Topic: 3RZ using almost double fuel it should be, any ideas?

[speedstar751]

I have a 2000 model twin coil 3RZ I've fitted to a 1993 extra cab hilux, its only been registered for a couple of weeks but fuel consumption is roughly 22L per 100km from all reports it should be roughly 13L per 100km. I'm in Australia if that makes no sense!

It's fitted with a 2 1/4inch mandrel bent exhaust, hi flow cat and muffler stock headers, stock air box and intake. I've cleaned the airflow meter, new plugs, new fuel pump, new filters etc has no air leaks in exhaust or intake, vacuum reading seems fine.

This model in australia is pretty simple has no oxygen sensor in exhaust, not fitted with OBDII until next engine model I think what sensors etc would make it run rich? Coolant sensor or air flow meter?

Motor has alot of hesitation when put under load on highway doesn't seem to make the power it should be, I've owned the same model 3RZ in a different vehicle and it went alot better than this one.

When in low range doing 4x4 driving with little load on the engine it seems to run alot cleaner revs out easier etc.

The ECU is from a 2WD but i can't see this being an issue?

Any advice on what to look for would be helpful.

thanks in advance.

[H8PVMNT]

I would check the mass air sensor to start with.  I had the opposite problem, mine likes to get a little lean and doesn't like to run on ethanol mixed gas at all.  When it intermitently gimps out I get no power over 3500 and I get an airfuel lean code.  I tested the mass air sensor and it is bad. In my case I have attributed the sensor failure to an oiled filter I have been using that fouled up the filiments on the sensor...

I don't think your 2WD ECU would cause any problems.

I'm sure some of the other guys will chime in here too.

[speedstar751 [OP]]

OK cheers mate. I'm getting it connected to a diagnostics tool tomorrow so hopefully that shows something up we don't have OBD2 until about 2006 in Australia. I'm still using the paper air filter and I cleaned the air flow meter with an aerosol designed for cleaning the sensors but i have no idea how to test the air flow meter?   I know when it gets unplugged while motor is running it stops straight away.

[Dr Phat]

If its a faulty sensor cleaning it wont do anything. They work on supplying a voltage and measuring the voltage drop as resistance varies with the increase of air flow rate. I'm guessing you can hook up and multimeter and check voltage or resistance against what the known values should be.

[TRACKER]

hook a scanner to it and see what s mass airflow reading at idle and wide open throttle

[speedstar751 [OP]]

Well i took it to a mates mate who is a toyota dealership technician and apparently when i did the wiring I've thrown out the DLC3 diagnosis connector which was in the cab somewhere and all i have is a basic DLC1 connector in the engine bay which he said tells him bugger all and I haven't got the engine check light connected to anything so he can't read the codes that way either. So I have to do some rewiring before i can get a proper scan done.

He suggested cleaning the fuel injectors and getting a new fuel pressure regulator as it didn't appear to be working correctly and it blows black smoke on start up after sitting over night which he said points to fuel injectors being stuck open and leaking so I will do that first and see what happens.

[3toys]

Is it possible that your wiring is messed up causing the injectors to be powered even with the key off?  Granted, dirty injectors will do this also, it's just a thought.  And FYI, the 3RZ has a Mass Air Flow sensor, not an Air Flow Meter as the older toys did.  Just a terminology lesson for ya, no charge...  Lol

[speedstar751 [OP]]

Is it possible that your wiring is messed up causing the injectors to be powered even with the key off?  Granted, dirty injectors will do this also, it's just a thought.  And FYI, the 3RZ has a Mass Air Flow sensor, not an Air Flow Meter as the older toys did.  Just a terminology lesson for ya, no charge...  Lol

I hope not but I'll check once its all back together, I'm not sure if that would affect the fuel economy when its running though. The injectors looked quite dirty but I won't know until i get them cleaned and put them back in as to if thats the problem or not. MAF sensor hey cheers mate!

Does the speed sensor wire out of the ECU affect anything as far as the way engine runs its not connected to anything?

[H8PVMNT]

I think the speed sensor does need a signal to the ECU. I had a 90s speed sensor that hooked right up but I know most guys hook something from their speedometer that sends the proper signal.  Look on the 3RZ database thread...

[speedstar751 [OP]]

I think the speed sensor does need a signal to the ECU. I had a 90s speed sensor that hooked right up but I know most guys hook something from their speedometer that sends the proper signal.  Look on the 3RZ database thread...

Cheers mate, I'm going to connect it its been throwing the engine check light on only just worked out its the speed sensor not being connected. Not sure if it affects the way it runs though.