2002 7.3 Injector TS Question
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2002 7.3 Injector TS Question
Just a question prior to me dropping $200+ on an injector/s. I have done some TS of my own and want to talk with some technically educated people to see if I am totally off base. I have a dead cylinder in my right bank (I hear a faint knocking sound). I believe it is the #5 because when I hold my laser thermometer to the exhaust manifold all cylinders progressively get hotter except #5 is 10 degrees cooler than #3. The engine light is not illuminated on the instrument pannel, however, I do believe that the only way for the light to come on is for the something electrical to be bad (wiring harness, etc.). I am also under the impression that there will not be a code to tell me that there is an injector not firing. Please let me know if I am completely wrong and if there is anything else I can do to TS this problem. Oh BTW, my fuel mileage has dropped from 15.5 to 12.3 since this has started (another reason it leads me to believe it is an injector/s problem). Thanks for any help possible. JYD
Lead Driver
Joined: Jun 2007
Posts: 7,760
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From: Hampton, Maryland.
Do you have access to AutoEnginuity? If so, you could run a buzz test on the injectors and a CCT- cylinder contribution test. It would be helpful to confirming your suspicions. I am pretty you are correct on the fact that you won't get a check engine light nor a stored code if the mechanics of the injector are not working properly.
Oh, and thank you very much for your service.
Oh, and thank you very much for your service.
Hotshot
Joined: Jan 2011
Posts: 18,849
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From: Puget Sound
That's a dead one... unless you reached the limit of your temp sensor. The best comparison is with number 6 cylinder - they are mirror images of each other. This could be as simple as a bad connection. If you have a multimeter, you can ohm out all the solenoids from the 42-pin connector located over the driver-side valve cover. It's a simple matter of pulling the plug (keys in your pocket, not in the ignition) with a 10mm socket and you will see this:
Lead Driver
Joined: Jun 2004
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From: Amarillo, TEXAS!
P+ is passenger side common, and D+ is driver side common. Ohm the odd numbered pins to the P+ pin, and the even numbered ones to the D+ pin. About 4 ohms or less seems to be what most people consider OK.
Hotshot
Joined: Nov 2006
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From: North of Greenville
Be careful about leaning too much on a small 10° difference alone based upon your IR thermometer... it may actually not be 10° different.
The laser thermometers are great, but any noticeable difference in the surface condition (or even color) can make almost a ten degree difference in temperature readings. Also, the laser is only a sighting tool for aiming. Depending upon the setup for your particular instrument, even when you aim at the same spot on each manifold discharge but do so from different angles, the reading can easily vary 10° just because of the region which is being measured. The article below makes this issue more clear.
Three common misconceptions about infrared thermometers | ThermoWorks
The laser thermometers are great, but any noticeable difference in the surface condition (or even color) can make almost a ten degree difference in temperature readings. Also, the laser is only a sighting tool for aiming. Depending upon the setup for your particular instrument, even when you aim at the same spot on each manifold discharge but do so from different angles, the reading can easily vary 10° just because of the region which is being measured. The article below makes this issue more clear.
Three common misconceptions about infrared thermometers | ThermoWorks
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