What fuel should actually be used? 99, 98 or 95

[texaxile]

Hi,
In my other thread I stated I've just got hold of an 04 WRX PPP. now, here's my question(s):

If the previous owner had run 95 in it and I'm now running Momentum / Vpower , will the ECU learn to run with the higher octane fuel, or is it needing a remap for it?.

Secondly, it's thrown a knock sensor fault code up and despite all my interweb searched I can't find out what type / part number I need to replace it, or even if the 04's had one (all info out there stops on 02's). It happened after I disconnected the battery to replace some bulbs, after it reconnected I took it for a drive and the CEL came on, so I used my very cheap and nasty OBD2 reader and got the code. I've left it on and not cleared it.

As a precaution I've not driven it on boost since, not only that I'm still waiting for Opie to deliver my 10W40 helix anyway as it's not been properly serviced for yonks.

[TEKNOPUG]

What's the code?

There are 2 sensors, predictably and post cat. The post cat just tells you that there is a potential fault with the cat or the sensor. It can be reset and ignored. The pre-cat one though sends data to the ecu and will effect running, do it should be replaced.

[texaxile]

Hi Teknopug

It came up as a knock sensor fault on my obd2 system, but the code it gave me doesn't correlate with the Subaru code 22. It's a cheapo ebay job , and the code it gave me I had to cross reference with a list it came with, when I looked it up on the list it just said "knock sensor error".
I think I'll run it into my friends workshop and get his snap on gear plugged in.

Whereabouts is the pre cat sensor, is it under the TMIC down on the block?.

Cheers for the quick reply mate.

[TEKNOPUG]

texaxile said:

Hi Teknopug

It came up as a knock sensor fault on my obd2 system, but the code it gave me doesn't correlate with the Subaru code 22. It's a cheapo ebay job , and the code it gave me I had to cross reference with a list it came with, when I looked it up on the list it just said "knock sensor error".
I think I'll run it into my friends workshop and get his snap on gear plugged in.

Whereabouts is the pre cat sensor, is it under the TMIC down on the block?.

Cheers for the quick reply mate.

I just use a cheap elm237 bluetooth OBD2 reader and the Torque App on my phone. Works perfectly with minimal outlay.

The pre-cat is in the Driver's side exhaust. There is an inspection panel in the wheel arch that allows access. They can be very difficult to remove without heat and often strip threads. You want to use genuine Denso sensors - false economy buying anything else.

I got mine from http://www.importcarparts.co.uk/ (for 2002 WRX)

Front sensor:ICP4822
Rear sensor:ICP5053

I've yet to fit the rear one. I get sporadic CEL's from it over the last 2 years but I just reset it. It's pasted 2 MoT's so I don't think it's the CAT at fault, much more likely the sensor. I've got a Miltek system to fit at some point, so I'll fit the new sensor then.

[texaxile]

Hi Teknopug
Thanks for the info mate, I appreciate it. I read about knock sensors on early cars being prone to failures and can be damaged through overtightening, but I always thought O2 / Lambda sensors were in the exhaust and knock sensors attached to the block.

I'll run it in this week anyway and get a proper code read. I thought about using Torque ages ago but my crappy Sony phone has run out of storage space, by all reports it seems to be a great little app.

[TEKNOPUG]

My bad - been reading this on my phone whilst out and about - didn't even see you had mentioned "knock"....

[Ahbefive]

tonyb1968 said:

Yeah ok, as you are not reading anything the OP has put down, ie the exhaust is still the twin pea shooter type, which as its stupidly restrictive with that and its 3 cats, it wont be remapped as there is no benefit to be had.

All you have done is said that the OP MUST run his car on sul, if you actually read my first post, post 3 on page 1, its the correct information for this car on which fuel it can run.

Of course there is performance benefit to be had from remapping alone, albeit less with the standard exhaust.

And please show me where I said he "must" run his car on SUL? I just advised its whaI would do and pointed out the negligable cost saving.

