My girl friends Grand Cherokee has me (an apparently the rest of the internet) stumped as to the problem. The jeep has 140k on it, starts fine, runs well … except when it just randomly dies at idle … or when stopping at a stop light or coming off the highway to a stop. The only time I can get it to consistently fail is by driving 61mph on the high way. This causes the jeep to stall and vomit the error code that there is a bad ignition coil. It seems to do it more in humid weather than at dry times; however, I’ve made it stall regardless of how nice a day it is.
Parts Replaced:
Ignition Coil
Plugs and Wires
Distributor Cap and Rotor
TPS
MAP Sensor
IAC
Fuel Pump
I’ve not replaced the crank shaft position sensor because the general belief on the internet is that fixes it for about a week and then the problem returns. I’m totally at a loss as to what’s causing this and searching for this on the web only shows 2700 results of people that have tried and failed to solve this problem. This is my last shot … any suggestions, please, anything?
When the engine stalls, what’s it take to get it started again? And when it does start, how does it run?
Tester
You need a mechanic. I’m quite serious. You’re throwing away the best asset to solving the problem: “…and vomit the error code…” The error code is NOT the enemy. Actually, it’s called the DTC (Diagnostic Trouble Code). The emphasis is on diagnostic, meaning: to diagnose. The DTC does not instruct you (or, anyone) to change parts. It refers to circuits.
It seems that you may have been listening to other parts throwers, on the Internet. Instead of looking for a list of parts to change, your mechanic would need the actual DTCs, and the symptoms. Ask around of friends, acquaintances, or enemies, for a recommended mechanic for this type of engine management problem.
Generally, it takes just dropping it into nuetral and turning the key again; however, sometimes it’s one of those set for 5min, and then it will start.
The code is ‘P0351’, which implies a an ignition system failure. This was the first place I started. I replaced the distrubtor, plugs, and wires because they were the originals and there was a visual need to replace them. The ignition coil was ‘oh, why not’ replacement since it was like $30 and I was already fixing the rest of the system. After that, I had pulled the pressure on the fuel rail and found that it was low so that was the rational behind the fuel pump. The throttle body replacements followed afterwards because the IAC was stuck in on position and the MAP sensor was clogged full of carbon and the TPS sensor didn’t product a smooth accurate reading when steadily turning it.
The code you have says the primary circuit to the coil has failed; not necessarily that the coil itself is the problem.
The primary circuit could be the power supply.
A quick look at a schematic shows the Automatic Shutdown Relay is the power provider to the coil and also provides a feed to the alternator, power to the fuel injectors, etc.
This means either the ASD relay is faulty or there is a problem in the relay control circuit. The latter includes the ignition switch and 2 grounds which are made through the PCM.
You could try simply replacing the relay and see what happens rather than trying to trace an ign. switch or PCM fault.
Hope that helps.
This is what I show P0351 code means:
P0351 Through P0360 - Ignition Coil A through J Primary/ Secondary Circuit Malfunction Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM). Open or short in Ignition START/RUN circuit
Open coil driver circuit in harness
Coil driver circuit shorted to ground
Damaged coil
Damaged PCM
Coil driver circuit shorted to PWR
Hope this helps.