QuestionQUESTION: the car starts fine and runs ok until it warms up. Then it stalls like there is water in the gas. Let it cool off and it will start again for a short time. A mechanic changed the fuel pump (expensive), distributor cap and rotor, spark plugs and checked other things. I am running out of money. Do you have a suggestion on fixing this problem?
ANSWER: Hi John,
Try for fault code using the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remains 'on', to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause; then repeat the process to be sure of an accurate set of flash counts. Then write back with the results and we'll go from there.
Roland
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QUESTION: The flashes gave a code of 1-2-2-4-3-3-4-2-55. I did the test 4 times and this is the result. Thank you.
AnswerHi John,
None of the codes are simplu or directly related to the temperature-dependence of the problem, but it may be an issue that is exacerbated by warming up to operating temperature.
The 12 and 55 are not relevant unless the battery has not been disconnected in the past 100 key-on-off cycles.
The 24 code points to a problem with the signal voltage coming from the throttle position sensor located on the throttle body. It might either be too high or too low than normal range or it may not be consistent with the vacuum reading from the manifold pressure sensor. The sensor has three wires that are connected to the engine controller and so you could look at those wires/harness to look for any melted insulation or damaged wires. The sensor has a 5 volt supply wire (violet/white) that comes from pin 61 at the controller. The signal voltage varies with the opening of the throttle as measured between the orange/light blue that goes to pin 61 and the sensor ground black/light blue that goes to pin 43. If you put a voltmeter across those two wires (after inserting fine pins through the insulation to which to attach the meter leads) you should find the voltage to vary smoothly between a little less that 5 and a little more than 0V as you move the throttle lever, and no discontinuities. If not then the sensor may have a discontinuty or a shorted/open wire.
The 33 says there is an issue with the a/c compressor clutch circuit which is not relevant to the problem.
The 42 says there is an issue with autoshutdown relay or the fuel pump relay control circuit. Either relay not being 'solid' could cause missing. You could observe the autoshutdown relay function by measuring the voltage at fuse 1 in the box under the hood where it should be 12v when the engine is running.
The fuel pump relay is located in the box too and its output is labelled 27 (the one that is directly adjacent to the three pins on the outboard side of its socket). You might be able to insert an insulated wire into the socket for the pin 27 and then put the relay back in the socket. Then you could check the voltage on that wire as compared to chassis ground (- post of the battery or any structural metal) and like the ASD relay it should show a 'solid' 12v when the engine is running (maybe it would be flaky with you are having the issue).
The main temperature-dependent sensor is the coolant temp sensor located in the coolant manifold and at the base of the pipe where you add coolant to the system. You would do well to remove the 2-wire plug (lift tab on side to release) of that sensor and measure that its resistance is in the range of 700-1000 ohms when the system is warmed to operating temp. When cold it should read 4,000 or more ohms.
So give those items a look to see if you can find one that is misbehaving.
Roland