You really just have to be right don't you? even though you know no more about the facts of this particular car than anyone else. I suggested it was the OP's decision to make and told him I wouldn't use 95 on a turbocharged petrol car.

I bet you could have an argument in an empty room.

[tonyb1968]

Ahbefive said:

Of course there is performance benefit to be had from remapping alone, albeit less with the standard exhaust.

And please show me where I said he "must" run his car on SUL? I just advised its whaI would do and pointed out the negligable cost saving.

You really just have to be right don't you? even though you know no more about the facts of this particular car than anyone else. I suggested it was the OP's decision to make and told him I wouldn't use 95 on a turbocharged petrol car.

I bet you could have an argument in an empty room.

Its great that you know more than the manufacturer of said car, its a standard car and as such can run 95ron fuel, which was my point to start with, if its designed to run 95 then it will happily run 95, 97 has some benefits but not necessarily for a standard car with 3 cats and a stupidly restrictive exhaust system. If you read what the OP put, momentum runs poorly in his car and thats 99 ron. Higher isnt always better but its down to the owner, my advice has been true and exact to how this car can operate.

[Ahbefive]

tonyb1968 said:

my advice has been true and exact to how this car can operate.

Yet you said you get no rewards from remapping an otherwise standard car. This is untrue to start with.

[texaxile]

TEKNOPUG said:

I just use a cheap elm237 bluetooth OBD2 reader and the Torque App on my phone. Works perfectly with minimal outlay.

The pre-cat is in the Driver's side exhaust. There is an inspection panel in the wheel arch that allows access. They can be very difficult to remove without heat and often strip threads. You want to use genuine Denso sensors - false economy buying anything else.

I got mine from http://www.importcarparts.co.uk/ (for 2002 WRX)

Front sensor:ICP4822
Rear sensor:ICP5053

I've yet to fit the rear one. I get sporadic CEL's from it over the last 2 years but I just reset it. It's pasted 2 MoT's so I don't think it's the CAT at fault, much more likely the sensor. I've got a Miltek system to fit at some point, so I'll fit the new sensor then.

Teknopug, you were right all along, it was the P0031 code which was picked up along with p0031(p) (which I think means pending). Either way the O2 sensor is bksed and I'm going to have to shell out for a new one.
One question, is it worth checking the voltage coming out of the harness to the sensor before spunking nearly £100 on a new one?, are wiring issues very often associated with this fault or is it almost always the sensor? reason I ask is because the sensor actually looks fairly new and has the Denso code of DOX357 on a label, but there seems to be another option, DOX0306. Any help appreciated...

[vxr2010]

the three jdm subarus i've had , have been fine on shell or tesco 99 before they we re mapped , plus above comment about mapping a standard car , it does make a lot of difference mapping a standard car , a cat back system adds to that

[TEKNOPUG]

texaxile said:

TEKNOPUG said:

I just use a cheap elm237 bluetooth OBD2 reader and the Torque App on my phone. Works perfectly with minimal outlay.

The pre-cat is in the Driver's side exhaust. There is an inspection panel in the wheel arch that allows access. They can be very difficult to remove without heat and often strip threads. You want to use genuine Denso sensors - false economy buying anything else.

I got mine from http://www.importcarparts.co.uk/ (for 2002 WRX)

Front sensor:ICP4822
Rear sensor:ICP5053

I've yet to fit the rear one. I get sporadic CEL's from it over the last 2 years but I just reset it. It's pasted 2 MoT's so I don't think it's the CAT at fault, much more likely the sensor. I've got a Miltek system to fit at some point, so I'll fit the new sensor then.

Teknopug, you were right all along, it was the P0031 code which was picked up along with p0031(p) (which I think means pending). Either way the O2 sensor is bksed and I'm going to have to shell out for a new one.
One question, is it worth checking the voltage coming out of the harness to the sensor before spunking nearly £100 on a new one?, are wiring issues very often associated with this fault or is it almost always the sensor? reason I ask is because the sensor actually looks fairly new and has the Denso code of DOX357 on a label, but there seems to be another option, DOX0306. Any help appreciated...

