j9fd3s

iTrader: (3)

it just closes the secondaries when the engine is cold, does not effect mixture. default on an FC is wide open.

it is an early method of limiting RPM on a cold engine.

GSLSEforme

The idea of the test is to compare ALL the spark plugs in operation-since you don't have an oscilloscope-and compare color and consistency of firing-so you can eliminate ignition system as cause for low power.
Not sure what resistance you are checking,if checking ignition coil resistance,all wires need to be removed from coils to check primary and secondary resistance or readings are not valid.
Have you cleaned the plugs or are they original you started rebuilt engine with?

derSchwamm

iTrader: (1)

I can try again tomorrow, the plugs are still out. What's the best of way of disabling the injectors without killing the trailing ignition? I could unplug the injectors but would have to pull the manifold to get to them. It's just a hassle.

I'll try to get a video too I can post back here. Like I said, I can't see color, so unless one is sparking a lot more than another I won't be able to tell much. Hopefully a video helps

Here's everything I've done and checked ignition wise so far:
1) Brand new plugs (after first startup). They are now soot-covered.
2) Brand new NGK plug wires
3) Brand new NGK leading coil. Trailing coil tested fine on primary and secondary resistances
4) Tested all my igniters. The two on the car passed
5) Check resistance in the wiring harness between the plug on the ignitor and the coil. 3.5 omhs trailing, 0.9 ohms leading
6) Tested for leading spark this morning by putting the plugs against the firewall
7) Set timing with a timing light

Thanks for the help

GSLSEforme

Disconnect fuel pump

derSchwamm

iTrader: (1)

Today I learned that the fuel pump plug is under the cargo bin....

Ok, got the spark test done with a slow motion video so you can actually see the spark. Plugs are laying on sheet metal sitting on the intake manifold. It looks like leading spark might be a little stronger than trailing but that's all I can tell up front. Maybe folks with more experience can tell me if this is weak or not


Plugs from left to right: L1, L2, T1, T2

derSchwamm

iTrader: (1)

Actually, I’m thinking the L2 plug is firing stronger than L1. Anyone else see that? If true it must be an issue in the distributor, or a fluke bad new plug wire...

don’t worry that some plugs are cleaner. I didn’t clean them all off

GSLSEforme

Essentially a waste of time...watched 2x,no usable conclusions can be made.

Ditch the sheetmetal,screws up ground path for plugs. Lay wires on intake manifold.

Put camera within 6” of plugs so spark can be seen clearly.

Do spark test indoors in shade or just before dark.

Use a cleaned or fresh set of plugs.

derSchwamm

iTrader: (1)

Ok, trying again. This time I cleaned all 4 plugs up and put them directly on the manifold. I also mostly closed the hood and put blankets around the gaps so it's darker. If this isn't dark enough I'll need to wait until tonight.

Plug order changed again. From left to right: T1, T2, L1, L2. I still think L1 looks weaker than L2.

Interestingly the two plugs that came out of the front rotor didn't come as clean as the two rear ones. In this video they are the two on the left (trailing spots). This was my last new set of plugs and they have about 2 miles on them, so these are best I have.

derSchwamm

iTrader: (1)

I tinkered with it all day but it's still running poorly. To add more clarity, the throttle responds fine until around half throttle, and beyond that point nothing happens (no additional power – like I'm still at half throttle). If I am going up a small hill, I can't really gain speed at all, at least not under 4000rpm with my fresh rebuild. I know it's not a powerful or torquey engine but it shouldn't be this bad.

I took apart the distributor today and didn't find any obvious issues, except the air gaps are a little tight. .021" leading, .017" trailing. Not sure how to adjust those. I also swapped igniters around and got rid of my jumping tach problem but no change in the power output. I'm leaving an older set of plugs in the engine for now until I sort this out, it seems to run the same way either way. I also finally added the ground between the strut tower and battery.

This is getting frustrating. It's been 2 years since I could drive this car and it seems so close. What next?

I'm thinking I need to inspect my throttle body for closely. I assembled it myself after thoroughly cleaning all the parts, and I'm wondering if something could be off and not letting more air in with more throttle...

derSchwamm

iTrader: (1)

I know I’m just talking to myself in this thread this afternoon, but I learned something. I think I’m running on only the rear rotor.

I unplugged both front spark plug wires and started the car. It sounded a little rough but mostly the same as before. Then I swapped and unplugged the rear plugs only and nothing happened. Not even a blip during cranking.

So, I figure it’s either spark, fuel, or compression. I broke out my cheap compression tester again for peace of mind and held the release valve down while cranking. I got 3 even pulses right around 90psi. Letting go of the release valve got it to about 110psi, but obviously that’s a maximum of the 3 faces. So thankfully I think my compression is fine.

Ive been testing spark all day, and even if I am getting weaker spark in the front I know I am still getting some spark, so I think I’m ok there too.

Next I unplugged all 4 spark plugs and cranked the engine to get some fuel into each housing. I pulled the leading plugs from each and the rear was wet but the front was dry. Finally! I found something useful.

The thing is, when I was getting the rebuild started I thought my rear injector was stuck open. Now in hindsight I think I had the opposite problem: the front wasn’t getting enough gas. I already replaced the pigtails and tested the leads with noid lights but I think I’ll do it again unless someone has a better suggestion

derSchwamm

iTrader: (1)

Last update here: I got it running on both rotors tonight. I started the car and reached under the manifold and pushed on the plug on the front injector. It fired right up. Big difference in sound, idle speed, everything. When I let go it went back to idling on one rotor.

Turns out when I replaced the injector pigtails, I didn’t set the wire clips in the new connectors well and they are popping out of the back of the connector when installed. It was a simple fix but it took me a while to find it!

Thanks to everyone who helped me troubleshoot in this thread!

j9fd3s

iTrader: (3)

lmao, glad you found it!