hi all,having **** loads of problems with my 94 wrx import, currently have o.5 boost and no revs between 2200 - 3500 rpm, ive pretty much checked every other possible cause and its now looking like the prova ecu that came over with the car is corrupt,the current ecu has four plugs,this is were i need your help, will an ecu from a uk car of the same year/model fit straight on? also will ecu's of 93/95/96 models fit?, i keep seeing them advertised with different codes like - 2c-3b-4b etc but don't know which one i need as haven't got the original ecu, spoke to a local tuning firm and they said id be better to get hold of an apexi fc ecu, does anyone use one if so are they any good? gratefull for any
suggestions - steve

 

You could just replace the J1 resistor on your prova ecu and that will run the standard map on the main board of the ecu. Peel back the prova sticker to see what the identity of the ecu is first though. Look on the board. you will see J1 and two holes. put a bit of wire between the two holes.

No you cant run a uk ecu but you can run any of these import ecus off ebay 1993-96 and they will work fine.

U8, 2C W6, W9 or Z4.

Z4 is the best of the bunch as it runs a bit more boost and has better fueling. I run a W6in my 93 wrx and its plenty quick enough. All are safe to use with 97 ron fuel.

 

U8, 2C - 1993/1994 WRX - 11.47psi saloon
W6 - 1993 WRX RA - 11.47psi saloon
W9 - 1994 WRX RA - 11.47psi saloon
Z4 - 1995/1996 WRX - 12.78psi saloon
Z5 - 1995/1996 WRX-RA - 12.57psi saloon
6K - Ver2 STi Sedan - 13.34psi saloon (not recommended - will run but not ideal some have had problems)
7K - Ver2 STi-RA - 13.19psi saloon
1C, 3B, V9, V5 - All WRX Wagons 10psi, dropping to 6.8psi (dont use these in a saloon)
V7, 7D, 6D - 1993 to 1996 UK/Euro 11.47psi (dont use these in a wrx import)

 

thanks for replying mate,is it true that the jap ecu's are often not able to be re mapped as they're often locked in some way? also why is it not possible to use a uk ecu? thanks

 

just thought , if i buy any standard ecu can it be remapped to run at higher boost etc cos i think the prova chip was running at around 16psi, can this be acheived with a standard chip?ta

 

OEM ECU would have to be fitted with 'ESL Live', which is a daughterboard that is infinitely mappable. This is only currently available for the MY93-96 4-plug ECU cars (which yours obviously is). You'd need to swap the MAP sensor for a MY97/98 OEM 2.4bar(?) one (boost cuts at 1.4bar), or a MY99/00 2.7bar(?) one (1.7bar cut). Or get an after market 3bar Bosch or Denso or similar MAP sensor - can run upto 2bar of boost on these.

Or alternatively junk the OEM ECU and try and get a cheapish 2nd hand Apexi PFC and its bespoke 3bar MAP sensor too (I have this combo). It overides the MY93-96 OEM 1.2bar MAP sensor as it plugs directly onto the side of the PFC (requires invoking via the Commander or mapper's s/w on his laptop).

 

cheers joz, what sort of money do the apexi ecu's go for? have you any idea if jap ecu's are somehow locked and therefore cannot be read by uk technicians ? (this is what the bloke from a local tuning firm said) i am starting to wonder if the jap import was a good idea ...

 

Unfortunately, due to the unfavourable exchange rates/financial climate, and the PFC's relative popularity, you'd be lucky to pick a PFC from an eBay vendor for any less than £400-450 - and that's WITHOUT Commander! Best try to hold out for a private seller on eBay or from a seller on here, at a the right price - check the Classifieds by setting up daily email subscriptions.

The chip in the OEM ECU as it stands isn't designed to be accesed and its values changed... But this is what that 'ESL Live' add-on allows!

 

yeh,thats quite pricey, do the chips in these ecu's plug in or is it a soldering job? im thinking if i can get another jap ecu and replace the chip with the prova one from the old ecu i will be onto a winner,or am i dreaming?

 

cant you just buy a performance chip and solder it in

 

- The ESL Live is a daughterboard that gets 'added' to (or replaces?) the ECU's existing motherboard. So if it gets added, then presumably soldering would be required(?). There was a 4-plug ECU with the daughterboard already in it on eBay the other day for £350 - don't know whether it sold though.

- Yeah if you get another donor 4-plug ECU (any one) for about £10-30 (loads always on eBay) then you can swap over the Prova chip and it'll hopefully work. This'll be the cheapest way of getting you back up and running 16psi/1.1bar again.

 

Or as said, get a ECU with the Polar Performance chip already installed for about £80 second hand. This is widely regarded as the 'best' and safest one and it too runs 16psi/1.1bar.

