[tristessa]

If I come across an extra distributor for this engine to modify that doesn't cost more than a flight from LAX to London, I'll look into letting Speeduino run the ignition timing. I'm trying to be as minimally invasive to this car as possible. An extra distributor to play with would let me put the original in a box with the worn-out stupid original carburetor, on the off chance some future owner wants to be a masochist and make the car stock again.

I took some time in the garage looking for the TFI module but no luck, so I'm hitting the wreckers on the way to work in the morning. With a little luck there'll be a PRW-2 or J121 module and pigtail I can pillage. They look smaller than I remember the TFI module being, and definitely fewer wires so it should be easier to hide.

[dazq]

If I come across an extra distributor for this engine to modify that doesn't cost more than a flight from LAX to London, I'll look into letting Speeduino run the ignition timing. I'm trying to be as minimally invasive to this car as possible. An extra distributor to play with would let me put the original in a box with the worn-out stupid original carburetor, on the off chance some future owner wants to be a masochist and make the car stock again.

I took some time in the garage looking for the TFI module but no luck, so I'm hitting the wreckers on the way to work in the morning. With a little luck there'll be a PRW-2 or J121 module and pigtail I can pillage. They look smaller than I remember the TFI module being, and definitely fewer wires so it should be easier to hide.

I saw this dizzy , it's a bit scruffy but if you are going to mod it anyways?

https://www.ebay.co.uk/itm/115243444396 ... media=COPY

[tristessa]

I saw that one in my search a while ago, would be perfect except that's a 6-cylinder distributor and my car is a 4-cylinder.
No biggie, these cars still show up in the local pick & pull yards occasionally so I just have to be patient.

Another thought I had is to make an extended drive dog for a Beetle distributor, since I have some of those on a shelf, plus access to a mill and a lathe and someone who can help me learn to use them. Got the idea after looking at 123ignition a while ago and noticing that their Mercedes and VW distributor bodies are identical in the nice dimensioned drawings on their site, just a longer drive dog with different tangs on the Mercedes unit compared to the VW one.

[tristessa]

Getting back to work on this after the holiday week.

I tried starting the car "real quick" before with no success just before heading out of town. Saw on TunerStudio that the engine speed while cranking jumped around from 200RPM-ish to over 4000RPM. Realized on vacation that Mercedes has some kind of ignition control box between the distributor points and the coil, and that I'd connected the Speeduino input to the wire to the coil from the box and not the wire from the distributor. Corrected that and now cranking RPM in TS is correct, but now the battery is low so it's on the charger. Need to verify that I'm getting spark from the distributor while the engine cranks, which means enlisting my wife or a neighbor to turn the key for me while I try not to get electrocuted. Getting zapped by the ignition is almost as much fun as getting stung by yellowjackets.

Spark settings are load source: MAP, output mode: SINGLE CHANNEL, advance angle: 0, output triggers: GOING LOW, locked timing: ON, fixed angle: 0 DEGREES, new ignition mode: NO. Spark table is all zeroes until I get an extra distributor to lock so I can let Speedy control the timing. Cranking dwell is 4.5ms, running dwell 3.0ms, spark duration 1ms, dwell map NO, overdwell protection: ON, max dwell time 12ms. IAT Retard and Cold Advance are zeroed. Does this seem reasonable for a starting point?

[PSIG]

It's an experiment. Give it a shot, as I can't tell you what to expect from 0/0/0. I'd also suggest getting a neon spark tester (under $10) to see if you have spark, which lights when you have spark inline or in a wire. It saves you from occasional overdoses of adrenaline.

[tristessa]

No sparky-spark as indicated by the ignition test light and verified by trying to shock the crap out of myself.

Wiring at the PRW-2 module is correct -- pin 1 to coil (-), pin 2 to ground, pin 3 to IGN1 on the NO2C Speedy board. Points signal is going to VR1+ and seems to function correctly since I see 200-ish RPM when cranking the starter. Tried another new module in case the one I have is no good, still no spark, so I'm guessing something in my tuning config? Fueling seems to work (smell gas, see wetness in the TBI unit) and ignition worked fine with the carb, only change being the coil is now triggered by Speedy through the PRW-2 ignition module and not the distributor points through the Mercedes control box.

Only posting this as a status update while I sit inside until the sun isn't shining directly on my driveway anymore.

[PSIG]

Post your last attempt tune and log files.

[tristessa]

Update: one spark when the system is powered on, so the module and wiring are definitely fine. Just no other spark.

Will post tune and log when I get home later. At autozone right now sourcing exhaust parts for one of the other cars so I can quiet it down. The Flowmaster was OK around town but way to loud & droning for highway trips.

[jonbill]

Guess: is your spark output set to "going high"?

[tristessa]

Sorry this took a while, I had other stuff come up that dragged me away from this project for a while.

Yes, spark output is currently set to "going high", but I've had it set to "going low" and it didn't seem to make any difference. Which is it supposed to be?

Current tune and log attached. IAT sensor isn't connected but otherwise everything is as it should be and *seems* to work fine.