Tech Forum : Air mass flow meter...

MayanArch

Posted Monday, Oct 9th 5:44pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1170

Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978

If you do the 2.7 stroker, and match it with an "is" intake and head.........you still have the E21 electronics.

What air mass flow meter should you couple with this engine upgrade to the E21 electronics?

Will the "is" air mass flow meter work with the E21 electronics?

BruceH

Posted Monday, Oct 9th 5:52pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1023

Atlanta, GA USA
81 323 Baur, 85 745

No. You will need the complete Motronic harness.

MayanArch

Posted Monday, Oct 9th 8:58pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1171

Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978

Thanks Bruce.

But arent these air mass meters responsible for a lot of the restriction on intake?

Does anyone do an upgrade or modification to help this?

BruceH

Posted Monday, Oct 9th 10:13pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1024

Atlanta, GA USA
81 323 Baur, 85 745

There are several different ways to make the change. They will require a system like Mega squirt to make them functional. You are talking about a lot of work.

redmist

Posted Tuesday, Oct 10th 12:57am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 981

NY USA
357i , 325i e30 turbo

I think the you use a m30 "127" MAF and put your e21 electronics in it. My son did the conversion on his e30 m20. Major improvement.

BruceH

Posted Tuesday, Oct 10th 2:10am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1025

Atlanta, GA USA
81 323 Baur, 85 745

Pete,

How can you use the MAF from a Motronic with a the "electrics" from a CIS system?

Bruce

MayanArch

Posted Tuesday, Oct 10th 4:05am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1172

Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978

What, when, and how are these AMF's restrictive?

Is it a matter of polishing or porting them?

I never understood the concept of getting a high performance filter in front of an AMF that then restricts flow.

I am suprised none of the tuners have come up with a workaround.

jrcook320

Posted Tuesday, Oct 10th 5:19am [Edit] [Quote] [IMS] [View car]

Junior Member
Post nr. 1

Van Wert, OH
'81 320i

Both the CIS flow meter and L-jet flow meter only measure air volume. They're both basically just sensor plates and are probably about equally as restrictive. Of course the CIS is purely mechanical and has a fuel distributor mounted to it and the L-jet has a potentiometer to measure movement and send a signal to the ECU.

They have come up with a solution, it's called new technology. Many fuel systems use a MAF sensor which uses a heated wire to measure the mass of the air flowing through it. The more air traveling through it the more electricity is required to keep the wire at a certain temp, thus there is relationship that can be measured. There is usually a grid or screen in front of the wire to protect it, so there is some restriction.

There are also MAP (manifold absolute pressure) systems, such as megasquirt, that measure air pressure in the manifold to calculate the mass and airflow based on temp and other a few other factors. This has pretty much 0 restriction.

To get rid of the sensor plate restriction on an E21 would require a complete fuel system conversion to something doesn't have a mechanical air flow meter, like megasquirt (or motronic if it uses a maf, not sure how it measures air flow). You can't use another sensor in place of the cis air flow meter. Pete's son could do it on his E30 because it has EFI (L-jet or motronic).

aussie323i

Posted Tuesday, Oct 10th 10:46am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 532

australia
1979 323i

MayanArch wrote:

Getting back to the original question... don't most peole use the Porsche K-Jet AFM for this or is it just the Porsche fuel distributor (haven't thought about it for a while since switching to L-Jet on my car)??

I have read somewhere (can't remember the source ) that the e21 K-Jet system can flow 600cfm in any case- so it's not all that restrictive considering many old V8s ran 600cfm carbys.

Pete's comment on his son's M30 AFM conversion for the M20... you use the m20 electrics (ie. from the e30 etc.) and splice these onto the M30 AFM- is known to work pretty well and be less restrictive... just a typo on Pete's part with the e21 electrics mentioned no doubt

MayanArch

Posted Tuesday, Oct 10th 2:09pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1173

Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978

OK, to go back to the original question:

The intake is off an E30 "is" so it breathes better than an E21 intake.............so I guess you would want to couple it with an E30 "is" AMFM? right?

Is it possible to couple it with an AMFM from another model that allows more air in?

What is the danger if you take the protective mesh off? I mean.....isnt this what the cold air filter's job is anyhow?

JJG323

Posted Tuesday, Oct 10th 2:28pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 1274

Reading MA USA
1979 BMW 323i

MayanArch wrote:

Hi, You can use a M30 Part with a cone filter like pete said, or you can use a full stand alone setup. Also if you have the "I" harness you can use the M20 e30 setup...

But Jeff has modified his K-Jet airbox to pull more air for his 3.0 liter stroker... He had pics of this a while back.

redmist

Posted Tuesday, Oct 10th 7:00pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 982

NY USA
357i , 325i e30 turbo

Bruce, yes you have to put the electronics in the AFM which correspond to your system so if he is converting to motronic he will have to put in e30 electronics either a 173 or 052 motronics computer, wiring harness etc.