Hardshifting, backfiring, and stalling
02-02-2020, 12:57 PM
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Year: 1994
Model: Cherokee (XJ)
Hardshifting, backfiring, and stalling
My 94 Jeep Grand Cherokee has been having hard starts, I've been having to put pedal to the floor, idle is fine, although when driving it gets very hard shifts, backfiring, stalling, and even loss of power. replaced every sensor I could think of. WTF?
02-04-2020, 06:52 PM
#2
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There are quite a few reasons this type of thing could result from...
Did you do any testing of anything yet? Or, did you just begin with replacing sensors? Are all of those replacement sensors Mopar branded sensors or aftermarket? These Jeeps run awful with aftermarket sensors in them. Especially, for the Crankshaft Position Sensor (CkPS), Camshaft Position Sensor (CPS), Throttle Position Sensor (TPS), and the Oxygen Sensors. All of those really kind of need to be Mopar.. almost mandatory. If the sensors are not Mopar branded sensors? Then, there would be a very good chance that they are at least contributing in a very big way to make whatever is the primary fault that much worse.
Is it 'coughing' and 'spitting' out of the intake? Or, is it backfiring out of the exhaust?
How are the spark plugs looking right now? Do you see wet-fouled spark plugs, or are they dry-fouled? After you read them.. maybe try cleaning them up with brake cleaner and a rag. Or else, just go ahead and get all new copper Champion spark plugs for it. These Jeeps sometimes do not run very well at all on any brand of spark plug except for copper Champion plugs. If they are old to begin with, they should probably be replaced with some correctly gapped new copper Champion spark plugs at this point.
What type of spark do you see happening on them when you check. Are they 'snapping' blue sparks, or yellow and red? If the spark seen on them is yellow or red that means a very weak spark. Blue is the best spark. White is just okay. Red and yellow is bad sparks.
A guess of mine would be there is something wrong with the TPS, the oxygen sensors, the spark plugs or plug wires, the engine temperature sensor, or poorly operating fuel injectors being clogged or leaking. Possibly low fuel pressure? Have you thought about checking the fuel pressure? It could very likely be the problem is from a combination of several different possible reasons which are happening on it simultaneously.
Did you do any testing of anything yet? Or, did you just begin with replacing sensors? Are all of those replacement sensors Mopar branded sensors or aftermarket? These Jeeps run awful with aftermarket sensors in them. Especially, for the Crankshaft Position Sensor (CkPS), Camshaft Position Sensor (CPS), Throttle Position Sensor (TPS), and the Oxygen Sensors. All of those really kind of need to be Mopar.. almost mandatory. If the sensors are not Mopar branded sensors? Then, there would be a very good chance that they are at least contributing in a very big way to make whatever is the primary fault that much worse.
Is it 'coughing' and 'spitting' out of the intake? Or, is it backfiring out of the exhaust?
How are the spark plugs looking right now? Do you see wet-fouled spark plugs, or are they dry-fouled? After you read them.. maybe try cleaning them up with brake cleaner and a rag. Or else, just go ahead and get all new copper Champion spark plugs for it. These Jeeps sometimes do not run very well at all on any brand of spark plug except for copper Champion plugs. If they are old to begin with, they should probably be replaced with some correctly gapped new copper Champion spark plugs at this point.
What type of spark do you see happening on them when you check. Are they 'snapping' blue sparks, or yellow and red? If the spark seen on them is yellow or red that means a very weak spark. Blue is the best spark. White is just okay. Red and yellow is bad sparks.
A guess of mine would be there is something wrong with the TPS, the oxygen sensors, the spark plugs or plug wires, the engine temperature sensor, or poorly operating fuel injectors being clogged or leaking. Possibly low fuel pressure? Have you thought about checking the fuel pressure? It could very likely be the problem is from a combination of several different possible reasons which are happening on it simultaneously.
Last edited by Noah911; 02-04-2020 at 07:11 PM.
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