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sceh

Yaris Very Rough Idle

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I have a 2004 1 litre VVTI Yaris. I disconnected the Battery for about a day to recharge it and then finally pout a new Battery in. Immediately it idled much slower and now after a week it has trouble starting and runs as rough as a bears butt. I tried the re-learn procedure for the ECU but no difference. I suspect it could be that the idle control valve is pretty dirty and would like to eliminate this as part of the problem if only I could find it! I have the useless Haynes manual which does not say where it is.

So, can anyone tell me where it is? Also if there are any other clues why this is happening or other things to check? ECU? Spark plugs? Whay has this suddenly happened?

thanks for any help

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Is the engine check light illuminated? If so, the fault codes need to be read. Idle speed control valve in the Haynes manual is Section 4A.12.

Regards Geoff Peace.

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Idle speed control valve in the Haynes manual is Section 4A.12.

I could be wrong but I read the OP as being that the Haynes manual doesn't say where the valve is on the car ...

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No engine check light. The manual has a photo on 12.35 but no indication where this is - behind the air intake or what? I can't find it. I cleaned the plugs and adjusted them and clearly need new ones. After this though it runs rough for a few seconds and there is plenty of blue smoke. Any ideas? I doubt it is the injectors since it would need all of them to be shot in one go - one being blocked is unlikely to do this since it would run continuously but rough instead of just stopping immediately.

It is still a mystery why this has suddenly happened since it ran well until last week when I changed the Battery - though this could be a red herring.

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I have the Haynes manual . There is a picture of it on 4A9 fuel system - see diagram 12.8a.

Other problems could be:

Dirty airflow meter

Dirty throttle body.

Blocked air filter. Wrongly connected piping.

PCV valve stuck.

It is unlikely there is an electrical fault as you should then get an engine warning light.

If any of the above are faulty, the ECU will not relearn a correct setting.. Hence your problems.

Blue smoke suggests Oil burning so check PCV valve first - an easy remove and clean job.(the breather from the rocker cover on the timing chain side at the rear of the engine. If blocked the crankcase pressure will force Oil down the valves/past the piston rings.

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The PCV valve seems to be something that just plugs into the crankcase cover. For some odd reason my engine bears little resemblance to the Haynes manual- Non of the sensors are in the same places so it is a bit of a mystery. Since I also have the dreaded MMT problem I am going to give it one more day and then take it to the scrappy. Pity since it only has 45k and is mint

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Idle speed control valve in the Haynes manual is Section 4A.12.

I could be wrong but I read the OP as being that the Haynes manual doesn't say where the valve is on the car ...

Ah yes! sorry, not concentrating! where is it? If you remove the air cleaner housing and look at the passenger side of the engine you will see two hoses which pass through the bulkhead to the heater. Each of these has a T piece with a small bore hose which runs to the idle speed control valve. The bore of these hoses is quite small and it is not unknown for the flow of coolant to the idle speed control valve to be restricted or even blocked. If the flow of coolant to the idle speed control valve is blocked, or has an airlock it will create the conditions you describe. I would check the hoses are clear and flush out the chamber on the valve to which they are connected. Also the PCV valve as previously advised. Hope this is of more help!

Regards Geoff Peace.

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Idle speed control valve in the Haynes manual is Section 4A.12.

I could be wrong but I read the OP as being that the Haynes manual doesn't say where the valve is on the car ...

You could be wrong Mike Sh, but, in fact, you are quite correct. My fault for not reading the post thoroughly. Good spot, Thankyou.

Regards Geoff Peace.

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There are two throttle body types on the Mk1 1.0 4cyl vvt-i one where the IAC is available separately and one where it is not, see attached:

post-45863-0-21065700-1387829291_thumb.p

post-45863-0-30329600-1387829299_thumb.p

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Mine is the integrated type. I dismounted it . There are two hoses going into it which seem clear (should I blast air through it to be sure?). Apart from that there is an electrical connector but no visible moving parts apart from the butterfly valve which can't be moved. Is this normal or should I be able to move it from shut to open?

thanks

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I can move the butterfly valve actually. The inside of the unit is a little bit dirty but negligible. Clues?

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Nobody got any ideas??

thanks!

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O2 sensor pre catalytic converter. This caused mine to play up after 10-20mins driving. Once it got hot the car played up at lights , especially with air con on. 

replaced many things but ended up being the o2 sensor. 

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