Could anyone tell me if putting 95 in tank instead of the usual 99 could be causing my terribly low and rough idle (about 400-500rpm)?

need more info is your's (j spec/uk spec) n/a- tt

 

modded un-modded etc?

Makes no difference to mine that I can notice, I just don't give it high rpm until I can get some high octane fuel in the tank. No engine mods on mine.

 

Paul

need more info is your's (j spec/uk spec) n/a- tt

 

modded un-modded etc?

 

j spec tt auto. k&n air filter + dump valves only engine mods.

I'd be putting at least (97) ron in , but im not saying this will solve ur' prob

 

i've read on so many threads that 97 is best for j-spec as they are mapped to run on higher than 95 ??

 

With mod's i'd put 97 in any way , but im sure all dont!!

 

I have a j spec n/a and it always has 97 or 98 in it

 

hth:D

 

plus have a search there where some recent threads on the matter;)

Try disconecting the MAF, could be knackered

No I doubt that the ron is your problem.

 

What is it like underload? Missing etc?

No I doubt that the ron is your problem.

 

What is it like underload? Missing etc?

 

sometimes misses but think thats due to the ambient temp sensor goin nuts constantly..... only ever used to rest at -86 but now is constantly changing.

clean the connector on the ambient temp sensor, under the offside front bumper, disconnect clean terminals reconnect should sort it.

I ran mine on 95 for 2 years with no problems at all! I use 99 now tho, cos i am running higher boost etc...

No, Fuel RON can have no affect on idle.

 

it could however be a number of things - Vacumn/boost leak , Missfire (1 or more cylinders not firing from missing spark or fuel), sticking Idle valve.

 

Sounds to me like a missfire, you need to check that all cylinders are firing. Pull of a coilpack connector 1 by 1, if you remove one that does not make a difference then that is the faulty cylinder.

 

sometimes misses but think thats due to the ambient temp sensor goin nuts constantly..... only ever used to rest at -86 but now is constantly changing.

 

clean the connector on the ambient temp sensor, under the offside front bumper, disconnect clean terminals reconnect should sort it.

 

Ambient temp sensor has no affect on the the engine running at all. It is connected to the Climate control display for showing outside temperature only.

 

The Water temp sender on top waterpipe does however have an affect on fuelling.

Edited January 18, 200916 yr by Yowser

j spec tt auto. k&n air filter + dump valves only engine mods.

 

Fuel RON should not make much difference; I think (and someone will correct me if I'm wrong) but on a standard car the ECU will do something clever to compensate for the lower octane fuel.

 

Higher octane fuel could improve performance and reduce detting in hot summer temperatures though. My UK spec runs perfectly on 95 RON and to be honest there is no point using super/V-power etc. But when outside temp reaches 28 degrees it definately runs better on super......

 

Richard:cool:

My car ran like s**t the day i had to put 95 in as both BP's near me were out of Super Duper Unleaded! i dreaded every moment until i got some nice stuff in :D

 

But as stated on previous threads Jap models tend to be worse off but some are fine(as ECU is programmed to over 100RON i think) so our best stuff here in the UK is still crap to it!!!