Urban Cruiser Petrol cold start

[Tr4ct0rF4n]

Please can anyone tell me what you look for to improve our 2009 Urban Cruiser's cold start?  It is the 1.33 petrol engine (same as Yaris presumably) and it starts OK but doesn't appear to have any cold start enrichment or higher idle speed that I'd expect, therefore it is a bit lurchy and tricky to drive until it has fully warmed up, and even then it's not very smooth.  As it is being used by my son for learning to drive, I'd like to improve it.  At the weekend we changed the oil, filters and plugs (new NGK Iridiums fitted), and it doesn't seem much better.  The car has done 89,000miles and has been regularly serviced before we bought it late last year.  Any ideas or links to fault scanner that I can try and ascertain that all the sensors are giving the right output, will be greatly appreciated.  We have recently fitted a new Battery, which helped a lot, but I'm sure it can be better.  My Mother has a Verso-S with the same engine, and I remember it being similarly jerky when cold, until it had a service by a main dealer, but obviously I don't know what they did, and it drives a lot more smoothly now. 

[flash22]

Disconnect the Battery and let the ecu reset it should then relearn the throttle position what fuel do you run it on ? Regular unleaded (95 ron)?

[FROSTYBALLS]

What grade oil has been used?

[Tr4ct0rF4n]

On 1/4/2021 at 2:06 PM, FROSTYBALLS said:

What grade oil has been used?

5W30 Mobil as recommended

[Tr4ct0rF4n]

On 1/4/2021 at 1:53 PM, flash22 said:

Disconnect the battery and let the ecu reset it should then relearn the throttle position what fuel do you run it on ? Regular unleaded (95 ron)?

Yes regular unleaded, the Battery was disconnected when we changed the plugs, it didn't start easily first time after reconnecting it, but then settled down.

My issue is why there doesn't seem to be any cold start enrichment or increased idle speed when cold, which I'd expect.  I suspect maybe a temp sensor may be giving false readings, is there any way to check, or does anyone know what the output/resistance should be from a good sensor?

[FROSTYBALLS]

Think you will find Toyota's preferred oil is 0W-20, and the owners manual says that 5W-30 may be used, but should be replaced with 0W-20 at the next service. One of the reasons for 0W-20 is that it may provide easier cold starting.

[Tr4ct0rF4n]

2 hours ago, FROSTYBALLS said:

Think you will find Toyota's preferred oil is 0W-20, and the owners manual says that 5W-30 may be used, but should be replaced with 0W-20 at the next service. One of the reasons for 0W-20 is that it may provide easier cold starting.

Thanks, I can see that the lower viscosity would help when cold, but I don't think that it the problem. Most cars I've had have a cold start routine where the ECU sets a higher rpm until it's warm, and this just doesn't seem to have that.  In fact I drove my Mum's Verso-s to get it MOTed the other day, and it started as I would expect.  I think I'll have to get it checked out by a dealer, or find someone with the right diagnostic equipment.

[flash22]

You will need a scan tool with live data to see the temp readout,

does the idle not pick up if you turn on heavy loads eg. heater blower, rear heated screen and headlights

An iQ owner had a similar issue recently after going through troubleshooting it (flickering lights and idle would not increase)

Final Diagnosis - Bad Battery

 

Be sure to get the correct Battery as some jap cars (if its an import) have the positive and neg swapped around to say a uk/euro spec car

[Tr4ct0rF4n]

15 hours ago, flash22 said:

You will need a scan tool with live data to see the temp readout,

does the idle not pick up if you turn on heavy loads eg. heater blower, rear heated screen and headlights

An iQ owner had a similar issue recently after going through troubleshooting it (flickering lights and idle would not increase)

Final Diagnosis - Bad battery

 

Be sure to get the correct battery as some jap cars (if its an import) have the positive and neg swapped around to say a uk/euro spec car

Thanks, we did change the Battery soon after buying it in the summer, which improved it, and used the correct Halfords Battery that is compatible with stop/start which this car has.  I wanted a Yuasa Battery, but Halfords didn't have one and told me that their branded one are made by Yuasa anyway and have the same warranty, so, as the original was dead we went for that. I'll see if the idle picks up with load as you suggest, but we usually tend to warm it up for a while before it's happy to pull up our steep drive in this weather, because my son is still learning to drive, it's not fair on him to try and do an nice smooth hillstart straight on to the road!  Have you got any recommendations on a suitable scan tool? We've got a few Toyotas of a similar era in my family, so I'm sure it will come in handy.

[Mooly]

I have the 1.33L in a 2010 Auris and I'm pretty sure the revs don't go much over 1k when idling straight after a cold start. It is all very tightly controlled via the ECU which can maintain correct fuelling to enable the engine to idle at low speed when cold. I use 5W30 by choice fwiw and feel it runs that little bit smoother (almost indefinable but noticeable long term). Fuel economy must be worse but its a quarter of a half of a percentage point and not detectably lower than when 0/20 was used.

Pulling away from cold is fine and not really any different to hot tbh, but for that first 0.5 mile or so from cold at say 30 in 4th and there is a slight hesitancy, like an old car with not enough choke. My previous 1.8L TSport was just the same. Our old 1.4 Corolla is better in that regard and pulls like train. The subjective power delivery is much more immediate and feels stronger and smoother.

I think you will find the 1.33L is just the way it is... normal in other words. 

 

  

[Gerg]

On 1/4/2021 at 1:43 PM, Tr4ct0rF4n said:

but doesn't appear to have any cold start enrichment or higher idle speed

I think the raised idle speeds that happens on some cat.-equipped engines during a cold-start, can give a slightly misleading impression as to what's happening and why. 

I think the fast-idle is partly to do with heating the cat. up to working temperature (600 degrees) as soon as possible, to get the exhaust emissions down quickly.  On four cylinder cars with a lengthy exhaust manifold (usually piped as '4 - 2 - 1' ) the positive (and the negative that follow) exhaust pulses can be summed on pairs of cylinders to create an 'extractor' effect, using waste energy to scavenge the exhaust gases in the alternate cylinder - which can be good for economy and performance. This is a win-win situation, except:-

This means the catalyst is a distance away from the engine and harder to warm up quickly.  Two Mazdas I owned had this arrangement, and the cold-fast-idle was above 2200 rpm, probably for the that reason - to get heat into the cat.

Your 1.33 engine has a very compact manifold and catalyst arrangement (for a four cylinder engine), so a shorter and easier catalyst warm-up phase is the likely result, and if the designers have put in a lower fast-idle, then fuel will be saved etc.  And as an added bonus, slightly less wear on a cold start! 

And your catalyst is then much, much harder to steal.

There may well be other reasons for the slower cold-idle, but I can't think of any 'deliberate' ones at this moment, beyond added refinement.

The 'extractor' effect doesn't really work on three cylinder engines as their phasing is wrong, so these small 'manicats' are popular now on modern 3 cylinder engines,especially so since a longer exhaust manifold will cause some unwanted 'lag' on those engines with turbos as well.

That's as I understand it anyway.  Always happy to hear someone else's views!

[Mooly]

I took note of mine this morning and it idled at 1200 RPM for about 8 seconds and then fell back to 1000 RPM. Once warmed a little it idles at around 850 RPM. Temperature was around 4C (its garaged).