Hunting the elusive gremlin

Problem: Intermittent no start. Engine cranks but will not fire. After about 10-15 minutes, starts normally as if nothing ever happened. Occurs on average 2-4 times per month. Never on first start of the day, but later after sitting for a few hours, or maybe during a series of short trips running errands. The dilemma: I’m being told that nothing can be done to troubleshoot it unless a mechanic with a diagnostic device is there when it happens, but it fixes itself before a mechanic can arrive. “Leave it with us,” they say, “and we’ll try to duplicate the daily trips you take. We think it’s the crank position sensor, but we don’t want to replace it without confirmation that it’s the culprit.” After a week without the car I gave up on that. The answer is for me to drive the car as I usually do with the diagnostic device hooked up. It happens, I take the car and device to them, they confirm what’s happening and fix it. But no, they can’t let me borrow the device. It costs too much and they need it at the shop. Understandable. So I begin looking for software and hardware I can use with my laptop to do my own diagnostics. I try to determine if the products can identify an intermittent failure of the crank position sensor or other components that might prevent the car from starting, but no one ever answers my inquiries. It feels like I’m in a maze with no way out. The questions: 1) Is there a diagnostic system available for amateur use (and at an amateur price) that can solve my troubleshooting problem? 2) With all the links to discussion forums that talk about this and similar starting problems with the Chrysler 300M, hasn’t someone identified the most likely components that can cause this? Someone out there must have dealt with this and fixed it.

I have this scanner. Plugs into a laptop and records data.

If you’ve got an android phone or tablet there is an app called Torque. You connect a bluetooth dongle to your obd2 port and use your phone as a real time scanning device.


Thanks for the suggestions. Just to clarify, this problem never throws a code. I’m no mechanic to speak of, but as I understand it, any code event will turn on the check engine light. I can’t tell if that’s happened when the car won’t start because the check engine light is always on when the engine isn’t running. But after the typical delay of 10-15 minutes and the car starts, if the fault that caused the no start had triggered the light, wouldn’t it be on then as an indicator that there had been a problem? When I read about these products, the descriptions don’t indicate that they can detect and record problems that don’t trigger the check engine light. Do you happen to know if either of these can do that? Thanks again for your advice.

Had a similar problem with 2000 Chrysler Cirrus 2.5L 6 cyl. No engine light. Intermittent very hard start without firing (took 15-20 minutes), but ran fine after finally starting. All accompanied by itermittent, sometimes severe miss. Finally, no start at all; still no engine light. They were finally able to diagnose–had to replace the distributor.

A live data scan tool might find the cause of your problem if you are willing to learn the operation of the engine control system and know where to look and what to look for in the diagnosis. If the scan tool has the crank signal on the screen and cranking the engine shows ZERO rpm while not starting it is likely that the crank sensor or sensor wiring or the computer at fault.

I have often connected several diagnostic devices to automobiles and kept them for days, driving them wherever I needed to go, ready to see what was causing a failure. Occasionally I billed the car owner for a wrecker bill when the problem left me stranded. I charged 1 hour of shop time for such a diagnosis if no wrecker was needed. Only regular customers were offered that service. Carrying ignition modules, relay jumpers and mop handles to bang on gas tanks was SOP. It was likely comical for the public to see a car driven with a fuel pressure gauge and half a dozen red and green led lights taped to the windshield of a car. And the front seat looked like the “Back to the Future” DeLorean. Intermittent problems are a nightmare for car owners and shops. Good luck on yours, @Mike.


A former colleague of mine was driving with all sorts of diagnostic equipment hooked up, including stuff taped to the windshield

He got pulled over by the police

It was September 12th, 2001

@rodknox I would have been happy to pay the diagnostics and the tow for you to work on my Rivy. For two months I’d run around at night for a few miles with a fuel pressure tester taped to the windshield and test light waiting for it to stall to try and figure out what it was. Replaced a lot of parts but never the right ones I guess.

Intermittent problems were as much a nightmare for me as they were for the owners. This subject has reminded me of the Break Out Box that could be connected to a Ford’s ECM, making it convenient to connect meters and test lights to the “switchboard” and prop it on the floor while driving.

i own a 2000 300M just turned 150k miles yesterday.has been good to me 2 years ago i had a problem with it starting, it would spinn but wont fire turned out to be a broken obd connecter a couple of wires where touching. you may have a bad relay or one going bad.i show alisting for 1 for fuel inj. and 1 for ignation.

This is an update to my elusive gremlin thread.

About a week ago, the check engine light came on and remained on after a start. The code indicated the cam position sensor, which according to our mechanic can also be triggered by a problem with the crank position sensor. He had suspected that one or both of the sensors might be contributing to the problem, and I credit him with not recommending that he replace them without additional evidence. But with this incident as justification, he did that and the car seems to be running better. I won’t know if the start issue is resolved until some time has passed, but for now it appears that may be the case.