anyone answer the age old question of which i should use?put tesco in last night but only tenners worth as wasnt sure,car seemed to miss the odd beat and slightly slightly hesitant?on optimax its fine but is a lot further away to fill up.could this be a slight little complaint by the scooby as shes not yet fully used to it?and maybe the ecu was having a little nag until she becomes more used to tesco?94 import wrx

 

get a full tank of 99 and reset the ecu. thats how id do it.

stew

 

I agree,
Fill up a couple of times to flush the Optimax through and see how it feels.
Because you have an import are you also putting in some octane booster?

Kev.

 

how do i reset the ecu?
thought i didnt have to put octane booster in every time i put petrol in as long as its tesco 99 or the optimax? am i wrong in thinking this?

 

Only on my 3rd tank of fuel on my PPP Sti (UK) I found so far:

Optimax. Car likes it a lot
Sainsbury's (Ultimate evidentally). Noticeable performance loss.
Tesco 99. In at the mo & seems to like it.

Not scientific, just how the car feels.

 

Its up to you, but your import was running 100 ron in Japan, so over here 98 and 99 ron are a little short, and under heavy boost/redlining it, that is where the detonation will happen...............................and engine rebuild time.

So you have two options, put a bottle of octane booster in your tank every fill up.............or save up and get an after market mappable ECU then it can be mapped to any UK fuel you want it to be.

Hope this helps
Kevin.

 

i use optimax (no tesco99 down here yet) withot octane booster no engine explosions yet. had a cocklink in my old wrx and never had any probs with just optimax

 

I recently switched from optimax to tesco 99. I have an sti 4 with full decat and uprated panel filter. It took afew tanks but I definatley get less det on the knock link with tesco 99. I do use NF octane booster aswell and did with shell. I use 3-4ml per litre.
With optimax + booster, I would get 2 greens and 2 orange on full throttle in 4th. With tesco + booster, I only get 2 greens.

 

I found with the cold weather I was getting a little knock link activity at high revs, had a couple of tanks of Tesco 99 through now and the knocklink has no activity at all in similar situations

 

I use Tesco 99 or Optimax in my MY05 WRX PPP ...... and can't say I notice much if anything between them - the car likes them both

 

I used tesco 99 ron for about 3 months continually during the summer (Winchester was one of the first branches to get it), after a while the car started to feel a bit rough, thought this was down to it needing a major service. However, after service it still felt the same, sort of like something wasn't quite right, also 'raw' ay high revs. Went back to Optimax and after a couple of tanks the car is smoother.

Nick