Mazda codes
This is the same vehicle that I’m changing the MAF sensor for. Pulled two codes off of it and has two Codes One was for the MAF sensor and the other one was 25, Signal shape/waveform failure. Any idea what that pertains to? Could it be the MAF sensor?
The first photo is the code 8: Airflow Sensor Flow Chart The 2nd photo is the code 25: Pressure Regulator Solenoid Valve Flow chart The bottom of the page of the 3rd photo is testing the Pressure Regulator Control solenoid The 4th photo is the Pressure Regulator Control Solenoid The bottom right of the 5th photo is a wiring diagram of the Pressure Regulator Control Solenoid The 7th photo is…
Hey Ray, thank you for those pictures and the diagrams! Sorry I didn’t get back to you sooner, actually I just noticed your reply the other day, been awful busy. I haven’t been able to get back to the vehicle yet mainly because it’s out in the boonies and I’ve been waiting for a MAF sensor to get in. I assumed it was the sensor because when I unplugged it it started and ran and the circuit was…
To eliminate the pressure regulator solenoid valve/circuit, manually activate and deactivate the solenoid, to see how the engine runs, with the MAF disconnected.
OK I will do that when I get a chance to get out there again. So the way I understand it is that when the valve is not activated it sends the vacuum to the vacuum regulator causing the fuel pressure to be lower and if that’s not activating then it’s not getting the fuel pressure it needs to run. And when the computer sends 12 V to it, it opens it up to the atmosphere causing no vacuum actuation…
In this fuel pressure chart, at idle with vacuum to the regulator, the fuel pressure is 28-37 psi. At idle without vacuum to the regulator, the fuel pressure is 38-46 psi. When the engine is cranking and when the truck is driven near WOT, the engine will have very little vacuum and the fuel pressure should measure 38-46 psi. I would also measure the fuel volume.
Hello again Ray. So I got the truck running, started A few times more and was running running good when I left, but when the customer went to start it later it won’t start again now. Sorry to bother you again about this but I checked everything but fuel volume and the burn off for the NAF sensor. The fuel pressure is as it should be, 35 psi regulator active, 46 psi unplugged. Kind of at a loss…
Maybe the fuel is bad or too old, which would make the engine hard to start. What is the engine vacuum when the engine is running. If you have a 4 gas analyzer, measure the HC ppm while cranking and measure the CO% and HCs when running. Are the plugs black or fuel fouled, Scope the ignition and measure the spark plug burn times while cranking. To ck the ignition timing, disconnect and plug…
Once again thank you so much for your reply and continued information Ray! I did test the airflow meter voltages and they were perfectly within spec when I was there last. The vacuum was good also. When I go back I will do these other tests and scope the ignition and injectors also. Also it has the code 25 and I can’t seem to find a whole lot of information on it, only ( Signal shape/waveform…