Really Rough Idle On 1.4 Diesel Yaris

[jem-123]

Hi there,

I've just purchased a 2004 / 54 reg Toyota Yaris 1.4 Diesel. When i started it up for the test drive it was very low on fuel, and sounded very rough - like it was struggling. I brought the car on the proviso thay sorted this problem.

I picked the car up on Monday, filled up with Diesel (v. impressed - only £40!) and went on my merry way, not really noticing the problem. The salesman told me the problem was sorted and that they'd changed the Battery only 2 weeks before so that was why it was running like it did on the test drive.

Hmmm - Tuesday morning i start it up, and the rev counter was all over the place, the idle was rough as! I took it straight back, and they had a look, they said they had cleaned the valves, solenoids and replaced the air filter and it was fine to collect. I collected the car and on start up on the forecourt the same problem occurred, this time the blue temp light came on too. Salesman told me to drive it for a bit to see if that would rectify the problem.

Took it down the motorway (it seems to fine fine when its moving, just rough when you stop) i wasn't happy so Wednesday morning camped outside the gate of the garage to take it back again!

They have had it ever since, can't find a problem with it, no fault codes etc, and have told me they have taken it to Toyota who also can't find a problem?

Has anyone else had this, or has anyone gat any advise on what i should do -- the garage has told me to pick it up later, but i'm still not convinced that this rough idle isn't going to cause more problems that will end up costing me a fortune!

I think i have a 28day colling off period so i think i could possibly back out of the sale too and get my old car back if i don't get any joy - anyone know if this is right?

Thanks very much for any info!

Jem

[stantheman1]

Welcome to TOC Jem,

I'm not too familiar with the diesel engine, but the fault you mention sounds very much like the problem petrol engines have. Poor or rough idleing is normally caused by a dirty MAF sensor which is usually rectified by a quick clean. The blue temperature light is just an indication that the coolant is cold, this is normal on start up ( it should go out when then the engine starts to warm up) The Battery being replaced would not have the effect mentioned.

Like I said i'm not over familiar with dielels and not sure if they have the mass airflow sensor.

[jem-123]

Welcome to TOC Jem,

I'm not too familiar with the diesel engine, but the fault you mention sounds very much like the problem petrol engines have. Poor or rough idleing is normally caused by a dirty MAF sensor which is usually rectified by a quick clean. The blue temperature light is just an indication that the coolant is cold, this is normal on start up ( it should go out when then the engine starts to warm up) The battery being replaced would not have the effect mentioned.

Like I said i'm not over familiar with dielels and not sure if they have the mass airflow sensor.

Thanks very much stantheman1!

I know, as soon as i got home and thought about the Battery thing i thought they were having a bit of a laugh, and i'm the same - i've done a little bit with petrol engines but diesel is all new to me!

Well they have given it a clean up, and i've just picked it up and the idle seems to be constant now - hopefully problem sorted!

The blue temp light was on for a few minutes so took it gently, but by the time we got to the motorway it had gone out - and she went really well!

I'm over the moon :)

Thanks again!

Jem

[alfiejts]

If they had replaced the Battery, the engine management system would have lost all its memory and would have to "re-learn" itself.

It would have gone into "default" settings (that might have meant the mixture wasn't as accurate as it could be) which would explain the rough idle. It would take a few miles and journeys for the software to bed down.

That might be the issue and would explain a link to changing the Battery.

[Cyker]

TBH, it depends on what 'rough' means.

My one is pretty clattery at idle (You can deffo tell it's a diesel!! ), esp. when cold, but once it warms up and/or the revs are a bit higher it settles down and is quite smooth.

If you want it really smooth and don't mind the extra cost (It's like, £2 on a full tank anyway) then try some V-Power diesel - I just finished a full tank of the stuff and it ran noticeably smoother even at idle.

I'm back on normal diesel now because the V-Power diesel felt a lot less torquey at the low rev end, which is where I spend most of my time and I didn't want to change my driving style. (To be fair it does gain it back in the 2500+ rev range 'tho; The V-Power lets you rev the nuts off the engine while staying smooth, whereas past 3000 on normal diesel the engine starts to get quite rattly again )

It's a bit odd actually as I've noticed most other <2.0 common rail diesel engines are a lot smoother than the D4D at idle, esp. Citroens and Fords.

[stantheman1]

If they had replaced the battery, the engine management system would have lost all its memory and would have to "re-learn" itself.

It would have gone into "default" settings (that might have meant the mixture wasn't as accurate as it could be) which would explain the rough idle. It would take a few miles and journeys for the software to bed down.

That might be the issue and would explain a link to changing the battery.

You may have a point there alfiejts, I'd fogotten about the time when the MIL light came on our 1st yaris and that i'd reset it by diconnecting the Battery for a few hours, after reconnecting the power the car felt awful to drive,then i read somewhere that the ecu resets all its settings and reverts to 'limp home' mode and has to relearn its self which takes approx 21 stop/starts. I then just sat in the car starting and stopping the engine 21 times and hey presto! It ran perfectly again.(The MIL light came back on after a couple of months and proved to be a dirty MAF sensor) It wouldn't happen though if it had been reset the correct way i.e by a trouble code reader as it must bypass the relearn part.

[jem-123]

Thanks everyone- i feel a bit foolish now taking the car back twice, but i was so paranoid i'd brought another doomed car from them. As for changing the Battery, i never knew that - i half thought the salesman was blagging me to get the sale, me being a girlie n all. Once bitten twice shy as they say!

It would also explain why toyota couldn't find anything wrong with it too- the garage i brought it from had been looking at it for 3 days prior, so had been starting it and stopping it a lot!

Oh well at least it got a new air filter and a good old engine clean for free, and they sorted out the tracking too! I'm so glad i was really polite with them, otherwise i'd feel awful!

I might give that v diesel a go, if the current tank ever drops- I've done 105 miles and i haven't even dropped a bar yet. My last car did about 16 miles before the petrol started to dive, so i'm well impressed so far!

How many miles do you generally get out of a tank?

Anyways i'm probably boring you all now, so thanks ever so much for all the help and advice - i'm sure i'll have another random question soon!

Jem x

[jem-123]

p.s the idle was awful - not just your average noisy diesel, and the rev counter was going up and down like a yoyo!

[jem-123]

I've been all the way to Brighton and back today, and it was superb - tickover was fine, and it only cost a tenner there and back!

Bargain!

[jem-123]

[Shappers]

Glad you're pleased with your purchase :)

[Madasafish]

"How many miles do you generally get out of a tank? "

From full to the brim to 2 bars between 420 and 480 miles depending upon short journeys or long.. 57 -64 mpg...

[jem-123]

"How many miles do you generally get out of a tank? "

From full to the brim to 2 bars between 420 and 480 miles depending upon short journeys or long.. 57 -64 mpg...

:) Thanks Madasafish - That's great, with a new car you never know how far to push it (and how quickly the fuel drops on the second half of the tank) and as it took such a long time for the fuel guage to drop a little i was paranoid it was wrong lol!

Happy Happy Diesel Motoring!! :D

[Cyker]

My V-Power tank was about 520 miles for about 38L.

Currently on my Sainsburys diesel, I've just hit the 3rd bar (So say, 15L used-ish?) and have done about 220 miles I think.

One nice thing about this car (And most diesels!) is that it'll roll for ages in gear unlike a petrol car due to the lessor engine braking, so you can save gobs of fuel going down slight inclines, coasting up to lights etc..

I was on the M25 during the weekend and I swear I had my foot off the accelerator for about 3 miles or so going down a slight hill during one section, gradually going back from 75 to 60 after overtaking a tanker!