Ron,
I had to do a search to find the write up on BW:
Quote:
The emission specs for the 117 engine according to the MB Technical Data Manual are:
Full load shifter position S 3,000 rpm = 2% - 5%
Upper partial load position S, 2,500 rpm 300 mm Hg vacuum 0.1% - 0.5%
Lower partial load 3rd gear shifter position S, 1,500 rpm 300 mm Hg vacuum = 0.2% - 0.5%
Idle neutral, idle speed, oil at operating temp = 0.5% - 2.0%
All % CO and would apply, I guess, to either dyno or road testing. I just used the idle and the full load for setting MPS & ECU.
Those are the North American specs. Euro are slightly different.
What type of meter do you have? Some of the old Wheatstone Bridge ones are apparently susceptible to moisture and kind of useless. If it is not one you can take in the car with, then you could try this:
First set timing so you have 5-8deg BTDC without vac and with A/C turned OFF. Check that you have good vacuum at idle (16-17" is normal). Also make sure your Throttle Position idle switch is functioning properly. Method is in engine manual (also HERE )
- Warm the car by driving it for at least five miles.
- Disconnect the throttle position switch plug (so as to disable the idle circuit) and set the ECU knob in the middle of it's range which is 11 clicks from right or left.
- Adjust the 4mm MPS screw in VERY SMALL increments so that you get about 3.5 percent CO at 2500-3000rpm. (at least as a starting point)
- Shut engine down and reconnect throttle plug.
- Start up again and set idle speed to about 750-800 rpm's.
- Use the ECU knob to set the idle co to about 1.5- 2.5 %CO. (rev enginel in between adjustments and taking new reading)
-Take car for a drive and then recheck CO at same conditions.
On my own car, I used this procedure. At first, I had a loan of an older CO meter - But it did not give consistent results. Since then, I have purchased a wideband Air/Fuel ratio gauge. (There are a number of manufacturers - mine is an AEM and is a permanent mount. Innovation makes portable units. Cost $200-$350 and well worth it.) This allows me to monitor AFR at all times. Better than watching TV
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I learned above from a long time MB mechanic,
but in this link, Steve Brotherton uses a similar technique, but seems to adjust the MPS at idle rather than at 3000rpm.
If you decide on using Pertronix, I can post a wiring diagram - the one that comes with the unit is not applicable to our cars when only doing a points replacement. But you don't really need a diagram - just connect the red to the 12v side of one of the resistors and the black to same place the green distr wire now connects. Also an idea to run a separate ground wire from distributor body to the battery or a good ground. A search on the Vintage forum should bring up many posts on this subject. (including
THIS ONE)
__________________
Graham
85 300D
,72 350SL, 98 E320, Outback 2.5