Ultimate MFI resources thread

[304065]

ignition miss

[356RS]

Almost sounds like some popping coming from one of the throttle bodies. Remove the air filter and take another listen. Also maybe a chain tensioner?

[rupydoo123]

Did u ever sort the popping out? I have got the same noise coming from what seems the same cylinder (first on the right).

[aradsinc]

I had a problem in my 1970 911s engine with an MFI in trying to solve the problem of the squirters to prime before starting.In other years I saw that the squirter where located at filter housing plumbing .

I check a 1974 Carrera 2.7 RS engine and way Porsche factory did was bore 1/8" holes at the towers and connect them in series to the start solenoid on top of the fuel filter.

If others have problem this maybe the way

1974 Carrera 2.7RS

[fbarrett]

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Frank

[Rslevin]

I am having an issue with my MFI relay. My MFI PCB has a transistor marked as D1. It is a three legged device that fell off, so I need to replace it. Diodes are 2 legged. The schematic in this thread shows T1, T2, T3 and are the small TO cans and T4 is the larger can. But a total of only 4 three legged parts. I have 5. I have 4 small TO cans that all seem to be the same part plus the larger T4. The relay PN is the same 0333.400.001. Is there a schematic error? Also where does D1 actually go on the PCB? Thanks for any help and any photos. -Rich

[Flieger]

That transistor is what you replace with the Zener diode. Only 2 legs of the transistor are used but I guess it was cheaper for Bosch to use another transistor rather than have a different component.

[Flieger]

see here

For MFI Gurus. . .and friends of Warren . . .

[Rslevin]

So why not use the transistor to replace the transistor. Any downside to do that. It keeps it original. Comments?

[Flieger]

The long leads are more prone to breaking due to heat and vibration making them brittle. I'm a mechanical engineer, though, so I can't give a great explanation electrically.

In the schematic it is shown as a Zener diode, so I would expect an EE would specify an appropriate Zener diode today if he saw just the schematic. I would expect that it would do a better job than a transistor. Sort of like using a swiss army knife for a task that really requires a fillet knife.

[911parts]

Lots to read in this thread. Does anyone have the R/H and L/H thread sizes for the linkage rods, need to buy tap and die