Proper ECU/MAF Combo For BP Swapped Mx-3

[Nd4SpdSe]

I've got a friend who got a Bp swap done on their 94RS. I'm not sure what was done harness wise, but he's complaing abot the poor fuel economy; about 300km on a tank, and he says the ECU is a B6DE, so that's of course the B6 ECU, but I've got 2 questions:

1) How do you tell the difference between a SOHC and DOHC B6 ECU? What's the label say?
2) What is the ideal ECU/MAF combo one would run with an N/A BP?

[progt91]

i can give you this answer tomorrow when i look under my hood, i have a space escort gt ecu and it says bp09 on it.

[progt91]

that was suppose to be spare not space, the only space is between my ears lol

[progt91]

the vaf on my pro gt is a u code bp05, i was able to squeeze 620 out of a tank, i have no clue if the tank in an mx-3 is smaller but it cant be half the size thats for sure.

[Redline322]

The BP ecu is BP09 for manual, BP10 for auto and the proper vaf is a U code one. The B6 sohc starts with B6 and the vaf for that one and the B8 is an S code. You can use a B code vaf from an rx7 on the BP but you need to turn the wheel inside back a few notches or it will run pig rich but it is slightly less restrictive and gives you a few more hp in the top end. I'm pretty sure the mx3 tank is almost the same size as a 323 tank and not much smaller than a pro or escort tank and seeing 500km-600km per tank is normal for them.

[havoc13]

thanks mike

[Ryan]

I'm running BP TB, BP09 ECM, Tracer motor, B6 VAF... 350-400/tank.... that usually just as light starts to faintly glow on some acceleration. Also motor has new rings, relapped valves. It often smells of gasoline.


I should try the BP VAF, or 1st gen RX7 if I can find. B code VAF....

[Dark_Rider2k3]

oh woah.. you have to turn a part inside the RX VAF to keep it from running rich?

does this apply to those w/out a BP, but still with said VAF?

I have one, though i don't think it's running rich.. so idk... (bought it off trevo so maybe he already fixed it up for me )

[Redline322]

There's a gear in the top of the vafs attached to the vane and when the vane moves, the wheel moves along contacts and send the signal to the engine. To make you car a little richer, you move the wheel so it stays open a touch more and to run leaner, you turn it the opposite. You have to remember the rx7 that had these B code vafs(86-89 I believe) had 440cc injectors running n/a and the turbos were 550cc so it's set richer to handle the fuel demand. To use it with a BP though, you'll need to lean it out, which involves holding the set spring back and resetting the gear so the set spring sits a few teeth back. Any other engine running this vaf and using any less than 400cc injectors should lean it out a bit unless it is being used with a turbo setup, then you might want to leave it as is to protect from boost creep. The ideal vafs for each engine are the S code for B6 and B8 and U code for BP. Those using an untampered B code on these engines are going to be running pig rich which will only hurt performance and fuel economy unless turbo.

[colinsmx3]

I remember Back when I had my Escort GT I used the RX7 Vaf and tunned it but DON'T let the wheel unravel! Thats a b----!

But when I test drove Havocs car it was REALLY lacking in the performance deptment... Like acceleration was out of stock non on the shelf at all!! I had my foot to the floor and I know it wouldnt beat my little K8!
I still don't think an Auto ECU will work correct....

[Redline322]

http://cgi.ebay.ca/86-91-MAZDA-RX7-RX-7 ... 7C294%3A50" onclick="window.open(this.href);return false;
Just thought I'd show how easy it is to find one, they are more expensive, but the opening is larger, 2 1/2" vs 2 1/4 I believe or something like that. You can usually grab a U code pretty easily at a junk yard but the B codes are a bit tougher to track down. If you arent trying to get every ounce of high end power and concerned about fuel economy, I'd go with the U code which is designed for the BP in the first place and you'll easily see 30 mpg+ if it is running right. I know guys that are running BPT's and getting almost 30mpg so the right ecu and vaf combo goes a long way in these cars.

[Redline322]

The only difference between a BP09 manual ecu and a BP10 auto ecu is the auto has an extra plug for the trans.

[Ryan]

And clearly the brain inside the box to run the trans. A plug doesn't do any computing.

[havoc13]

whats the difference in the letters in the coding on the ecu? like it says bp09 and it also has a letter after that

[Redline322]

They have the extra letters as a variance if they make more than 1 ecu for the motor in upcoming years. The easiest example is for the K8v6, which started off as the K801 ecu, then I believe went to K834 and so on.