Yes I would check all four tower's for spark and for being corroded also inspect that coolant temp sensor connector if it's green or blue it's corroded and need's to be changed. Also for the no start we could be loosing fuel pressure. The code 12 is normal it should have that code. The code 34 is for the map sensor feed back voltage to the computer being too low. That could cause the no start etc stalling out all that. It can be caused by a bad sensor bad wiring bad pcm etc.I would check the feed back voltage when the car stall's out and won't start or just not starting at all. The problem is you will need a scan tool that read's obd 1 and will also read live data display on the obd 1 cars to diagnose it yourself without guessing. Here is the trouble tree for the code 34 let me know what you find.
MAP CIRCUIT - VOLTAGE OUT OF RANGE LOW
The manifold absolute pressure (MAP) sensor is a variable resistor that responds to changes in manifold pressure (vacuum). The PCM measure the voltage drop across the MAP sensor. The voltage ranges from 1-1.5 volts at idle (high vacuum) to 4-4.5 volts at wide-open throttle (low vacuum).
DTC PARAMETERS
DTC 34 will set if either:
* Engine speed is less than 1200 rpm.
* MAP is 0.2 volts or less.
* DTC 21 and 22 are not present. Or
* Engine speed is greater than 1200 rpm.
* MAP is 0.2 volts or less.
* TP sensor is greater than 15.2 present.
* DTC 21 and 22 are not present.
DIAGNOSTIC AIDS
When attempting to diagnose an intermittent problem use the Scan tool[1] to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.
Intermittents or opens suspected to be at the connector can be detected by using Diagnostic Service Probe. Voltage can be read on both wires without disconnecting any connectors.
With the engine Off and key On the map reading should be the same as to barometric because manifold pressure is equal to atmospheric pressure (no vacuum - high voltage). Comparing this reading to a known good vehicle with the same sensor is a good way to check accuracy of a suspect sensor. Readings should be within 0.4 volts.
[1] Select Malfunction History from Scan toot Engine Control (EC) menu.
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Thursday, January 20th, 2011 AT 5:48 PM