Toyota 1az-fe Engine Problems

[Sofiel Kustra]

Browsinga forum on the (New Zealand) Automobile Association website whilst researching options for a new car for a family member, I noticed repeated advice to avoid the D-4 petrol engines because of carbon build-up causing problems such as rough idling. The recommendation to owners of the engine was to use 98 Octane fuel to minimise the problem. (Example here)

The only reference to such a problem that I was able to find on the web, other than the original NZ AA forum, was an item about the first generation (2001-2005) Premio on the Kenya Toyota Club homepage

I don't really see what switching to 98 oct fuel will do.Putting higher octane fuel in will only help if either you alter the the timing to make use of the extra knock resistance or it's knocking already.

The only thing I can think is perhaps the engine is in a different state of tune in NZ,perhaps for emissions reasons or the quality of the fuel over there as I've never heard anything like i over here.

I don't think our petrol is inferior to that elsewhere in the world, though until recent years I believe our diesel used to be somewhat inferior to European diesel and caused grief with some high-end Euro diesel cars here.

Another New Zealander here with the same car and the same engine who also became similarly concerned when I read the comments on the NZ AA website.

In my experience (and my own opinion), running BP Ultimate 98 RON for 3 consecutive tank fulls in the car made the engine less smooth overall -- rougher acceleration, rougher idle, rumbling when cruising along at 50km/h at low RPM (Auto transmission), 10% worse mileage (all 3 tank fulls), in fact, I felt that the engine actually ran better on that initial fill of BP Regular 91 RON (when I first got the car) strangely enough!

Switched to using Caltex Techron Premium and Z ZX Premium (Both 95 RON) and the engine performed much more smoothly overall and this is what I've been filling the tank up with ever since I got the car almost a year ago. Haven't noticed any problems (yet), engine is still running smoothly. As far as I've been able to decipher, 95 is the recommended RON for this engine.

The fact is though, more and more of these gasoline direct injection motors are appearing on the NZ market such as SkyActiv, Ecoboost, SIDI. I've known 3 other people who drive the NZ New 2003-2008 Avensis wagons with the same 1AZ-FSE D4 engine and they have put about 200,000km on the car and said they were unaware of such problems.

Not sure if anyone has any experience with this, but there are comments around the place that spraying some Upper engine cleaner every now and again through the air intake, might be able to reduce (but not eliminate of course) the carbon build up enough so that it doesn't cause a problem?

I did get a bit worried when idle suddenly became quite rumbly but have concluded that it only happens from time to time when the aircon compressor is running - as if the computer isn't asking for quite enough power from engine and it is labouring a little as a result. Haven't been able to tie that down to a particular fuel being in use. I will try to be a bit more systematic about observing engine behaviour and fuel economy and report back if I can see a real pattern. I get the feeling that even within brands you can get quite a lot of variation in quality from different outlets at different times, if so that doesn't make it any easier to be scientific about it.

All cars get carbon build up on their throttle bodies, it is because of the exhaust gas reciculator valve and the usage of the crank case vapour in the combustion chamber. The throttle body connects the air filter line(tube) to the inlet manifold. But attached to this is a rebreather that introduces the crank case gases to the inlet. The carbon collects around the circumfrance of the throttle body, when you take the inlet pipe off it might look clean and nice, but take the throttle body off completely and look at from the back, you should be able to see light between the housing and the butterfly valve. When this is clogged up the ideling is affected because the ECU has to open and close the vale continously to allow the engine to breath. The job is simple to do, just need the right tools and some throttle body cleaner, carb cleaner is to aggresive. When the piece is removed beware, you will lose some coolant, yes the engine has coolant flowing through the throttle body, it is to keep the ideling smooth and the metal at a constant temprature. After you have cleaned and replaced the throttle body the ideling wil be high, around 2200 rpm, dont take the car to the shop saying it is busted, the ECU will addapt the ideling to the new flow of air, the engine can breathe again. Drive it around for a couple of hours and repeat the next day, the computer needs both hot and cold readings to reset its fueling. If however after three days it still runs like a meth head, take it to the shop and tell them what was done to the car. The ECU might just need some direction. I am sure that somewhere on youtube is video detailing how do all this. I did it because my car was heavy on fuel and idled like a pig. REMEMBER NOT TO STICK YOUR FINGERS IN THE THROTTLE BODY UNLESS IT IS DISCONNECTED FROM THE ELETRONICS, YOU WILL LOSE YOUR DIGETS.

The problem with D-4 is real. I have experienced the same issues trying to fix they get complicated until replacement of the engine. Carbon build up, excess fuel consumption, lack of power, stalling when accelerating are rampant. So the way to go is to fix new engine the sooner. The more you try to work on the engine, the troubles keeps shifting from fuel rail to ignition errors.

It depends on the location/territory/country and the grade of fuel available. Also notice the measuring standards. Same goes for the ZZ series and the later ZR series which replaced the AZ and ZZ engines when the T27/T270 cars and other models that were updated.

I have a 2007 avensis 1azfse had a 2005 2azfse when was younger and ive heard horror storys a issues about the avensis. Mainly the earlyer ones. Head studs lifting head gaskets trans issues etc. The 2.4 have oil usage issues to do with the pistion rings the 2.0 is pretty good and do high ks without to much problems as long as maintain. When i first got mine i cleaned the egr valve cleaned carbon build up in throttl body cleaned air flow meter serviced trans irdium plugs etc and ive had zero issues. I do run a bottle of cat/egr cleaner in gas tank every 20.000ks but there pretty bullet proof! Had couple of mates who have got 400.00ks out of a moter in 2 of theres! Also DONT RUN GULL 98 the added **** to the 98 frys the lines injectors etc can run Mobil 98 and bp98 as far as i know

I would like some help please. I have an 51 reg avensis estate 2.0L petrol vvti auto. regulary serviced and stamped by toyota dealers. i had the cam chain kit replaced as the chain was very noisy also a full service to go with this. i spent over 500 for parts and labour, having done this i was told the engine was excellent in top condition. 3 days later having took the car on the motorway, happily driving at 70mph in the 3rd lane, the engine suddenly cuts out. Managed to let the car roll to a halt on the hard shoulder of the motorway. called the RAC who had a look and said there seems to be some sort of resistance thats stopping the engine from turning over. Battery was checked, alternator checked, all fine. Got the car towed to the same garage that did the work, got a phone call 5 hours later telling me that the bottom end of the engine had gone. All the lights show up on the dash when ignition is on. when you try starting the car theres a clicking noise, but engine wont turn over.

I need some advice if i should get a second opinion. i know its a common fault with the vvti engines, i thought it was only due to poor maintainence and mainly taxi drivers that were hit with this problem.

Hi guys, need an advice from someone more experianced. My 2004 Ave 1AZ-FSE (direct injection) has 4 oxygen sensors, 1 was faulty and car reported it by warning light for like 1.5 year or so. All the time car was running perfect, really fast and agile, with consumption of 8-9 liter / 100km.

I finally decided to change the faulty sensor and followed my mechanics advice to buy cheaper Denso sensor, which was supposed to be exactly the same as from Toyota just with different connector. They cut connectors and climped new sensor to old connector.

Now the car doesnt report any errors, but dont want to accelerate. It goes perfectly below 3000 rpm, but every acceleration above that and every take-over is nightmare. Also sound is bad then, I can hear something is wrong in engine. Consumption is 8.5 liter / 100km, so no benefit here.

What we tried to do with another mechanic was to unplug this sensor (+ another one in the line), which supposed to force engine management unit to exclude oxygen sensors from engine control and use "standard fuel map" recorded in its memory.

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