammy AFM move into areas where it doesn't normally go causing it to get stuck

What are the symptoms exactly?
- you fill it up, start the car and the AFM is immediately stuck and the car is over fuelling
- you fill it up, start it and everything is OK. After a blat the AFM is stuck and the car is over fuelling



i filled it up, start it up and everything was ok for a few miles approx 12 then overfulling started car got hot pulled over got rescued then the car will start but put ur foot on the accelartor and it drops revs or will only rev to 1000 rpm

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jgtcracer
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 6:36 pm 
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Location: Chirnside, Scottish Borders
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if your picking up another afm on thursday, i would wait and plug that in 1st before fiddling with anything else, cant see how a change of fuel would directly effect the afm and jam it

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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 6:38 pm 
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thats what happend last time i belive they said (the garage that repaired it last time) the afm is telling the e.c.u to add more fuel but its adding to much

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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 6:40 pm 
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going to try by putting normal fuel mixed with high octaine see if that helps then slowly convert to high octaine fuel bit by bit

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two_OH_five
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 7:40 pm 
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It's probably worth a reset of the ecu (pull the defi fuse for a bit) just in case it's learned some long term corrections based on poor fuel quality
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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Mon Feb 18, 2013 7:58 pm 
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thats an idea might leave it out over night see if that helps

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sketchmyster
 Post subject: Re: high octaine fuel
PostPosted: Tue Feb 19, 2013 11:20 pm 
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well big test tomorrow had the efi fuse unplugged for a day and cleaned the afm so fingers crossed it runs but it still will have 1/4 tank of high octaine fuel

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