I ran one in my 93 WRX saloon foir a year - engine had no I'll effects. Pistons/rods/crank were all fine (when it was opened up for a forged rebuild later on)

 

i have a performance chip that will work mate it runs high boost and fueling you can have that for 25quid posted it also comes with a solder in base so you can switch between chips pm me

 

nice one,i will probably try the cheaper routes before i go out and spend a fortune on an apexi ecu as when the car was running good the performance was more than enough, if i do get another jap ecu is it then essential to get a re map? as the car is far from standard spec so presume this would have to be done to get the most out of it..ime going to have a look at the ecu tomorrow and see if its pos to remove the chip if not i may take ur advice and get hold of the pp chip..

 

you dont need to remove the chip. it can stay on the board. placing the j1 resistor will over ride it with the original map on the ecu. but make sure the original ecu is one of the ones above as prova might have used any old ecu as a base.
if i were you i would run no other chip than a polar chip. these are very safe.
they pop up on flee bay no and then.

 

i have a z4 ecu for sale £70 deliverd

cheers
stew
07906 598849

 

I don't think the OP wants to go back to OEM boost levels. I think he wants to run the Prova chip but thinks (hopes!) that it's his ECU that isn't working, hence why he wants another ECU to be able to run it in.

This happened to me when I bought my 2nd hand PP-chipped ECU - it didn't work. Scott T kindly tested it for me and it turned out that the PP chip/board was okay... but the ECU was indeed dead! Scott kindly supplied me a doner ECU and soldered the chip/board in it too for £80 (I got this money back off of the chap that sold the original to me on eBay).

But yeah, I also think the OP would be better off, all said and done, with a PP-chipped one...

 

Thanks for the suggestions all, basically I have ruled everything else out and now believe the ecu to be at fault, trouble is im not that good with ecu's, not sure if the fault is on the board or on the chip,whichever way the signal from the throttle is ok,I've tested with a multimeter an found there are no dead spots throughout the rev range so it must be the way the ecu is interprets the signal, would anyone know if the chip or the board reads the signal?sorry if this is a dumb question as said knowledge of ecu's not great,

 

Just looked under the prova sticker and just as dj said the original label is there, it's a 4b , anyone know if this is a wrx ecu?

 

4b is from wrx wagon, fitted with a tdo4 turbo.

 

Scott T. Knows how to test ECUs (he tested mine - see my prevoius post).

Drop him a PM/email - he may be able to help you...



STOP PRESS!... That 'ESL Live' chipped ECU is still available!:-

Subaru Impreza wrx/sti ESL daughter board chipped ecu!! on eBay (end time 07-Sep-09 16:53:21 BST)

 

Thats not the ESL live board, but the earlier board that emulates the 27C1028 chip, so is not live re-mappable.
The live board is different and does not use the same PGA devices.
See below :

 

Yeah sorry Scott - thanks for pointing that out.

I've also acknowledged this in that other thread.

OP, just to clear this up... that ECU in the eBay link I posted is NOT mappable (just in case you were thinking of getting it for thinking it was mappable). Sorry for any confusion caused...

 

no probs,to be honest i was just thinking "Thats not the ESL live board" but scott got in there first anyway ive decided to buy a cheap 4b ecu for now, got one for peanuts off ebay, just want to confirm that it is the ecu that is screwed on mine, ime pretty sure its not a mechanical failure,took my ecu apart today and sure enough the prova chip/chips are mounted onto a separate board which is soldered onto the main board, dont think i will have a go at removing it, looks a bit fiddly, ive emailed scott as you suggested just waiting for him to come back,also checked my o2 sensor output and found it to be reading a bit high, its 1.126 at idle, it does drop to under 0.7 when driving, do u think this is a concern?

 

When engine's up to temp and at a steady idle, lambda should continually cycle up and down between 0 and 0.9V.

I have a brand new one (well, a year old) and I see typically c.0.05 to 0.85V (from memory).

 

Hmm,mine cycles between 1.1-1.2 at idle, Do you think that when my misses overdosed the o booster it may have clogged the sensor up as the smoke coming out the exhaust was proper thick black,have still got a mm of soot around the tailpipe,can the o2 sensor be cleaned?if so what's the best method,ta

 

Strange as that's out of range(?)

Regardless, it's stuck high - normally meaning the motor is running rich for some reason... And that reason could well be the ailment you've pointed out. For sure, the black soot certainly seems to corroborate with your sensor's stuck 'rich' reading!


See here for a more detailed explanation of how O2 sensors work, etc.:-

Just Lambda, Suppliers of Bosch and NTK lambda sensors including zirconia and titania sensors by post