Idle issue on 2007 Yaris 1.3

[VinceSA]

Hi Guys,

Greetings from sunny South Africa.

My wife and I both have 2007 Yaris 1.3 manuals. My wife's Yaris (Has 117k on the clock) and has picked up an issue which Toyota are not able to sort out. When the car is hot the revs drop to below 400 rpm, the engine starts to shake and the car eventually cuts out. Sometimes the revs are so low that the rev counter does not register at all.

Symptoms:

- In start/stop traffic the car's revs drop (less than 400rpm), engine start to shake and eventually car cuts out
- Twice in the past week, the car idles abnormally high +- 1750rpm (normal operating temperature). This lasts for about 5 min and then goes back to normal.
- Intermittently the car also seems to have an abnormal flat spot below 2000 rpm in second gear/low RPM
- My wife has also complained about the car jerking in heavy start/stop traffic i.e. 1st, 2nd low revs then stop
- Whilst driving the car myself the past few days at an intersection, the car started idling low and shaking, I then tried to get the revs up, pushed the throttle with no response. After a few seconds, the car "woke-up" and I managed to give it a rev before making it across the intersection (thankfully before being T boned by oncoming cars)


A couple of clues:

- Only happens when the car is hot (+- 20 min of start stop driving)
- Intermittened problem - does not happen all the time
- Seems to happen more easily when its hot outside
- Aircon/lights etc make no difference - does it irrespective

So far Toyota have swopped/done the following:

- Cleaned the throttle body and MAF sensor
- Replaced the throttle body
- Run diagnostics - no error codes
- Disconnected the alarm and anti-hijack
- Disconnected battery to reset ECU/fueling/throttle position

I have done the following:

- Swopped the battery with my Yaris
- Swopped the MAF sensor with my Yaris

I am afraid the problem still persists.

Otherwise the car runs perfectly. She is regularly serviced, returns good fuel economy etc. In every other way, its the same as my Yaris.

Do you guys perhaps have any suggestions?