Author Topic: E21 With M20 N/A  (Read 19848 times)

Offline Sam8888

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E21 With M20 N/A
« on: October 08, 2016, 10:06:24 am »
Hi there!

I have a BMW E21 with M20B25 VEMS'd

Engine specs:
M20B25
ported cylinder head
headers
3 angle valve job on the intake
lighweight flywheel (around 4-5kg)
Carbon airbox (chinese BMC knockoff)
VEMS
Wasted spark
M50B25 green injectors with 3.5bar fpr (190cc)
Running on 100 octane fuel
Factory exhaust from the headers, which i think is very restrictive for the engine.

Sometime in the future i want these updates to the engine:
ITB's (from some bike)
build a M20B28 N/A

Here's my config (but i always find something to change):
https://drive.google.com/open?id=0B2LftYmTraGcWmIySmtzTDVvQms <- any comments welcome

Engine bae:


Engine harness is modified to the VEMS, i cut out everything that i don't needed.


And here's some pics of my ride:




And here's some launch control practice:
https://www.youtube.com/watch?v=ySLmMfz6Kec
« Last Edit: October 08, 2016, 10:48:57 am by Sam8888 »

Offline wersch

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Re: E21 With M20 N/A
« Reply #1 on: October 08, 2016, 04:30:26 pm »
Realy nice car!  ;D
I noticed that the trigger settings are 2 degrees incorrect.
Should be 60 degrees if you trigger on tooth #4.

Offline Sam8888

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Re: E21 With M20 N/A
« Reply #2 on: October 08, 2016, 05:29:06 pm »
Realy nice car!  ;D
I noticed that the trigger settings are 2 degrees incorrect.
Should be 60 degrees if you trigger on tooth #4.

Thanks!  :)
Triple checked that with a timing light gun, and it's spot on with the 62 deg.

Offline wersch

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Re: E21 With M20 N/A
« Reply #3 on: October 09, 2016, 09:07:33 am »
Maybe you need to turn around the +/- cables on the primary trigger then, because it should be 84 degrees trigger angle on standard M20 if you trigger on tooth #0.
You can see this if you make a triggerlog.

Offline Sam8888

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Re: E21 With M20 N/A
« Reply #4 on: October 09, 2016, 10:19:12 am »
Maybe you need to turn around the +/- cables on the primary trigger then, because it should be 84 degrees trigger angle on standard M20 if you trigger on tooth #0.
You can see this if you make a triggerlog.

My FTT is 4 (so the 5th tooth after the missingtooth), so that is giving me 62 deg. It's kind of the factory M20 setting in the VEMS, only adjusted 60 deg to 62 with a timing light.

Should i modify FTT to 0 and 84? Why? (i just want to know why is it better to have on 0 and 84)
« Last Edit: October 09, 2016, 10:22:33 am by Sam8888 »

Offline wersch

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Re: E21 With M20 N/A
« Reply #5 on: October 09, 2016, 10:50:31 am »
60 deg. with FTT #4 will give the same setting as 84deg. with FTT #0.
As i understand the synchronisation is faster if you trigger on tooth #0.

I have done many ECU installations on BMW engines and both M20,M30 and M50 have 84deg. triggerangle.
« Last Edit: October 09, 2016, 10:53:28 am by wersch »

Offline Kamuto

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Re: E21 With M20 N/A
« Reply #6 on: October 09, 2016, 11:44:44 am »
just leave it how it is :)
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Offline Sam8888

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Re: E21 With M20 N/A
« Reply #7 on: October 09, 2016, 06:40:34 pm »
Okay, i'll leave it like it.  ;)
Thoughts on the VE/ignition maps?
I guess my injector dead time isn't any good, because there's a valley in the VE table at idle.

Offline Sam8888

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Re: E21 With M20 N/A
« Reply #8 on: October 16, 2016, 03:43:21 pm »
I wonder about the sequential injection. I should just add a cam sensor, set up the 2nd trigger in VEMS, and engine setup odd fire and that's it? (ofc. when the injectors is individually connected)

Offline Kamuto

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Re: E21 With M20 N/A
« Reply #9 on: October 16, 2016, 11:35:48 pm »
I wonder about the sequential injection. I should just add a cam sensor, set up the 2nd trigger in VEMS, and engine setup odd fire and that's it? (ofc. when the injectors is individually connected)
not odd fire :) but yes you are right
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Offline Sam8888

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Re: E21 With M20 N/A
« Reply #10 on: October 17, 2016, 09:06:05 am »
Okay then i'll do it.  :D
I have a spare crankshaft VR sensor, i guess that'll be fine for camshaft sensor too.

Offline Kamuto

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Re: E21 With M20 N/A
« Reply #11 on: October 17, 2016, 01:14:40 pm »
Okay then i'll do it.  :D
I have a spare crankshaft VR sensor, i guess that'll be fine for camshaft sensor too.
check what ecu you have, hall sensor connection may be much more easier
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Offline Sam8888

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Re: E21 With M20 N/A
« Reply #12 on: October 18, 2016, 02:26:21 pm »
I did pictures from my Genboard back in the days. I have the 2nd LM1815 installed, and the wire that needed to be there, but unfortunately can't see the required solder blob (it's under one of the injector drivers). I have to disassemble it to check that.

Correct me if i'm wrong, but according to the pictures all i have to do is solder that blob at the back of the board (if it's not soldered already) and it's ready to accept the 2nd VR. (It's easyer to me because i have plenty of VR sensors at home)

Pictures:




« Last Edit: October 18, 2016, 02:29:13 pm by Sam8888 »

Offline Kamuto

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Re: E21 With M20 N/A
« Reply #13 on: October 19, 2016, 02:40:57 am »
I see that you have sec trig vr installed on ec18-7 pin :) all must work out of the box :)
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Offline jrussell

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Re: E21 With M20 N/A
« Reply #14 on: October 20, 2016, 08:03:49 pm »
I think you mean ec18-12 pin for the 2nd VR. Pin 7 is at the far right of the pic.
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