Missing while cold
Grab your stethoscope and pull the tip off and blow across the tip of the open hose, you'll wish you had done this years ago. Even the slightest bit of blowing across it is very noticeable so it's excellent for even the smallest leaks.
First I want to thank you guys for your insight and interest in this thread. Second, I finally had a chance to work on the car today. A friend of mine came over with a heat sensor and a 42lb injector. I mean I wasn't surprised when he checked the pipe and it read 180-200 while the rest were around 500, or higher as you got closer to the firewall. So before removing the manifold, we decided to try the green top on number 1. Within a minute or so the pipe hit 400. OK.
Also I first pulled the plug and it was brown (fuel stained) from not burning. Second, I pulled the plug on number 2 and it was grayish, also OK. Before we changed the injector, I unplugged it and it didn't make a difference at all. I used a noids light to check the wiring and it flashed away. Thats when we decided to change the injector.
Yes, I know I replaced a 30 lb LS6 injector with a 42. The motor at first threw a 200 code, but after clearing it out and a few starts the EMC made the adjustment. Tomorrow I am going to take it for a longer drive and check the plug afterward. Keep in mind although the injector failed there were no codes. Probably a mechanical fault. I'll post the results after the drive, and thanks again for the input.
Also I first pulled the plug and it was brown (fuel stained) from not burning. Second, I pulled the plug on number 2 and it was grayish, also OK. Before we changed the injector, I unplugged it and it didn't make a difference at all. I used a noids light to check the wiring and it flashed away. Thats when we decided to change the injector.
Yes, I know I replaced a 30 lb LS6 injector with a 42. The motor at first threw a 200 code, but after clearing it out and a few starts the EMC made the adjustment. Tomorrow I am going to take it for a longer drive and check the plug afterward. Keep in mind although the injector failed there were no codes. Probably a mechanical fault. I'll post the results after the drive, and thanks again for the input.
I also use my stethoscope for listening to injectors but I use it with the standard tip. It's excellent for hearing when an injector has a mechanical fault.
The pcm will only notice a bad injector if the internal windings go bad and cause an open circuit, or I believe also for short to ground or hot. So I think you're probably right about it being just a mechanical failure in the injector.
Glad you found it and now know what you need to do.
The pcm will only notice a bad injector if the internal windings go bad and cause an open circuit, or I believe also for short to ground or hot. So I think you're probably right about it being just a mechanical failure in the injector.
Glad you found it and now know what you need to do.
I also use my stethoscope for listening to injectors but I use it with the standard tip. It's excellent for hearing when an injector has a mechanical fault.
The pcm will only notice a bad injector if the internal windings go bad and cause an open circuit, or I believe also for short to ground or hot. So I think you're probably right about it being just a mechanical failure in the injector.
Glad you found it and now know what you need to do.
The pcm will only notice a bad injector if the internal windings go bad and cause an open circuit, or I believe also for short to ground or hot. So I think you're probably right about it being just a mechanical failure in the injector.
Glad you found it and now know what you need to do.
Also, I ordered the correct injector. I should have it tomorrow. I can smell gas from the 42.
A healthy injector will (bear with me while I try to type out sounds and hopefully they make sense).. a healthy injector makes a sharp clack like sound, I would say the sound ends with a k, if that makes sense, and a dead injector will make a thud, and the dead injector isn't actually making any sound, it's sound transfer from the others. You can also practice listening to them while the engine is running and just unplug an injector and plug back in and listen to the difference. I like to place the stethoscope tip on the injector body closest to the intake while not touching anything but the injector, sometimes I'll put it on the connector. I just always make sure I listen to them all at the same spot for consistencies sake.
OK, GOOD TIP. But, I have a new twist. While the injector was bad and I installed a replacement, the motor still misses on cold start. When warm the motor runs great with the new injector, but still has the miss when cold. So, I cleaned the AIC and I am beginning to suspect the connector, even though the noids light showed a good connection. I ordered an EV-1 connector today and will solder it in tomorrow. I think it maybe the plug in and when I hooked up the noids the jiggle or prong size made a good connection.
Also, and if so, this will be the third plug in I had to change during the last three years. This car is tough on electrical connections. I had to change the MAF plug in and both coil pack plug ins. The strange part are there are no codes. You would think a voltage drop from a bad plug in would send a code. There is another reason I think its the plug in, after I cleaned the connection and put on some dielectric grease, the header pipe temp went up.
Stay tuned for the latest drama.
Also, and if so, this will be the third plug in I had to change during the last three years. This car is tough on electrical connections. I had to change the MAF plug in and both coil pack plug ins. The strange part are there are no codes. You would think a voltage drop from a bad plug in would send a code. There is another reason I think its the plug in, after I cleaned the connection and put on some dielectric grease, the header pipe temp went up.
Stay tuned for the latest drama.
Last edited by rednari2; Sep 28, 2020 at 09:55 AM.
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I finally figured it out. It was the injector plug. I should have known from this car's past, that being three prior plug problems. The clue came after I replaced the injector with a borrowed 42 from a friend. The motor at first ran great and the heat sensor showed the pipe was hot. But, the next day, the cold miss returned and I knew then it was not caused by the injector. What threw me off was that the noids test indicated good plug and wires. Apparently, plug movement while making the test and changing the injector, created a good connection. Anyway, its Ok now.
This car has had numerous issues with connectors. I was taught to always check the simple things first, but you can throw out that theory with this car. Case in point: (1) The car missed so badly once I hardly got it home. The car tripped a MAF code. Did the MAF need cleaning or replacement? Of course not, it turned out to be the plug in. (2) Random misfires set off O2 codes. Did it need O2s or have bad wire extensions to the headers? Of course not, I had to replace the coil pack plug ins. (3) Two months ago the motor started missing at speed. The miss tripped a temp sensor code, Did I need to replace the sending unit? Of course not, two days after replacing the sensor the miss returned, so I rep[laced, what else, the plug. Voila, no more misfires.
And now, the same garbage with the injector plug in. You can take code readers and other diagnostic equipment and stick them. Only my intuition and a multi test meter have figured it out!! If I ever have a straight forward problem, I'll never believe it. From now on, I'm starting with the wires and working may way to the easier. GEES!!
I hope this helps the other guys on the board.
This car has had numerous issues with connectors. I was taught to always check the simple things first, but you can throw out that theory with this car. Case in point: (1) The car missed so badly once I hardly got it home. The car tripped a MAF code. Did the MAF need cleaning or replacement? Of course not, it turned out to be the plug in. (2) Random misfires set off O2 codes. Did it need O2s or have bad wire extensions to the headers? Of course not, I had to replace the coil pack plug ins. (3) Two months ago the motor started missing at speed. The miss tripped a temp sensor code, Did I need to replace the sending unit? Of course not, two days after replacing the sensor the miss returned, so I rep[laced, what else, the plug. Voila, no more misfires.
And now, the same garbage with the injector plug in. You can take code readers and other diagnostic equipment and stick them. Only my intuition and a multi test meter have figured it out!! If I ever have a straight forward problem, I'll never believe it. From now on, I'm starting with the wires and working may way to the easier. GEES!!
I hope this helps the other guys on the board.