Weird idle problem today

[Mr.Fixit-Norm]

Well, after 5 years of ownership and never having let us down our 51 plate beastie decided to throw me a curve ball today.

She was fine yesterday, usual short trip to take the missus to work around lunchtime then pick her up around 7pm. Today about 11am I went to pick my mum up to come round ours for lunch, she started fine and I drove the 3 miles through town no problems at all. Went inside and got my mum ( about 5 mins ), went to start the car up and as soon as I took my foot off the accelerator she died, I restarted her and every time instead of idling she just died?? I managed to get back home, but we stalled at every junction and traffic light ! 

As dinner was ready I left her on the drive ( the car not me mum ! ) and after lunch decided to see if I could find out what was wrong, I had a quick look under the bonnet to see if there was anything obvious like a loose sensor plug, but not having found anything I decided to start her up and see what happens.

Lo and behold she started and ran fine ! , I let her get up to full temp whilst idling then took her out for a 5 mile run, plenty of stops and starts including a 10 min stop at a shop, the result, no running issues at all. I then took my mum home about 3 hrs later and still no issues.

The only thing I can think of was when I took the wife to work on Saturday I put £20 worth of petrol in ( yes, it def. was petrol ! ), and I wondered if it was contaminated with something or if some dirt somehow got through, the only thing is why does it appeared to have cleared without any intervention from me?

Anyone got any ideas ??

Norm

[bonjo]

that is a strong possibility. cheap fuel (like supermarket) can cause erratic idle and they have been know to have been contaminated in the past.

I have also been told that when a station is being filled up by the tanker, sediments are disturbed and can start to float in the tank; potentially ending up in your car.

Frankly of all the cars I have had, RAV 4 (petrol) has the worse idle stabilization!

you may want to put a can of fuel system cleaner in case it helps
 

[Mr.Fixit-Norm]

Hi Bonjo,

I'm thinking it could have been a temporary blockage as you suggest, as she's been fine all week with no hint of a repeat of Sunday's issue.

To be fair I've owned her for 5 years now and probably 95% of the petrol I've put in has been from our local Asda where my wife works. I don't honestly think that in the average family motor that supermarket petrol makes any real difference either to performance or reliability. After all they buy their petrol on the spot market and it still has to meet laid down DIN specifications, and given how many thousands of motorists fill up from supermarket filling stations every day, if the fuel was that bad there would be queues of cars packing up all over the place and it would be all over the news !

From what I can glean from reading about supermarket fuel on loads of different websites, the base fuel meets the laid down DIN specifications but there are different additives which are put in to 'improve' performance / engine cleaning / starting etc

A lot of people put a higher octane rated fuel in their vehicles than the manufacturers recommend, this may well improve it but for me Toyota say put 95 Ron in the Rav and that's all I ever do.

Although I've never owned a diesel car, I think putting quality fuel in this type of engine may well be more important than in a petrol one, especially wintertime when additives are vital to keep the fuel flowing properly, something us petrolheads don't have to worry about 

Fingers crossed the old girl will be ok now.

 

Norm

 

 

[redlew]

I cry when I can't use supermarket diesel and couldn't agree more with  "given how many thousands of motorists fill up from supermarket filling stations every day, if the fuel was that bad there would be queues of cars packing up all over the place and it would be all over the news ! " 

[Mr.Fixit-Norm]

Hi redlew,

 I was half expecting a backlash of people saying I was talking rubbish ! I'm glad you agree with my view.

Something I forgot to put in my last post was that I owned a 1988 Porsche 944s for 3 years from 2011 to 2014 and ran that almost exclusively on Asda petrol, it never gave me any problems which were in any way related to fuel type, and always passed the emission tests with flying colours. It had a lovely power delivery right through the rev range, and was a joy to drive :)  

I honestly don't think it would have performed the way it did if the supermarket petrol was as bad as some people reckon it is.

Norm

[pmb]

This is the same thing that happens when the Battery is disconnected. Takes a few miles for the ecu to stop doing it.

[bonjo]

From what I know I agree with your comments.

All fuel start off by meeting the required standard 95, 98... What the big companies claim is they put additives for improved performance and longevity which I think adds to the cost compared with supermarket supplies.

Similar reasoning from engine oil differences to baked beans!

To what extent this helps is debatable. I certainly do not expect a regular fuel to harm the engine.

