Power loss

[Red Dexs]

I have a 2010 Yaris 1.3 manual and it is slowly losing power, when once I could zip up hills in 6th gear I'm now changing down to 4th gear. The car has only done 81500KMs I have had it from new, and it has a full service record. It is now starting to hunt whilst idling and sometimes cuts out on me when waiting at road junctions etc. Thinking the obvious I ran a full tank of petrol mixed with injector cleaner and this has achieved nothing, I am now running a second tank full to try again. I took it back to the agent and they said it was the fuel /air sensor and we tried a new one but it was exactly the same ( there are no dash warning lights showing by the way). The spark plugs are fairly new and have been checked and tested, the air filter is clean. Anyone experienced this before?

[Devon Aygo]

The 1.33 can suffer from carbon build up on the valves/valve seats causing poor valve sealing and a lack of cylinder compression, symptoms can include:

Poor startability / extended cranking

Poor / unstable idle

Engine stalling

Lack of power

Excessive oil consumption

Engine rattle

The official fix/modification was a big one consisting of modified: Rocker cover, Piston oil Jets, Piston Sub-Assy, W/ pin, Ring set, Piston and a strip, clean and rebuild of the Cylinder head in all about 20 + hours of work in a workshop.

[Mick F]

10 hours ago, Devon Aygo said:

The 1.33 can suffer from carbon build up on the valves/valve seats causing poor valve sealing and a lack of cylinder compression, symptoms  .............

I don't know if you all know, but I spent a career in the RN.  Retired in1996 after nearly 30years.

We owned a Talbot Horizon for some years in the 1980s and after coming home from sea, the car had only been used locally for short journeys for months on end.  I drove it after getting home and noticed how sluggish and poor the engine was.  I considered taking it to Talbot to sort it out even though it was out of warranty.  We had a journey to do up the A38, and we were short of time, so I went as fast as I could.

On the way back, the engine began to feel so much better.  The total journey was about 100miles and almost flat out both ways.  it was only a 1.3, so "flat out" was a little above 80mph.

From then on, the engine was fine.  All it needed was to be used for longer distances and given some work to do, and not just for ferrying children to school.  I got the impression that the engine had "coked up" and a good blast had cleared it all out.

Mick.

[Red Dexs]

Thank you Lee and Mick. Apart from the occasional trip to Heraklion airport ( I live on Crete) most of my runs are short so perhaps a carbon build up could be a contender. I'm waiting delivery on a compression tester.

[Bomber209]

Hi, 

 I agree with Mick F.  Take your car out for a good run. Once warmed up, race it in each gear, and watch in your rear view mirror, when you dip the clutch you should see sparks coming from the exhaust, as any carbon deposits get red hot and break away. Best done at night, for a spectacular showing.

[Madasafish]

20 miles at 5,000 rpm should clear it out...Or Yaris d4d failed mOT on emissions. Free retest 1 hour later after that showed emissions fell by 70% and it passed.. (and felt livelier too.Bit noisy though.) 

[monkeydave]

is the 1.33 a direct injection engine?

[Devon Aygo]

47 minutes ago, monkeydave said:

is the 1.33 a direct injection engine?

Yes it is

[monkeydave]

4 hours ago, Devon Aygo said:

Yes it is

thanks, so the carbon buildup you get behind the intake valves should go if you go on the motorway a lot or will it just build up as cleaner would never reach it ?

[Devon Aygo]

An "Italilian tune up" will help remove some but not all of the carbon build up & on the 1.33 unfortunately like many direct injection engines where no fuel passes the valves carbon will build up and once it has to a point where it is affecting compression the only guaranteed way to remove the buildup is to remove the cylinder head and re-lap the valves

[monkeydave]

1 hour ago, Devon Aygo said:

An "Italilian tune up" will help remove some but not all of the carbon build up & on the 1.33 unfortunately like many direct injection engines where no fuel passes the valves carbon will build up and once it has to a point where it is affecting compression the only guaranteed way to remove the buildup is to remove the cylinder head and re-lap the valves

thanks for the explanation, i take it the replacement 1.5 that is in the current yaris is a direct injection too ?

also how many miles on average will it last before the carbon will effect the engine in normal use ?

[Red Dexs]

What compression figures am I hoping to expect when I eventually do a test. Thank you.

[Bomber209]

Red Dexs Hi,  Min 156 psi, Max 213 psi, with no more than 14 psi difference between cylinders.

[FROSTYBALLS]

On 2/21/2019 at 8:37 PM, monkeydave said:

i take it the replacement 1.5 that is in the current yaris is a direct injection too ?

It is a development of the 1.33.

[Red Dexs]

2 hours ago, Bomber209 said:

Red Dexs Hi,  Min 156 psi, Max 213 psi, with no more than 14 psi difference between cylinders.

Thank you very much Phil.