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Hi,
I have a 1990 Maxima. The engine does not run smooth. A friend who looked at it thinks that the injector on #3 cylinder is not working. He checked the ignition and compression which are both OK. There is no change when the ignition lead is off on this cylinder.
Is there any other test that can confirm this?
Thanks in advance.
Re: Hi,
I have a 1990 Maxima. The engine does not run...
Using a probe you should be able to hear the injector working, use a noid light to check signal at the injector, and replace the spark plug just for fun
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1. The injector on cylinder #5 is clogged and not injecting. 2. The Ignition coil on Cylinder #5 is not firing. 3. One of the exhaust valves on #5 is sticking due to carbon build up.
Hope one of these gets you closer to the solution.
Fuel injector #4 is for engine cylinder #4, below is a diagram of the engine cylinder layout. So #4 is the center engine cylinder in the front bank of cylinders, the front bank is the 3 ( cylinders 2,4,6) engine cylinders closest to the radiator.
With that many injectors not firing, I would look at the ecm or engine computer seriously.
I had a 1990 Cadillac Deville that after changing all 8 inj. and an egr valve, and other parts... it finally turned out to be the ecm not firing one of the injectors, causing a miss on an OBD-I automobile.
You could try to replace the injectors that are on 1,3, and 5, but it if that doesn't work, it's probably the ecm, in my opinion.
It is possible that the two spark plugs could have become fuel fouled and not respond. A quick way to tell is to remove the suspected spark plugs and switch them with known good spark plugs in the engine and see if the problem follows the spark plugs. If the problem doesn't more from those cylinders then you may need to investigate the injectors (even though they are new) as being on the shelf a long time and operating incorrectly. Not opening enough and doesn't make the cylinder operate therefore cause fuel to enter the exhaust.
A faulty IAC would cause a random misfire rather than a misfire in a specific cylinder, as would an intake air leak, both of which would cause a high idle amongst other things.
Run the engine until its good and hot, disconnect the injector harness plug so the injectors are disabled, remove all the spark plugs, disable the ignition by unplugging the wiring connector(s) from the coil pack(s), and then carry out another compression test on al the cylinders.
If the compressions are now all relatively the same then you very highly likely have a faulty injector in cylinder 3.
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