B230 - AMM???

Hey Volvo Gang,
I'm from DTMpower.net... no I didn't get lost
In any case, some info for all those who wonder: e30 generation BMW shares the same injection computer system with Volvo - Bosch Motronic. I already found out that stock Bosch injectors fro B230 Engine (white tops)fit the M3 and flow about 30-40% more fuel than stock ones.
Now, what does that engine use for intake air measuring? I hear it's so-called AMM - Air Mass Meter. BMW M3 uses AFM - Air Flow Meter... Any difference between both? I hear AFM is not precise or reliable. Plus, it's useless when you boost the engine. (It's a flapper door attached to a resistor and operated by vaccum pressure of the intake manifold, I imagine once you boost the engine the system would be totally out of wack unless you replace the return spring for the flapper for a much stiffer one, then calibration becomes a problem) Would someone please explain to me how Volvo's AMM works?? Thank you much!

"In any case, some info for all those who wonder: e30 generation BMW shares the same injection computer system with Volvo - Bosch Motronic."

Only in Europe. North American Cars were fitted with LH-Jetronic.
So if you are in Europe, correct you are.

"Now, what does that engine use for intake air measuring? I hear it's so-called AMM - Air Mass Meter."

North American LH-Jetronic cars use an AMM, also called an MAF.
It is basically a geated wire strung across a pipe. It has circuitry which seemks to keep the wire at a set temperature by passing current through it. More air passing the wire means more cooling of the wire, which means it needs more current, which results in a gretaer output signal to the ecu. Please nobody flame me for this crude description, I know it's crude.


"BMW M3 uses AFM - Air Flow Meter... Any difference between both?"

Yeah, completely different for sure as you probably realized after my description of the AMM. However, in europe they use motronic with a flapper door like you describe.

But the system that uses the AMM rather than the flapper door is LH-Jetronic which does not interchange.
I think what you're asking is if an AMM from a volvo can be used with motronic, since you have heard that they also use motronic. They do, but the motronic cars use flapper doors as well, The AMM cannot be easily adapted to the Motronic system.

What you need to do is essentially a draw through system. You put the flapper door in front of the turbo outlet and it is drawn open via turbo induction air. And yeah they'd be some spring fiddling. But that is minor compared to the fiddling youd need to do to make an AMM work since it has a different (and non-linear) response curve.

HTH. If anything was unclear feel free to seek clarification.

I see.... Yeah, MAF changes things dramatically. There is a kit that replaces AFM, but it goes for around 950 green ones. Well, thanks for the info anyway.

Could a MAA from a LH be used to swap over a AFM from a L-jet system?

BMWs from this era were turbo charged (though usually the Big 6, not the little six used in the E30). Last time I checked Korman still sold a turbo kit for the E28.

Somebody should have an idea how the factory, Korman, Callaway, etc solved these issues.

There are kits available for the E28 that allow you to hook up a AMM to the Motronic computer. Both devices have completely different outputs, so a converter is needed of course and part of the kit.

ADent said:

BMWs from this era were turbo charged (though usually the Big 6, not the little six used in the E30). Last time I checked Korman still sold a turbo kit for the E28.

Somebody should have an idea how the factory, Korman, Callaway, etc solved these issues.

There are kits available for the E28 that allow you to hook up a AMM to the Motronic computer. Both devices have completely different outputs, so a converter is needed of course and part of the kit.

Click to expand...

Just thought id clarify..i have a 84 528i L-jetronic....the Saabs and Volvos run the LH jet.

the only real diffrence is the Air meter..or AFM or AMM in Volva and saab case.

I just bought a SAAB or parts and am going to swap the AFM from my 528i L-Jet to that of the SAAB AMM LH-jet.

I can see the problem with the Motronic..no workys.

but the only thing i can see being a problem with the AMM over the AFM is the Resitance.....The ECU and all the other parts of the EFI on the saab are almost identical.

I think this may work and would be awesome if it does..cant wait.

Megasquirt it - no AFM, MAF, AFM needed.

When we tune the B230ET cars here, which is the description of the Motronic engines, it's normal to get a MAF/flapper from a big 6 BMW, as this will not bottom out so easily. It's not a problem to use the MAF with a turbo, you just have to mount it pre-turbo. The problem with the tuned cars is that the flow exceeds what the flapper was designed for, and it bottoms out.

This is because the MAF will only measure flow, while the AMM measures mass of air entering. That means the AMM can be placed anywhere, even post-turbo, although that's not ideal.