98 XJ no spark at the coil Help!
02-03-2017, 09:08 AM
#1
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Model: Cherokee
98 XJ no spark at the coil Help!
no spark at the coil on 98 XJ 4.0
I see this is a common problem with late XJ'S The no start issue. I've owned this jeep for some time now and really has been great for me. My ohm meter reads 0 to 1000 so it is not a very expensive one but it serves me well. I do All my own mechanic work. Before I throw to much money at this, I just get lost when it comes to electrical stuff. This infinite resistance really confuses me. I think this means zero. Well when I put my probe on B and C on the crank position sensor, I get 1 ohm. Would this low reading still let the coil fire? this is where I get lost because in one thread I believe I read a new one was 10000 ohm. Fuel pump is new and runs with the key on and when I jump it at the relay. Wires are new and so is the coil. The engine turns over great. Some times I have to put it in neutral to start it or push hard on the floor shiftier when it is in park.This is a 4 speed auto on the floor. This might be dirt or rust on the linkage or the safety neutral switch. I read in of the treads that some one thought that may be a issue could it? I really get uneasy when parts start costing 225 or more. Some reply's ask for info on my gauges. All work perfec. Eletric is at 12 V at idle when it was running, a little higher at 2100 rpm, oil psi 40 at idle an 60 at 2100 rpm, tach an speedo good all dash lites good . ( 2100 is my sweet spot for gas mileage,I get16-17 mpg an at 2200 it drops to 10-12 mpg. 2100 is 65 mph an 2200 is 70mph
thank you for any info
I see this is a common problem with late XJ'S The no start issue. I've owned this jeep for some time now and really has been great for me. My ohm meter reads 0 to 1000 so it is not a very expensive one but it serves me well. I do All my own mechanic work. Before I throw to much money at this, I just get lost when it comes to electrical stuff. This infinite resistance really confuses me. I think this means zero. Well when I put my probe on B and C on the crank position sensor, I get 1 ohm. Would this low reading still let the coil fire? this is where I get lost because in one thread I believe I read a new one was 10000 ohm. Fuel pump is new and runs with the key on and when I jump it at the relay. Wires are new and so is the coil. The engine turns over great. Some times I have to put it in neutral to start it or push hard on the floor shiftier when it is in park.This is a 4 speed auto on the floor. This might be dirt or rust on the linkage or the safety neutral switch. I read in of the treads that some one thought that may be a issue could it? I really get uneasy when parts start costing 225 or more. Some reply's ask for info on my gauges. All work perfec. Eletric is at 12 V at idle when it was running, a little higher at 2100 rpm, oil psi 40 at idle an 60 at 2100 rpm, tach an speedo good all dash lites good . ( 2100 is my sweet spot for gas mileage,I get16-17 mpg an at 2200 it drops to 10-12 mpg. 2100 is 65 mph an 2200 is 70mph
thank you for any info
Last edited by khillier246; 02-03-2017 at 04:08 PM. Reason: people would like more onfo
02-03-2017, 12:05 PM
#3
CF Veteran
khillier246,
First, you are doing the right thing by trying to test the CPS. I would recommend searching google and/or youtube for "measure resistance with multimeter". You could also search for things like "troubleshoot crankshaft position sensor jeep xj" (or similar search). Because there is so much on this topic already. Understanding what your ohms readings are telling you is going to be pretty important, and a little google effort will get you squared away on that.
Testing the CPS with the multimeter is a "connectivity" test and is the right place to start. But those tests help to identify if the CPS has failed from an electrical connection perspective. So they can "rule in" the CPS as a culprit, but if the tests pass, unfortunately they do not entirely "rule out" the CPS as being the culprit.
Does your dash cluster have a gas gauge and voltage gauge? (I ask because not all xj dashes will have a voltage gauge). If you -do- have a voltage gauge, and you turn your key to the on position, what do the gas gauge and voltage gauges do?
First, you are doing the right thing by trying to test the CPS. I would recommend searching google and/or youtube for "measure resistance with multimeter". You could also search for things like "troubleshoot crankshaft position sensor jeep xj" (or similar search). Because there is so much on this topic already. Understanding what your ohms readings are telling you is going to be pretty important, and a little google effort will get you squared away on that.
Testing the CPS with the multimeter is a "connectivity" test and is the right place to start. But those tests help to identify if the CPS has failed from an electrical connection perspective. So they can "rule in" the CPS as a culprit, but if the tests pass, unfortunately they do not entirely "rule out" the CPS as being the culprit.
Does your dash cluster have a gas gauge and voltage gauge? (I ask because not all xj dashes will have a voltage gauge). If you -do- have a voltage gauge, and you turn your key to the on position, what do the gas gauge and voltage gauges do?