My engine fuel and ignition are mapped for 95 grade fuel so putting higher octane does not make any change to the power. If I do use this it would be for the additives they put in it compare to the regular petrol and reduced or no ethanol.

One other possibility for your short lived issue is the wrong seasonal grade of fuel was delivered (as in summer or winter)
 

[cobh18]

Japanese engines are quite often mapped for higher octane fuel being as it is commonplace over there. Whether they are remapped for Europe I have no idea. I suspect the advice to use 95 here (or abroad especially Eastern Europe perhaps) is simply that a lower octane would cause knock sensors to act,  giving retarded ignition and loss of output. This isn't to say that the engine would not benefit from higher octane. I recall a a magazine article (EVO) where a number of vehicles were driven for reasonable distances using premium and non-premium fuel. Endoscope examination before and after showed clean-up had occurred. Dyno tests showed mid range gains in most. Except a BMW M6 I think, where there was no change. 

[Mr.Fixit-Norm]

4 hours ago, bonjo said:

From what I know I agree with your comments.

All fuel start off by meeting the required standard 95, 98... What the big companies claim is they put additives for improved performance and longevity which I think adds to the cost compared with supermarket supplies.

Similar reasoning from engine oil differences to baked beans!

To what extent this helps is debatable. I certainly do not expect a regular fuel to harm the engine.

My engine fuel and ignition are mapped for 95 grade fuel so putting higher octane does not make any change to the power. If I do use this it would be for the additives they put in it compare to the regular petrol and reduced or no ethanol.

One other possibility for your short lived issue is the wrong seasonal grade of fuel was delivered (as in summer or winter)
 

Mines the 2litre VVTi petrol engine so wouldn't have the seasonal fuel issue like a diesel, ( unless there is a difference for petrol as well? ) and as you say they're mapped for 95 octane fuel so no real reason to use anything else.

i don't think it was the fuel itself as I ended up with just over half a tank in total and the problem only lasted for the equivalent of around 3 miles, the more I think about it the more I think it must have been a bit of muck that got stirred up when I filled up and it then cleared itself. The main thing is I've now driven it for over a week with no repeat of the problem :) 

Norm

 

 

[firemac]

On 4/22/2016 at 10:02 PM, Mr.Fixit-Norm said:

Hi redlew,

 I was half expecting a backlash of people saying I was talking rubbish ! I'm glad you agree with my view.

Something I forgot to put in my last post was that I owned a 1988 Porsche 944s for 3 years from 2011 to 2014 and ran that almost exclusively on Asda petrol, it never gave me any problems which were in any way related to fuel type, and always passed the emission tests with flying colours. It had a lovely power delivery right through the rev range, and was a joy to drive :)  

I honestly don't think it would have performed the way it did if the supermarket petrol was as bad as some people reckon it is.

Norm

With respect, an '88 Porsche is, IMHO, going to be a lot more robust and tolerant of fuel quality than modern engines which have much more critical operating parameters for various emissions and therefore are encumbered with lots of relatively sensitive "clean-up" technology. The fact is that, if it weren't for the ECU and it's network of sensors, modern engines would probably not even run or, at best, run badly. Consequently  the higher the quality of fuel used, the less clean-up needed and therefore the less liklihood of clogged EGRs, filters, etc.

I am no chemical expert but as a result of my own experiences since 2002, I only use quality fuel and would certainly never use supermarket pee on its own. We owned an '02 RAV from new for 11 years and for the first 8 years of its time with us, it was run almost exclusively on supermarket petrol, mainly because it was cheap. In that time it needed a number of EMS/O2 sensors and eventually the cat failed completely and had to be replaced (£600+!!!). We have subsequently owned two other petrol RAV 4.2s which have only been run on quality branded fuel (Shell, Esso, etc) sometimes the high octane stuff but usually just their standard brews. Neither of those cars had any sensor nor CAT issues - same sorts of journies & mileages were involed.

I would never put supermarket fuel in our diesel vehicles due to the greater sensitivity of those engines to fuel quality and operating regime. Admittedly the high octane stuff like Shell V-Power and the like are stupidly marked up -vs- standard fuels so now I use standard diesel plus Millers additive, which works just fine at a fraction of the additional cost of V-Power and the like.

At the end of the day you pays your money and you takes your choice. However I reckon cheap fuel is a false economy - certainly £600 pays for an awful lot of the extra cost of branded fuel over supermarket pee!