Toyota Auris 2007 1.6 Engine randomly turning off

[brlmat]

Hello!

I am having an issue with my 2007 Auris with the 1ZR-FE engine.

Sometimes, when driving, the engine loses power for a couple of seconds and then works fine. If I press the clutch and try to rev the engine when in this state, it revs to max 3k-4k RPM. Also, sometimes when I put the car in neutral, so the engine is idling, it just shuts off, just like I would have turned ignition off. Nothing vibrates, idles normally, power seems ok.

When losing power while driving, I've had it happen both when coasting and under load. I couldn't find any pattern.

I went to a mechanic and he said that it's most likely the spark plugs and coil packs, so I replaced those and the issue wasn't fixed. Another mechanic said that it could be the RPM sensors so I've replaced those as well. The car ran fine for a while, but the issue came back.

Car details:
Toyota Auris 2007 E150
1ZR-FE engine with 93K km
~70K km in the city, 23K outside the city.
Always used high quality oil and serviced it regularly (no more, no less than every 15K km)
No accidents or other engine problems.

Does anyone have any idea what to try next?

 

[obi_waynne]

If I recall correctly these engines have a drive by wire system, so don't have an idle control valve.

It's annoying when you have to fix things with a trial and error guess approach.

Here are my guesses, based on experience with this kind of fault....

Does the engine have a good earth connection, and are all the leads securely mounted, this is my first check.

Is the fuel filter blocked or clogged?

Clean the throttle body, or replace if it's really bad then get a garage to use a scan tool to reset the idle in the ECM. After a couple of hundred miles driving it will settle down and should hopefully be ok if the fault was in the throttle body.

The timing chain tensioner can also cause this but tends to rattle a little so it's unlikely to be this.

 

[brlmat]

I believe you are correct, it is indeed drive by wire. The acceleration pedal is only connected to wires (as in, electrical, copper wires), and so is the throttle body.

Engine seems to have good earthing, however, my battery terminals are slipping on the studs a bit. I cannot pull them off, but they move side to side.

I'll have to check the fuel filter. That was my first guess, but didn't get around to checking it because I don't really know where its located. Worst case, I'll have to trace back from the injectors, but it's not that easy of a task, given that I don't have a garage, thus no good lightning.

I'll take the throttle body off this weekend and bring it inside to have a good look at it and clean it if need be. For resetting the idle, you don't need a scan tool. It's enough to leave the battery disconnected for a couple of hours. After that it will idle very low and a bit rough for 20-30 minutes and then will work normally.

As for the timing chain tensioner, the engine sounds very healthy. No rattle, no banging. If I recall correctly, my mechanic checked that recently.

Thank you very much! I'll update as soon as possible.

 

[brlmat]

I got around to taking the throttle body off. I have to tell you, it looks pretty bad and smell of unburnt gas. Front looks decent, but the backside is a mess. I'll give it a thorough cleaning. I also pulled out the MAF sensor, but it didn't look awfully dirty or anything. When I get some MAF cleaning spray, I'll give it a whiff. I'd post pictures, but I understand that I have to have 10 posts before I can do that.

 

[brlmat]

I can't, for the life of me, see how to edit my post. I hope it merges automatically

I cleaned the throttle body: the front (intake side) came out pretty clean, while the back side (engine side) remained like stained on the very edges of the paddle. Looks way better than before, that's for sure!

After relearning the idle got these measurements:
- idle with no consumers: 660RPM, MAF 1.76 g/s
- idle with all consumers (low beams, high beams, AC on high and cooling, bassy music - 200w subwoofer): 870RPM, MAF 4.65g/s
- while flooring it (not in gear) - i've seen a maximum of 86g/s reported by the MAF

I wasn't smart enough to take these measurements before cleaning the throttle body unfortunately.

I can see that the MAF is working well, which is what I expected given that it didn't look dirty. The idle is very consistent, doesn't jump around, really stays put

Now guess it's a waiting game to see if it stalls again...

 

[obi_waynne]

Sounds like that might have been the problem, and I'm sure you'll pass the 10 posts limit very soon. Your pics will be a good reference for any others with this similar issue.