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BLACK SMOKE??????????

487 Views 5 Replies 4 Participants Last post by  yellowboneZX
What I did: Replaced injectors with New Nissan injectors; replaced injector connectors and solder/spliced them in; replaced all hoses and vacuum lines. The car, 1981 280zxt, was running great before I did this, I was painting the engine and bay so I decided to replace injectors.

Problem: After all of those replacments and I started it up, the engine would run for a few seconds, run like it had a huge miss, and pumped out thick black smoke from the exhaust pipe. Every step that I took, I wrote down so I wouldn't forget to connect everything back right, so I'm confident that it is connected right. The injectors that I bought were from the Nissan dealorship, the 1984 300zxt recall kit.

Question: What could have suddenly happened to cause this problem. Where do I start looking. I am a novice and have only the basic tools, no computerized equipment.

Thanks for any input, Craig
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You probably plugged the coolant temp sensor (on rear of head between rear set of spark plugs) into the wrong place or it's getting a bad signal etc. I've used these injectors on several cars, they work fine as they are the exact same injectors. Actually have a set in my hotrod NA car.
Where can you plug the temp head sensor connector to around that area? Nothing should fit that plug around that vicinity. If you left this plug disconnected the car won't start. I have experienced with this black smoke problem before. After swapping parts from my running ZXT into a non running ZXT and then when I put everything back to the running ZXT the car smoke like crazy. I quickly found out that the AFM connector wasn't plug in. So check that first. Other than that there is only 1 more thing you need to check is the Vacuum control valve. I doubt you mess around with this valve. This is the valve screwed into the 4th runner of the intake. If you remove this you will get plenty of smoke too. Good luck

Post Edited (Oct 12, 8:13am)
... black smoke means you are runnin' rich. Very black = Very Rich. All the above comments and suggestions seem real good to me . Follow their advice and suggestions. Goodluck.
"replaced injector connectors and solder/spliced them in", I have no idea if he changed the connector on the temp sensor and conected it to the windshield washer pump etc. Seem people do all sorts of crazy things when they start cutting up a wiring harness. BTW the car will run with that sensor disconected, go try it and see.

I think I'm just going to stop posting to ZXT electronics questions, it's not worth the abuse from people who think they -know everything-. Good luck guys!

BTW I'd love to hear how the vacuum control valve can make the car blow clouds of black smoke! Yea only 2 things could be the problem... :)
Hey Steves280, please don't let someone else's comments, be it right or wrong, stop you from helping others, like myself. I for one really appreciate your input. I have come to realize from being on this forum that you in particular are the one to ask technical questions and I take your advice to heart.

So, I did not replace the temp sensor connector. when I looked at it, per your advice, it looked a little loose with some corrosion on it. I played with it a little, as well as the connector to the AFM. I then started the car. It started and ran for about 5 seconds with no smoke and then cut off. Each time I tried to start it, it would run for a few seconds smoothly and then cut off. If I give it gas, it would cut off immediately. I still don't know what the problem is. I guess I'll try to replace the connectors.

Any comments help me

Post Edited (Oct 13, 6:29am)
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