Yaris 2006 intermittant difficult start-up (wobble/low-rpm) and exhaust smell in the cabin

[mooder]

The problem arises intermittently and it manifests by the engine wobbling and the RPM jitter. The RPM is lower than what is normal on start-up. Pressing the acceleration pedal makes the problem worse, i.e., the engine stall.

This problem more often arise when it is cold outside. During summer I don't have any vivid memory of it happening. Conversely, when it was -20C outside the engine stalled bad and I thought I'd have to call a tow. However, after waiting a bit, I was able to start the engine and after wobbling a bit, the RPM went back up and the engine regime went normal (music to my hear). Note: no code showed up after wobble events which started a good 3 years ago!

I did have a code that kept showing up, I forgot the number, but it was associated with the O2 sensor (exhaust) which I attributed to the hole in exhaust system just in front of the catalyc converter (fixed last summer). I also have to put the air intake in the cabin as taking the air from outside cause a smell of exhaust inside of the cabin which I believe is due to the donut gasket between the header and the down pipe (see: http://www.yarisworld.com/forums/showthread.php?t=59145). This might also have contributed to the sensor error code showing up...

Recently (2 days ago), I got the P0304 code showing up which is misfire of the cylinder #4 after a wobble event. I did a compression test on cylinder #1 and #4 (at that time I didn't know which one was which) and it came out fine. I have to redo the test for all of the cylinder with all the spark plugs removed though but so far the pressure was >120 psi for both.

I've seen the mention that there could be a vacuum leak, a broken valve spring (which could be confirmed with compression test), fuel filter and fuel injector as potential source of the problem. Now, I wonder if the exhaust sensor reading could affect the air injection and cause the symptoms I'm experiencing? The car runs fine otherwise (218 000 kilometers)...

[flash22]

An 02 sensor, or vacuum leak could be the cause, intermittent fault are notorious to diagnose in person let alone on a forum

What engine and what country are you from ? When did last have an oil change ? how many miles between changes ?

 

 

Off the top of my head

 

Intermittent egr

VVTI solenoid

02 sensor heater circuit

Coil pack - common and a cheap fix

vacuum leak

A dodgy Battery or corroded terminals

 

 

[mooder]

11 minutes ago, flash22 said:

An 02 sensor, or vacuum leak could be the cause, intermittent fault are notorious to diagnose in person let alone on a forum

What engine and what country are you from ? When did last have an oil change ? how many miles between changes ?

 

Off the top of my head

 

Intermittent egr

VVTI solenoid

02 sensor heater circuit

Coil pack - common and a cheap fix

vacuum leak

A dodgy battery or corroded terminals

 

 

Yaris Hatchback 2006 1.4L Canada

I oil is changed 2 times per year. The last change was in October. I sadly am quite sloppy when it comes to oil change km but I do 15k-20k km per year so I don't think I've ever exceeded the threshold. I also change the filter once every year if not twice lately.

I guess I'll get the exhaust fixed and test any vacuum leak if the problem arises again. I'll test the coil pack and clean the Battery terminal as it's easy to do.

[flash22]

1.4 ? Petrols are usually 1.3/1.33 or 1.5

[stantheman1]

3 hours ago, flash22 said:

1.4 ? Petrols are usually 1.3/1.33 or 1.5

Not forgetting the 1.0 and 1.8 variants.

[flash22]

OP is in Canada, most of the North American cars are 1.5 but don't quote me on that lol

[stantheman1]

I would agree with that statement also, I'm not sure they even offer a diesel variant out there.

[mooder]

20 hours ago, flash22 said:

1.4 ? Petrols are usually 1.3/1.33 or 1.5

Wow I'm really sorry, yes 1.5L. Petrol. Sorry for the confusion all.