1FZ-FE 75 series "96" heavy fuel consumption

Submitted: Friday, May 02, 2014 at 00:13
ThreadID: 107568 Views:9342 Replies:4 FollowUps:2
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Hey Every one,

I have a "96" 75 series 1FZ-FE, 200,000klm on the clock and running a duel fuel EMER vapor injected gas. Located south east Melbourne.
I am trying to fix the excess fuel consumption problem,
fuel consumption is almost even LPG to Petrol and is under powered guessing 20/30%.

Just wondering if any one out there has any geeky info on re-calibrating a MAF (Alloy type) on a 1fz-fe engine that does not run a O2 sensor.
Does the MAF meter uses a thermistor to adjust the fuel ratio? and also does the flap spring tension have anything to do with fuel mixture.

If i replace the MAF meter with a new one and it does not fix the problem I will waste $1300.

I'm guessing the previous owner has tried to fix the fuel issue/surge/ sensor issue and put many of hours and $$$$$ into it.

It has reco injectors, new fuel pump, filters, leads, Plugs, cap, rotor button and the intake manifold has fresh gaskets and Vac hoses, strong spark, Good compression, 6th cyl is a fraction low but still gets up there.

I just found it had a Toyota Camary MAF meter fitted (25lts per 100klm on h/way running smooth on gas but extreamly surging on petrol from 2/5 to 4/5 throttle with little low down torque)
I have replaced it with a second hand 80 series 1FZ-FE MAF meter (new one is $1300) after calling Toyota to cross ref the MAF meter part number and it suits this model plus other 1FZ-FE models, (35-40lts per 100klm on h/way, throttle is very smooth on both fuels now, better low down torque) but still a at a guess 20-30% under powered until 4000 RPM.

I am looking at setting the vehicle on a dyno and opening the D shaped cap to adjust the air flap spring tension and to see if we can re-calibrating the air temp sensor with a resistor or a potentiometer. I am guessing the small plastic stem in the intake side of the MAF meter is a thermistor??
I'm not sure if this is possible but after opening the Camary MAF meter, it may be.

I have read the "Land Cruiser 105 fuel issue" thread

Has anyone had any operation similar to what I am looking at performing?
If so, detailed info would be greatly apreciated,

May the forest be with you!
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Reply By: Ross M - Friday, May 02, 2014 at 08:30

Friday, May 02, 2014 at 08:30
Have you had a tune up check on the vehicle?

Many of the Toyota cam and bucket valve engines have NEVER had the valve clearances checked or adjusted. This has happened on a number of 80 series diesels and AFTER the valve adjustment/correction and with normal valve clearances restored they had proper compression and ran smoothly with better economy.

SO, unless the basic mechanicals are correct, anything you do like replacing and substitution of other systems may not have any noticeable effect.
The fuel pressure regulator on the injector rail has to have a good vacuum supply ie, not leaking /split hose in order to work and control fuel pressure correctly. The reg may be faulty?

At 200,000 I would be seriously checking the throttle position sensor for wiper track wear, it may be worn, very likely to be worn in the areas where it has mostly operated for 200,000km. They never get better by themselves.

Until those basics are done there isn't much point in replacing the items you mentioned.
AnswerID: 531619

Follow Up By: Michael G19 - Friday, May 02, 2014 at 09:57

Friday, May 02, 2014 at 09:57
Thanks Ross,
The fuel reg is new and all vac hoses are new.
I had a new repco workshop spend 5 hours bench testing all sensors, fuel pressure, checking all electrical wires, plugs and cleaned all terminals via my suggestions etc, they passed fine and they also tuned the vehicle.
I will check the valve clearances, engine tuning and recheck the throttle position sensor track wear and see how I go from there.
I guess I will only know the accuracy of tuning and sensor conditions if I see it myself.
Now I have found the correct MAF sensor (second hand!!!) I should be in the right ball park.
Thanks again Ross.

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FollowupID: 814666

Reply By: Robin Miller - Friday, May 02, 2014 at 08:36

Friday, May 02, 2014 at 08:36
Michael , power and economy of 20-30 less is the way its meant to be particularly on vapour gas systems, so not sure of your exact issue.

Dynos are good idea though , with the right operator , I used one in Bayswater that didn't mind me hanging around to assist.



Robin Miller

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AnswerID: 531620

Reply By: olcoolone - Friday, May 02, 2014 at 09:21

Friday, May 02, 2014 at 09:21
QUOTE "If i replace the MAF meter with a new one and it does not fix the problem I will waste $1300"

That's part and parcel of DIY diagnostics, we see it all the time where people spend excessive money of self diagnostics and it turns out to be something cheap or simple.

There are many reasons in including fuel supply rates, first off you have to know what is the symptoms and then work out what would cause these symptoms.

AnswerID: 531631

Reply By: Member - Chriso100 - Friday, May 02, 2014 at 10:18

Friday, May 02, 2014 at 10:18
Hi Michael,
I have a 100 series dual fuel, and do find the consumption is huge. I get around the 20-22 litres per 100kms, but understand that is about the norm. I suggest also to have the clearances checked. I had LPGAS 1 in Lilydale do mine. They were very very helpful and the cost was the best part. They quoted me a figure even with all the shims replaced, and when I picked it up, they charged me heaps less. Pretty honest I reckon, and well worth the hour drive to take it to them. They even provided a car for the day! Maybe get onto them, the sound pretty switched on.
Good luck,
Chriso.
AnswerID: 531634

Follow Up By: Member - Chriso100 - Friday, May 02, 2014 at 10:43

Friday, May 02, 2014 at 10:43
Forgot to mention.... LCOOL may be of interest with the technical stuff. It can be a useful tool in some of these cases.
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FollowupID: 814670

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