Tim_

I'm new to Subaru's so apologies for the questions!

I've got a JDM STI (Bug) and although the map has been checked by the importer and it's running fine on V-Power for the 10 months it's been in the UK I've started thinking about getting the engine checked again to make sure there's nothing lurking before it becomes a problem. I've spoken to a reputable specialist who's advised they can do a map check, diagnostics and a couple of runs on the dyno whilst logging to see if there's any gremlins lurking. Doing this isn't all that expensive especially if it means I catch something before it becomes an issue. It'd also be nice to know how much power it's retained after 21 years and 66,000 miles. However a map check is a third of the cost of a remap which has got me thinking whilst it's on the dyno...

I want to keep the car mechanically standard and I've been advised the cats are quite restrictive when tuning, I'm happy to leave them in as I don't want big power but I don't know if they're so restrictive the standard power output is all I'm going to get or if it is in fact capable of a mild uplift and if so what power levels could it go up to as is?

If I were to go ahead with a remap I'd want something safe with drivability over power, has anyone gone down this route before and can comment on the difference drivability maps make on STI's?

Last question, I carry octane booster just in case, but it'd be nice to know if I can map it to a switchable map (either the ECU self detecting or via a switch, I don't mind how) that can run on 95RON in case I get caught short when occasionally visiting family where 99RON fuel is pretty hard to get hold of?

JDM_Stig

iTrader: (3)

You haven't tried searching for your answers then?
Everything you have asked has been covered in the last 15 years at some point, its why the Forum has a search function.

jaygsi

iTrader: (46)

Yea the cats will hold you back. If you remove them, you could either replace with the standard Prodrive down pipe, if you want to keep original as possible. Or 200 cell sports cat, both will pass mots as long as your in the UK.

Tim_

Yes I've done a search and read quite a few threads, I get where you're coming from, I thought there'd be a fair bit of info on this too. Most people don't stick with the standard set up and change hardware at the same time so they do it all in one go which makes sense but doesn't fit to what I want to do. There's one post which talks about a re-map on a standard set up which suggests 300-320bhp is achievable depending on the individual engine but there are lots of other posts which suggest this isn't possible without a downpipe and de-cat or a sports cat plus an air filter (I don't mind changing the air filter). I've found lots of people stating drivability improves greatly with the mods which is great but there's nothing really on doing this with standard hardware so I'm not sure if there's any room for making a difference without other mods.

As for the ECU switching maps some say it needs an aftermarket ECU, some say the UK ECU's can't but the JDM ones can. I'm hoping for a safe set up, it might just be getting a re-map on V-Power and carrying on with octane booster for when I can't get 99RON.

I'm 51% sure a safe re-map is the right thing to do to stop the engine lunching itself because it's not running quite right and 49% thinking I'll end up with other running issues and needing regular re-maps to sort those out.

adam.pah

Hi Tim,

A few things to consider here.
- Is the importer reputable (Torque GT, Hurst, etc)? If so, the map is likely fine. If you take it somewhere to have it 'checked', they will undoubtedly find some kind of tweaks to make and then you're in it for a full map session anyway. Where are you based as I'm sure we can recommend a good mapper to you. I pay around £350 for a full map usually. The cats are restrictive, but I kept mine as I wanted to keep the car mostly standard. I replaced the fuel pump, air filter and fitted a 3 port boost solenoid before mapping. It's worth going decat or sports cat with a 3" exhaust if you want to find some extra power. It's an easy switch back to OEM at any time after that too.

- I've never heard of being able to switch maps on a standard ECU. Someone like Bob Rawle would be able to tell you if that's possible, but I doubt it is. It would also require 2 mapping sessions, switching out the fuel in between; seems like a ball ache to me. With an aftermarket ECU you can run a flex fuel sensor which will adjust the map based on octane level (this is my understanding).

Tim_

Thanks Adam. The car is from Hurst and any mapping would be through TDR so whilst I don't expect to find anything and gain peace of mind knowing there's nothing lurking, or if there is I can fix it, I'm thinking it's an opportunity for a small but safe improvement in the drivability.

I don't think it's worth the idea of a new ECU just for a lower RON map.

adam.pah

Mark (TDR) has a pretty good reputation for mapping, where are you planning on taking it for the check?
Dyno mapped cars do drive differently (IMO) than road mapped cars. I've used 4 different over the past couple of years, 2 on dyno and 2 on road. The road maps always feel more fun to drive although a dyno map can be much smoother if done properly. A good mapping session will take several hours in my experience.

I had a Syvecs ECU in the last blob I sold, but that was running over 450bhp. I don't see the point in putting one in a standard car though.

johno01

You sound a little paranoid mate so If it gives you peace of mind get it done 👍👍

adam.pah

I speak from experience when I say if it’s not broken, I’d leave it alone. These cars need regular maintenance but other than that they are extremely reliable at standard power. Once you start tinkering, one thing can lead to another and the bills start mounting up without really needing to.

