My mechanic tells me the diagnostic computer gave him codes for the EGR Valve and the Map sensor, which triggered the check engine light. He tells me both will need to be replaced before the light will go off.
Trying to budget as I am a college student and know nothing about cars. Which one should I budget to repair 1st? He also mentioned the EGR silinoid (spelling?) may be the 'real' problem with the EGR valve.
Note- I take really good care of my car, tune ups, engine steamed, oils changes etc.
Unfortunately, both of these items are equally important and repairs can't normally be avoided by taking care of your car.
Your MAP (Mass Air Pressure) Sensor measures intake manifold vacuum pressure to help control the air and fuel mixture and timing. It contains a pressure-sensitive element that connects to an electronic circuit, generating a signal that changes with pressure changes in the manifold.
Your EGR (Exhaust Gas Recirculation) valve recirculates exhaust gases through the intake manifold to be burned again, cooling peak combustion temperature. Dilutes the air and fuel mixture to keep the nitrogen oxide emissions within breathable limits. And yes, it could very well be that the EGR solenoid that is causing the issue.
Both units effect your vehicle's fuel/air mixture. This is important because your vehicle running lean/rich can cause "snowball" problems. For example, a faulty EGR can cause the vehicle to run rich/lean. If not repaired, in time, the exhaust caused by the wrong rich/lean fuel mixture can damage the O2 sensors and/or catalytic converter.
If I had to pick, I'd start with your MAP Sensor. One guess I would have is that your MAP Sensor failed and made your vehicle start burning the wrong fuel/air mixture. Assuming I'm right, this could have damaged the EGR Valve. So, I see no reason to replace the EGR Valve alone, just so it too can be damaged by the poor fuel/air mixture caused by the still-faulty MAP Sensor. If your lucky, you may see the faulty EGR code disappear once your MAP Sensor is replaced.
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Hi, these codes indicate both the MAP sensor and the EGR valve. You will need to troubleshoot a bit to see exactly what is wrong. It's possible a vacuum leak could cause both of these codes. I have pasted a procedure to check the MAP sensor below using a voltmeter. If you can run this test and tell me the results, it will help to diagnose the problem. You should also check all of the vacuum hoses, including the ones from the intake manifold to the EGR solenoid and from the solenoid to the EGR valve. The run some jumper wires from the battery to the EGR solenoid pins to see if the solenoid clicks open.
TESTINGSee Figures 3, 4 and 5
Backprobe with a high impedance voltmeter at MAP sensor terminals A and C.
With the key
and engine off, the voltmeter reading should be approximately 5.0 volts.
If the voltage is not as specified, either the wiring to the MAP
sensor or the ECM may be faulty. Correct any wiring or ECM faults before
Backprobe with the high impotence voltmeter at MAP sensor terminals B and A.
Verify that the sensor voltage is approximately 0.5 volts with the engine not running (at sea level).
Record MAP sensor voltage with the key
and engine off.
Start the vehicle.
Verify that the sensor voltage is greater than 1.5 volts (above the recorded reading) at idle.
Verify that the sensor voltage increases to approximately 4.5. volts (above the recorded reading) at Wide Open Throttle (WOT).
If the sensor voltage is as specified, the sensor is functioning properly.
If the sensor voltage is not as specified, check the sensor and
the sensor vacuum source for a leak or a restriction. If no leaks or
restrictions are found, the sensor may be defective and should be
Fig. Fig. 3: Location of the MAP sensor-TBI system shown
Fig. Fig. 4: Probe the terminals of the MAP sensor to check for proper reference voltage
I too replaced the egr valve and was discouraged that the check engine light came back on with the same "insufficient flow" code. I took it to my mechanic to put it on the monster diagnostic machine. It said "check all vacuum line, and or map sensor". After looking real close we found a melted vacuum tube, and a cracked vacuum angle connector. Replaced both vacuum pieces, reset the codes, and good to go. If that fails than the next thing is the map sensor, that tells the EGR valve what to do.
crank shaft position sensor is most likely cause. Do check ignition and fuel pump relays with an ohmmeter to make sure they are not faulty. Check power to ignition module. You can also check crank sensor with the ohmmeter. Check all vacuum hose and also check throttle position sensor.
Sounds like a bad temp sensor, it has several, you need a Clymers or Chilton's repair manual, good investment if you do your own repairs! One sensor is next to the water neck just below the distributor . other is above alternator on the intake. Also there is one on the air cleaner housing that the black connector plugs to. It's late or I would look up the resistance readings for those sensors. Do you have a check engine light on? You can jump the diagnostic plug and get a code to tell you what the ECU is seeing.
I think the 97 uses a crank sensor where the 94 doesn't. (not sure) I don't see any reason you can't just leave it unhooked. I put a 92 engine in a 94 but because of the differences in the emission controls, I had to use the 94 intake and injection system. It worked out fine. Still driving it. Some advice, while you have it apart, clean the EGR valve and journals especially the ones going from the exhaust manifold to the EGR valve (driver side of motor). That is a common problem with these cars and it usually ends up ruining the engine. (My experience is with the 3 cyl model).