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Mr.Spoons

Previa - Loss Of Power And Engine Warning Light

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Please can somebody help.

I have a new shape Previa 2000 X reg, 2.4 petrol, automatic, 98,000 miles.

The engine warning light has come on in the past and I have followed the advice on this forum to clear it with no other apparent problems.

However, now the car is hesitant when pulling away and seems to be struggling for power. It stays in 1st gear longer than before and seems to be struggling. I suspect an engine management type problem. Fuel consumption appears to have gone up.

I have read all the posts on the forum (I think) but do not know what to do now.

Ray99 - if you are out there (or anyone else) I cannot seem to locate the MAP sensor to check the vacuum pipe isn't blocked. Is the MAP sensor a balck plastic box the size of a large coffe mug on the near side under the bonnet?

I don't really want to go to a dealer for an unneccessary expensive repair if at all possible.

Please can someone suggest something to try.

Many thanks.

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Your loss of power could be anything from a vacuum leak, to your timing has slipped, to a duff spark plug, to a bent valve, to a cam belt that has jumped a tooth. Without having a good look I doubt anyone could do more than hazard a guess.

What I can tell you is that the reason you can't find the MAP sensor is because your car doesn't have one. Modern fuel injected cars either have a MAP (Manifold Absolute Pressure) system or a MAF (Mass Air Flow) system and yours has the latter. This is located at the air intake box where the air filter goes and is identified by the wiring loom that plugs into it.

I could let you have the relevant manual diagrams/pages but I fear that without the relevant level of experience you may end up doing more damage than good.

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Thanks for the reply 'propnut'.

I asked abut the MAP "sensor" as someone else had posted that a vacuum pipe from the inlet manifold to it can get blocked with Oil and lead to a loss of power/engine hesitation.

I think that the loss of power is related to the engine warning light as the problem (loss of power) only occurs after I've cleared the light by disconnecting the Battery/removing the fuse. Then after a few journeys the loss of power goes away but the light comes back on. I'm afraid I don't have too much in my local Toyota garage (my car had a current drain leading to a flat Battery if not driven for 4/5 days) - which they thought would be fixed by fitting a bigger Battery!

I would really appreciate it if you could let me have a copy of the relevant manual pages. You are right I don't have much experience of this type of problem. But I do have a logical approach and a pretty good understanding of mechanical and electical principles.

Thanks,

Mr.Spoons

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Ok, drop me a PM with your personal email and I will send you the info.

P.S. You should never have Oil in an inlet manifold. If you do there is another issue at foot.

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Got exactly the same problem...have just changed the cat...the old one was knackered having cut to pieces to inspect....but car still exhibiting exactly same symptoms as yours. I have had it on a Snap On diagnostic tool...it has identified a Lambda sensor error message...related to the heat up coil only but does not tell which sensor has the issue. Going to ask Toyota on Monday if their diags have ability to identify which sensor has the issue. I am concerned that the lack of performance is not down to the Lambdas and having changed them will cost a chunk of money but still will have the problem. Have you made anymore progress?

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It is possible to test a lambda sensor. The are effectively two types Zirconia and Titania the difference is one works by generating a low voltage when heat is applied to it and the other changes in resistance when heat is applied.

Typically if yours has three or more wires then it is the voltage type if one or two then the resistance type. You can take sensor out place it in a vise (carefully as they are sensitive) and connect a DVM to the output wires. If it is the volatge type two of the wires will be responsible for the preheat circuit and the other one or two will be the output.

Set the DVM to measure DC and using a butane or similar blow torch (the type you buy from B&Q) and heat the sensor portion (that is the part that goes into the exhaust pipe). After 1-5 seconds you should start to register a voltage between 0.5 - 1.0 voltsM as soon as you move the heat away it should drop instantly. if it does this the chances are it is ok.

If of the resistance type set the DVM to measure ohms and you should see a rapid variation in resistance change.

If none of this makes sense then you should not attempt it but rather should take it to someone who knows what they are doing.

Two last things.

1 . If you choose to do this it is at your own risk.

2. You can buy after market sensors which do the same job and are a damn sight cheaper than Toyota

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Car is booked in at local Toyota so will let you know. I, too, am concernd about possible expensive repairs that don't fix the issue.

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Car in the garage now. They say that there is a "hard fault" and that the light comes on again immediately after it's been reset. They said that it was code P 1135 and that meant the Air Flow Sensor. I have agreed to let them change this which will cost me nearly £300. I'm not confident but the car was becoming undriveable and have 4 young kids so had to do something. Will let you know what happens next.

