Mi16 Conversion- Which Motronic

[Guest Cartooner]

I am currently planning to drop a D6C from a BX into my 205 Gti. I am wondering which Motronic system I can best use. I have two options the Motronic 3.1 which was originaly in the car (DKZ Cat/lambda engine) or the Motronic 4.1 which originaly came with the engine.

 

Motronic 3.1 has the advantage of using a lambda sensor- which I think may come in handy, furthermore I can use the excisting wiring and ECU.

 

I realise I have to use the appropriate choke device( SAD with 3.1 or stepper with 4.1). I need a distributor adapter plate also.

 

The mapping of the ECU will be modified regardless of the ECU I use, so rev.limit ( too low on 3.1)and maps will be changed anyhow, so are of no issue.

 

Any pros & cons.

[Hilgie 16 2 Cars]

Always Motronic 4.1 as it does have the stepper motor for idle and it's just a better system for an Mi.

[petert 586]

you would have had a Motronic 1.3, not 3.1, with the DKZ. Unfornately this would limit the performance potential of a 16V. Use the old 4.1, unless you can find the correct Motronic 1.3 ECU to suit a 16V.

[Guest Cartooner]

cheers guys

[C_W 3 1 Cars]

I though the 8v cat was on 3.1 Motronic?

 

But yes the 4.1 is the one to use.

[Guest Cartooner]

No Peter is right in fact, it is Motronic 1.3. Still, I am not convinced. Isn't it so, and please correct me if I am wrong, that the main difference is in the way the actual chip is mapped?( Set aside the choke/tick-over device and rev.limit) If so, why can't I benefit from the 1.3 ECU, which enables use of a lambda sensor, running on a custom mapping suited for thr 16V?

 

Or should my choice be solely based on the use of the stepper motor for idle? Will the SAD just not do on the 16V?( is that what You suggest Hilgie?)

[petert 586]

You can certainly use the original 1.3 ECU, but you'll have fuelling and rev limit issues. The original ECU was designed to deliver 122hp, not 160hp. Rev limit will be 6700, not 7100.

 

One solution is to find a 161 ECU from a Motronic 1.3 equipped Mi16. You'll need to add wires for the stepper motor and knock sensor. The 161 is common as mud in Australia, but I'm not sure about the UK.

 

Another solution is to get your chip remapped. I know someone who has the 161 bin file which could easily be burnt into your chip.

[Anthony 1,003]

I though the 8v cat was on 3.1 Motronic?

205 GTi CAT (XU9JAZ) was M1.3 (AFM based)

It's ZX Volcane 1.9 (XU9JA/L) and 405 SRi's (XU9J2) that are M3.1 (MAP sensor based)

 

The 161 is common as mud in Australia, but I'm not sure about the UK.

161 ECU's are very rare over here AFAIK, as CAT equiped Mi16's are almost non-existent compared to non-CAT ones (which have 119/125/139/140 ECU's in 2-row ML4.1 form, and 354/355 in 3-row M1.3 form)

[Guest Cartooner]

Well, I'll settle for the Motronic 4.1 for the time being. I have an ECU with the 119 at the end. Am I being thick when I think that the lowest number is the oldest ECU and that the ones with the higher number are more evolved with better mappings? Or is just the auxiliaries on de engine( eg hydr.pump on citroens) and other trivial facts that made them chose this one?

 

It's just a shame that, although the citroen Bx wiring loom should go right in, Citroen used so many green wires! Did they get it for free or what .

 

Anyway, thanks for Your input guys and maybe it won't matter anyway and I'll just opt for an aftermarket system.( Emerald? Halltech? Megasquirt, but that's a different discussion and I am shure there will be plenty topics around tackling this question).

[Hilgie 16 2 Cars]

The 119 is a fine ECU. The're also the 125 but that was on the 309GTi16 afaik

The Mi16x4 has also a different ECU number.

[C_W 3 1 Cars]

I've got a 125 ECU on mine, plus a spare, its the best one . Think they were on some 405Mi16s tho.