Alright so about a month ago i bought a jeep that was said not to run. got it back home and had it running in about 10 mins. but had a missfire. we changed coil rail, spark plugs, still miss fired cam out to partially be the tps, the other issue was a bad injector connector bought a replacment and spliced the new one on. and it cleared it up but a newbie mistake i made is didn't wrap it up immediately and is came in contact with something and shorted out and immediately cut off and hasn't stared since . Since then i have changed crank position sensor and cam position sensor and i also got a new/refurbished ecu installed and still have no injector pulse or spark.

Anyone have any idea on what it could be?

no check engine lights, no blown fuses that i have found, and ASD relay and fuse has been changed.

 

have you tried starting it in neutral or wiggling the shiftier in case it the nss? doubt it, but don't cost anything. it sounds like it shorted something out. have you jumped the asd relay to see if the fuel pump kicks on. I shorted out something in my 1998 xj when i put in a remote starter, had to splice a ground to the battery from the ecu.

 

You may have done some serious damage by making the mistake you did. It sounds like you sent an electrical surge which could have possible been able to get by the usual stop-gates. These stop-gates would ussually be standing in the way to prevent such an occurrence under normal conditions. Because of this, you will not be able to completely rely on the usual order of electrical current flow, and all of the typical laws of electricity. This may cause some difficulty when trying to use logic and think of the reasons for the problems your Jeep is having with how they are being presented for you to see. You are most likely going to need tools in order to locate the problem areas. Particularly, I think you will be required to start testing the circuitry associated at the immediate vicinity of where the electrical surge originated. You will probably end up having to branch out from this point, and go looking in all of the other areas which are presumed as having been effected in one way or another. There may be burnt out wires somewhere all along the way to deal with, and you will not be able to know about them if they are not visibly showing their defects.

First things first though. I recomend to fully inspect every single last fuse located under the hood in the Power Distribution Center (PDC), and the ones located on the kickboard fuse panel inside of the Jeep. Looking at the fuses with only your eyes is not really going to be good enough to determine wether or not all of the fuses are actually okay. In order to be certain a fuse is actually okay, you need to test them for continuity with a voltmeter. Most decent voltmeters have a continuity setting which can be set in such a way to give off an audible alert signal to make the task of doing these types of tests easier and a little quicker for you. It does not really take very much longer either way though.

Fully scrutinizing all of the fuses, every single last one, is an extremely important thing to do for this type of scenario you just described. The fuses are designed to be taking the hit during such an event as this, to kill themselves off instead of having a sudden surge of electricity go on to destroy the other more expensive components.

Do you know how to use a voltmeter to test all of the fuses like this? The fuse panels are also a good centralized hub to use in helping to determine wether or not the power is getting around on the many different circuits too.

I have a few thoughts on what has happened. However, these thoughts lead all the way to nowhere.. if we do not know wether or not the fuses are all okay or not?

No spark and no fuel ussually means something has gone wrong in the circuitry in the Automatic Shutdown (ASD). Definitely, I would want to check and know if the fuel pump is priming the fuel system fuel lines when you first turn the ignition key on into the run position. Are you able to hear the fuel pump being energizing and priming the fuel system lines when you turn the key? Have you checked for having fuel pressure happening at the fuel rail by pushing in on the shrader valve located on the fuel rail?

Having already replaced the PCM complicates things even further. How do you know you did not just install a crummy new PCM with all sorts of other unrelated issues about it, and is making everything that much worse?

 

my 1995 jeep cherokee I bought stopped running recently, and has no spark, we thought it was a fuse or something and when we looked under the steering column we noticed the previous owner had a remote starter on it, could the remote start have shorted something out to where it has no spark? If so, do you know how I could fix it?

 

while it's possible, if your jeep was running and driving fine with the remote starter on it I would check things like the crank sensor, coil, etc. see if you have power to them.

