This Mazda 3 was using a lot of fuel and running rough so we replaced the airflow meter - then the dashboard warning light came on so the owner brought it to us for some more diagnostics and help.
Using the scan tool, we monitored air flow meter data: grams per second and air temperature. Both readings were out of specifications. We diagnosed the air flow meter as faulty due to the air flow and temperature from the component being out of specifications.
We replaced the air flow meter and tested everything again - the air temperature was good and grams per second came in around 2 grams per second, all within specifications, and also during the road test all indicators were okay, the car was no longer running rough!
The vehicle returned to us approximately one week later with a warning light on the dashboard. There were no running issues, that had been fixed - just the light present on the instrument cluster. We read the message - P0171 (bank one system too lean). Intake air temperatures from the air flow meter were okay, grams per second were down. We suspected there might be an issue with the new air flow meter that had been installed. We fitted a replacement air flow meter for the customer and everything was okay!
But the vehicle returned with the same code, but this time the engine light was only coming on intermittently. We pico scoped the fuel pump and that showed us slight wear in two of the pump cells, so we the checked fuel pressure which was within specifications every time. We also checked the operation of the front air fuel ratio sensor, all okay.
So again we started looking at grams per second reading from the air flow meter and we noticed that the reading would drop occasionally. Suspecting a slight intake leak we filled the manifold with smoke to inspect for leaks - yet there were none to be found.
After finding no EXTERNAL intake leaks we started suspecting an INTERNAL intake leak. When disconnecting and blocking the evaporative emission purge solenoid valve between the valve and the manifold, the grams per second reading rose to within spec. So we checked for a leak through the evaporative emission purge solenoid valve - there wasn't one. We reassembled the purge valve and hose to intake manifold with a clamp , all readings were within spec. A further test drive indicated no faults.
A few weeks later guess which car was back, yep, and the same code. Still going with the evaporative emission valve and internal intake leak theory we removed the hose between the purge valve and fuel tank, this time there was a huge intake leak, this wasn't happening last time we checked!! Also, the scan tool showed that the purge valve should be closed. By blocking the intake leak all readings were within specifications, most importantly, the grams per second through the air flow meter had risen.
We found we could use the actuation tests on the scan tool to control the duty cycle of the purge valve. Finding the purge valve intermittently not shutting when commanded, even though the signal was getting to the purge valve from the engine control module, all okay, we suggested replacement of the purge valve. Once the purge valve was replaced we tested it with the scan tool, it shut every time we commanded it to...brilliant!!
We took the vehicle for a good long test drive while monitoring the purge valve duty cycle and grams per second from the air flow meter - everything was operating normally and whenever the purge valve was shut the grams per second was within specifications. WE DID IT. #CELEBRATIONS
Sometimes car diagnostics can be a tricky business - sometimes there can be more than one faulty part and fixing the first one found can lead to finding more problems. Even experts like us sometimes need to use extra investigations and some out of the box thinking to solve the problem. But the most important thing about this story - This customer's vehicle is now running smooth and no warning lights!
If your car isn't performing as well as it should, or your warning lights are shining - give us a call at Blackwood dyno tune for expert diagnostics and service.
What does it mean when there is a warning light on Mazda 3?
Your car's dashboard lights will let you know if there is a fault in your vehicle and when they do, they should never be ignored. There are different warning lights and your owner’s manual will contain an explanation of these symbols and what they mean.
What dashboard warning lights are on a Mazda 3?
There are many different warning lights and combinations of different warning lights that can light up on your dashboard. The best place to get an explanation for all of them is in your users manual. A few that you might see include:
Master Warning Light – This is a red triangle with an exclamation mark – and can signal a number of different faults. You should bring your vehicle in to Blackwood Dyno Tune & Service so we can look at the issue and remedy the situation.
Brake System Warning Light – This is an exclamation mark in a circle which lights up to let you know when the parking brake is on. It should turn off when the parking brake is released but if it doesn’t – it could be dangerous to continue driving. If you find yourself with a brake warning lights that’s not switching off please call Blackwood Dyno Tune & Service.
Oil Pressure Light – This is a red oil can symbol. This light will come on briefly during start up and then switch off – this is normal. However – if this light comes on when you are driving you should take immediate action: stop driving and switch off the engine. Do not restart your vehicle as you could damage your engine and call Blackwood Dyno Tune & Service to discuss the situation.
What does triangle with exclamation point mean on Mazda?
This is the master warning light – and can signal several different faults. You should bring your vehicle in to Blackwood Dyno Tune & Service so we can look at the issue and remedy the situation.
Why is my car using more petrol than normal?
There can be so many reasons why a vehicle starts using more fuel than normal. Sometimes it can be a system fault as experienced with this case study and sometimes it can be about how you are using your vehicle.
Have you changed the way you use your vehicle? Heavier loads can increase the amount of fuel you use, so consider what you might be carrying around unnecessarily.
Change of weather? Using the car air conditioning will increase the amount of petrol you use and in the hot Adelaide summers it can be necessary to use the air con a lot!
Checked your tyres? The air pressure in your tyres should be maintained for many reasons and fuel consumption is one of them, properly inflated tyres will use less fuel.
If you feel your vehicle is using more fuel than normal, and you haven’t changed the way you use your vehicle you should discuss this with Blackwood Dyno Tune & Service before your next service – we may be able to diagnose the issue and get your fuel use back on track.
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