Unicornowner

It's all good. Thanks for the effort!

What/where would that be Cosmo?

Here is a link to the car running and acting up. I've got a guy looking at the computer under a magnifying glass to see if there could be any issue there. He's also going to come by and help me check the grounding system to see if there's a chance that there is an issue there.

Coil was replaced with correct part. It was the stock one in the first place, just old. The weird thing is that it used to just misfire when I put it in gear, and then it started to do it under no load/ all conditions

Plugs are all light tan like they should be. Yes I did the plug trick, plenty of spark. I swapped #1 and #2 injector plug like you suggested to see if it was the resistors.

So, Mike, I've switched the plugs and it's not changing anything. At this point, I may redo the leak down check and see if I am missing any issue there. I did not replace the fuel regulator yet. Is there a possibility that an air bubble has formed at injector one and is causing it to lean out? I wouldn't think so, but cars can do dumb stuff. Also, can a dead battery cause any of those symptoms? The battery is shot, but the alternator is doing what it's supposed to do at 14.1. I'll try again next week with the leak down check

It does run fine at first and after revving it a bit, but once back at idle it drops that cylinder. I have to pop the throttle to get it to pick the cylinder back up. I'll try to post a video of what it's doing.

Mike, that's pretty much what's happening. I still have yet to swap the injector plugs to see if it moves. The fuel lines have been blown our forward and backward and then I ran welding wire through the rail to make sure that wasn't it. I may have to do a recheck of the leak down test. Compression check shows they are all the same after 3 seconds of cranking.

I've verified the spark going into the wire at the distributor while the engine is stumbling. We swapped wires from 1 and 2, and we also swapped plugs as well. I am not sure if there is somehow a way for the distributor to ground itself out at a certain point which gives #1 a weaker spark. Which could explain the situation as well. I don't have a spark gauge handy to see what kind of spark I'm getting. But, spark has been verified at the cylinder. We've checked for cracked porcelain, bad connection at the plug end, correct resistance on the wire. The whole 9 yards at this point.

Haven't had a chance to check it today. Would the resistor being bad keep the injector from firing? You can feel it click even when the cylinder has dropped. I'll try to check it tomorrow, hopefully work will be slower so I can peek at it.

Quick question on that one though if it does happen to be the injector wiring, what would that symptom be cause by? Bad wiring from the car being almost 40 years old? Or a deeper issue?

We've swapped injectors from 1 and 2, plugs from 1 and 2, and wires from 1 and 2. I'll give swapping plugs a shot tomorrow and see if it moves with that. Thanks

We did a leak down check to see if it was a leaky valve, and that wasn't the case either

We've done the whole pull a spark plug wire truck to see which cylinder isn't firing. It stumbles along on 3 cylinders. When we pull the wire off of 2,3,or 4 cylinder the engine stumbles to a halt. The idle pattern doesn't change when we pull the plug on number 1. I know 125 is low, but the manual says it's the very low end of in spec. Now, I haven't put a noid checker on the injector plug to see if it stops firing, but you can feel it continue to click which tells me that it's still working. The AFM sweep functions correctly at all positions as well. I'm scratching my head like crazy on this one.

So, sorry to revive an old thread at this point. But, it's my thread and here is more progress. I've done a lot in a year. A lot of cursing this stupid car and some minor mods. I've gotten a lot of stuff replaced like hoses, fuel pump, injectors, filter, spark plugs, wires, cap, rotor, shocks, struts, brakes, tires, coil, and probably a bit more. I've cut the coils so it sits lower and installed shorter length strut inserts in the front and shocks off a Celica in the back. I slotted to strut mounts to allow for camber adjustment. I widened the stock wheels from 5" to 8.5" I modified an S13 driver seat to fit into this car. Stripped the old and busted defrost unit out of the rear window and have plans to put in a new one whenever I can source one. I modified some seals off a muscle car to work on the windows in the rear. Over all, I have had a lot of frustration with this thing while learning so much about the early FI system. I've learned that it is a whore that must be beaten. I've eliminated every wrong issue at this point and the darn thing still drops cylinder one after a few seconds of running. Compression is perfect at 125, leak down check shows nothing. The injector was bad and we replaced all 4 with guaranteed good remanned ones. I had my guy check them on a flowbench before putting them on. It isn't a sticky valve, the cylinder looks fine with a boroscope, the only things I haven't checked/changed are the distributor itself, the ignition module, and the control unit. But, these cars aren't like 240sx's. Nobody has them in my area. So it's really hard to swap parts to see if I can find the issue. And I have a FSM! I've done all the voltmeter and resistance checks I can think of and nothing should be telling this thing to drop a cylinder. So I'm lost. Here's some pics