p1391 Crank Position Sensor and Cam Sensor info needed
Code p1391 like clockwork over 2500 RPM or over 50% throttle. I reset the code, drove around, went to smog guy told him to keep it under 2000 rpm and it passed.
I drive out, give it 50% throttle or more and misfire + CEL.
It used to happen when it got hot only, now it happens when it warms up, gets turned off, allowed to cool till next day, and then restarted. When it misfires on a cold restart though i only feel it for the first stomp on the pedal. After that it seems to clear up until it warms up. But if i give it a good load 2 starts in a row the p1391 comes up.
A month ago the symptoms got bad. I had a cracked coil and unknowingly replaced it with a bad autozone coil. This led me to replace a LOT of other parts. Subsequently my entire ignition system, injectors, TPS, o2s etc...are brand new OEM or better.
I have begun back probing all my sensors to check for readings within specs.
-Cam PS seems to be in order. 5.18v in feed and when bumped into position the output to PCM shows the same.
-Crank Position Sensor seems funky. On harness side of connector the Purple/white stripe is 5.18v with key on grounded to the middle black/blue stripe. And when bumped into position the grey/black stripe is 5.18V when grounded to the middle black/blue stripe wire. BUT on the other side of the connector (CPS) the MIDDLE black/white stripe has 5.18V. Isnt this supposed to be a ground? If I ground the engine harness side of the middle connector i get 0.00V but if i ground the middle wire on the CPS side I get 5.18V! Is this correct?
Am I doing this right? The resistance values are infinite on all leads 1, 2, and 3 (reads 1_______ as if the probes were in mid air).
So my questions would be: Are these readings normal? If not since i forgot to disconnect the battery when removing and installing both CPS's did I kill them? If the sensors are ok and normal can i do this:
P1391 is intermittent loss of either the crank sensor OR the cam sensor. The vast majority of the time, replacing the faulty sensor will resolve this problem.
You can try testing both of the sensors with the factory service manual and a meter. But test data may very well be inconclusive for a sensor that is faulty, but not dead.
In that case, you should start with replacing these sensors with MOPAR sensors from Jeep. There is a BIG difference in quality of engine management sensors. I'd start with the crank sensor as it fails more often than the cam sensor. But if that doesn't resolve it, replace the cam sensor.
Here is a thread that gives some good information on resolving the P1391 code....
Oh i know what 1391 is. I have replaced both sensors as well as the distributor. I have also tested both. I have done more searching then one can do (read that link posted, have it saved on my phone already ). I need someone to answer my few questions i posted. The answers arent going to be in your link.
Can i do the toothpick trick on a 97? Are my sensors toast? Did i kill them? Does anyone know where to find a mechanic in SoCal that can use an oscilloscope? I posted test results that dont seem correct and need advise.
Also* i have a new computer, entire ignition system, and EVERY SINGLE SENSOR. Ignition, and fuel delivery are all new except for the pump. The pump is at 49psi and stays there when reving.
When it decides to run good it does. But too much skinny pedal and it throws a code. Need a data logging scope to find this one.
A code does not always indicate a faulty part or sensor. If you are having wire harness issues or have corroded wire connectors, the ECU thinks that no data is the same as a faulty sensor. Inspect your wire harnesses for pinched wires, chafed insulation, mising/bent crushed wire plug pins, and failed wire splices.
A P13191 can be a faulty sensor, or a distributor that is not correctly indexed.
Use genuine Jeep sensors.
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*Made 17 calls to all local mechanics open today. Only found ONE that owns and knows how to use an oscilloscope. The place is called Budget Transmissions in San Bernardino. He told me "what we can do is hook up the scope and you drive us around until it triggers the code" thats what i wanted to hear! He can look at it monday. So i guess ill wait.
Side note i cant f*****g believe how many shady freakin mechanics there are out there (~10/17) that told me "scopes are useless" "we dont use those tools we have better ones like OBD scanners" "oh that year/car/engine is hard to work on/has many problems" "bring it down i fix everything" 1/4 didnt even speak english.
p1391 code, misfires, PCM RPM signal lost, all due to a faulty wire harness on BOTH my jeep (female harness loose not grabbing male side of cam sensor pin), AND my cheap autozone cam sensor harness having a crimped male pin in it making the problem worse after the new dizzy.
After months of this diagnosing and $$$$$....a 1.25$ cut harness from the junkyard and some solder, plus a quadruple checked re-index ....IT TRULY APPEARS FIXED
***The pin can be used on a 96/97 to line up the dizzy but it goes in vertically.
***Scanner and Scope discovered RPM signal lost, and that i was losing my 5volts into my cam sensor when the jeep got hot or under tremendous load.
***Re-Index the dizzy with the valve cover off to inspect valves during this time of bad running conditions and misfires, and to set the motor at 100% certain TDC.