Rav 4.3 Fast Idle

[stevedale5]

Hi

Can any one shed any light on my Rav 4.3 D4D idling at 1100 revs to 1500 revs even when it has warmed up and also noticed slight tapping noise from engine area.The engine seems to surge on tick over as well. Also mpg dropped by 4 to 6 mpg new engine fitted last august and have been using bp ultimate but just had 2 fills of Shell vpower, full service 3 months ago, any ideas!

Cheers Steve

[+Steve]

Maybe a sensor... any lights on the dash? Maybe Maf sensor?

[anchorman]

Wait till it warms up and just see if turning the heater off (with the "OFF" button on the panel) drops it to 900rpm. If it does - all OK.

[stevedale5]

Have turned off all electrics,but still idling at 1200 rpm this is intermittent though and will drop to 850 rpm sometimes, temperature of vehicle not effecting it.There are no warning lights on the dash and plugged in code reader no fault codes. Could it be the low outside temperatures causing the cold start to kick in.

Steve

[anchorman]

Is there anything else untoward like the temp not normal, heater playing up etc?

BTW I don't just mean the electrics to turn off I specifically mean the heater OFF button.

Does it go OK?

[igormus]

what about coolant temp sensor el lcontact ot itself ?

is A/C turnef off ?

[bigend]

Mine is doing the same steve, but sometimes not at all. Weird.

Keith

[stevedale5]

Don

The heater fan is off so is the A/C,air recirculation off,Heated rear screen off.Started it up tonight it idled at 1200 rpm let it warm up to 80 degrees engine temp still idling at 1200 rpm took it for 10 min drive and noticed if you cruise in neutral the revs drop to 850 rpm.Returned home and she was idling at 850 rpm.Went out again and the idle was normal she runs ok the only other thing is sometimes I can hear a slightly hissing or sucking noise near the air filter box but checked all the pipe work and air filter box but this is only occasionaly and very hard to hear and I think she may be using more fuel but that could be down to the cold weather and short trips.I think Keith as the same problem it is intermittent, I think I had the same problem when I bought it last January but it disappeared shortly after purchase but has come back.Was wondering if there was any Toyota TSB,s that any one could remember.

Steve

[anchorman]

With the engine idling, just spray some WD40 down the back of the engine and in particular where that hissing was. If it revs as a result you can home in to an inlet leak. Stay away from the hot exhaust and turbo while you do it.

[stevedale5]

Don

I will try that Don when the weather picks up

Steve

[bigend]

Just been for a 12 ml round trip to get some mail, idling perfect, turn heater motor off rev's drop straight to normal idle. Outside temp +1 now. I notice that there was a post about the fuel tank return cooler under the car being done away with in later models, there is'nt a temp sensor on that is there by any chance.

thanks keith

[stevedale5]

Don

[stevedale5]

Don

I didn't quiet grasp what you were telling me but have worked it out now.Took the Rav out to take the dogs for a walk returned to the car and put the heater onto the hot (red section) and when I pulled up the revs rose to 1200 rpm so I turned the temperature control round to cold (blue section)and the revs dropped to 900 rpm.So is there afault with heater temperature control valve.Sounds to me Keith is having the same problem and could it be a common fault emerging on the 4.3s in very cold weather.

Regards Steve

[Guest]

I believe that this is by design, when you ask for full heat, there is a electric heater element (600W) that kicks in when it is cold, the higher revs make sure there is enough power to supply this.

Most of us only feel the heat when you are starting from cold on a very cold day and need the front window to de-ice.

Gus

[benxt5]

Yeah. My 56 plate 136bhp and 62 plate 150bhp Ravs both did/do this. I thought it was just how this engine dealt with the cold!

[anchorman]

You,ve got it Steve. No faults as explained by Gus and you can see from Ben that both his did it too.

These modern vehicles have very high output alternators to cope with big Battery demands. The heater that Gus has described is a bit like a 3 bar electric fire (with up to 800w output in 3 stages). When the system cranks that thing up to asist in heating the interior it can put over 5 bhp load on the alternator which is quite capable of stalling the engine. The engine ECU gets a warning and it goes to "idle up" which both stops the otherwise rough idling but also ensures enough alternator output on top of the heater to cope with lights, wipers and whatever else. It will do it less as the weather gets warmer which will help us get better fuel consumption. Don't forget early Austin 7s were 7 hp and a RAV alternator on full chat is nudging that. You don't get 'out for nowt!!!

The pre 150 engined RAVs had 500w PTCs (positive temperature coefficient) heaters. They don't exactly churn out hot air but they do take the chill off. This increases heater efficiency because the first few degrees take the biggest requirement.

[bigend]

Thanks for that info Don.

Keith

[stevedale5]

I'II second that from Keith,Just been out in rav and backed the heat off slightly and the revs dropped back to normal its very similar to the focus we have with the heated screen and you can here it pull the alternator down to the point its rattley.So thanks again to everyone and especially Don for his contributions.

Regards Steve