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350matt, Engineer
Category: Mazda
Satisfied Customers: 21711
Experience:  Mechanical Engineer BEng Hons22 years experience
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At first it was bogging down when pressing on the

Customer Question

At first it was bogging down when pressing on the accelerator, when I would press the gas pedal...lost of power. I took it to a mechanic and tried changing, I think it was the airflow valve...something like that and now it revs up very high and does not come down...he is a bit stumped and thinking the part may be defective...any ideas?
JA: Is the power loss consistent, or does it fluctuate?
Customer: Truck is a 2003 Mazda pickup truck B3000.
JA: Are you fixing your B3000 yourself? What have you tried so far?
Customer: Yes, it was consistence when prior to me taking it to the mechanic. It just started all of a sudden just after I filled up truck with a tank of gas.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No, I am not fixing myself. I took it to my mechanic, but I think he is still diagnosing the problem.
Submitted: 4 months ago.
Category: Mazda
Customer: replied 4 months ago.
Truck is automatic transmission.
Expert:  350matt replied 4 months ago.


this sounds like your mechanic may have replaced the MAF ( mass airflow sensor) and in doing so hasn't refitted a vacuum hose or similar so you now have a vacuum leak

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Customer: replied 4 months ago.
Problem still not fixed. Mechanic checked if there was a vacuum leak and he tested and no leaks. Fuel pressure okay. Any more suggestions?
Expert:  350matt replied 4 months ago.


OK I'd next check if the throttle is opening fully

with the ignition on but engine off, remove the air iintake pipe to the engine so you can see the throttle

then have your assistant slowly push down on the accelerator whilst you watch the throttle

it should open fully and smoothly and slowly

if not then try cleaning it out and check the wiring for any damage

if this doesn't help then replace the throttle

other possibilities for a lack of power are:

clogged air filter

collapsed exhaust catalyst - remove the O2 sensor bung and peer inside to try and see the condition of the cat brick - if its not smooth and even with all the honeycomb clearly defined then it may need replacing

finally do a compression test across all cylinder as they should all be within 10-15 psi of each other

Customer: replied 3 months ago.
Mechanic was able to find the issue. It was a sensor causing the problem.
Expert:  350matt replied 3 months ago.


glad you got it sorted

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