multiple missfire
multiple missfire
09-15-2009, 07:28 PM
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Year: 1985 shell
Model: Cherokee
Engine: 1996 6 cylinder Briggs & Stratton
Bad tps will cause multi missfire code. My experience thru 97, not sure about 01
09-15-2009, 10:56 PM
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09-15-2009, 11:25 PM
#8
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Year: 1996
Model: Cherokee
Engine: 4.0
The first thing I would check is the plugs, check them for carbon tracking on the white part of the plug. It will look like a black line running from the top of the plug down the porcelin. If you see this it is a good chance that the spark from the coil is "leaking" out and not letting the plug fire properly.
Next are they the correct plugs for that engine? The emissions tag located under the hood has the correct spark plug part number and gap listed right on it. Use those plugs and gap them correctly.
Fuel pressure must be in spec 55-60 psi
The foil debris/heat shield that covers the intake on most 4.0 engines can direct the heat from the exhaust at the injectors and cause a misfire. Most of the time it is just the #3 cylinder and there is a TSB out to insulate the #3 injector.
These are just a few Ideas, you could also do a compression test and a cylinder leak down test to see if it something inturnal to the engine like a sticking valve, broken valve spring, or heavy carbon build up. This would be a good idea if it were isolated to one cylinder, you probably won't need to go this far.
Last edited by BLKXJ 96; 09-15-2009 at 11:28 PM.
09-16-2009, 10:37 AM
#9
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There's a lot of things tha can cause a misfire.
The first thing I would check is the plugs, check them for carbon tracking on the white part of the plug. It will look like a black line running from the top of the plug down the porcelin. If you see this it is a good chance that the spark from the coil is "leaking" out and not letting the plug fire properly.
Next are they the correct plugs for that engine? The emissions tag located under the hood has the correct spark plug part number and gap listed right on it. Use those plugs and gap them correctly.
Fuel pressure must be in spec 55-60 psi
The foil debris/heat shield that covers the intake on most 4.0 engines can direct the heat from the exhaust at the injectors and cause a misfire. Most of the time it is just the #3 cylinder and there is a TSB out to insulate the #3 injector.
These are just a few Ideas, you could also do a compression test and a cylinder leak down test to see if it something inturnal to the engine like a sticking valve, broken valve spring, or heavy carbon build up. This would be a good idea if it were isolated to one cylinder, you probably won't need to go this far.
The first thing I would check is the plugs, check them for carbon tracking on the white part of the plug. It will look like a black line running from the top of the plug down the porcelin. If you see this it is a good chance that the spark from the coil is "leaking" out and not letting the plug fire properly.
Next are they the correct plugs for that engine? The emissions tag located under the hood has the correct spark plug part number and gap listed right on it. Use those plugs and gap them correctly.
Fuel pressure must be in spec 55-60 psi
The foil debris/heat shield that covers the intake on most 4.0 engines can direct the heat from the exhaust at the injectors and cause a misfire. Most of the time it is just the #3 cylinder and there is a TSB out to insulate the #3 injector.
These are just a few Ideas, you could also do a compression test and a cylinder leak down test to see if it something inturnal to the engine like a sticking valve, broken valve spring, or heavy carbon build up. This would be a good idea if it were isolated to one cylinder, you probably won't need to go this far.
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