Tim_

Well that's an excellent bit of advice.

Vxr2010

if you are worried about fuel , get it mapped to 95 and if you put a better octane in then should be no issues , it will probably be slightly less power but by the time the map is on it what you loose from gong to 95 will be outweighed by what you gain on a re map , my sti jdm ver 7 wagon was around 350 bhp on the standard cat , changing to a sports cat helps reduce lag unless yours is a twin scroll , deleting the centre cat and or silencer again helps with flow plus a bit more noise , but also as above if you are happy with it don’t worry , i’ve had a number of jdm imports all have been fine on tesco’s 99 or shell with no re map required , 95 in it maybe not such a good idea , the slight issue you can get on the 2 litre in cold weather the boost increases quite a lot and can hit the boost cut but there are corrections that can be mapped in to reduce this , other option was change boost solenoid set up but i did not want to do that 👍

jaygsi

iTrader: (46)

Well thats putting me off a remap lol
Wanted take my Impreza from standard 220 too close to 300 without massive changes.

Tim_

It's been the theme when I've been looking into more serious modifications but that's with people running very different hardware such as injectors, turbo's, fuel pumps, exhausts etc. I believe if you're going to upgrade a WRX from 220bhp to 300bhp all the changes required will get you a higher output again (320-350bhp) however you risk the 5 speed gearbox becoming the limiting factor/a serviceable part (some are ok, some aren't).

Dreep

Sounds like you are really overcomplicating it all. Im pretty sure if there was a significant issue regarding fuel quality in the OE map whilst using UK 99RON (which I assume is what your concerned about), the car would have already grenaded itself, given its now 8 months down the line of ownership.
Having said that, personally, I would always be looking to have the car mapped for UK fuel.
The newage ECUs are a bit more forgiving in comparison to the old classic ones. Pick a mapper you are happy with and discuss options - whether its Open Source or ECUtek on the OE ECU. Map it for 99RON, keep some octane booster for emergencies and enjoy the extra power. You'll net extra power regardless of the OE cat being in place.

RetroPug

In my opinion, it is worth it, but you have to accept that you're pushing an engine that does sometimes suffer failures (like HG etc.) that is also likely old by now, and that there is a risk involved with that. Equally, it's old now and it could blow up on your next drive at std. power.

Vxr2010

subarus respond very well to a remap you just need to keep if sensible levels of power , a good map will have a small impact on engine life , it’s probably more important to drive with lower revs on a cold engine till it fully warms up , a warmed up engine being once coolant is up to temp then double how long that took and that is the oil warmed up too , plus don’t rag it then turn it off , the head gasket issue plus crank bearing issues are greatly reduced on a 2 litre engine v a 2.5 , as yours is an sti and a 2 litre then less to worry about as you have the 6 speed box any way 👍

adam.pah

I ran an 04 WRX as a daily for 8 years at 290bhp. It had an updated fuel pump, air filter and full decat 3” system. I sold it on 104k miles and never had any issues with it, one of the most reliable cars I’ve owned. It was even still running on the original clutch!

MB84

Rather than start a new thread I'll ask here, my car is a JDM 2008 Forester turbo it has the 2l EJ205 engine and it's automatic with the SI-drive
I'm at the point where I'm considering a remap but I'm more concerned with reliability than power gains it's more than quick enough as it is for me, coming from a diesel VW the forester is a beast to me ....

So in terms or re-map if done any point in getiing a decat and a 3 port boost solenoid before ? or should I look into other upgrades instead ?

If I'm only concerned in reliability any point in geting a remap just because it's a JDM and mapping for UK fuel will help ?

Will a remap affect the automatic transmision in a negative way (more stress etc?) just a bit worried because it's automatic and SI-drive

Vxr2010

keep the standard turbo , a sports cat plus exhaust system will reduce lag and give you better flow , maybe another 10 to 20 or so bhp , a sensible map will be fine with the auto box , probably need a new fuel pump , but not always my Fsti went from 265 to 330 and was fine on the standard pump and was still fine at 198 k miles , a map is a good improvement just get a good mapper and just a sensible map , i don’t know where you are based but a few mappers listed above my money with Richard at FB tuning

MB84

Sports Cat vs decat the only sports cat I can find compatible are
https://www.haywardandscott.com/suba...cat-3-2-5.html or
COBB https://www.demon-tweeks.com/uk/cobb...t-cbbc-524203/ both very expensive £700 vs a japspeed decat pipe for £220 https://www.japspeed.co.uk/subaru-im...decat-downpipe

do I need a 3 port solenoid also for a decat/sportscat?

Vxr2010

I have a jap speed on mine no mot issues , it’s not a crucial mod it just helps the re map to get the best out of it 👍