Hello, I was hoping someone here could be of some assistance. A little bit ago I had my check engine light come on although I was not having any real problems with the car. I mean I had noticed that the acceleration was down and what not but thought that came with the car getting older as I have a 96 S model with about 96,000 miles on it. Anyways I had it scanned and it came up as an EGR Flow Malfunction and they prompted me to replace my EGR Valve which I did. A day later the light was back on and it was the same issue when scanned. I asked around and someone had suggested that the EGR ports in the throttle body may be clogged and that I should remove them and clean them out with some fuel injector cleaner or something similar. My question is two parts; one: does that sound right to anyone? And two: how would I go about doing that. I mean the guy showed me on his Mazda but it was not an S model and it was near his air filter, but on mine that is not the case. Someone told me to look on the supercharger, but I am fairly lost. I am nowhere near a mechanic, but am limited on how much I can spend to fix this, so if it is possible to do myself I would like to at least try. I was wondering if anyone had detailed instructions or a diagram or knew where I could get this information as my local dealership is no help whatsoever and most other places have acted like they have never seen a car like mine. Thank you so much in advance for any help you can provide.

 

Jim, What kind of code was retrieved when you had the codes checked? Have seen a great number of people that have codes checked and the code description was not even close to what the acual problem was being indicated. The code should start with a P and then have 4 following numbers such as P0400. Very few problems with any EGR systems on the Millenia to date. Give a post back with any other info you have.

 

First off, thank you very much for responding to my message. You were right on actually, even though I am sure you were just giving an example, but the code came back as P0400 when they checked it. EGR Flow Malfunction it said after the number. Like I said I have replaced the EGR Valve, they suggested looking at the vacuum hoses, and another website said to check the EGR ports in the throttle body, but any thought you have would be welcomed. Thank you again.

 

The ports in the throttle body would not apply to your engine as the EGR is no where near the throttle body but you could still have a plugged or restricted port for the EGR boost sensor. This sensor and its solenoid are located at the passenger rear area of the engne compartment. The sensor and solenoid will be located right next to each other, the sensor having one vacuum line to it from the solenoid and the solenoid would have one other vacuum line to it from the engine. With the engine at an idle, carefully remove the line from the engine and check for a good strong vacuum. If no vaccum at all is felt or is weak ( vacuum line should instantly stick to a wet fingertip with good strong vacuum ) then the port is either partially or completly restricted.
Added a pic but is not very good to help in location of this line. Boost sensor and solenoid are labeled #6 at very top of diagram.

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Thank you so much. I will work on checking it this weekend and let you know what I find out. Assuming that there is little to no suction what would I have to replace exactly? Thanks again for your time.

 

If no vacuum is detected at the line then is not a matter of parts needing to be replaced but only needing to clean out the port that is blocked. May require removing the entire upper manifold to clean out or only adding a good cleaning solution down the vacuum line. Let know what you find out from the check.

 

So I checked it out and the suction on the vacuum hoses were okay. Any other suggestions? Thanks in advance.

 

Jim, the only vacuum line that should have suction is the one from the engine to the solenoid valve. Vacuum should not be allowed past solenoid valve to the sensor unless the engine is fully warmed up and engine speed is increased and held at over 4000 rpm ( there is a little test you could do although doubt that is the problem). If vacuum is either being supplied to the sensor at all times and/or there is no vacuum to the sensor at any time ( even with rpm over 4000, then probably have a bad solenoid or signal.
Another thing you can do to see if the passages in the intake and exhaust are ok is too apply full vacuum to the EGR valve at idle. When vacuum is applied to the EGR valve the engine should run fairly rough if not stalling. If you do not have a vacuum pump to apply that vacuum to the valve then use the line from the solenoid that you checked earlier.

 

They did both have suction with it just idling and the engine cool. I will check again and if so then I will replace the solenoid I suppose. I am checking the right area I hope, it is right where it says boost sensor is that correct? Thanks again.

 

Sounds like you are in the right area. Boost sensor and MAP sensor interchangeable. Just to double check though the sensor should have three wires going to it with wire colors being : Black w/ Red stripe, Blue, and Light green w/ red stripe. The solenoid in question should be right next to it on the same bracket at the passenger side of engine compartment towards the rear corner. Below is a pic of the solenoid with ports labeled A, B, and C. The vacuum line from engine should be connected to port 'A'. Short vacuum line connects port 'B' to the boost sensor. At an idle and/or the solenoid connector unplugged you should have vacuum up to the line removed from port 'A' but with the line reconnected to port 'A', you should not have any vacuum at port 'B'.
If battery voltage is applied to the solenoid as shown in the pic then you should then have vacuum at port 'B'.
Hope that makes sense.

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