I am working on tuning my 72 350sl right now and I am getting a lot of misfires. Timing is set 5 degrees BTDC (about 27 total advance @ 3k rpm), but it jumps with misfire. Dwell is at about 33 and all injectors seem to fire just fine (I listened to them). She seems to misfire a lot before reaching operating temp, but not as much afterwards. Plugs are a little white, I set them at 0.032" Ecu is set to all the way rich, she misfires more if set leaner. I did check the air temp sensor and water temp sensor, but map.... there isn't a test for it? Right now I plan on cleaning the injectors and then replacing the fuel filter. Fuel pressure is also good, 31 psi. Can I soak the injectors in carb cleaner, or will that destroy the electronic or rubber parts? I haven't seen much information on the best way to clean them yet. I am also going to replace the soft top and paint the hood. I don't like the way the soft top bows up right now (on the back), is there a thread that deals with this? What is the best manufacturer for the soft top?
Read the section in EGV107 about setting the Throttle Position Switch (TPS). Make sure it is set properly so that it will signal to the ECU that you are at idle. You should be able to set knob in middle or range and fine tune idle mixture by going a click at a time followed by short burst of throttle.
Resistance testing of MPS is covered in the shop manual. Also check with Mityvac or similar that it will hold say 20" of vac for 15-30min. To test if it is working properly and make adjustments, you need an exhaust analyzer or a wide band AFR meter (I could never get my car right until I installed an AFR meter, but hardly anyone here has one!)
Probably not your problem, but you can immerse the injectors in carb cleaner. There are small screens on the inlets. You can remove those for cleaning by screwing in a suitable sheetmetal screw and pulling to extract. I set up a kind of crude system to flow test the injectors using my pressure brake bleeder. I think it is in the Comprehensive guide in the stickies. Later, I did 4 at a time using spare fuel rails and compared the amounts collected. At first I used Seafoam to clean, then carb cleaner. For flow testing I used clear mineral spirits/Varsol (not gasoline!)
Don't know why you are getting misfires. Usually timing or ignition problem. Follow what Cush said and get things in good shape firts (Sounds like you are well on your way). Pertronix eliminates points as a potential problem - covered in Stickies. Make sure rotor and cap are aligned. Check for damage to contacts in cap.
