TPS Connector and Injector connectors off mk1a please

[jimi]

Jeremy posted further down that same thread

I tried an early shaped ECU (don't know what code) that ran my '89 model fine for a short run up the road. Maybe it was a change over year ECU.

Yup, Both of my mk1s are 1989 with 89661-17140 ECUs.

I have run the mk1a (89661-17030) and early mk1b (89661-17070) ECUs in my mk1b (and also the 1985/6 AE86 ECUs) without problems.

However. the mixture screw wiring is different so with a mk1a ECU (or a 89661-17070 ECU) in your 89661-17140 mk1b the mixture screw ceases to have any effect.

Also, the MAP sensor (and injectors?) are different types apparently.

For these reasons you should stick to the correct ECU for your car.


What about the differences in the engine mk1a vs mk1b? The ribs on the engine are different and so are some of the internals. Also my red mk1b was one of the last made and it has a slightly different cam cover to my blue 1989 mk1b. (different as in colours of the cam lettering)


The mk1a ECU (89661-17030) has a bigger 3D ignition map. It is mapped up to 7200rpm.

The mk1b (89661-17070) is only mapped to 5200rpm for the ignition.

The later mk1b (89661-17140) is only mapped to 5600rpm for the ignition.

[Evo4Jon]

Jimi. Can you check if map sensors are showing different part numbers in relation to the 17030 / 17070 and 17140 ecus please?

[jimi]

There were only 2 MAP sensors used on AW11 MK1 MR2's world wide
MAP = 89421-17020 until Frame number AW11 0091542 then changed to MAP = 89420-17020
Change was mid Aug 1986
Edit
Did a bit more checking and noticed that the MAP sensor change date (and frame number) coincides with the ECU change from the 89661-17030 ECU to the 89661-17070 ECU

[Evo4Jon]

I have ordered:
MAP = 89421-17020
1 set of 4 grey injectors (1985) 23209-16010
1 set of 4 red injectors (1987) 23209-16090
1 throttle position sensor
TPS = 89452-20070 (1987)
1× throttle position sensor connector
(Square early type)
1 x ECU = 89661-17030 (1985) ( Ihave 17070 and 17140 already)
1x spare solenoid resistor to modify (short out or add load) for use with high impedance injectors or if I run older ECU on newer injectors.

I wanted to get a mk1a TPS = 89452-28010 so I could look at the calibration. It wont fit to later Throttle body though

[Sweetpea]

Yes, I noticed that they changed injectors on the 17070 ECU. That means that the later injectors are either high impedance or low impedance with a dropper resistor.

My current working theory is that any ECU can run any injector. But you must use the resistor if you use the low impedance ones. God knows what it does to the injector timing though. My reason for thinking this (apart from Jeremy doing it) is that the difference in current isn't that massive between the two systems. The power transistors are going to be well over spec just for reliability. In fact I'd guess that the real problem isn't the forward current when they are turned on, it's coping with the back EMF when you try and turn them off again.

The blown fuses story is interesting. I suspect something else was going on there. Or they got it wrong and it was a MK1b ECU in a MK1a car. I can see that might cause blown fuses.
The 1b ECU is trying to control fuel pressure by grounding the FPU pin. But if it's in an early car that wire is connected to the battery via the INJ fuse. So the poor ECU tries to short the battery.

James

[Evo4Jon]

I can see how a mk1b crossover using the 17070 could toast a 17140 via that BF terminal. Neil Jones will be sending out my bits on monday so I will be able to compare pinouts on the 17030 and also the resistances of injectors and map sensor under different states of vacuum.

Whats the 2nd electrical box under the mk1a 17030 ecu? Do you know?

[jimi]

Have a look here:
http://club4ag.com/tech-data/tech-sp...dentification/

Pin 10 Is BF and the wire colour is Yellow. The description says Power from Run position to ECU and main injectors

If you open up a 17070 the pin 10 is also marked BF.

You need to be careful when referring to links like the above, looks to me like the way they have numbered the pins is wrong i.e. not the same as the standard Mr T method, although the location of the pins is correct the pin number is wrong. The pic below will illustrate the difference this is looking at the ECU



This could be very misleading if you refer to the pin numbers not the actual locations.

[Evo4Jon]

Good point well made Jimi.

The bottom right pin is the one I have added a bullet connector to on my X-over loom ready to break the circuit and connect the +ve from the injectors so all it good.
On the later Mk1b which uses the 17140 ECU the colour of the wire is Green with a black line which goes to the VSV.

I have a 2nd Solenoid resistor pack which I have modified so that I can bypass it and using a damaged ECU I cut out the socket and soldered the plugs from an old loom onto the pins. Then I heat shrinked where the pins were soldered and then used black hot glue to prevent flex on the joints. I will used this as my loom changer so my original wiring stays intact



(If the engine runs well and I intend to keep any of the setups permanently, I will then properly solder any joints and not use Bullet connectors!)

[Evo4Jon]

Also
Whats the 2nd electrical box under the mk1a 17030 ecu? Do you know?

[Sweetpea]

I don't know, but an exploded diagram says...



"Relay, Fan". I take that to mean it's the control box for the fan in the side of the engine bay.
Problem is, I have no idea which model or year the diagrams are for.