Exhaust woes

[bigduke12]

Hi, I have a 1.3 Yaris T3 2005 (South Africa).

I recently noticed what can best be described as an exhaust drone at 3800 to 4100 RPM.

Toyota dealership agreed with this but did not offer a solution.

The exhaust is stock standard except for a power flow tail pipe (which all Exhaust fitment guys told me would not cause the drone).

On visiting two well know fitment centres the opinions were:

Exhaust fitment centre 1-These guys reckoned it is either the front muffler (just behind the catilytic convertor), or the convertor itself. They were also concerned aboud the pressure of the exhaust at idle which may have indicated a cylinder head problem. Toyota states that due to VVT, the exhaust pressure is low at idle.

Exhaust fitment centre 2-These guys seemed a bit more knowledgable and reckon the exhaust sounds "hollow" and that the problem is with the front muffler.

The car is still under warranty and will be sent back to Toyota for full check up.

Anyone experienced a similar problem? The car has only done 20 000km so the mufflers should be good.

Thanks

[toyomoho]

Exhaust drone is usually caused by exhaust system resonance. Suspect a muffler over a cylinder problem. Was this a new car and the drone always present?

Keep in mind the dealer’s position may be to avoid warranty work as they make less money on it. Since the car otherwise runs OK, the issue may not be large enough to motivate them to take action.

[bigduke12]

Hi,

thanks for reply.

The car was purchased a few months old with 7000 km on the clock. The drone was always there I think, but never got around to having it checked until now.

I also suspect a muffler as the performance seems fine and the car pulls well, and after the exhaust guys knocked the exhaust around a bit it seemed to have lessened.

Not really concerned if the dealer does not wanna replace the muffler as it only costs about US $ 40 to have done, but I wanna rule out any possibility of a problem with the catilytic converter or engine. If they rule that out then at least I know a new muffler should sort out.

[bigduke12]

The car was at the dealer last week and they got the Toyota factory rep in (there was another Yaris there with the same problem, just at different RPM).

There diagnosis was the intake manifold, which they have ordered from the factory to replace.

As I understand this seems to be a common problem? Dont know if anyone else has experienced it?

Once they replace the manifold I will advise if this has sorted the problem out or not.

Cheers

[bigduke12]

Ok, after the wrong part arriving and then a massive delay in getting the right part in (had to scream and shout), the intake manifold was replaced by the dealer.

Guess what? Absolutely no difference.

I guess now I will have to get them to replace the mufflers which the exhaust guys say the problem is.

[bigduke12]

Ok, so after the car going to the dealership for the noise 4 times, and after a new intake manifold was replaced after a two month wait, the noise was still there.

By this stage Toyota customer care over here in SA were not even returning my calls.

I took the car back to the exhaust guys who were adamant it was the exhaust.

I had a 30 000 km service at the dealership last week and specifically told them to check the exhaust.

Guess what!! Well it turned out that when the powerflow tip was put on they put another additional exhaust mounting on (which I was not aware of).

This was loose and vibrating against the exhaust causing the drone. Obviously the manifold was fine.

When I questioned such an apparent mistake by the specialists the answer was, wait for it....

"Yaris is a relatively new model is SA (2005), so the mechanics are not that experienced in this model".

This bears the question why take the car to a dealer for service and repairs as they seem to add no more value then a reputable non franchised mechanic. This is rhetorical question as we all know the answer.