cannot rev if ignition is over ~27 degrees

azaad · Post by **azaad** » Thu Feb 12, 2015 5:33 pm

i am running a bmw m20 2500cc 6 cylinder engine using MSD firing a single coil. If i crank the ignition over approx 27 degee the car wouldn't rev, once i reduce the ignition the car would rev fine.

what might be the reason for this. I put a timing light and ensure that the ignition is correct.

.log file attached

Post by **jsmcortina** » Fri Feb 13, 2015 3:14 am

Distributor phasing causing cross-firing to another cylinder?

James

azaad · Post by **azaad** » Fri Feb 13, 2015 9:23 am

What's the best solution?
Change to waste spark?

Matt Cramer · Post by **Matt Cramer** » Mon Feb 16, 2015 9:09 am

Check the condition of the distributor cap and rotor.

azaad · Post by **azaad** » Mon Feb 16, 2015 3:06 pm

New cap....and decent rotor

Post by **jsmcortina** » Mon Feb 16, 2015 4:14 pm

Have you checked the phasing ?

i.e. what is the crank angle when the rotor aligns with tower?

James

azaad · Post by **azaad** » Wed Feb 18, 2015 6:35 am

when i get back the car i will pull the cap and check.

Rgds.
Azaad

ihateforums · Post by **ihateforums** » Mon Feb 23, 2015 12:18 am

Distributor shouldn't be an issue. I ran 40 degrees at part throttle on one of these. How about posting your wheel decoder and spark settings.

azaad · Post by **azaad** » Mon Feb 23, 2015 12:32 am

I have attached my tune file.

Rgds
Azaad

ihateforums · Post by **ihateforums** » Tue Feb 24, 2015 12:50 am

I may be overlooking something but I don't see where you've posted a tune file. In any case, these are the settings I used for the 60-2 wheel
Trig pos A 6
Trig return pos A 14
Trig pos B 26
Trig return pos B 34
Trig pos C 46
Trig return pos C 54
Trigger Angle 60

azaad · Post by **azaad** » Wed Feb 25, 2015 7:26 pm

i am using a 36-1 wheel \.

see attached .msq file.

ihateforums · Post by **ihateforums** » Thu Feb 26, 2015 1:36 am

Trigger angle of 32 is a problem. I would say move the trigger tooth numbers ahead, to get the trigger angle to 52. Then, presumably you will be able to use as much as 47 degrees (which is plenty for this engine). Try this:
Trig pos A 1
Trig return pos A 5
Trig pos B 13
Trig return pos B 17
Trig pos C 25
Trig return pos C 29
Trigger Angle 52
Cranking advance Angle 12

azaad · Post by **azaad** » Thu Feb 26, 2015 4:31 am

Tks ...will try this next week Sunday when I get to the track

azaad · Post by **azaad** » Sun Mar 22, 2015 7:43 pm

I tried these settings today and I went as high as 38 deg. However I didn't put back a timing light to confirm the spark angle.....tks again.

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cannot rev if ignition is over ~27 degrees

cannot rev if ignition is over ~27 degrees

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Re: cannot rev if ignition is over ~27 degrees

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Re: cannot rev if ignition is over ~27 degrees

Re: cannot rev if ignition is over ~27 degrees

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Re: cannot rev if ignition is over ~27 degrees

Re: cannot rev if ignition is over ~27 degrees

Re: cannot rev if ignition is over ~27 degrees

Re: cannot rev if ignition is over ~27 degrees