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So my parent's 94 Grand Marquis has been driving weird lately. It would randomly buck and jerk sometimes while driving. Yesterday it kept stalling but my mom was finally able to coax it home. I went out there today and it started up just fine, but started running rough after a few minutes.
I immediately suspected the fuel pump after yesterday's symptoms, but I decided to pull codes anyways. Here's what I got:
KOEO Hard Codes:
636 - Transmission Oil Temp
KOEO Soft Codes:
122 - TPS below minimum voltage
157 - MAF below minimum voltage
158 - MAF above maximum voltage
332 - EGR valve opening not detected
337 - EGR valve pressure transducer circuit above maximum voltage
KOER Code:
157 - MAF below minimum voltage
So I can now see why it wouldn't hardly run. But all those sensors were working perfectly a week ago, so instead of throwing new sensors at it, I'm looking for a common trend. What I see is alot of electronics going haywire all at once.
Checking the aftermarket Sunpro voltmeter I have installed revealed that the system voltage was about 16.2 volts at idle. I know it should be about 14 at idle so this seems high.
I then removed the alternator and had it tested at Autozone, which came back as a pass. But I still suspect the voltage regulator. Or perhaps the whole computer is throwing in the towel.
Anyone got any ideas? Should I order a new voltage regulator?
I immediately suspected the fuel pump after yesterday's symptoms, but I decided to pull codes anyways. Here's what I got:
KOEO Hard Codes:
636 - Transmission Oil Temp
KOEO Soft Codes:
122 - TPS below minimum voltage
157 - MAF below minimum voltage
158 - MAF above maximum voltage
332 - EGR valve opening not detected
337 - EGR valve pressure transducer circuit above maximum voltage
KOER Code:
157 - MAF below minimum voltage
So I can now see why it wouldn't hardly run. But all those sensors were working perfectly a week ago, so instead of throwing new sensors at it, I'm looking for a common trend. What I see is alot of electronics going haywire all at once.
Checking the aftermarket Sunpro voltmeter I have installed revealed that the system voltage was about 16.2 volts at idle. I know it should be about 14 at idle so this seems high.
I then removed the alternator and had it tested at Autozone, which came back as a pass. But I still suspect the voltage regulator. Or perhaps the whole computer is throwing in the towel.
Anyone got any ideas? Should I order a new voltage regulator?