Stalling when accelerating?

FLORANG2123

MEMBER
2007 MAZDA 3
2.0L
4 CYL
AUTOMATIC
130,000 MILES

I recently purchased the car listed above last week and it was running smoothly the whole time. However, yesterday whenever I was at a stop light and pressed the gas pedal to accelerate, it kind of hiccups and the RPM meter jumps down and up. At some points, it stalls but it starts back up just fine. No codes on the OBD scanner except for some air bag sensors malfunctioning. I cleaned the throttle body thinking it might've been that but no luck. The battery is also 2 months old. What else can I check for the issue?

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

It could be water in the fuel or a weak fuel pump, we can start with a fuel pressure test. It also can be the catalytic converter being clogged due to the catalyst material breaking apart. Let's use these guides to help us eliminate problems:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

and you can rent a fuel pressure gauge at the auto parts store for cheap or free.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Fuel Pressure Specifications

LF / L3

Fuel pressure (Reference)
350 - 410 kPa 3.57 - 4.18 kgf/sq.cm, 50.8 - 59.4 psi

Fuel hold pressure (Reference)
250 kPa 2.55 kgf/sq.cm, 36.2 psi or more

L3 With Turbocharger

Fuel line pressure
410-490 kPa 4.2-4.9 kgf/sq.cm, 60-71 psi

Fuel hold pressure
More than 230 kPa 2.3 kgf/sq.cm, 33 psi

I have seen the primary cats have issues so you might want to remove it for inspection. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)