I am the original owner of the car, which has approximately 125k miles on it. The car has given me great service, but lately a strange problem arose that has my mechanic stumped. When I try to accelerate, the car typically does not respond. After 5 seconds or so, the engine suddenly comes to life and the car begins to accelerate. At high speeds it is not an issue, but the engine sputters once in a while. It has never stalled. It is not the transmission because the RPM stays low during low-power times.
The mechanic initially thought that it was a dirty fuel filter. But, changing it has not helped. Once the engine light came on, and the code was for the air-flow sensor. But, the mechanic is not convinced about that.
The problem tends to become worse after driving for a while, after the engine has warmed up.
Does the mechanic actually test anything, or just make guesses?
You don’t have to guess about a fuel filter, for example. You put a fuel pressure gauge on the car and find out whether or not the pressure is within specs. Aside from that a fuel filter isn’t a “part” that you replace to fix something that is “broken” - its just a regular maintenance item like all other filters. If one suspected an old fuel filter was a problem and wanted to know, one could simply check the fuel pressure, then replace the filter, then check the fuel pressure again.
A MAF sensor could be the issue. Did the mechanic at least clean the sensor? This is a very simple job that wouldn’t require very much time or materials. Did the mechanic check the wiring/voltage for the sensor? Does the mechanic have a scantool with which one can get live data regarding the sensor’s behavior? If you can get the actual, specific code that was read from the computer (like “P1234”) post it.
How old are your spark plugs & wires? Air filter?
‘Dirty MAF sensor’ was my first thought when I started reading the OP.
Without reading what Cigroller wrote…I was going to say to clean the MAF…(Mass Airflow Sensor)…then I saw that your mechanic Poo-Poo’d that idea…and why may I ask? I STILL say to pull your MAF and use some spray cleaner… either Brake Cleaner, Carburetor cleaner…or the MAF Sensor Spray Cleaner that they have out now …All usually widely available at the Auto parts stores.
The fact that Cigroller and Circuitsmith concur …only makes the idea sound that much more correct. It literally was the first thing that sprung to mind aside from the TPS (throttle position sensor)…BUT CERTAINLY BEFORE looking into the TPS, I would absolutely clean that MAF…Besides being SUPER EASY to do, this is a very common procedure, and needs to be done from time to time. Nothing out of the ordinary for certain…DO IT…FORGET what your “Mechanic” told you… I swear I’d love to meet some of these “Mechanics” LOL
I would definitely clean the MAF and see if you get a change…IF YOU DO…then proceed to do a regular tuneup…(AGAIN Cigroller on the same page) Plugs, Distrib Cap and rotor (if equipped), Air Filter…you already did the fuel filter…
I am going to defend your mechanic on the fuel filter, they seem to be an issue in Mazda’s of this age and mileage, and they are relatively easy to replace.
But I can’t defend his advice to ignore what the code is telling him. The MAF is pretty easy to clean.
Thank you all for the advices. I’ll clean the MAF sensor and see what happens.
To answer Cigroller’s question, spark plugs and air filter are a couple of years old. Spark-plug wires are about 5 years old.
The mechanic cleaned the MAF, but that did not help. A few days back, the car refused to start! The engine will crank, but that’s it. I had the car towed to the mechanic. He found that the piston pressure was half the minimum needed. He said that he could fix it, but is recommending that I junk it, because it will cost nearly $1,000.
By piston pressure do you mean a compression test? If so, what numbers did he give you about that test?
I’m getting a bit suspicious (maybe very) about this mechanic who chooses to overlook a MAF code and we’re to believe that piston pressure (not defined but possibly meaning compression) is one of those things that comes and goes? An engine with low compression is not going to “spring to life” at varying times.
Cleaning the MAF is only the first step to fixing the problem. He has to check for any air leaks that may be occurring after the MAF, such as a leaking throttle body gasket, vacuum line or even the intake manifold gasket.