Kop2381

Morning all im looking for a bit of advice. I have an 1990 s2 but the loom was completely fucked. So i bought a good loom which came out of a 1987 E plate Rs turbo. My concern is will i need the earlier type ecus or will the ones from my 1990 car & loom be compattible??.

Any help appreciated guys.

CheeRS

mgtkr1

all s2 ecu's are interchangable. im unsure if s1 and s2 ecu/looms ect are. the post 90 cars have a knock sensor, early cars dont.

Karlos G

iTrader: (4)

That's not accurate mate... very early S2's didnt have a knock sensor but E plate and onwards with the blue red black ECU did (not just 90 spec ones, hearts and diamonds).
But to answer the OP, so long as the loom has the wiring for the knock sensor yes your ECU's will be fine.

mgtkr1

i stand corrected, my apologies

Kop2381

Thanks mate. Where abouts would the knock sensor be??.

Karlos G

iTrader: (4)

Right hand end of the inlet manifold.

Kop2381

Yep all appears to be there thanks mate.

AstoN_B

iTrader: (1)

Do the later ECU's look for knock sensor? How would it affect running if using a late loom with early ECU?

My understanding is that the knock sensor isnt much good anyway.

Karlos G

iTrader: (4)

If it's not plugged in then it behaves as if it's knocking, pulling the timing right back (you'll make fuck all power) so what most people do as they are a tad sensitive anyway is to remove it from the manifold and wrap it in a rag leaving it plugged in and tuck it out the way... Of course blocking the hole in the inlet! lol

Using a late loom with an early ECU (pre knock) is spot on, no need to do the above!

AstoN_B

iTrader: (1)

Confusing. We were using det cans plugged into knock sensor and it didn't do much different to plugged in. If anything. Possibly an early ecu, it'd been painted so no idea on age or originality. With the sensor unscrewed there is no hole to plug.

Karlos G

iTrader: (4)

Yeah does sound like it could be an early ECU then mate.
No hole? Oh well that makes it easy then, been a long time since I've looked at a MFI inlet! lol

AstoN_B

iTrader: (1)

It's a 90 spec car but possibility the ecu had been swapped since it was chipped.

I understand most of the system, just don't get how it adjusts timing while still being on a dizzy. I thought the dizzy just fires as the rotor arm passes the points in the cap. does the coil get fired like a modern coil pack, and the rotor arm have a large enough tip to enable it to still fire either side of centre?

Karlos G

iTrader: (4)

The timing is controlled by the silver ECU (the one thats chipped), the dizzy has a hall effect sensor on the top the signals the ECU it's position, the ECU then signals the coil (timed earth pulse) via the green wire that runs from the ECU to the coil round the front of the engine bay... Often the cause of a no spark situation when it breaks.

AstoN_B

iTrader: (1)

I get how it knows when to fire, but I meant I don't get how it judges amount of retard/advance per cylinder.

I thought with a dizzy it wasnt adjustable besides the advance curve (which in itself is alien to me at the moment as I've spent more time looking at full ecu's), I thought a dizzy could only actually make the connection when the rotor arm was close enough to the points which was always at a set point due to being mechanically fixed to the end of the cam.

That's what made me wonder if the rotor arm had a larger end to allow the ecu to fire before or after the point I'd assume would be 'normal' I.e the centre of tip where it's closest to points.

Louis_RST

Exactly what Im running on my E plate.