Elliott Watt

just wondering whats the difference between z4 and z5 ecu's? also what difference dose a 'black label stick mean?'

Sprint Chief

Z4 is the 95/96 WRX ecu. Z5 is from the 96 WRX RA, and is designed for modified heads, with a higher red line.

julesf

Not strictly true. My 1995 WRX RA had a Z5 but has the V2 engine with coil packs and the Rev limit was 7500.

I thought the later V3 engine with the higher rev limit had the later three plug ECU and coil pack on engine with H.T. leads and wasted spark.

I think that the Z4 is for Ver 1 WRX and whilst it is very similar to the Z5 the map limits to around 240 Bhp where as the Z5 for the WRX (non STI) is stock mapped for 260 BHP. However, both have the redundant chip socket, so both are capable of receiving pre burnt maps from third party developers. I had the Scott.T chip in mine and it took the power safely up to 275 Bhp at 1.1 Bar with additional torque. Be aware of poor maps on chips that can end up melting your engine.

So with a chip fitted into the spare socket both ECU's are equally capable IMO.

Hope that helps.

Jules.

www.type-ra-sprinting.com

Andy Stevens

Sprint is right, some of Jules info is a bit dodgy.

Z4 is for V2 WRX and is 260PS.

Z5 is V2 WRX RA and has the elevated redline of 7500rpm.

Neither have sockets as standard, you need to solder them in.

dj219957

intrested to know any difference between blue sticker and black sticker z4 ecu.

Sprint Chief

Blue vs. black labels are just different production runs of the same thing. Usually there is little or no difference between them.

Jules, as Andy notes, the redlines are as follows:

Z4, 6K - 7000rpm
Z5, 7K - 7500rpm

The Z4 (260ps) was not fitted to the V1 WRX, they had ecus such as U8, 2C, W6 etc.

The later V3 (MY97) ecus had an 8k rpm redline on the STis, on the STi EJ20K engines.