Edinburgh-Chris

People some help please,

I recently just bought a jap import STI2 up in Edinburgh.
I had it out on the open road up here for a while with no problems and it went like the wind.......until i finished the Exhaust of with a new uppipe and downpipe from Helix. (Group buy on Headers)

The car ran fine with uprated headers but as soon as we put the down/up pipes on it seems to cut out at exactly 110mph every time. There is absolutly no problem on the first 4 gears, the problem is definatley surrounding the 110mph mark!!!!

Any suggestions please, it's getting rather puzzling even for the garage who brought it into the country.

Its running standard ECU and has not been mapped.

Cheers,

Chris

RB5SCOTT

jap speed limiter mate set at 112 mph

Dark Blue Mark

As said, the japs fit a speed limiter. Surprised the garage didn't know this

MB

mo,s scoobymonster

yes speed limiter get a mph converter from www.svasoloutions.co.uk for about £70 then on your PRIVATE ROAD let it rip

TopBanana

Make sure you're using Optimax + booster especially for sustained high power runs

Edinburgh-Chris

the garage have checked that and it is converted. The car reads in mph.....
The garage are unsure but do know the majority of problems around a impreza. the problem is a bit more advanced than that.

Chris

Gear Head

iTrader: (2)

Still sounds abit weird though, have they actually checked that it connected?? Sounds stupid, but have heard of it happening before

mo,s scoobymonster

hi mate it maybe reading in mph because the clocks may only have been changed i still think its the converter.

Dark Blue Mark

Yep there's a difference between the convertor and de-limiter from memory? The convertor is just a mechanical (or digital) box which sits inline with the speed cable from the gearbox. Not sure where the delimiter is fitted.

MB

cong

yep agreed theres a difference betweeen a delimiter and convertor, you need to buy a delimiter and even then i heard the jap ecu wasnt mapped above 112mph so you have to be really careful!

tweenierob

PMSL!

Cars are mapped per RPM rather than speed, ROTFL! Mr Subaru Japan decided to stop mapping the car at 112mph

What does your speedo read to? if it is 110mph it has not been converted. When a scoob has a convertor inline (mechanical speedo) it does not need a delimiter.
The ECU as std cuts when it senses the ammount of speedo cable revolutions created at 112mph, when you use a speedo convertor and 180mph speedo face the cable drive is slower.
With the convertor in place, the cable rotates at 1.6times slower. The cable therefore rotates at the same speed at 180mph as it did at 110mph without the convertor..... Think that makes sense..

R.

Jay m A

iTrader: (2)

yep, basically the car would originally have a 180kph speedo. 2 ways to get it to read in MPH

1. fit a 1:1.6 gearbox on the speedo cable and put a MPH sticker over the KPH, then you have a 180 MPH speedo, delimited (or should I say speed limiter at 180MPH)

2. Get a MPH dial sticker overlay and stick it on the clock. It would only read to 120 MPH or so, and speed limiter would be at 112 MPH (180 KPH)

If the speedo reads to 180 MPH and road speed is as indicated in MPH, then its not the limiter IMO

Edinburgh-Chris

Right, now it beginning to get to the stage, me and the Garage are at. The clocks read 180mph. and the cable has been converted. When the car cuts out it is actually traveling at 110mph, so it is not the de-limiter as "Jay mA" has noted. its getting tricky, the car originally travelled at 150mph when it first arrived in the country, but once we inserted the uppipe and downpipe we disconnected the battery and hay-presto the car will not go over the 110mph stage.
Any help would be sweet.
Don't get me wrong, i am not a speed junkie but when i come to sell the car it will def. upset a few people if i tell them it will not do 111mph!!!!

Best Regards,

Chris

Dav 27

here mate ive been asking that question since i first got my jap import over a year and a half ago, never been to garage with it though as sort of new it wasnt a problem and it was quite upgradable , but now i dont think it is so straight forward ,no one as ever answered that question ,maybe top secret . my problem sounds exactly the same as mine 180 clocks , running in mph , de cat system etc.then at around 110 ,112 mph it just totaly cuts out and the revcounter just goes right back to zero and when it slows abit it kicks back in , so im flumoxed like you and your garage .......

TopBanana

Follow the speed sender up from the gearbox to see if there's a converter on there. It's on the driver's side of the gearbox, about halfway back.

Jay m A

iTrader: (2)

It could be overboost

Not sure exactly how the fuel cut on the STI2 is, but basically if its over xx.x psi for more than a second or so then it'll cut out. Perhaps in top gear the load is just enough to get the fuel cut.

Do you have a boost gauge? what boost is it at?

What rpm in top does it cut at?

Can you cruise past 110 MPH (as in don't use full throttle to get there)

Does it happen all the time, or recently now that the weather is colder?

just a few thoughts

TopBanana

If the rev counter goes to zero, it must be ignition cut not fuel cut.

