I really have to say replace the spark plug wires, I MEAN MAJOR CLUE, big rain will not start, see previous post.
There is no spark at the coil pack. And it has been sunny for days. No start this morning.
Earlier you stated that the fuse has power to it but have you checked to see if power getting to the ignition system side of the circuit while the trouble is occurring? I suggest you get a service manual that will have the proper test procedures for you to make in order to track down the problem. Trying to solve problems like this without doing proper testing basically just becomes a guessing game.
That is the problem. There is no power to the coil when the no start condition occurs. And so this is my thought: something is telling the PCM not to feed power to the coil. While before I thought removing the battery cable and clearing the PCM was what made it start, I now believe that some sensor is telling it that and whichever sensor it is appears to be sensitive to heat. Whether or not I disconnect the battery cable it will start as soon as the temperature gets above 85 or 90 degrees. Again, then it starts and runs perfectly all day. I am wondering which sensors have the ability to tell the PCM to not power the coil. And what sensors are the most likely to be affected by heat?
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The coils & crank sensor are wired to the PCM. The coils wont fire without a signal from the crank sensor. Iâd drive it up on my ramps & check for a clean tight connection at the crank sensor.
If the PCM controls the power to the ignition system then you need to verify power is getting to the PCM.
Removed and cleaned the negative battery ground to the engine. It didnât feel loose but I gave it a tug counterclockwise and it loosened up. No start. Remove negative cable at battery and let sit an hour and a half for good measure. Reconnect negative cable car starts. 68 degrees. This is the first time in 2 weeks that the car has started below 85 degrees ambient temperature. I wonât believe it until it starts for 5 mornings straight. But that is a pretty tenuous connection. I know that heat expands and cold contracts, but I still find it hard to believe that 15 degrees difference can do that. That tells me that there are 2 or 3 metals in contact, the stud to the block, the cable end (softer) and the nut and they expanded or contracted at different rates. If that is what it was doing I guess I donât feel too bad. That is a tough one to chase down. But again, I wonât call it fixed until 5 morning starts. Thanks for all the suggestions, I hope this isnât a curse to post until I am sure.
Cursed it. No start this AM. Will try crank sensor today.
I would think if the crank sensor was causing the trouble then the ECU would have a code indicating there is a problem with it. It seems to me the real trouble you are having is due to a flaky power connection, perhaps going to the PCM or something else related to the ignition system. If you donât have a good wiring diagram of the engine electrical system I suggest you use your money to purchase that instead of guessing at what may be the real trouble.
Brokemercury, if you are really good at following instructions your problems are just about over. Your instructions are to raise the hood & look at the center section of the firewall just below the cowl. Wish I could post a picture. Theres a ground screw with 2 wires. One wire grounds a pin on the PCM, the other grounds the crank sensor shield. The most important part of your instructions is that you are to find the screw is loose. Tighten it up & call it a day.
Cougar is right about there should be a code if the crank sensor is bad. But with the battery being disconnected so often I wonder if ANY pending trouble codes that might help figure this out are being erased.
If you have a scanner , hook it up & check for pending trouble codes.
If you dont have a scanner & dont live in Cal. see if Autozone etc. will check for pending codes. Theres no charge for this.
Also if you want to check voltage at the coils, you should see 12 volts from the fuse on the red/light green stripe wire with the key on.
What you stated about the ground connection could very well be the cause of the trouble @87_Ranger. It is just the kind of thing the problem seems to be. Nothing is faulty, just a bad connection.
Yeah, if brokemercury is really lucky he will find a broken wire or bad connection of some sort at that ground.
No spark this morning until temperature above 80 degrees. Starts over 80. It has never had a CEL on and I have scanned codes even after battery connected for 2 months. No codes either my scanner or others, pending or hard. Never has shown any pending codes.
I will check that ground, but canât test if that works until tomorrow morning since it has been started today.
Brokemercury as i mentioned earlier you need to check the connection at the crank sensor. You wont be the first to solve this problem by cleaning up the connector
Hopefully this link works
http://www.ford-trucks.com/forums/1158979-97-explorer-4-0-cranks-but-no-start.html
That link didânt work, but clean up the connector & see what it does.
One more try
http://www.ford-trucks.com/forums/1158979-97-explorer-4-0-cranks-but-no-start.html
Still didânt work.
If the crank sensor was acting up when the engine is running youâd get a crank sensor code.
I wiggled the connections to the coil packs after a no spark this morning and it started. But the temp had also just clicked up to 84 degrees, so I canât tell if that really did anything since now it will start the rest of the day so I have to wait until tomorrow morning for more troubleshooting.