Stalled after Dizzy Cleanup, Won't Start
 

This past weekend I finished an ignition system cleanup. (http://forums.pelicanparts.com/porsche-911-technical-forum/856863-bouncing-tach-when-cold-zap-noises-7.html)
New cap, rotor, wires, and coil. Replaced green pickup wire. Took distributor apart, cleaned, oiled, reassembled. She ran great and I've driven about 200 miles since last Friday.

Today about 2 miles home from work I was at a light and she stopped and wouldn't start. Pushed her to the side and tried a few more times. Mostly I got no response. A few times, she would puff a little with a really low RPM, and then quit. When she was in this low almost-idle, she had no throttle pedal response at all. Shortly after, I got a notable breath of smoke (but no backfire) out of the airbox. She rumbled a few seconds once or twice on later attempts, but since then no combustion. CDI whines properly, and starter is turning strong.

I suspected my connector I added to install the new green pickup wire was faulty, but after taking out the distributor and unplugging the wire, it passed continuity check. I pulled a spark plug and am fairly sure I was smelling gas. Plugs aren't as clean as I'd like (probably from improper ignition before I worked on the system last week), but I would think I would hear some combustion.

I checked all my fuses and found no faults. I tried to check for spark with my timing light, but I didn't see anything. It was very bright and sunny so it is conceivable I missed it.

I forgot to line up to TDC when I pulled the distributor, so I tried both rotation positions after reassembly but still have no combustion. I guess I'll need to depth-gauge to ensure I have it in TDC at the rotor mark.

The current plan:
- Ensure I have TDC at the rotor mark.
- Pull a spark plug and check for spark.
- If no spark... what next?

Hopefully I can get back on the road soon. I was soooo happy for about 5 days, and now the no-car doldrums are back.

What I would do....


Take the dizzy out, connect a spark plug to the COIL HV post, twist the dizzy drive gear by hand.

No sparks.. Find out why..

Sparks, put the Dizzy in the loop.

Report....

Recent work would indicate ignition problem.

Doing this test, do I turn the key so CDI whines, but not turn key to Crank position?

No need to go to crank position.

OLD Kettering (points) systems bypassed the ballast resistor when cranking.

Not as issue for CDI.

Know anyone local with a spare CDI box to swap?
Bet the car will run fine with a known good cdi.

I'll be working on the problem tomorrow morning. I do have a friend with an '80 SC. If the initial tests don't reveal the issue, I'll see if I can get his help to swap the CDI. Reporting back tomorrow!

Make sure the trigger wire (green) is not frayed. It's a COAX (inner conductor with braided shield). After that it's pretty much down to the CDI box given that it ran fine.

A whining box is not necessarily an indicator for a working box. It's the other way around. If its not whining its dead for sure. But even if you hear the whining noise there still can be something wrong preventing it to produce a spark.

Let us know what you find.
Ingo

cd or coil.
check for spark first. wwest's idea is a bit laborous. just connect a plug to a plug wire and ground it while cranking. or use a timing light on one of the plug wires.
did you put the screw back in the clamp that holds the plug into the dist.
is the igniton wire all the way in on the coil
check ground on coil.

regardless of "how" I would eliminate the dizzy HV section first by connecting the coil tower directly to a spark plug.

Timing lights are highly subject to "false" firing IMO/experience.

New rotor.... open resistor..??

I replaced the trigger wire last weekend. It is all new and shiny.

I did indeed screw the screws that hold the pickup connector clamp in place.
I replaced the coil last week as well. Wires are all tight on their spots.

Headed out to check for spark now!

I pulled cylinder 4's wire and it had a nice blue spark when cranking. I pulled 4's injector and it smelled lots like gas. We cranked and it had a fuel spray. I also had a backfire as soon as we did the crank with the injector out. Nearly made me fall over - so loud! Airbox seems fine - popoff valve doing its job?

I didn't get time to inspect the spray too carefully because I was busy almost falling over. It happened immediately on crank with the injector out.

I put the injector back in and it still just cranks with no ignition.

Maybe I'm lacking air? And when we pulled the injector now it could ignite? Heart rate is still coming back down from that noise 1 foot from my head.

Yikes! That's just your car's way of making sure you're healthy enough to drive her once you get this fixed. :)

You have spark and fuel so it's starting to sound like you have a big vac leak. Check the seal on the pop-off valve. One of those backfires may have loosened it. You also may have a not-so-obvious crack in the airbox. But check for loose connections on the CIS components before jumping to any conclusions. Also check the pressure plate arm position.

When I was putting my engine back together it was a good reminder for just how many single points of failure there are for CIS vac leaks.

Dizzy 180 degrees off?

Dizzy rotor actually turning?

Tirwin: car was idling at a traffic light, stopped, wouldn't restart.

No mention of backfire plus not likely at idle...

Sheared drive gear roll pin?

I'll check over the popoff seal and box carefully. No backfire until after the car had stopped working for a while. Loose connections - you mean check all the hoses/wires to verify they are tight on their spots? Pressure plate arm is the one you reach from inside the airbox, correct?


Dizzy rotor turns. I had the dizzy out and handled it on Wednesday after the stop in traffic, and I'm sure the drive gear is working and fine.

I also tried the distributor at both 180 degree positions (because I lost TDC while I had it out checking other things).

Airbox seems tight and solid. No discernable cracks. No loose hoses or connectors. Grrrrrr!

The little arm/valve thing in the top back of the airbox moves smoothly up and makes a little swoosh noise and then settles back down when I release. Seems consistent with motion in previous years when I've poked around there.

Not only is it possible for a CIS car to backfire at idle, I've seen it happen many times.

Plenty of opportunity for something to come loose and create a vac leak.

Turn the engine by hand and see if the dizzy moves. Verify position of rotor relative to Z1 mark. Easy enough.

Yes to both.

It sounds like you have covered all the basics. Could you swap a CDI with a known good one locally?

After that you might want to check fuel pressure to make sure you're getting enough flow to the injectors.

Have you tried this? Take the air box cover off and turn the key to the ON position (not cranking) to energize the fuel pump. Lift up on the air pressure plate arm for 1-2 seconds -- just until you hear the injectors squeal and then let go. Then try cranking the car and see if it starts.

Turned by hand it it moves smoothly and turns the dizzy. After the stall, I took the dizzy out to check the pickup wire but didn't leave the engine in TDC, so I might be 180 off. But since then I've rotated it 180 and it didn't fix the issue.


I can try to get a friend to come by sometime this week with his 80 SC and check out his CDI box.

I tried the airbox cover thing and the injectors squealed right away. But then when I cranked it afterwards I got no combustion - just fast happy cranking.

At this point it's going to likely be poor fuel delivery or poor spark quality. Did you smell gas when you heard the injectors squeal?

I pulled the injector out and put it in a bottle and I'm getting fuel in the bottle. Strong gas smell around when I do that. I don't know how to be certain I'm getting the right amount of fuel. I swapped fuel pump relays without any effect.

I replaced the fuel filter a couple of years ago - maybe it needs that again? Its been somewhere around 16K miles since then.