It Hunts On Cold Starts!

[claireozjones]

Hi everyone,

I'm new to Toyota and new to forum. I've just spent 6 years of saving on a lovely 09 plate Yaris, 1.4 D, 31000 miles. Bought for the reliability and driveability due to a job where the commute is 80 miles a day. :)

Does anyone know about this model doing this 'hunting' on cold starts? It's intermittant, (only once last week), when it happens it lasts for a minute until warm, or if throttle is depressed. Doesnt seem to be causing a performance problem. Nothing displaying on computer. First garage thought thermastat, second thought diaphram in fuel injectors. Has full service history with Toyota, last in March 12.

Should I be worried?

Thanks,

Claire.

[Cyker]

Mine's started doing this too. Kinda pulses the engine and the revs keep bouncing between say 600-800 rpm and can kangaroo the car if I let it idle with 1st gear engaged. (2nd and up, the car's momentum and inertia smooths the pulses out)

Engine's completely fine after a few minutes, but it only happens first time I fire it up in the day. I thought it might be temp related but when I drive home in the evening, after the engine's presumably had time to cool down, there's no sign of the problem at all!

Car's up for service in a couple of months and I'm going to get them to change everything with the word filter in it as a first test, but if anyone has any suggestions of places to start that'd be welcome!

[Madasafish]

The only thing I can think of is that one or more injectors have a very slight leak. No impact on normal running but when left overnight and the engine is cold, fuel leaks out and stays in one cylinder. (or one injector is sticking when cold) . Does not happen in day as temperatures are warmer and the engine has warmed up enough to evaporate the diesel which leaks.

[Cyker]

Okay it's getting a bit worse :(

Now also happens in the evening before I drive home, but nowhere near as bad. Maybe the engine wasn't getting cold enough to trigger it before?

Did notice the airfilter is very dirty; Gonna change that when I get a chance and see if that helps...

[Madasafish]

If the airfilter has not been changed for ages, the MAF sensor may be dirty as well.

(but change the filter first).

MAF sensor cleaning is easy - requiring carb cleaner but requires great care as easy to break.. and a new one is £70 plus (eBay non original. OE is more)

[Cyker]

I might have a go, how hard could it be!?

*2 Days later: Bits of exploded Yaris D4D suddenly land in fishy's garden*

Something for the weekend anyway! :)

Although I think I'll use contact cleaner rather than carb cleaner as in the toyotaownersclub guide!

[Cyker]

New air filter, cleaned MAF, idle still pulsing between 600 and 800 rpm :(

I thought cleaning the MAF fixed it at first as, after it all dried out, I hooked everything back up and fired up the engine and it didn't seem to be doing it!

Took all my tools off the little 'shelf' under the windscreen, closed the bonnet then had breakfast. Later I fired it up again to go pick up the air filter and it started doing it again

Looks like I'll have to turn this over to a garage...

[Cyker]

Aha! Was looking under the bonnet with the engine running and immediately noticed the EGR* kicking the hell out of itself every time the engine idle hunted up and down.

So it looks like that is the most likely culprit!

I was considering having a go at cleaning it but there seems to be a paper gasket of some sort (I'm assuming that's what the black crispy thing was that's sandwiched between the two metal sections) which is not mentioned in the various guides on here - Will this need to be replaced if I open it up?

I'm thinking it may be safer to get a pro to do it as it looks like a bit of a PITA to get out...

*Just to confirm, the brass/gold thing attached to the front left intercooler pipe that looks a bit like a flying saucer sweet is the EGR, right?

[Madasafish]

The EGR is the rusty vertical cylinder to the right of the engine as you look at it from in front of the bonnet. Held on with 2 bolts.

The Gasket is metal .at least in mine. Reusable.

Easy to clean...Carb cleaner and a tooth brush.

[Cyker]

Oh... what's the flying saucer thing then? It's left of the dipstick, down and left from the intercooler and above the starter motor.

I really should take a picture of the damned thing but gotta goto work!

[Madasafish]

http://tinyurl.com/8m93w2p EGR valve..

"Oh... what's the flying saucer thing then? It's left of the dipstick, down and left from the intercooler and above the starter motor."

Part of the throttle assembly..

[Cyker]

Well, checked both the EGR and throttle body. Both seem okay; Bit sooty but nothing blocked as far as I can see :(

So... time to get the pro's in methinks.

However, I was going to book it in with the Toyota Jemca near me but they want £132 just for an hours' worth of diagnostics and I have to leave my car with them for the whole day! Does that sound right? Everyone I've spoken to at work reckon diagnostics should have been £35-50!

[Cyker]

Durrrr... feeling stupid now

Turned out the problem was exactly what was described in this thread:

http://www.toyotaownersclub.com/forums/index.php?showtopic=85740

After balking at the Jemca Mr T quote just to look at it, I had another look at the airways - EGR was indeed fine, but I realised that there was a hole in the throttle body that was indeed blocked!

I didn't realise when I first looked at it because it was so sooted up it looked like part of the pipe wall.

Pushed out the worst with a pipe cleaner then cleared out the rest with some carb cleaner. Bingo! Car idling like a dream and launch from a standstill back to its usual punchy self :D

Only downpoint is I dropped 3 of the bolts for the throttle body (That's one fiddly SOB...) and wasted over an hour trying to get them back off the under tray (I was bascially stuffed until me neighbour, who'd been watching me the whole time, offered to lend his telescopic magnet-on-a-stick! )