98 Saturn air flow restriction fault


Old 04-30-11, 03:54 PM
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98 Saturn air flow restriction fault

Stepdaughters car keep coming up with an egr valve air flow restriction fault, i have replace the intake gasket an cleaned out the ports, has a new egr valve. Took to a shop they said computer not working egr valve, so they installed a new computer, the fault is still coming up any suggestion what to do next.
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Old 04-30-11, 04:19 PM
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Whats the actuall code #????

I am sure they looked at the MAF, MAP, oxygen sensors, etc.. correct?

Just wondering if you paid for all these repairs? Seems like if you change enough parts you will find it..LOL.

Sometimes codes get thrown and it shows something else then what it really is. Its a 98, and codes were not as detailed on specific components as they are today.

What you need to do before changing anymore parts, is to test the part in question. You cant just assume a part is bad.

Post the actuall code. It will help to better troubleshoot from this forum.

Mike NJ
Old 04-30-11, 04:51 PM
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As Mike said, get the code. I had one once, and it threw a code regarding the Mass Air Flow Sensor. You can buy Mass Air Flow Sensor cleaner at better auto parts stores. The MAFS is located in the intake tube just ahead of the air filter. It has two leads and two clamps on it. You can remove it from the intake tubing and clean it. Maybe it will work, but get the code first and don't throw any more money at it until you know for sure what it is.......computer, not.
Old 05-18-11, 04:12 AM
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I think code was p0404 computer was already installed at a shop. I drive truck over the road only home once a month, so I need a shop to do i will look at MAF next time home.
Old 05-18-11, 04:33 AM
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P0404 Exhaust Gas Recirculation Circuit Range/Performance
Old 05-18-11, 12:39 PM
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i think, you pay for more repairs, and it will be enough to buy another Saturn like this. 98 is cheap on craigslist.

P0404 - Exhaust Gas Recirculation Circuit Range/Performance
OBD-II Trouble Code Technical Description

Exhaust Gas Recirculation Circuit Range/Performance
What does that mean?

The EGR (Exhaust Gas Recirculation) system's purpose is to redirect exhaust gas back into the cylinders. Since exhaust gas is inert, it displaces oxygen and fuel, thereby lowering cylinder temps, which, in turn, lowers oxides of nitrogen emissions. For that reason it needs to be carefully metered into the cylinders (via the EGR valve) so as not to adversely affect the engine's performance. (Too much EGR and the engine won't idle).

If you have a P0404, then the EGR valve is likely an electrically controlled EGR valve instead of a vacuum controlled EGR valve. Also, the valve will usually have a feedback system built into it that informs the PCM (Powertrain Control Module) what position the valve is in; open, closed, or somewhere in between. The PCM needs to know this to determine whether or not the valve is operating as needed. If the PCM determines that the valve should be operating, but the feedback circuit shows that the valve is not open, this code will set. Or if the PCM determines the valve should be closed but the feedback signal indicates that the valve is open, this code will set.

There may be no symptoms of a P0404 DTC other than the MIL (malfunction indicator lamp) or check engine light. However, Exhaust Gas Recirculation systems are inherently problematic due to carbon buildup in the intake manifold, etc. This normal buildup can lodge in an EGR valve, holding it open when it should be closed. If this is the case, the engine may idle rough, or not at all. If the valve has failed and is NOT opening, then symptoms would be higher combustion temps and as a result, higher Nox emissions. But the latter symptoms aren't going to be noticeable to a driver.

Usually this code points to either carbon buildup or a bad EGR valve. However that doesn't rule out the following:

* Open or short in the 5 Volt reference circuit
* Open or short in the ground circuit
* Open or short in the PCM controlled voltage circuit
* Bad PCM (less likely)

Possible Solutions

1. Using a scan tool command the EGR valve to open while watching the actual EGR position (it will probably be labeled "desired EGR" or something similar). The actual EGR position should be very close to the "desired" EGR position. If it is, then the problem is likely intermittent. It may have been a lodged piece of carbon that has since dislodged, or it could be a bad EGR valve winding that intermittently opens or shorts as the valve temperature changes.
2. If the EGR "desired" position is not close to the "actual" position, then unplug the EGR sensor. Check for a good 5 Volt reference voltage to the connector. If it doesn't show a reference voltage, repair an open or short in the 5 Volt reference circuit.
3. If there is a 5 volt reference voltage, activate the EGR with the scanner, monitor the EGR ground circuit with a DVOM (Digital Volt/Ohm meter). It should indicate a good ground. If it doesn't then repair the ground circuit.
4. If there is a good ground, then check the control circuit. It should indicate voltage that varies according to the percentage that the EGR is open. As it's open more, the voltage should increase accordingly. If it does, then replace the EGR valve.
5. If the voltage doesn't increase incrementally, then repair open or short in EGR control circuit.

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