Z31.com Wiki

This information was compiled in the hopes that someone might find it useful for ECU/injector/O2 sensor interchange. This should be particularly useful for those swapping an 88-89 ECU into their car. As these are the only major differences in the Z31's stock engine management, this should be what you need to figure out if a particular configuration will work for you. Granted, there are other small differences and this should not be taken as having been “set in stone”.

Click to find out what year your ECU is based on the front cover markings.

There is absolutely no difference between a regular 88 Turbo ECU and an “88SS” ECU. There is nothing special about a ECU branded “88 Shiro” or otherwise, it's a marketing ploy to make it SEEM more desirable.

All NA injectors are ~180cc/min and all Turbo injectors are ~260cc/min, the ECU’s are programmed accordingly.

High impedance ECU on a low impedance injector will require installing six 6 to 10ohm 10W dropping resistors to keep from frying the injector driver units.

Low impedance ECU driving a high impedance injector should operate normally.

Feed type does not matter to the ECU as impedance and flow rating do, however the lower intake manifolds are different and will require shaving/shimming the injector mounting area for fitment if your engine came with the other type of rails/injectors.

Titania-type oxygen sensors are not compatible with zirconium type, and vise versa. Zirconium sensors relay a 0-1v signal and Titania sensors vary resistance to give the ECU its mixture feedback data. If you wanted to switch sensors to accommodate a 86-89T ECU, the wiring in the engine wiring harness would need to be changed, as well as the oxygen sensor bung (Titania are 17MM and Zirconium are 22MM).

CALifornia and FEDeral ECU’s can interchange. The only known physical difference in the CAL version is the presence of an EGT sensor.

Automaitc transmission ECU's can be used in cars with manual transmissions, but a manual ECU in an automatic might not function correctly (idle speed, etc).

The PROM chip on 88-89 NA and turbo ECU’s can be swapped. That is, if you want an 88-89 ECU and would like to use a Zirconium type oxygen sensor you can put the turbo PROM in the NA ECU. This should save a lot of time in swapping out the sensor bung, sensor, and re-wiring. Hence, the desirable unit for 84-85T cars would be an 88-89NA ECU, and the desirable unit for 86-89T cars would be the 88-89T ECU.

The Turbo ECU has a daughter-board for the detonation sensor, Non-turbo’s do not. (Note: the TP/RPM feedback region for the detonation sensor is very small, it is not even used under boost or at any time above 3000RPM.)

The Turbo and Non-turbo cars do not use the same type of idle control. The wiring in the engine harness is also different for these controls. Not really an issue: I, and many others have perfectly running cars with all idle control devices removed.

88-89 Turbo ECU’s have a timing map that runs more timing under boost on account of the smaller (T25) turbocharger only running 4-5PSI boost pressure. Keep this in mind if swapping.

84-85 ECU’s (all) have been reported to have a small lean surge problem during the first 30 seconds or so of engine warm up. This is most likely an issue with the cold-start enrichment and can be remedied by switching from CHTS to FTS signal during startup.

There are many small differences in engine wiring harnesses relating to the placement of sensors on turbo vs NA and some other small differences through the years. Nothing hard to work around, but keep it in mind.

¹⁾