1FZ-FE Fuel Economy (1 Viewer)

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Oct 1, 2022
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Location
Darwin, NT
I have a LC100 FZJ105 with a 1FZ-FE in 5 speed manual and 33s. Car is weighing in at 3200kg with all the gear in it. Engine has had complete rebuild 15,000km ago. Fuel consumption was 24L/100km (10MPG) Replaced injectors and fuel consumption is now 38L/100km (6.2MPG) Ignition system is new and fuel system is new. Most of the engine bay has been replaced radiators etc. Electronics have NOT been touched.

9 days from now I will have a Link G4+ ECU and wide band O2 sensor installed and tuned in the hope of fixing the terrible economy.

What fuel figures have people been getting with their 1FZ-FE and has anyone experienced any success in correcting the economy issues?

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Oxygen sensors. Replace.

I got anywhere from 10-17 mpg depending on city vs interstate.
 
Oxygen sensors. Replace.

I got anywhere from 10-17 mpg depending on city vs interstate.
It's an Australian 100 series. They never were released with O2 sensors, which it seems the rest of the world has O2 sensors. If the car has been tuned on an open loop and there is not even a narrowband O2 sensor. I can only imagine that this is the reason I am suffering bad economy.
 
Looking forward to what you come up with. I’ve been looking into doing a stand-alone; ditch the distributor, run COP ignition, new injectors, and tune my own fuel and advance maps.

I probably won’t improve much but I doubt it’ll hurt. Been running a Microsquirt in my Porsche for years, and been eyeing the LC ever since.

I suspect you went too big with your injectors, and since it’s closed loop, yeah, you’re likely running pig rich.
 
I get 13 to 16 mpg pretty consistently. I dont weigh as much as you do. Also, dont drive much over 70 mph. I did the cylinder head job and rebuilt injectors 2 years ago. Installed new O2 sensors a few years ago. Interesting that your truck has no O2 sensors. So you might make sure your water temp sensors are working correctly.
 
Looking forward to what you come up with. I’ve been looking into doing a stand-alone; ditch the distributor, run COP ignition, new injectors, and tune my own fuel and advance maps.

I probably won’t improve much but I doubt it’ll hurt. Been running a Microsquirt in my Porsche for years, and been eyeing the LC ever since.

I suspect you went too big with your injectors, and since it’s closed loop, yeah, you’re likely running pig rich.
I am not sure what happened but I did ask the mechanics for OEM injectors. They came up with new injectors for the 1FZ-FE however they are out of the 79 series cruiser 1FZ-FE.
 
I get 13 to 16 mpg pretty consistently. I dont weigh as much as you do. Also, dont drive much over 70 mph. I did the cylinder head job and rebuilt injectors 2 years ago. Installed new O2 sensors a few years ago. Interesting that your truck has no O2 sensors. So you might make sure your water temp sensors are working correctly.
I pressume I will see the full extent of what is going on in about 7 days with the new ECU and wideband O2. They said they would like to go over the car quickly before installing the new ECU. If anything is faulty I will know about it soon.
 
16-20 L/100km here. At 30L/100 something isn't right. I'd start by looking at the injectors that you've just replaced.
 
I pressume I will see the full extent of what is going on in about 7 days with the new ECU and wideband O2. They said they would like to go over the car quickly before installing the new ECU. If anything is faulty I will know about it soon.

Sounds like an expensive fix for what is probably a simple problem. Either your mechanic ballsed something up, or has overlooked something

My 93 was getting about 17-18L/100km, a bit less in the city.
26/100 is what I'd expect for low range work or towing
38/100 would be flogging it mercilessly in low range up and down sand dunes.
 
Sounds like an expensive fix for what is probably a simple problem. Either your mechanic ballsed something up, or has overlooked something

My 93 was getting about 17-18L/100km, a bit less in the city.
26/100 is what I'd expect for low range work or towing
38/100 would be flogging it mercilessly in low range up and down sand dunes.
 
Look at what's been altered, or messed with recently.

Non standard injectors, particular off brand aftermarket parts would be high on my suspicion list.

Check everything associated with timing is working properly, and installed properly.
Crank position sensor
Cam and sensor
Cam shaft timing.

Check other sensors test out ok. EFI temp sensor. Knock sensors.

MAF testing out ok?

Check valve clearances are correct. Check compression and check valves are sealing.

Are the correct spark plugs in it? Gapped correctly?
Are coil packs all good?
Plug leads ok (not sure if 100 series have top mounted coil packs?)

Are all engine wiring harness connectors clean, and clipped in place securely.

Fuel pressure and fuel pressure regulator ok?
Air filter and intake clean, and free of obstructions?
 
I did not do any of this work myself. Requested the mechanics replace the injectors and trusted they would source an appropriate replacement. Idea behind an ecu and wideband is chasing the economy. I accept it is expensive but better than burning fuel for a car that lacks even a narrowband O2. I accept what you are saying about dodgy workmanship. Fortunately this time my hands were not on the tools. No claims of innocence however.
 
There's a lot of basics I'd want ticked off before I went to an aftermarket ECU and added a bunch of new variables to a problem situation
Using a Foxwell I70 diagnosis tool. MAP sensor has been replaced. To be fair I did not mention the gradual build up to this point. I think 24L/100km is too much. Especially dealing with an open loop tune, no O2 sensor and this will be a very long term vehicle. I appreciate your knowledge on this. I had been taking the vehicle to mechanics and auto electricians as it may have been something I have missed or simply know nothing about. They came up empty handed and here we are.
 
I've got no confidence in 80% of Australian mechanics, just because your mechanic did it doesn't mean it's right and doesn't mean they fitted good quality parts. You need to work out what's going on before you throw a $2500 ECU at it.
If it came to us for an aftermarket ECU and tune, nothing would be getting fitted or tuned until it was running well on the stock ECU. The last thing you want to be doing is fighting with parts that aren't working.
Tuning with questionable injectors would be like tuning with a brand new maf that hasn't been calibrated. Very time consuming and tedious.
 
I've got no confidence in 80% of Australian mechanics, just because your mechanic did it doesn't mean it's right and doesn't mean they fitted good quality parts. You need to work out what's going on before you throw a $2500 ECU at it.
If it came to us for an aftermarket ECU and tune, nothing would be getting fitted or tuned until it was running well on the stock ECU. The last thing you want to be doing is fighting with parts that aren't working.
Tuning with questionable injectors would be like tuning with a brand new maf that hasn't been calibrated. Very time consuming and tedious.
Fortunately, that is what the mechanic I am sending the car to for an ECU is doing. He wants to sort the car first or at least try and work out the issue before fitting the issue. The mechanic that gave me the car back after the injectors were installed stated "running better than before" but the car was idling roughly. My argument for not taking it back was clearly they do not know what they are doing so I sought more competent help.
 

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