Avensis Misfire - ideas?

[Barks]

I'm running an '04 Avensis with the 2.0L D4 engine, and I'm having constant problems with the engine missing at around 2000 RPM in top gear.

So far I have:

Changed the air filter
Changed the plugs
Cleaned the MAF sensor (using CRC's MAF sensor cleaner)
Run 91 AND 95 fuels
Beat my head against a brick wall.

What Toyota have told me is that the D4 engine runs incredibly lean to achieve fuel economy, but it doesn't take much to push it just over the edge into lean-out related misfires. With this car it seems to be when you apply very gentle throttle at around 80km/h or the car comes under load at around that speed.

What I want to know is - Is there anything else I can try?

Ideally I'd like someone to *spring* from the woodwork and say they can reflash the ECU to fatten up the fuel map in that rev range, but I won't hold my breath.

Can I try something redneck like connecting a 10k pot across (or in series with) the supply and signal wires from the MAF sensor to fool the computer into thinking the airflow is higher and causing it to slightly overfuel?

My daily commute from Otumoetai to Papamoa is driving me bat-shit crazy right now, because roughly 90% of the drive is now at 80k, and I'm starting to get close to putting a screwdriver through the rocker covers....

[BZG Wagon]

Have you or Toyota connected it to a scan tool?

IMO plug one in, check for error codes. If there are none then press record & take it for a drive to see what everything is doing + what the sensors are reading.

It could be something simple like a faulty sensor.

[strx7]

roughly 90% of the drive is now at 80k,

gotta love that now dont ya??

[Mr Revhead]

Option A: Definitely use proper scan tools and someone who knows what they are doing.
If I had to guess I'd say check for dodgy injector.

Option B (preffered) : get rid of it

[whynot]

perhaps a weak spark as well? it would take a fair bit to ignite such a lean mixture. Have also had a coil burn out on one of those before (as well as 2 spark plugs and 2 pistons)

[Mr Revhead]

oh heck, yeah coil on plug. Check that first. Thats what I had in my head when I said injector

[Simon K]

Fuel filter clogged?

[matt dunn]

lol, D4 petrol.

we have had a few earlier model D4 corona's etc in through work with exactly the same problem,

even one that came from the toyota dealer that they had sold,

in the end there is no fix for it. They even went as far as looking at an aftermarket ecu, but did not in the end.

You can do the basic's, but if that doesn't fix it nothing will,

We also have an Avensis at work as a work car and it does the same thing,
we all hate driving it and the old 1922 2.2 manual camry wagon we had before the avensis beats it in every way.

You can try the Subaru Upper engine cleaner which is a foam spray cleaner we use specifically on GDI engines to remove carbon buildup,
or we also fitted a resistor inline witn the Airtemp sensor ( which is part fo the AFM)
It improved it but did not fix it.

Only thing that did make a noticable improvement was running it on 98 octane.

[Barks]

Strange thing about the 98 tip is that the problem is worse on 95 than 91 :s

Hey Shelfie, any chance of tracking down some of those coil packs?

Any particular place to get the upper cylinder cleaner Matt? I might as well try what I can. The local Toyota dealer suggested removing and cleaning the intake manifold, so I've got that up my sleeve as well.

The way I'm going I'd almost consider driving the shitbox legacy my brother left me to sell for him when he headed for Oz. Why the hell Toyota decided to make an engine that runs that lean is beyond me.

[allencr]

Plug wire/s if it wasn't coil on plug.
Narrow the plug gap if you think the coils aren't putting out enough.
Higher heat range plug if you think its running rich, cooler if it's running lean at that rpm with high load.

[matt dunn]

the upper engine cleaner is a subaru genuine part so subaru only.
About $20 a can from memory but been a while since we got it as we bought in bulk last time.

[Barks]

Different tack.... What about modifying the signal coming back from the o2 sensor? if you could insert a resistor to make the computer think the sensor was reading lean, it should compensate shouldn't it?

I figure if I brainstorm this enough I should be able to find a solution, and if I manage to, it should help a crapload of D4 engines as well.

[matt dunn]

Different tack.... What about modifying the signal coming back from the o2 sensor? if you could insert a resistor to make the computer think the sensor was reading lean, it should compensate shouldn't it?

I figure if I brainstorm this enough I should be able to find a solution, and if I manage to, it should help a crapload of D4 engines as well.

Which sensor it has four 4 wire sensors ?

and they run so lean on cruise that the 02 sensor is saying full lean anyway.

We have been through all the easy options before.

[MAGN1T]

Aren't they supposed to run on 98 only?
10.5 to 1?


Steve

[Barks]

Anyone have an ODB II scanner that they are happy to loan out? Managed to track down the Toyota service manual for the 1az-fse with all of the expected sensor ranges etc etc.....

If it's a no and I have to buy one, is there anyone out there that could use a loan?