QuestionQUESTION: I have a 1999 3.2 litre concorde, it has an intermittent problem of completely stalling while driving down the highway. When I try try to start it the engine is trying to start but it seems like it isn't getting fuel. I can drive it for days around town and I don't have any problem, but when I drive it on the highway at higher speeds (70-75mph) it just stalls and will not start. It has 116k on it and I bought it a week ago aware of the problem. Of course this usaully happens while driving to work, and I have come back (in as little as 3 hours) and it starts and runs fine when I come back to start it. I have had it towed to the Chrysler dealer twice and they say the fuel pump checks out and they can't find a "code" that will tell them what is causing the problem. The check engine light codes that they got were power steering pump switch and multiple random misfires. I decided to change the plugs and noticed a coil pack wire that had a wire spliced into it that ran to nothing???. I fixed this and changed the plugs, and I am going to replace the power steering pump switch. I currently don't have any other check engine light fault codes except for the the switch. My question would be do you think an open coil pack wire could have caused stalling on the highway and where else should I look? Thanks!
ANSWER: Hi Billy,
I would keep trying for fault codes which you can either get readout for free at an Autozone parts store if there is one near you or if you use the ignition key, "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time, then watch the odometer window on the instrument cluster to see the mileage reading to possibly change to show 4-digit fault code number. Then let me know if you find any.
My suspicion is that either the camshaft or crankshaft sensor is beginning to fail, which is exactly the symptoms that you describe. When it gets hot it breaks down, then recovers as it cools. It should show a code soon: P0340 or P320, respectively.
The coil could cause a stalling out, as could unfortunately many other things. You could bring along a digital ohmmeter and when the car acts up remove the primary wire for the coils and measure the resistance of each to ground (engine block). See if any are quite different from the rest. The resistance in in the range of 1 ohm so you need a digital ohmmeter and good clean connections to the wires and the block. There are also many other multiple misfire possibilities that I can list for you.
Let's see if either of these approaches bears fruit.
Roland
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QUESTION: With the price of gas and towing, I will replace the sensor and go on a 30 mile trip down the highway and see if I have a break down. I would have thought that the code for the camshaft sensor would be stored when it failed so I was thinking fuel pump, hopefully you saved me some serious time and money. I will let you know how it works out, can you follow me to Manistee Michigan today in case of a break down?
ANSWER: Hi Billy,
Thanks for the kind evaluation and remark.
I am not certain I would go 30 mile out, after changing the cam sensor, as that may not be the cause. (By the way I accidentally reversed the codes for the sensors: cam is 0320 and crank is 0340).
You could check the voltage pulsing on each sensor the next time it fails: measure between the signal and ground wire at each sensor while turning the engine by hand with a socket on the crank pulley bolt. The voltage should oscillate between 5 and 0.3 V as you turn it with the ignition "on". The wires are:ground (light blue/black) and signal for the cam is tan/yellow, crank is gray/black. The other possibility if the issue were as you conjecture fuel/mixture is that the MAP sensor has gone inaccurate, again without setting the code(s) for that which are 0107 or 0108. Its signal wire is dark green/red and the ground is light blue/black. It should be same voltage when you can start the car as when you can't start the car (measured with the ignition 'on' but the engine not running). If the voltage were significantly different then that would implicated the MAP as the problem, but not so defective as to cause a code. It would normally be about 4.7V with the engine 'off'. I have experienced such a defective MAP sensor where the engine wouldn't start but there were no codes. There is a threshold level for setting that code which may not be met.
Roland
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QUESTION: Thanks for your help so far. I have replaced the cam and MAP sensor because it is hard and dangerous to troubleshoot while broken down. I drove 240 miles and the car just stalled like someone turned the key off. I checked for any OBD codes and there were none. I immediately tried to start it and it rolled over but it seemed like there wasn't any fuel, I then tried to start it after 15 minutes of being idle and the car started. I continued for an additional 65 miles with no problems. On the trip home I thought that it was a high speed problem and set the cruise control at 65 MPH and I had no further problems and made the 315 mile journey. Since that time I have been driving it around town and I finally have a OBD code via the ignition that reads p0171 and p0174. I was wondering where you would look from here. Thanks for the help, Bill
AnswerHi Bill,
Both those codes are saying that at some point the mixture was too lean, on both cylinder banks. There are a number of possibilities:
restricted fuel supply line
fuel pump inlet strainer clogged
fuel pump itself not putting out sufficient fuel pressure
oxygen sensor (but that would mean both sides' sensors were bad, which is not likely)
throttle position sensor has discontinuity in its sweep
map sensor
engine coolant sensor
engine mechanical problem
fuel filter, pressure regulator
the engine computer has a problem.
Perhaps as you read over the list you might recognize an item that has a history connection to the previous experiences. I doubt it is the throttle position sensor, and the MAP was changed.
You could check the fuel pressure at the test port on the fuel rail, to see if it is around 58 psi.
The engine coolant sensor should read between 700 and 1,000 ohms when the engine is hot, just release the plug to test it.
You might want to shake the various harnesses while the engine is idling to identify a short/open wire situation. Also check the PCV valve. Lastly see if the egr valve might be sticky in its action as far as closing tightly to a stop with the help of its internal spring action. It could be sticking ajar which would cause a too lean condition for idle.
At least so far it hasn't left you in a permanent shutdown, so keep checking and testing.
Roland
