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72 D-Jet tuning

1985 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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Browser: I used Firefox with an ad and pop up blocker. The ads have gotten out of hand.

5 BTDC is correct at idle if you have no vacuum on the distributor. Vacuum at idle should be eliminated if AC is on, but when on, it should retard the timing 10 degrees to 5 ATDC.

Injectors can be soaked and "cleaned" in a vibrating jewelry cleaner I think. I've never tried myself.

There are threads on soft top replacement, but I assume you have stitching or the connection to a bow undone. Just don't damage the frame. Tops are only a couple hundred bucks if you DIY, normally about a thousand if you go to a pro.

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Don’t discount the timing when considering both emissions / AFR and MPG.

You can also investigate the spray pattern you are getting from each injector.

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