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I'm having this problem for some time now.

Usually in 2nd (and mostly 3rd) and higher gears, when gas pedal is completely pressed to the end, the car is accelerating, but when it reaches about 2100-2500rpm, the accelerating power drops for a half a second and the continues to rise normally. I took the car to the dealer but the told me it is ok.

It's really hard to show the problem to mechanic because it happens not 100% of the time - sometimes the drop is milder, sometimes it feels like brake is pressed. Could this be issue with electric or engine mechanics?

Car is Mazda 3, 2.0 petrol, 6 gear manual transmission, manufactured 2007, odomoter 130000km

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I have a 2011 Mazda 3 hatch and have this exact same issue, dealer said there was nothing wrong when they checked it out –  user3970 Nov 15 '13 at 21:24
    
Got this problem too on a Premacy 2005. It seems to be very common on a range of Mazda's and I haven't found a definitive answer –  Matt Aug 29 at 2:32

3 Answers 3

The first major symptom that appears when spark plug gaps get too big (from wear) is that you get a band of hesitation only at full throttle and somewhere well below peak torque. This is the band where the most voltage is required for a successful spark, because at this time mixture is most dense. Below this band the mixture is less dense because less mixture is drawn in with each stroke. Above this band the mixture is less dense because the spark occurs earlier in cycle (spark advance). The result is that this is the first rpm at which old plugs will misfire.

2100-2500rpm seems about right, but I don't know your car.

Check your spark plugs, or if you don't like (buying) wire gauges just replace your spark plugs. Cracked high tension leads also reveal themselves in this same rpm band.

The next step would be to look at sensors, but I'll wait for you to confirm that your plugs and leads are fine before going further.

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Thanks, I will them. Is there something specific i should look at after removing spark plugs? Like measure the gap or rust or something like that? –  Deniss Kozlovs Mar 14 '12 at 13:07
    
I forgot to mention one thing, don't know it may be related to that. When i fuel up with 98 petrol, the car becomes not faster, but significantly loses power - pressing gas pedal makes rpm rise, but acceleration is slow. –  Deniss Kozlovs Mar 15 '12 at 10:50
    
Your second comment is interesting. I'm guessing 98 is more difficult to ignite, but I don't know this for a fact. Does it just get generally slower? is it slower only under full throttle? or does the band of hesitation get wider? Anyway, in my mind this definitely points to an ignition problem. –  kahbou Mar 15 '12 at 17:46
    
How long (how many kilometeres) has it been since the spark plugs have been replaced? It's better use of your time replacing them, if they're near their service life (which can be found in the car's service schedule). If you wanted to inspect them you need to measure the gap with a 'wire feeler gauge'. It's basically a device that holds a number of wires of different thickness. The only other thing worth inspecting is that all the plugs look roughly the same, in terms of deposits and colour. –  kahbou Mar 15 '12 at 17:52
    
I bought a car in November 2011 and since then i was using 98 petrol, because with it the car was more faster :) The spark plugs were replaced in December, but problems started to appear later in January. I will check the plugs anyway tomorrow and maybe replace with new to be sure. –  Deniss Kozlovs Mar 16 '12 at 7:21

At this engine speed the EGR valve is operated. A slow operation, caused by exhaust debris will cause this to happen. A second symptom would be intermittant rough idling.

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Quick pointed question: Does this tend to happen when the fuel tank is nearly empty, or does it also happen when the fuel tank is full? It's possible that the fuel pickup tube is displaced or otherwise starving the vehicle of fuel under hard acceleration. That may result in normal acceleration until the fuel rail runs out of pressure, then the drop in speed would surge fuel forward to the fuel pickup tube again, which would permit you to resume accelerating.

This would ONLY apply if your symptoms did NOT appear with a full tank, though - with a full tank, the entire fuel pump is fully submerged in fuel.

It's a straw, but it's worth grasping at.

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