Possible cause of flat spots when accelerating

[Lettuce]

My 2009 1.6-petrol manual Toyota Auris has some flat spots when accelerating in all gears (but mostly 2nd and 3rd) between 2000 and 3000 rpm. The most obvious one is at about 2900rpm in every gear, which also happens to be 70-72mph in 6th. There's a couple milder ones around the 2300rpm point. Also I can hear a faint ticking when stationary, neutral and idling.

It's done 52000 miles. Any thoughts on what it could be? At its last service 4000 miles ago I suggested new spark plus to the garage but they said no you won't need those yet, they're iridium and last into 70000 miles.

Just looking for suggestions on what it could be please, as it's getting worse.

Thanks in advance.

[Konrad C]

Hi Brady. So you have a 1.6 Valvematic engine.

The ticking sound is the vacuum pump. These engines do not create enough vacuum, so the pump is needed for servo. Just like diesel cars. 

I would change the spark plugs anyway.  That's what I did a year ago on my then '09 Avensis. I ordered mine from this site on eBay:- http://www.ebay.co.uk/itm/Genuine-Toyota-Prius-Spark-Plugs-Set-of-4x-90919-01253-SC20HR11-Denso-IRIDIUM-/251364419952?hash=item3a867ca970:g:QvgAAOxyg7xSaOMa

The Spark plugs are Denso SC20HR11.

These plugs need a smaller 14mm socket to and a long reach extension, in case you are not aware. I bought mine from Machine Mart, but you can source from anywhere.

The plugs look like they were originals and the car had done 53,000+ miles (Nov' 2015). 

Some of the front covering and one of the wipers had to be removed on the Avensis to make access easier. It may be different for the Auris.

I can assume the oil and filter has been changed, and the air filter. The oil should be 0w=20, but most garages (including Toyota) may use 5w-30.

If after all this the engine still has a flat spot, it could be the MAF sensor located near the air filter, or the throttle position sensor connected the accelerator pedal.

My car can feel flat below 2000 rpm, but from that point on in the lower gears, it pulls fine. Then real power is high up the revs from 3000 rpm on. 

I have noticed that some garages don't always change the air filter, but since the flat spot is getting worse, then maybe get the MAF sensor cleaned with a suitable cleaner. It is bottom right of the last photo with two silver screw points, and a cable running from it. It is on the air filter housing. Make sure it is connected properly.

Your car revs a few hundred RPM more than mine (70 mph - 2500 rpm)  at the same speeds you quoted, and not much higher than my older 5 speed Avensis which showed 3000 rpm.

Hope you get to the source of the issue.