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79 450SL
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65 Posts
Discussion Starter · #1 · (Edited)
So... I posted about misfire a while ago... after doing a pre check for the smog... high CO failed at 1.67%... but the HC was 2x the previous... 105ppm

I focused on misfire... therefore ignition... changed the spark plugs to non-resistor, NGK BP5ES... the previous bosch looked a bit lean... cap and rotor were replaced too with bosch parts...

So after fiddling around for a few hours... the WUR is getting battery voltage, 13.4volts... resistance is 24.1 ohms either cold or warm, here cold is 60F... the junkyard one is reading about 18.9ohms... even warm, laid on the valve cover

After too much frustration.... still misfire testing 2 ignition box... at least one of them lasted 10miles... the OEM with 28700miles did not last too long... new coil european , not brazilian did not improve.... OK at idle until 1500-1800 rpm, but failing when giving more gas or uphill... it misfires...

A few months ago, I tried to installed a GM HEI... no go... so this afternoon, I installed the spare MSD box... and it is a bit fiddling... but it ran... very well at high rpm... but crappy off idle.... hummm may be the timing is off... for sure it was 40degrees... lowered to 0... perfect at idle... but not so good at higher rpm... brought it to 5 degrees... now I have to install it in a better place so the MSD box does cook above the exhaust...

and the distributor connection hack

As usual... comments are more than welcome
 

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Premium Member
1976 450SL, 1992 190e 2.3, 1984 300D turbo, 1966 VW bus
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1,241 Posts
I can't help you with aftermarket rigging.

Put in the correct factory components and we can walk you through this.
 

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Registered
79 450SL
Joined
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65 Posts
Discussion Starter · #4 ·
Not enough time for a test drive... Relocated the MSD box under the windshield washer reservoir and made everything looking cleaner... of course in the process one of the connector got loose, no start... and it was time for troubleshooting... even the tach is working with the aftermarket box.

The 3mile test around a few blocks netted that the coil is a lot cooler... warm to the touch not scalding... intake vacuum is up from 9 to 14" of Hg...
 
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