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80 200sx owner here!


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 125 isn't perfect. Over 150 wouldn't be too bad. Higher would be even better.

 

 Drops a cylinder? what does this mean? The injector doesn't fire fuel? The plug doesn't fire? How would you know this and how do you know it's #1?

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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.

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125 is ok if the other cylinders are about the same. They should all be within 10% of each other.

 

 

Swap a new plug wire on or trade wires with another cylinder. Problem move?

 

Swap the plug to another cylinder. Problem move?

 

Swap the injector wiring with #2 and see if the problem moves. This is a batch fire system, all injectors fire once per revolution of the crank. Or half the fuel needed two times.

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Each injector has a resistor connected in series with it. If a resistor is bad the injector won't fire. The resistor pack is small and It's located under the MAF down near the frame.It's about the size of your fist, maybe smaller, and has a aluminum shield or heat sink around it.

 

Switching the injector wiring should move the problem.

 

Maybe checking the injector wiring for power? Isn't there a test for this?

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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.

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If clicking, probably working electrically, at least.

 

Take the spark plug off and put an old plug in the end and lay on a grounded surface. Start it up and see if there is spark.

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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.

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I'm sure you have , I've helped as much as I can. Ha

 

Always worried about the "computer" on an '80 and that resistor situation. After a quick look , not sure FSM has values for resistors or voltage at injector , click is firing

 

Car looks great man, good luck

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Swapping the wiring and then the injector should cause the problem to move. If it doesn't then not the injector or wiring. I suppose the fuel line might be blocked?

 

Check for spark... if spark it should fire.

 

Last is an engine with good compression on all but one cylinder. Three are working to hold idle but the forth is lagging. When you pull the wire off not much will change.

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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.

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                             You might want to park it next to an Aztek....

......or a Juke. 

 

 

Pontiac Aztec.

 

Ugliest car ever.

 

And still people bought them. Like, "Hey! Look at me in this fugly shitheap! I'm so cool now."

 

I can see the designers in Detroilet. Having just finished carving the thing out of clay, they all stand back, and some dipshit engineer says, "Well boys, I think we have a winner here."

 

Makes me wanna puke.

 

And that rhymes with Juke. Clearly the second ugliest car ever.

 

Even an AMC Pacer or the AMC Matador looked better. And they were fugly too.

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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

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What do the plugs look like? Plugs are a great way to see what's happening inside the combustion chamber.

 

Did you swap the #1 wire with one of the others?

 

If you pull the wire off and put a plug in the end and start it up do you get a good spark???

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I put new nickel plugs in it. It loves the new gas. I'm looking forward to seeing what new wires and a new coil does to it as well. The coil is testing low tight now. So, probably going to go with an S13 coil as they are plentiful.

 

 

I assume the S13 coil will be ok but the impedance you should look for is between 0.8 and 1.0 ohms.

 

 

Mike, I've got 1.3-1.5 ohm depending on the temperature right now.

 

 

For the '80 4 plug engine the coil should have a resistance of 0.8 to 1.0

 

This is what the matchbox coil should be.

 

 

The coil you have has probably been replaced. POs just love replacing coils because... well Because they just don't think. They probably got an old points coil by mistake.

 

 

Did you ever replace the coil with the correct one???????????????

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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

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  • 3 weeks later...

 

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.

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