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72 D-Jet tuning

1992 Views 9 Replies 5 Participants Last post by  MBGraham
Hello everybody. Thank you for the great information that has been posted. I have spent a lot of time reading through all of the posts, especially the encyclopedia germanica sticky. I want to start off by asking what browser is best for this website. I usually spend 5-10 minutes trying to load the page I want :( 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?
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D-Jet tuning: Your ECU is operating on assumptions that you are read up on. The best overall tuning concept I've read recommends bringing ignition, vacuum (air), then fuel delivery up to spec - in that order.

ECU rheostat only controls mixture at idle defined by TPS closed. Has your MPS been tampered with? If the protective black domed cap is gone, the assumption has to be made that it has. MPS tuning is the absolute last item to ever touch - independent mechanics and DIYers violate this a lot.

Many of us are advocates of Pertronix to eliminate problems caused by worn distributor bearings and resultant worn contact points; never worry about dwell again.

We can talk engine harnesses later . . .
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