QuestionQUESTION: I have a 1991 chrysler newyorker 6 cyl 3.3 eng. 2 weeks ago it bogged out on me like it ran out of gas (had half a tank) and it would not restart. The next day it started, got me about 4 miles and bogged out again. I had it towed to a shop and it was there for 6 days they ran it every day and it ran fine for them. I got it back and it ran good for about 100 miles then it bogged out again. The guys at the shop said they found nothing on the diagnostic computer. when it boggs out it sounds like it's missing any ideas would be great.
ANSWER: Hi Fred,
Before guessing may I suggest that you try to get the codes by yourself? Use 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 begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to be sure you have the count accurately. Then group the counts in pairs in the order of appearance to form the two-digit code numbers that might tell us what is wrong. The last number will always be 55, eg. two groups of five flashes each, which means 'end of readout'. Then write back with the other numbers.
Roland
PS Use the 'thank/rate' tab below to get back to me with the results, without having to wait for me to be available to take a question. I have my suspicions about what is wrong but let us see what the computer tells us.
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QUESTION: the code was 12
ANSWER: Hi Fred,
That is good to know, but unfortunately it just means the battery was disconnected from the computer sometime in the past 50-100 key on-off cycles. We don't know if the shop disconnected the battery at the clamp or not. It will go away in 50-100 key cycles, but if it persists then that would be a possible explanation (that would be the red wire direct from the 30 amp 'fuel pump/trans' fuse in the underhood box). It would be good to take a look at that fuse to see if it might have a subtle crack in its wire which could open and close spontaneously.
The behavior you describe reminds me of one of engine rotation sensors (crank and cam) failing when it heats up and then recovering upon cool down. At an early stage of such failure the signal loss might be too slight to set a code, so if it is the case you may just have to wait until it fails more definitively. Another possibility is the MAP sensor which can loose accuracy but not so much as to set a code. You might try reading the voltage between the dark green/red and black/light blue wires with the ignition switched to 'run' and then with the engine starter and let me know what the readings are.
Perhaps the best part to check out now would be the egr (exhaust gas recirculation) valve which might be sticking ajar and causing too lean a mixture at starting and when slowing down. It is located in a pipe that runs from the rear exhaust manifold back to the underside of the throttle body at the rear of the engine. The body of the valve is bolted into the pipe, it has a round vacuum operated top, and in between a flange inside of which you will see a rod with a slot (the valve stem). Try moving the stem back and forth with the tip of a screwdriver inserted in the slot, against spring-action in one direction that closes the valve. If the action seems sticky, or the spring doesn't bring the stem to a dead stop then try spraying some WD-40 on the valve stem where it enters the valve body and work the stem some more. If it still hangs us without reaching a dead stop then take off the valve and clean out its internal passageway and valve seat.
This possibility is worth pursuing, particularly if it seems to be bogging down when you let up on the gas, as opposed to when you are cruising at part throttle, because that is when it has to close down tightly or the engine will die and be hard to restart.
Roland
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QUESTION: i replaced the ignition coil package, map sensor, plugs, wires, and it ran for another 15 miles then bogged out again like there was no gas but it had half a tank. what is the easiest way to check if there is anything in the gas tank (neighbors may have put something in it due to me getting a reserved spot on the street reciently)
AnswerHi Fred,
There is a port on the fuel rail onto which you can fit a pressure gauge to see if you are getting 48 psi. You will want to have a hose routed to a pail when you first open it so as to not have it spray on the engine, particularly if hot. Otherwise, you would have to raise the rear and lower the tank and remove the pump, alot of work. Still no codes other than the 12? How soon after it bogged down did it start up and run normally? I still would wonder about the cam or crank sensor. When it bogs down try measuring betwee the black/light blue sensor ground wire, and the signal wire of the cam sensor tan/yellow and the crank sensor gray/black wire, respectively, while you turn it over by hand using a socket and ratchet on the crank pulley and the ignition in the run position. The voltage should bounce between 0.3 and 5V several times for each revolution. If it recovers in a few minutes and runs again I would suspect one of those sensors is beginning to fail when it warms up.
Roland
PPS The voting for 'expert of the month' ends tomorrow afternoon. If you would be so kind as to find the "nomination?" area of the 'thank/rate' tab and change the 'no' to a 'yes' that would give a vote. Thanks
