5.2 Stalling - Page 5 - JeepForum.com
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post #61 of 69 Old 09-17-2021, 02:57 PM Thread Starter
Hempinfool
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I apologize to PolkaPower

You stated Camshaft Position Sensor and I kept reading Crankshaft Position Sensor.
My bad.

More work to do!!!

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post #62 of 69 Old 09-18-2021, 11:19 AM Thread Starter
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Yet another update

Removed and replaced PCM and recleaned contacts which all seem tight.
Started right up.
Had 2" more vacuum at idle, 18, than ever before at the same RPM. Not sure why.
Wiggled Camshaft Position Sensor wires and no change.

Drove 20 miles.
Stalled twice at 60ish mph.
Fuel pressure constant at 38 psi.
Restarted both times before reaching a stop.

New Camshaft Position Sensor will be here tomorrow.
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post #63 of 69 Old 09-19-2021, 06:11 PM Thread Starter
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Today I replaced the Cam Position Sensor.

Started right up
Idled for 15 minutes
Drove for 15 minutes then it died while going about 45mph.
Would not restart right away.
I proceeded to touch and wiggle a connector and then try to start it.
I did this to about 10 connectors in the engine bay but nothing.
I put the hood down to get a ride home.
Tried to start it one last time and it started.
Went 20 feet and it died but restarted right away.
Drove 15 minutes home with no problems and no codes.

Open to suggestions.
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post #64 of 69 Old 09-24-2021, 05:31 AM
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I have not kept up with this thread.

Do you have spark when it won't start?
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post #65 of 69 Old 09-24-2021, 01:28 PM Thread Starter
Hempinfool
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One time it stalled, didn't restart, towed home, and sat for a day.
Still no start the next day which is the only time that it refused to start over multiple days.
I tested spark at the plug, then the coil, and had no spark, put back together, and still no start.
Of note: I did not smell any fuel during the starting process even though I pumped the pedal. Not sure if that matters with MPI.

Then I checked wires and connectors going to the coil. Found a slight nick in the wire at the connector on the harness side but didn't feel it could touch anything. I ran new wires from that connector to the coil connector because there was a splice on both sides.
The jeep starts right up.

Drive down the road quits again at 60mph. Just like the key was turned off.
Coasting and not touching anything, key still on, still in drive, Jeep refires at 20mph.
I head home and it "misfires" a few times but it makes it.

I am currently going through the "12 things that cause stalling" by ZeeJay1997 again and tearing into connectors.
Had a few mechanics stop by and have replaced a few relays many times..

Open to most anything at this point.
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post #66 of 69 Old 09-26-2021, 03:35 AM
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Make yourself an engine test board to find out what is really happening. It's not quite the same as having an OBD1 scanner, but it should help you shed a light on where the problem is.
Get yourself a bunch of red 5mm LEDs and 720Ω or 1KΩ resistors. You'll also need some thing gauge wire. I like to use old phone line wire or network cable. Network cable is great since it has twisted pair wire and it's easier to keep track of which two wires go together. Solder a resistor to the short leg of the LED. Solder one wire to the long leg of the LED and the other to the resistor. The wire going to the resistor will be your negative wire. Cover the resistor and LED legs with heatshrink tubing. Now glue the LEDs to a board so that you can watch them while driving. These are your new indicator lights. You can also buy pre-made LED with wires and resistors soldered on for 12V.

Pull the other end of the wires into the engine compartment or under the dash and hook them up to the thing that you want to monitor. You can run them past the door molding and under the back of the hood. The nice thing about the thing gauge wire is that you can run them down into the relay sockets, etc. to see what is really going on.

For relays hook one across the relay coil pins and one across the relay contact pins. When the relay is untriggered the contact LED should be lit and the coil should be unlit. When it triggers it reverses. Some relays are triggered on the negative side by the computer, so make sure you connect across the terminals and not to ground.

I would hook one up to the +12v side on the coil, one to the ignition switch, and one to a fuel injector. I would also hook one up to the shutdown relay. You can hook LEDs up to any other 12v item that you want to check. The LEDs use so little power that they wont impact or harm the computer. When you take it for a drive, keep an eye on or video the LEDs and see if there are any changes to their pattern. This should help you find out where the problem is or is not and you can stop spending money on random sensors and switches.

The whole test setup will cost you less than $20, and don't forget to mark which LED goes to which component.

'95 ZG 5.2 x3, '96 ZG 5.2 x2, '98 ZG 5.2
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post #67 of 69 Old 09-26-2021, 09:41 AM
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Post a list of all the stuff you replaced please. I kind of like the idea above. Something to turn to when you are wit's end.
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post #68 of 69 Old 09-27-2021, 12:17 PM Thread Starter
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DeOrellana, that is the most astute first post that I have ever seen!
That may be my next plan if I am smart enough to pull it off.

I had a couple of Master Technicians stop by for collaboration on my current issue. Sorta like we do here except with drinks and Drift Trikes. After a couple of hours of listening to me describe the 20+ stalling events and testing theories, the general consensus is that the PCM is bad or is losing power or ground.

The fact that I do not need a key in the ignition to start the engine was not well received.
So I am replacing the ignition lock cylinder, Ignition Switch, and Hazard Warning switch. The reason for the ignition switch is that we found a could lose connectors on the switch at the base of the steering column. The Hazard warning switch will complete the whole YJ steering column rebuild and hopefully fix the self-canceling signals.

Another issue that doesn't sit well with this crowd is that a bunch of circuits is missing because they weren't needed 20 years ago when the engine was replaced. A few examples are the ABS system, ABS Pump, Fog lamp, Aux Lamps, Head Light Sys, Blower Motor, Security, Cruise Control, etc. They were cut out to the extent that even the fuse/ relay wires were removed. I'm not sure of the "proper" method of unused circuits but I've got what I got and drove it 15 years before this.

Here is the current list of replaced parts. Please understand that in the middle of the 6 months of stalls there was a month of no issues but the idle RPM was erratic. I actually did test most of these sensors but replaced them anyway because the Heep works great 95% of the time.

PCM, Plugs, Plug Wires, Rotor Cap, Rotor, Crank Sensor twice, Cam Sensor, EGR Transducer, Idle Air Control, Throttle Position Sensor, Every fuse has been cleaned or replaced, Every Relay has been replaced, Grounds have been cleaned/sanded, Fuel Pressure Guage installed, Vacuum gauge installed, Still working on inspecting every splice and connector in the engine bay.

I appreciate everyone's time in this endeavor.
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post #69 of 69 Old 09-27-2021, 04:29 PM
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Replacing the ignition switch is good idea.
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