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That code is actually P1135/21 and is the Air/Fuel Heater circuit malfunction bank1 sensor 1

In other words it is telling you that the Lambda sensor has gone. The sensors on these cars are a 4 wire system which I outlined above.

In that documentation I sent you I provided a parts location. If you look at it you will see where that is. I also provided you the info on how to check the Air Flow sensor as you stated that you had a "pretty good understanding of mechanical and electical principles". I takeit however that you did not run through the tests.

I hope it comes right for you.

Best of luck

P.S. Bentaxle it sounds like your SnapOn diag tool read the code right.

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Thanks again for your help propnut - after our exchanges regarding the dark brown coloured auto transmission fluid I was worried that the auto gearbox had had it "a very very bad sign". I didn't want it to fail completely with the wife and 4 kids out in it so decided to put it into the Toyota garage.

As it turns out the fluid and gearbox are fine and the problem was all down to the sensor. I'm sure that if I'd had the time that following your advice would have worked.

Best regards.

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Excellent, glad it got fixed. Can you please confirm for the other guy who asked whether or not is was the Lamda sensor or the Air Flow sensor. The Lambda sensor is the one on the exhaust header pipe and is a long cylindrical thing with 3 or 4 wires coming out of it.

Black Oil is never a good thing in an auto box. I would still have that changed if I were you.

All the best.

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As I understand it it was the Air Flow sensor, "Fault Code P1135 A/F Sensor Bank 1 Sensor 1" is what is printed on the receipt.

Thanks for your help.

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Great many thanks for confirming this, they have misinterpreted the meaning of the F. The Lambda sensor role is to detect the presence of free oxygen in the exhaust gases which will exist in the correct proportion to volume based on the correct AIR/FUEL ratio. If it detects that that this ratio is too lean it tells the ECU which richens the mixture, if it detects that the mixture is too rich then accordingly the ECU leans out the mixture. Nominally a lamda of 0.9 - 1.0 should exist. For some reason Toyota has chosen to refer to the Lambda sensor as an A/F sensor which can be confusing if one doesn't realise that they are one in the same.

This is just for the reference of others reading this, the important thing for you is that your problem has been rectified.

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That code is actually P1135/21 and is the Air/Fuel Heater circuit malfunction bank1 sensor 1

Propnut.

You speak more sense than anyone I've asked thus far so forgive me for jumping in with a question. I drive an Estima 2.4 Auto which I imported on a 2000 W last summer (2nd generation - ACR30). Whilst I experienced some early engine hesitation which I put down to the effects of a drained tank for shipping, the addition of Redex every 4 or 5 tanks seems to have cleared that with a strong performing engine since particularly round town. However, my check EM light has started coming on at around 50mph and the diagnostic I got was lean fuel mix - no code given. Could this be the same problem as Mr Spoons or could it still be related to fuel flow? I have looked at purchasing diagnostic software and an OBD conector for my laptop - is this worth it (about $150 from US)?

Regards,

moffball

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It is very difficult for anyone to ascertain exactly what is wrong without seeing the car. All one can do is hazard a guess based on the reported symptoms.

So a question for you----if there was no code how exactly did whomever gave you that diagnosis arrive at that conclusion?? I think you really need to get the code from the ECU to ascertain what it thinks is going wrong and then go from there. An OBD scanner is definitely worth its weight in gold as far as new cars go but you should note that there are a number of different protocols and different ones in the US and in Europe. Ideally try and get one that covers as many as possible and is updateable. There are a number for sale on Ebay right here in the UK.

Lets assume for a moment that the diagnosis was correct and you are running overly lean. The ECU would be getting this info from the Lambda sensor and should be trying to rectify it by richening the system. You say the engine is running fine but have you noticed any major change in fuel consumption. If the ECU was constantly receiving a lean condition and was constantly trying to compensate I would say you should have noticed lower mpg by now.

Now if adding Redex to your system alleviated a missing chances are this may be being caused by a sticky injector, problem is the redex could well be coating your Lamda sensor causing it to send erroneous info back to the ECU.

Again this is all just supposition, start with the code and lets go from there. You could use the test procedure I have outlined above to test your primary sensor which should be found at the top of the first cat closest to the exhaust header. As always if you choose to do this it is entirely at your own risk. A perfectly good sensor can be damaged if not treated correctly.