Turbo_Steve

I think what he is referring to is that over 112mph you hit load/rpm points that you would not hit elsewhere in the rev range...you can certainly get EGTs that you wouldn't see in 4th gear at similar RPMS very often...and how regularly do you sit at 5500rpms for more than a few seconds in 4th when cruising around normally?

Certainly it may have a valid map there, but who knows how thoroughly it was tested and revised? Subaru cut as many corners as they can everywhere else...can't see them paying Mr. Yakimoto for 12hrs extra mapping and testing for a bit of the ECU that never showed up in testing.

I can certainly understand his desire to be careful given the track record of non-remapped STis which have "blown up on a high speed run", so I think he has a fairly valid point. Certainly if you look at the maps on the older STIs, I wouldn't describe them as "over rich" in the sort of areas I can imagine with short ratios and high wind resistance and no speed limiter, especially compared to the "over generous" UK ones.


edited to add: Also, if the problem only occured after fitting an exhaust, it's possible you're getting fuel cut due to the boost racing, though this normally manifests itself in 4th gear, not 5th. What RPMS is 110mph at? Is it about 4500rpms?

Dav 27

well my car ,seems to cut at about 112 mph ,rev counter rockets to zero then when me car slows slightly it will kick back in and so on , only realy tried it in fifth gear ,the rev counter is around 5k to 5.5k when it happens fitted with corect clocks etc , it doesnt cut in 1st 2nd 3rd never tried fourth mainly fifth for higher speeds , high speeds dont realy intrest me so i think thats why nevr looked into it more. still curious to know though.....cheers lads

tweenierob

what part of they didnt map over 112mph didnt you understand?

Rob.

megrac

Check if you have a ratio box in your speedo cable. if you don't and your speedo is reading in mph and is right then the hair spring might have been changed or stiffend to suit the mph face.
doing it this way will not change your cable rpm so the limiter will still be at 112mph or 180kmh.
you could put a switch on the speed signal wire at the ecu and see if you can go faster than 112mph. you only get about 30 seconds befor the ecu goes into limp mode, just get somone to switch it off just befor you hit 112mph. if you don't get the speed cut that means the cable is still doing the factory number of turns witch is 637 rpm/km up at the speedo.
you could do all this on a hoist.

Turbo_Steve

OOPS! The bit where I saw the word "NOT" when it wasn't there!
What a waste of typing!

TopBanana

Whoosh

Dav 27

the part were turbo steve asked what the rpms were at when car hit 110 mph , so explained in more detail , so what your saying is a z4 ecu wont go past 110mph unless remapped ?

Dav 27

oops 112 mph

leon26

thats weird if they mapped by rpm why dont they just map the car in first gear only? and not bother to map it through the rest of the gears? i read somwhere were tsl mapped the s202 saying that it wasnt mapped past 112 mph think i saw it in a banzai or som other mag

Turbo_Steve

It's not JUST Rpms....maps are very complicated. Effectively you're looking for RPMS against Engine loads. So there is probably a very rudimentary map in there, however chances are it never got tested, as how do you test a car that is limited to 112mph?

You go past 112mph, and you start entering parts of the map (high revs, high load) that you can't get to the rest of the time...or more to the point you DON'T STAY AT FOR VERY LONG. So if you manage to hit these points in another gear, it's usually accelerating, which doesn't take long. You start holding it at 5000rpms at a 75% load, in a part of the map the car is designed to spend 3 seconds in, not 3 minutes, and you might just start seeing nasty side effects. Trouble is, this has never been proved. The Z4 ECU is a lot less likely to cause this than the STi one, which runs a lot of advance.

It sounds in this instance (to me) like either the speedometer conversion / delimiting has caused a problem, or that the exhaust is more free flowing, probably coupled with a airfilter and that the boost control is not reacting quickly enough, and it is surging in 5th gear (which is a fairly high load) and he is getting a bit of fuel cut. But that's a guess.

Dav 27

cheers steve , nice to know.

Turbo_Steve

I'd certainly have an EGT gauge if I was running a Scooby delimited, I think. Costs about the same as getting it delimted and converted, and is a bit of piece of mind. A knocklink would be a good investment too.

tweenierob

Ok let me explain for the slow people in the class....

So, steve do you think that the pt cars used for mapping were limited to 112mph?
IIRC you have access to Z4 maps, i suggest maybe you take another look at them.

Because different gears give different load.
Load can be a mixture of things, TPS/Map/MAF or a combination of all of them.

No, i am saying quite the opposite... Having looked at plenty of std ecu maps i can say for certain that the map has been adjusted to suit over say 5k at full load (ie. over 112mph) i am not just plucking **** out of the air.

Rob

is that a yes or a no then? i think?

Knocklink is always a good investment IMHO too