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Thread: smoke test injectors

  1. #11
    Senior Member
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    Very common for the seals to leak. They get hard and don't seal well. I used the teflon tape just to show you can seal the old. hard seals but replacement is always better. maybe the new seals you get now don't seal as well as the NOS stuff we used to get. Another very common leak is the "O" ring for the air pipe at the bottom of the mixture unit. Hard to see the small leaks when you have big ones.
    David Teitelbaum

  2. #12
    Senior Member 82DMC12's Avatar
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    Quote Originally Posted by David T View Post
    Very common for the seals to leak. They get hard and don't seal well. I used the teflon tape just to show you can seal the old. hard seals but replacement is always better. maybe the new seals you get now don't seal as well as the NOS stuff we used to get. Another very common leak is the "O" ring for the air pipe at the bottom of the mixture unit. Hard to see the small leaks when you have big ones.
    Yeah but he has a smoke machine now. He's gonna be seeing EVERY leak.

    Good news is, if all the vacuum leaks are fixed, now you know the problem isn't vacuum leaks!

    Smoke machine was a smart move. Only way to be sure.

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    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!
    Total frame-off restoration completed 2021-2023

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Kansas City

  3. #13
    Senior Member glockworks21's Avatar
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    none of the fixed leaks changed it at all. Its not even getting fully warmed up before it starts doing it. Is there anything mechanical or electrical that will kick in at a certain temp that is screwing it up? I know that may be a stupid question but how does it run so perfect every time for the first 5 minutes and then start the dance every time? The ism is new. I unplugged it last night when it was hot just to see what it would do. It just made it jump all over. It gets
    half way to the first notch on temp gage and starts doing it. and its always the same. I do not have a dwell meter and have not messed with fuel mixture. all those injectors sealed up quite a bit better and it didnt change anything. It still has the exact same rhythm at the exact same time. can a bad o2 sensor cause any of these symptoms?

    Thanks again

    Dave

  4. #14
    Senior Member 82DMC12's Avatar
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    The O2 sensor does not begin to produce a reading until it reaches a certain temperature, like over 800 Fahrenheit or something. Normal operation of the lambda system is that the fuel mixture is set to a fixed reading until it begins to receive a signal from a warmed up O2 sensor. If you had to dwell meter, you would see the needle does not move while the engine is cold and it is warming up. 1 CO2 sensor begins to produce a reading, then you see the dwell meter go into the narrow swing that we often refer to. The swing is not the same as an idle speed that fluctuates. The engine actually tends to run a bit smoother when it is cold and warming up. Once it goes into closed loop hot operation, the engine gets its characteristic idle but the tack needle should be really quite steady at about 750 RPM.

    At this point you're probably going to have to get a dwell meter so you can see what is happening and do four or five different tests that are possible only with a dwell meter. It's also possible your O2 sensor is faulty. Personally if it were me, and I didn't know when the last time the O2 sensor was replaced, I would replace it and then hook my dwell meter up and give it a check.

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    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!
    Total frame-off restoration completed 2021-2023

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Kansas City

  5. #15
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    Quote Originally Posted by 82DMC12 View Post
    The O2 sensor does not begin to produce a reading until it reaches a certain temperature, like over 800 Fahrenheit or something. Normal operation of the lambda system is that the fuel mixture is set to a fixed reading until it begins to receive a signal from a warmed up O2 sensor. If you had to dwell meter, you would see the needle does not move while the engine is cold and it is warming up. 1 CO2 sensor begins to produce a reading, then you see the dwell meter go into the narrow swing that we often refer to. The swing is not the same as an idle speed that fluctuates. The engine actually tends to run a bit smoother when it is cold and warming up. Once it goes into closed loop hot operation, the engine gets its characteristic idle but the tack needle should be really quite steady at about 750 RPM.

    At this point you're probably going to have to get a dwell meter so you can see what is happening and do four or five different tests that are possible only with a dwell meter. It's also possible your O2 sensor is faulty. Personally if it were me, and I didn't know when the last time the O2 sensor was replaced, I would replace it and then hook my dwell meter up and give it a check.

    Sent from my Pixel 6a using Tapatalk

    Thanks to your post I finally bought a smoke machine ($82 on amazon) to test for vacuum leaks. All my injector seals also leaked. I bought new seals from
    ebay. I pulled the old injectors off and they were still flexible. I decided to clean up the injector seal support using a bottle brush that just fit into the hole. They were all dirty with black soot from the leaking seals. Then I used lacquar thinner to wipe the injector clean and the top of the seal support. Fitted the clip and new seal insuring it was all the way up the injector to where a stop can be felt. To ensure it does not leak I used Permatex ultra black sealant aroung the lip of the seal where it contacts the top of the support. Waited 4 hours and started up. Ran the best it has in years!!! Now to look for more leaks.

  6. #16
    Senior Member glockworks21's Avatar
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    Had some free time and motivation today. Tried to remove the o2 sensor. I bought one months ago and never installed. It wont budge. I can get a wrench on it barely and would love to hit it with a hammer to knock loose but the wrench lines up right near the frame. I used penetrant oil and even torched it. My next thought is to drop axle on the transmission side to get more space. Any thoughts?

    next part to the story. before I put it back together I held torch on the old sensor for a beat. I decided to make sure everything worked and drove it around a bit to get it warm. It was 80% better on the warm rhymitc idle... It was barely doing it at all. I parked it and let it cool... wanted to see what it would do from cold start and it was right back to its idle dance.

    Would heating that sensor with a torch break something free? Does any of this make sense? I will get back under it on a day when its not 105 degrees outside and hopefully get the old one out.. Welcome to all advice on removing it... I was going to even try getting a deep socket and wratchet on i it but there is not enough room before you hit frame to get it in there..

    Thanks again...

  7. #17
    Senior Member 82DMC12's Avatar
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    Just heat it up by running the engine! Can you cut the wire off of it so you can put a six-point socket on it?

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    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!
    Total frame-off restoration completed 2021-2023

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Kansas City

  8. #18
    Senior Member Bitsyncmaster's Avatar
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    I do it all the time with an open end wrench but mine has anti-seize on it. You could cut the wire off and use a boxed end wrench to get better angles.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  9. #19
    Senior Member Rich's Avatar
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    Get a proper 22mm offset O2 sensor socket, then carry on with whatever thread loosening ideas you come up with. It will allow you to use a breaker bar, assuming a box wrench is too short to provide the torque you need.

    Any good auto parts store will sell you one like this.
    These items look like they're on loan.

    These short offset sensor sockets slide into place without cutting the wire on the old or new one. The offset ratchet hole gives you max clearance from the frame and better leverage than a deep socket can.

    Be sure to use anti seize on the sensor threads as a favor to the next owner. Not much and none of it on the sensor probe itself.
    March '81, 5-speed, black interior

  10. #20
    Senior Member glockworks21's Avatar
    Join Date:  May 2022

    Location:  lincoln ca

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    Quote Originally Posted by Rich View Post
    Get a proper 22mm offset O2 sensor socket, then carry on with whatever thread loosening ideas you come up with. It will allow you to use a breaker bar, assuming a box wrench is too short to provide the torque you need.

    Any good auto parts store will sell you one like this.
    These items look like they're on loan.

    These short offset sensor sockets slide into place without cutting the wire on the old or new one. The offset ratchet hole gives you max clearance from the frame and better leverage than a deep socket can.

    Be sure to use anti seize on the sensor threads as a favor to the next owner. Not much and none of it on the sensor probe itself.





    Thank You! Just ordered the tool on the link you sent. I will update later this week

    Thanks again to all

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