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karrs2fix, ASE Certified Technician
Category: Ford
Satisfied Customers: 893
Experience:  ase master technician,L1 certified, Iatn sponser, tech net training
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99 ford ranger: 4.0 changed fuel knocks real bad

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99 ford ranger 4.0 changed fuel injector now when i start it it knocks real bad.
When you replaced the injector did fuel spill down through the injector hole into the cylinder? If so you could try to remove that cylinder spark plug, DISSABLE the ignition system and crank the engine to allow excessive fuel to be pushed out of the cylinder through the spark plug hole.
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Customer: replied 4 years ago.
thanks. now the knock comes and goes. any other ideas.
You can try to narrow the noise down to a specific cylinder by disabling spark to the cylinders one at a time. From there it could be a few different things rod bearing , wrist pin at the piston. I am not sure why you had to replace the other injector but if you have some other injection problems and some misfiring you could be getting to much fuel into the cylinders contributing to the noise.
Customer: replied 4 years ago.
There was a dead miss at no 1 cyl. Good compression, good pulse with noid tester.. We even powered up the injector while it was unplugged. It would click but it wasn't spraying fuel. We had already changed the spark plugs. No 1 was firing fine. So we decided to change no. 1 injector. It did not have a noise in that motor before we changed the plugs. No tap and no knock. It sounds more toward firewall. We pulled all the plugs out again. One at a time like you said. we pushed out all raw gas. Wasn't much. Now like I said the knock comes and goes but it's a lot better than it was. The oil is thin. We are going to change the oil in the morning and let you know what we got. Do you suggest any oil additive? Lucas or? Thanks. Chuck Varner
Lucas is a good additive, we use BG products most of the time Moa for a lower mileage cleaning additive and RF7 for higher mileage engines. You can try to pinpoint the noise to a specific cylinder if it is still present after the oil change. Leaving all plugs in run the engine and remove one spark plug wire or unplug fuel injector one at a time to try to pinpoint individual cylinders, that will stop the firing event in that cylinder .