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I have had very similar problem with Previa 2.4 X reg. 78000miles. The Toyota dealer initially diagnosed oxygen / fuel sensor problems (based on reported error codes) and replaced both of them (there appears to be one either side of the cat apparently) and also the cat, which was all carboned up. This didn't solve anything so they had to get a special diagnistic tool in from Toyota (probably Japan judging by the time they have taken almost a week and the car is still not fixed) and now say it is in fact the air / flow sensor that is also gone.

Does anyone know why these sensors (which seem very expensive for what they are) seem to be very unrelaible or is this a design feature to generate revenue for garages ?

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My W 2000 Previa was recalled last week and they changed 4 engine coils. Unusual for a seven year old car. Now the engine management light that's been on and off for the past 6 years (mostly on) is off all the time. Probably just coincidence!

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Hi!

Just bought a Previa 02 diesel with 132,000 miles. All was fine when i bought it but now suddenly had lack of power going up-hill and didn't want to rev above 2500 revs. It seemed to have lost its umph! when pushed hard.

I cleaned the mass air flow sensor located directly behind the air filter box in the air tube to the turbo and hey presto....It goes like a rocket now!

Hope this helps you guys.

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i wonder if that could also make the turbo over boost as if that sensor isn't working right then it must affect the air flow to the turbo which surely would make the turbo work harder than it would normally and then it dips out .

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hi every body my first time here got a few questions about my previa 52 2003 plate d4d .what happend is i was on motorway and the turbo gave in iimmediatly stoped the aa came they said its the turbo so i got a recon for £650 had it done by a good local guy drives ok on straight road but up hills boy is it struggling had diognostic done now it says air flow meter .because the turbo went there is Oil in the exhaust pipe system could yhat be a reson aswell so all of the guys like propnut and anyone who knows somthing they can shed some light on this poor soul all info welcom thanks to all please reply

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hi every body my first time here got a few questions about my previa 52 2003 plate d4d .what happend is i was on motorway and the turbo gave in iimmediatly stoped the aa came they said its the turbo so i got a recon for £650 had it done by a good local guy drives ok on straight road but up hills boy is it struggling had diognostic done now it says air flow meter .because the turbo went there is oil in the exhaust pipe system could yhat be a reson aswell so all of the guys like propnut and anyone who knows somthing they can shed some light on this poor soul all info welcom thanks to all please reply

Oil in the exhaust would soon be blown out so I doubt this would be causing your issue unless it seriously coated the labda sensors which again is unlikely. If the system is complaining about the MAF then have that checked out, otherwise take the car back to your turbo man and ask him to check its boost, the waste gate and waste gate actuator.

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thanks for your reply propnut i am taking car back to the mec to have maf meter put in i bought a new one such a small thing but very expensive then i will give it a go see what happens.one more question i dont know much about cars so can you please explain what wast gate is and acutator is and how do you check the boost and does that mean he will have to take the turbo out again to check all that stuff ;)

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thanks for your reply propnut i am taking car back to the mec to have maf meter put in i bought a new one such a small thing but very expensive then i will give it a go see what happens.one more question i dont know much about cars so can you please explain what wast gate is and acutator is and how do you check the boost and does that mean he will have to take the turbo out again to check all that stuff ;)

hi all ihave changed the air flow meter of my d4d but the problem exsists what to do now any suggestions could it be the turbo but i have had that done only 2 weeks back a recon one with one year garantee please help :(

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thanks for your reply propnut i am taking car back to the mec to have maf meter put in i bought a new one such a small thing but very expensive then i will give it a go see what happens.one more question i dont know much about cars so can you please explain what wast gate is and acutator is and how do you check the boost and does that mean he will have to take the turbo out again to check all that stuff ;)

hi all ihave changed the air flow meter of my d4d but the problem exsists what to do now any suggestions could it be the turbo but i have had that done only 2 weeks back a recon one with one year garantee please help :(

Your mechanic will know what those things are. Take the car back and have the turbo checked. Most cars have a boost tap off somewhere where a boost meter can be attached to check the output pressure (boost) of the turbo. Of course it could be other things e.g. insufficient fuel flow due to a blocked fuel filter or dirty injectors.

Do you have a warning light on your dash ? You say it runs ok on the flat but not up hill. This could be insufficient boost from the turbo or simply insufficient fuel being delivered to the cylinders or you have a loss of compression. Unfortunately no easy answer, the car will need to be diagnosed properly.

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thanks propnut i will surely have that done but one more thing i like to know is that before with the old turbo there was no kind of noise but after i have had this one installed i can hear a kind of whisteling sound when i take off could that be a reason . anyway i have had no kind of lights lit up on my dash. so hope fully when i have time i am going to see a turbo technition. thanks again for your reply ;)

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