Car Fixed Itself

[Neeranam]

So I have a Mazda CX3 which had a problem 5 weeks ago and I took it to the service centre. I needed a new battery. There was no acceleration and driving was slightly dangerous. The mechanic said it might fix itself.

For 2 days later, I had practically no acceleration still and didn't drive it for 4 weeks. When I started it again, it had great acceleration. 

 

Does anyone know why this could happen?

 

The mechanic had also thought it could be the petrol, but that wasn't different from normal and not changed since the issue. 

[Kwasaki]

When battery is dead or low and taken out of some cars, the loss of power apart from other things can play up. 

Once started up what happens usually is an ECU re-calibration takes place and puts things right. 

 

I found this out with our once owed Toyota 1.5 Yaris. 

[Crossy]

 

[Neeranam]

12 minutes ago, Kwasaki said:

When battery is dead or low and taken out of some cars, the loss of power apart from other things can play up. 

Once started up what happens usually is an ECU re-calibration takes place and puts things right. 

 

I found this out with our once owed Toyota 1.5 Yaris. 

What I thought, the lack of power upset the computer. 

[Kwasaki]

4 minutes ago, Neeranam said:

What I thought, the lack of power upset the computer. 

Basically yes and it in most cases correct itself but if there's still a problem it need to go dealer for a plug in computer ECU analysis check out. 

[d4dang]

you can buy the plug in computer for relatively cheap.  The engine light that often comes on for some reason and won't turn off without the plug in computer reader is a common problem and some dealers or mechanics charge up to $100. Fortunately your car reset itself. 

 

[stubuzz]

https://www.cx3forums.co.uk/viewtopic.php?t=1873

[VocalNeal]

3 hours ago, Neeranam said:

When I started it again, it had great acceleration. 

Not unlike what happens if one "restarts" a mobile phone. I now do this before bed.

[couchpotato]

You've been here long enough to know its ghosts--quick temple trip and all's well.????

[HauptmannUK]

Disconnecting the battery for more than about 10 minutes will cause the ECU to forget some of its learned values (fuel trims, idle air valve calibration, transmission shift point calibration). None of these would be particularly detrimental to performance and new values would be learned after 10-20 miles of driving.

From the symptoms you described I would think an intermittent problem with the MAF sensor is a possibility. These are a common problem on various Mazdas, resulting in poor acceleration and lack of power. Scan the car for stored fault codes.