Question-------------------------
Followup To
Question -
i have a 1991 chrysler lebaron. i finally got the timing marks aligned properly thanks to your help. now i need to correct another problem. the car will idle but it surges and stutters for a couple of minutes than dies. it will start right back up only to do the same. i did the trouble code check at the ignition as i do not have access to a scan tool and i received trouble codes for the alternator not switching properly anjd the map sensor out of range. the motor is the 3.0 l v-6. my question is what other components are on the same circuit as the map sensor so i can be assured that it is not another component causing the problem before i start buying parts to insure i dont purchase unecessary parts YOUR HELP WOULD BE GREATLY APPRECIATED. thanks
Answer -
Hi Duane,
The only other items that share the same circuit are the 5V supply to the sensor which is used by many of the other sensors too. The three wires to the sensor are:
black/light blue common ground for all the sensor
violet/white 5V supply (should be present when ignition on)
dark green/red MAP signal (should be 4.3 or so at idle, dropping to low value when you snap the throttle valve).
You can check the first two wire by removing the plug and seeing that the first one is reading 0 ohms to engine ground. The second should read 5V if you have the key in the run position. And the third could be read by inserting a very fine pin into the place where the wire enters the plug and reading the voltage on the pin when the plug is reconnected and the engine is running.
The other possibility is that the vacuum line is cracked or has a loose connection at either end of it so that the true vacuum is not being applied to the MAP sensor.
So check those items and let me know what you measure/observe. I agree with you about not throwing away money on parts, but if you have such a code, you should investigate whether that item is indeed working properly or not. If all the wires, voltage supply and ground, and vacuum line check out, but the signal voltage is not varrying when you rev the throttle or doesn't change when you start the engine then the MAP would certainly be suspicious of needing to be replaced. If you want to verify the wires to the PCM, they go to pins 4, 6, and 1 of the PCM plug, respectively. Try shaking the harness to see if you can cause any intermittant change in voltage or resistance value.
I am glad to learn that the timing mark problem got resolved for you.
Roland
HOW DO I CLEAR THE CODES TO SEE WHICH ONES ARE STILL A PROBLEM?
AnswerHi Duane,
To erase the memory you merely have to disconnect the - post clamp from the battery for a few minutes. There will still be one code after doing that, a 12 which signifies that the battery power to the PCM was lost, which of course it was, and that too will pass after 50-100 key on-off cycles.
Roland
P.S. Thanks for the positive feedback.