 

I have not checked all fuses with a voltmeter was thinking about just replacing all with new and test. as for the asd we have changed the fuse and relay with a new one already. but i havent heard a fuel pump but we did have pressure in the fuel rail

The pcm is supposed to be a complete refurbished and programmed to the exact model and has life time warranty.

 

test both sides of every fuse with a test light, takes only a few mins

to the best of my understanding the PCM injector circuit is common to all injectors (could be wrong), I have read some conflicting things, a shorted injector is known to damage the PCM

I would also try resetting the PCM

 

If you replace all of the fuses for new ones before testing all of the older ones first. You may possibly be missing out on easily obtainable and valuable information? When you pull a fuse and if it fails the test? This is how you could possibly be shown where to start looking further. It is just one of the relatively easier ways to go about trying to find a troubled circuit, should it show you something is wrong by doing it this way.

It sounds like you have an energizing and working fuel pump if you have pressure at the fuel rail. No fuel injectors pulse or any spark though.. (I am just thinking out loud in text). This could be something to help isolate the issues a little further even more.

Have you tested the fuel injectors to know they are not being energized? If you know there is no injector pulse.. The one that shorted to cause all of the problems could now be internally corrupted. If so, and it is still in there, it would be the likely injector to possibly cause the fuel injectors driver circuit to shut itself down in the PCM. Pulling this injector out could result in seeing the injector pulse return to the rest of the fuel injectors when the PCM injector driver turns itself back on again... As an internally shorted bad fuel injector is known to pull too much current, and this can shut down the PCM injector driver for all of the rest of the injectors when this happens.

Last question that I have right now is are you sure there is fuel pressure at the rail? It takes several long seconds to relieve all of the stagnant fuel pressure from out of the fuel rail, and not much pressure to cause it to be able to spray out... If you completely empty it to remove all of the fuel spray from coming out of the fuel rail, does it return back the next time when you turn the key to the run position again, and the fuel pump primes the system again?

 

I will have to drain the rail and see, and i never though of checking to see if the injector was the problem. will check it tomorrow and see kinda makes sense that it could be causing the circuit to fail though

 

I am curious to see the results.

 

The injectors have 12-volts to them when the auto-shutdown relay is engaged, The engine computers switches the ground. So shorting the injector to ground should not damage the engine computer, but it could burn up the injector itself. If you have a meter check for +12-volts on the injectors. If not, then start looking upstream at the ASD relay, fuses, etc. Does it start if you unplug the suspect injector? Check that the resistance across all the injectors looks right. I don't recall the ohms they should read, but they should all be similar. Since you have a meter handy, check that you've got +5-volts at the TPS sensor too. If you're missing spark as well, that might be crankshaft sensor.

For the wiring, look at the injector harness near the back of the firewall. It gets flexed there a lot and could be damaged. It also sometimes gets loose and rubs agains the intake manifold.

 

Been a while but. Unplugging the injector did nothing. but we are defiantly getting fuel pressure. just no spark. going to pull the injectors to see if they are pulsing even though we wanted to avoid that.

Still need to check fuses again with a voltmeter but have to find the cables to the one i have or buy a new one.

Should be noted that crank and cam position sensors are brand new. biggest thing that could be a issue is the crank position is not a mopar genuine one which could be the issue. but mopar parts are expinsive

 

Crank Position Sensor (CkPS), DOES control ignition spark AND fuel injector pulse.

If the CkPS is not creating a signal, then the measurable and testable effects of this condition are not but limited to: No fuel injector pulse. The Triggering Device is the Ignition Control Module or the Fuel Injection Computer component; also known as The Switching Device.. it will fail to produce a switching signal as also is the same to the ignition coil.

 

Not sure if its bad or not just going off what people said about non mopar ckps.

Becasue we just put it in before i made this post. so that might be the next step even though its a bit expensive for a gamble

 

I say test it first. Look to see if the CkPS is producing a 5 VOLTS signal. Also, look to see wether or not the CkPS is actually recieving any power at all, which is needed in order for it to be able to produce a signal in the first place. You may as well test and check the CkPS ground wire as well while you are at it.