Discussion
I went through all this trauma.
Depending on which ECU is fitted, you can run some of the 2.9 v6 engines on ordinary unleaded but you need to check the ECU model number.
Have you got a bible yet, if not drop down the panel in the passenger well and have a look and come back to the forum with the number and somebody will look it up for you.
Or if you wish Email me the numbers.
Welcome, it is fun you know. well ish
Depending on which ECU is fitted, you can run some of the 2.9 v6 engines on ordinary unleaded but you need to check the ECU model number.
Have you got a bible yet, if not drop down the panel in the passenger well and have a look and come back to the forum with the number and somebody will look it up for you.
Or if you wish Email me the numbers.
Welcome, it is fun you know. well ish
spivvy said:We should start another raffle, a syndicate actually. The money buys a trailor with a big reinforced fireproof mirror that we can take turns owning for a week at a time, and hauling it along behind us watching for dragonfire
ran mine on unleaded for a while and it rattled and ran awful
,switched to optimax and it runs nice now ands pops and makes noises![]()
still trying to see if it spits flames

The ECU is 86GB 12A650 AC type so I assume the modification is required unless it has already been done, or will it still run OK on Optimax. What is Optimax?
If I have to do the modification in the book, what does the EEC IV module look like.
I never thought that putting fuel in a car could be so difficult and it's almost empty so I can't use her.
If I have to do the modification in the book, what does the EEC IV module look like.
I never thought that putting fuel in a car could be so difficult and it's almost empty so I can't use her.
Optimax is shell`s brand of a higher octane brand of unleaded, some have super unleaded, rating I think is 97octane, were as normal unleaded is 95.
I live on the isle of wight and I have yet to find a garage selling the stuff, so whenever I go to the mainland she gets a treat and is filled up, it goes much better!
I live on the isle of wight and I have yet to find a garage selling the stuff, so whenever I go to the mainland she gets a treat and is filled up, it goes much better!
Yep
You will need to either run on super unleaded or Optomax unless you retard the timing 4 degrees.
This must not be done with a strobe, you have to earth the brown/red wire that is one of the wires attached to a round 3 pin plug wiring harness that will be floating arround next to the ECU.
The ECU is inside a drop down panel in the underside of the dash in the passenger footwell.
In answer to the question about pumps cutting out, the S series seems to have a larger filling hole in order to accept the leaded petrol fuel nozzle, the smaller unleaded nozzle seems to pump faster, thus causing blowbacks, nothing you can do I'm afraid.
You will need to either run on super unleaded or Optomax unless you retard the timing 4 degrees.
This must not be done with a strobe, you have to earth the brown/red wire that is one of the wires attached to a round 3 pin plug wiring harness that will be floating arround next to the ECU.
The ECU is inside a drop down panel in the underside of the dash in the passenger footwell.
In answer to the question about pumps cutting out, the S series seems to have a larger filling hole in order to accept the leaded petrol fuel nozzle, the smaller unleaded nozzle seems to pump faster, thus causing blowbacks, nothing you can do I'm afraid.
I agree, my S3 does not run great when cold, it does splutter a bit but I am waiting to check out the airflow sensor and also the sensor thingy that messes with the fuel mixture when hot running.
I'm going to plug the car into the Ford computer to see which, if any of the sensors are kuput.
If nothing found, I will just run it on Optimax but I am nervous because I have heard about older cars not liking the popping and banging from this fuel and burning out valves.
I'm going to plug the car into the Ford computer to see which, if any of the sensors are kuput.
If nothing found, I will just run it on Optimax but I am nervous because I have heard about older cars not liking the popping and banging from this fuel and burning out valves.
Not sure about the specifics of the ECU numbers but my 1990 S3 was set to run on standard unleaded and I think most others are as well (early cars set for 4*?). As I understand it, unless you have the timing adjusted for super unleaded, there is no performance enhancement using shell optimax or super unleaded.
Using the higher octane rating should not cause any damage (except to your wallet) and all the 2.9's can run on unleaded.
p.s. nozzle upsidedown worked for me as well.
>> Edited by chris_chim on Monday 29th November 07:58
Using the higher octane rating should not cause any damage (except to your wallet) and all the 2.9's can run on unleaded.
p.s. nozzle upsidedown worked for me as well.
>> Edited by chris_chim on Monday 29th November 07:58
chippy wedge said:
Speaking of puting fuel in the car...does anyone here have trouble getting the fuel in without it cutting out at the pump every 2 seconds...is there a knack to it???
Fun when you forget and it blow back over your paintork causing you to run around and wipe it up. I always picked up a few paper clothes just in case, as some pumps go ballistic. Even so it takes an age to fill such a small tank... You can watch a 90 gallon truck fill up quicker!
Always ran mine on standard 95 RON unleaded (Shell if possible) without problems, tried Optimax a few times and it felt marginally smoother but not enough to make a difference.
Had no cold start problems with either fuel.
chippy wedge said:I keep the nozzle 1 inch from the entrance of the fuel cap, twisted slightly so I can watch the fuel go in, angled to squirt the upper roof so the fuel corkscrews down into the tank.
getting the fuel in without it cutting out at the pump every 2 seconds...is there a knack to it???
A little experimentation and you should be able to maintain 80-90% of full pressure. Otherwise, like you say, it takes a while to fill up as the fuel just bubbles back up and the pump cuts out.
I agree with the rotating the pistol grip from the pump through 90 or 180 degrees when putting it in the filler.
I would be reluctant to use supermarket petrol here in the UK as there is so much written regarding lack of detergent additive in said petrol and its octane number. (Remember, the BS only requires the octane number to fall within a range over a sample period - or that's my understanding, at least!)
Optimax and Texaco super both contain sufficient additive to keep the injectors clean.
Optimax guarantees a minimum RON of 98.
I would be reluctant to use supermarket petrol here in the UK as there is so much written regarding lack of detergent additive in said petrol and its octane number. (Remember, the BS only requires the octane number to fall within a range over a sample period - or that's my understanding, at least!)
Optimax and Texaco super both contain sufficient additive to keep the injectors clean.
Optimax guarantees a minimum RON of 98.
nawarne said:
I would be reluctant to use supermarket petrol here in the UK as there is so much written regarding lack of detergent additive in said petrol and its octane number.
Won't touch supermarket cack for the fun cars unless I have no choice. Way back when (around 8 years back) I was filling a petrol can with supermarket unleaded and spilt some on the top, I came back from paying to find the fuel had evaporated and left a dark powder substance in its place...
Things might have changed but something like that could not be good for injectors

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