GM TBI swap - I'm stumped

[MysticRob]

Hopefully this whole thing works out for you. How do you propose to get by the CA smog nazi requirements for this pieced-together system you're running?

[Herk]

So this is the only way I can get it close to starting, and if I flutter the throttle and hold it open a bit it will run really rough. At TDC the rotor is so far past the #1 cylinder post that it appears closer to the #8 post. When I put a timing light on it while cranking, the mark shows up real close to TDC.

Is your mark on your timing damper anywhere close to reality regarding TDC?


Also, in the above picture it looks like the reluctor on the distributor shaft isn't aligned with the center of the pickup coil. At TDC (engine static), the reluctor wheel should point directly at the center of the pickup, or be ever so slightly before the center (distributor goes clockwise). Then with the dist visually zereoed, and assuming the computer is set for an offset of zero, with the tan timing set wire disconnected, it should start and idle well enough to zero it completely with a light. As for phasing, the tip of the rotor should be a bit before (distributor goes clockwise) the contact in the cap. Really it looks like you would be pretty close if the #1 wire was where you have #8 marked.



If you pulled the factory distributor apart to lock out the advance, you may have noticed that there are two slots in the reluctor wheel for the little pin that aligns it on the shaft. So there are two ways that the wheel can be keyed onto the shaft. One is correct, the other is far enough off that the engine will barely run. I finally figured this out after burning plenty of midnight oil on a rainy work night.

[elskeptico]

To confirm, my main problem appears to have been some bad (old) gas. With fresh fuel, and after redoing all the initial setup procedures, it seems to start right up every time now warm or cold. Sometimes still a bit rough when cold but it starts.

There doesn't seem to be a consensus around here about the "right" way to hookup the coil pickup wires to the ignition module P and N terminals, but this tidbit I found from Bill on binderplanet helped me determine what was right for my setup:

[After setting engine to TDC and rotor to just past #1 terminal, and after setting the reluctor wheel to point at the PU coil] "Crank engine to check timing. If the wires are connected properly then the timing will be within 5* of 0*. Just set timing to 0 and your good. If the timing is 20-30* away then swap the P and N wires and check again."

Thanks again for the help. Hard to believe I was pulling my hair out over bad gas, but on the bright side, I now know how to diagnose nearly every primary part of this system.

[babywag]

To confirm, my main problem appears to have been some bad (old) gas. With fresh fuel, and after redoing all the initial setup procedures, it seems to start right up every time now warm or cold. Sometimes still a bit rough when cold but it starts.

There doesn't seem to be a consensus around here about the "right" way to hookup the coil pickup wires to the ignition module P and N terminals, but this tidbit I found from Bill on binderplanet helped me determine what was right for my setup:

[After setting engine to TDC and rotor to just past #1 terminal, and after setting the reluctor wheel to point at the PU coil] "Crank engine to check timing. If the wires are connected properly then the timing will be within 5* of 0*. Just set timing to 0 and your good. If the timing is 20-30* away then swap the P and N wires and check again."

Thanks again for the help. Hard to believe I was pulling my hair out over bad gas, but on the bright side, I now know how to diagnose nearly every primary part of this system.

If you look closely on the diagram I linked...
A stock Duraspark pickup has a wire that is purple or a wire with a purple tracer.
That wire is always "P" on the module, every one of these that I have set up, or helped troubleshoot is that way.
The other wire "N" is generally orange or with an orange tracer.

[rang-a-stang]

Yeah, if I hook my pickup backwards it will not start. I had found a page on the megasquirt page that had them the other way and it would not fire. I swapped them IAW Babywags diagram and it fired right up. I have crossed them on accident in the past and it would not fire. I come out, swap them, crank it and it fires to life.

[elskeptico]

If you look closely on the diagram I linked...

Yup, I see it now. But I had come across other posts that suggested hooking it up the other way. At least that's how I remember it in the midst of all the hunting I did to try to figure this out.

As they say, it's all water under the fridge now

Thanks again! Glad to have EFI working now and looking forward to the fine tuning stage later on.