BP swap ECU

[Domnknpimp]

Hi, I'm planning on doing a BP swap at the end of next month, and wanted to know if I really need to change my ECU. I know the BP ecu will make it run better, and the VICS wont work with out it, but will I really need it to run the engine, or could I leave the stock ECU temporarily (for about a month) before changing it.... Thanks

[LongJohn]

I have heard it runs like crap on the BP06 ECU (the SOHC one). Here is one of many things to think about. The ECU has a map that determines the pulse width for the injectors based on airflow readings from the VAF, etc. The BP injectors are different and will squirt a different amount of fuel for the same pulse width. Also, if your wiring harness is the same as mine, you have 4 individual wires running from the ECU to the injectors, and the BP ECU runs 2, one for injector 1 and 3, the other for 2 and 4. This was a surprise to me since the Chilton's manual shows 2 wires up through 93 and doesn't switch to 4 wires until 94. If the ECU thinks each wire is only firing 1 injector, you will be firing them half as much as you should, and therfore running incredibly lean (unless the ECU fires 2 at a time anyway).

I'm still getting blink codes that don't match any of the charts I've found, so what do I know anway.

Please do me a favor. What year is your car, and how many pins were on the distributor connection on your old engine? Also, on your new BP, in what direction is the distributor connector pointing? I have mine at around 2:00 which means it is between sparkplug wire 1 and 2.

<small>[ December 08, 2004, 03:41 PM: Message edited by: John Long ]</small>

[Domnknpimp]

Originally posted by John Long:
I have heard it runs like crap on the BP06 ECU (the SOHC one). Here is one of many things to think about. The ECU has a map that determines the pulse width for the injectors based on airflow readings from the VAF, etc. The BP injectors are different and will squirt a different amount of fuel for the same pulse width. Also, if your wiring harness is the same as mine, you have 4 individual wires running from the ECU to the injectors, and the BP ECU runs 2, one for injector 1 and 3, the other for 2 and 4. This was a surprise to me since the Chilton's manual shows 2 wires up through 93 and doesn't switch to 4 wires until 94. If the ECU thinks each wire is only firing 1 injector, you will be firing them half as much as you should, and therfore running incredibly lean (unless the ECU fires 2 at a time anyway).

I'm still getting blink codes that don't match any of the charts I've found, so what do I know anway.

Please do me a favor. What year is your car, and how many pins were on the distributor connection on your old engine? Also, on your new BP, in what direction is the distributor connector pointing? I have mine at around 2:00 which means it is between sparkplug wire 1 and 2.

I'll let you know as soon as I get the engine (Middle of January)

[LongJohn]

I thought about the injector thing some more. Actually, each time the ECU fired injector 1 it would really fire 1 and 3, but then when it fired 3 it wouldn't fire anything, so all in all, each injector would be fired about as often as the ECU thought. This is not as bad as I originally thought.

So the main issue you face is that the pulse width for the injectors selected by the ECU based on engine load (airflow etc.) will be wrong, but it might tune some of that out based on the oxygen sensor.

Also, with either ECU, if you are using an Escort BP, the fuel rail wiring is different. Your PRCV won't be hooked up for instance.