settings again ezl

[optimusprime]

Hi after a few posts on the forum about the settings on the knob for fuel types .I think i have had answers from most of you on this. But my book Haynes said that all 2.6 engines have trimming socket to be set on number3 thats N on plug. for 95 ron fuel .Most of you have said set it on S .My car as no kat .It said nothing about S settings. Can someone set my mind at rest on this .

 

[grober]

Your car should be set at S for normal UK Fuel >95ron setting the switch to N retards the ignition to allow it to run on low grade fuel without pinking. If you still have doubts use a timing light to check what happens with the two positions.

 

[optimusprime]

Graeme i did fill up with 98 ron the day i took it for its health check [MOT] It was set on N for 95 ron.Would this be the problem with the stuttering problem So now i wil fill up with 95 ron Regular .If it no change then i will put the timing light on .Thank you .

 

[optimusprime]

This was what was confusing me . 3 is letter N

 

[grober]

Running a higher octane than required will do no harm. Running a lower octane such as 91 octane [ don't think if you even get that in the UK now] will result in pinking. Ignition timing is related to compression ratio and fuel octane rating . A long time ago after my M102 had its head skimmed for a head gasket replacement I was advised to use the higher 98 octane fuel rather than the 95 stuff. I suggest you check the ignition timing with a timing light against the recommended values for 95 octane fuel.

 

[optimusprime]

fuel ron

Grober this head was done a few years ago also.

 

[optimusprime]

Very hard to read the list you sent,even in my pictures, as i have exploded it but it goes blurd.Is it for none kat engine.

 

[grober]

http://www.startekinfo.com/StarTek/outside/11832/Resources/201Create/PDF/50006.pdf
PAGE 5.
catalytic converter cars German KAT HAVE TO USE UNLEADED FUEL that's all
Leaded fuel has normally a higher octane rating 97/98 which means cars without a KAT can run a few more degrees advance.
This is academic as you can't buy leaded now- only 95 or 98 unleaded.
If your dial has S and N use the S setting if it has numbers use 3

 

[optimusprime]

Grober i will switch it over to S again. I have been on all afternoon one web page or forum , to find something like my problem ,to no avail.I dont know what to do first ,injectors ,i have only got the inserts and o rings and holders . Then i was looking at relays for the fuel pump . Then i think about when it happened ,i dont know . Or was it the time it would not start and i had the chap from auto electronic to remove the immobiliser .Could this be something to do with it ,i just dont know. I must start some place .Its just a nagging problem and nothing realy .As it starts runs nice, other than that. I am just a fussy old git.But wont stop till i put it to bed.

 

[GadgetBoy]

That's very like the octane adjuster on GM/Rochester throttle body injection systems. As has already been said all does is advance/retard the ignition by a few degrees. With UK Unleaded or Super-Unleaded you won't notice any difference.

 

[optimusprime]

Just to cap this .I set the trimmer socket to S its not very good to start up on this . On N it starts up but dips down and starts up fine after.So i left it there for now.

 

[ray_hennig]

Just to cap this .I set the trimmer socket to S its not very good to start up on this . On N it starts up but dips down and starts up fine after.So i left it there for now.

In Kidderminster you can get 95 fuel. In your shoes, I'd set the thing to 'S' and then find the real cause of the problem.

Also, I think that low grade fuel, as stated in that info sheet, is not available in the UK - 95 or 98 are the norms.

Is the HT in 1st class condition?

Check the easy, cheap things first, before getting gloomy and thinking that high priced parts are faulty.

Bonne chance.

RayH

 

[John Jones Jr]

For what it's worth I've always had my mine set at 'N' when using 95 fuel. That's on a cat 2.6, non cat 3.0 and non cat 2.5-16.

 

[ray_hennig]

For what it's worth I've always had my mine set at 'N' when using 95 fuel. That's on a cat 2.6, non cat 3.0 and non cat 2.5-16.

That doesn't sound right for the UK. In the USA, regular fuel is far less octane than UK. See what Grober said up ^^^there somewhere but I have a feeling that that refers to the USA.

Am I right Grober, or talking b0ll0cks?

R

 

[stwat]

'S' is the correct setting for all cars in the UK. 'N' is for lower RON fuels of 91 or lower ron.

 

[John Jones Jr]

Euro engines of that period were designed to run on a minimum of 95 RON which would be classed as minimum premium fuel. Thus I use the 'N' setting, as I use 95 RON. Better safe than sorry. Premium fuel 98 RON or better the 'S' setting would be appropriate.

 

[grober]

All fuel in the UK is >95 octane afaik. Running at the N setting will do no harm but as far as I understand retards the ignition timing by about 4/5 degrees meaning the engine may run hot with slightly reduced power . Running at the S setting should optimise the ignition timing for higher octane fuels. If folks are concerned about exactly what's happening a sure way is to get a timing light and check the degree of advance on the two settings and check it against the recommended setting . One thing which might might effect timing/ pre-ignition for example would be if the head has been skimmed a couple of times following say a head gasket renewal which effectively raises the compression ratio from standard. If you then started to experience " pinking" on 95 on the S setting it would be advisable to to run on 98. -- Ignition timing has always to be optimised in relation to the octane of fuel being used and the compression ratio of the engine.

ps for pre-cat cars it may also be necessary to retard the ignition timing slightly to run on standard unleaded 95 octane as leaded fuel was 97 octane. That or run 98 unleaded. Cars equipped with catalytic converters from the factory should have appropriate timing and compression ratio to run on standard 95 octane unleaded fuel unless it specifically recommends 98 octane.

pps this may in fact be the source of confusion since those rotary ignition timing switches existed during this leaded to unleaded transition period meaning that early instructions may appear to contradict later ones.

 

[optimusprime]

Just replaced the fuel pump relay .I can now rule this item out as being the cause of dirty start . Another web site information was the OVP relay ,as i have a spare new one i will try that next. Its like all plugs fire up it starts and then it drops down and then up to normal revs .

 

[jonnyboy]

that does sound like it could be OVP - very similar to my 300SE's reaction to a bad one...

 

[optimusprime]

I have eliminated Ovp ,the Fuel Pump Relay and .Plugs . cleaned the distributor and all the leeds. Once it as started it runs normal I have just picked up a new petrol filter and new accumulator .Thinking now of fuel starvation after shut down. Just going to book the car in to our local garage to get them put in, because i have no pit or ramps t I want to do this before i fit new injectors and the injector holders, plus the o rings. I will let you all know the outcome after this.