Start another thread

[texaxile]

lol cheeky sod, ok good idea.

[V10 SPM]

I ran my 2009 STI Type UK on 95, 97 and 98 fuel for 6 years, I never noticed any difference whatsoever in performance, economy or reliability.

[tonyb1968]

Ahbefive said:

tonyb1968 said:

my advice has been true and exact to how this car can operate.

Yet you said you get no rewards from remapping an otherwise standard car. This is untrue to start with.

Yeah... try reading STANDARD car, mapping just that will give you no real gains, you have to MODIFY the car and then MAP or else you will be stuck with a restrictive exhaust system and a waste of money on a map giving you about 10bhp.

[Ahbefive]

tonyb1968 said:

Ahbefive said:

tonyb1968 said:

my advice has been true and exact to how this car can operate.

Yet you said you get no rewards from remapping an otherwise standard car. This is untrue to start with.

Yeah... try reading STANDARD car, mapping just that will give you no real gains, you have to MODIFY the car and then MAP or else you will be stuck with a restrictive exhaust system and a waste of money on a map giving you about 10bhp.

Wrong.

[tonyb1968]

Ahbefive said:

tonyb1968 said:

Ahbefive said:

tonyb1968 said:

my advice has been true and exact to how this car can operate.

Yet you said you get no rewards from remapping an otherwise standard car. This is untrue to start with.

Yeah... try reading STANDARD car, mapping just that will give you no real gains, you have to MODIFY the car and then MAP or else you will be stuck with a restrictive exhaust system and a waste of money on a map giving you about 10bhp.

Wrong.

Shows how much you know about these cars, ie sweet fa.

[Ahbefive]

Considering I have one its obvious I know a great deal more than you. A remap on a standard wrx can yeild 25bhp over standard. Anyone can look that up on google and see that you are talking nonsense.

[Pig benis]

Hello Subaru folks

I have now had my Impreza for 3 months and in the time it has used a LOT of fuel. Which has given me the opportunity to sample different fuels, and here are my findings -

Tesco momentum - the car runs smooth and feels like it should do, but the MPG is shocking
Tesco unleaded 95 - the car runs exactly the same as above, but I will get on average 40+ miles more per tank
BP Ultimate - No different to Momentum
Bp unleaded - Juddering on idle

The thing that surprised me the most is the Tesco unleaded. My car ran perfectly fine, and I got more MPG on every fill up. I did make sure that I put two tanks of this stuff into my car before I started noting the figures, as I still has 1/4 tank of Momentum. Why would my mpg have increased? It goes against all the advertising, and also the car felt perfect.

My Subaru is box standard, so maybe it is just the mapped cars that need to run the more expensive juice?

[TEKNOPUG]

Pig benis said:

Hello Subaru folks

I have now had my Impreza for 3 months and in the time it has used a LOT of fuel. Which has given me the opportunity to sample different fuels, and here are my findings -

Tesco momentum - the car runs smooth and feels like it should do, but the MPG is shocking
Tesco unleaded 95 - the car runs exactly the same as above, but I will get on average 40+ miles more per tank
BP Ultimate - No different to Momentum
Bp unleaded - Juddering on idle

The thing that surprised me the most is the Tesco unleaded. My car ran perfectly fine, and I got more MPG on every fill up. I did make sure that I put two tanks of this stuff into my car before I started noting the figures, as I still has 1/4 tank of Momentum. Why would my mpg have increased? It goes against all the advertising, and also the car felt perfect.

My Subaru is box standard, so maybe it is just the mapped cars that need to run the more expensive juice?

Which Subaru?
How many miles to tank are you getting?
How are you measuring MPG?
what roads are you driving?