VN V6 in 84 4Runner - bad fuel economy

Post by **mates85** » Tue Dec 08, 2009 11:12 am

Hey guys ,

ive got a 1984 toyota 4runner , i bought the car basically as is it has had a VN V6 fitted it runs the turbo 700 auto trans which i have had rebuilt , marks 4x4 adapter and im unsure if diff ratios have been changed from factory.

anyway im getting roughly 250km to a tank of petty, now ive changed the coilpack to VR , new leads , new plugs , i modded a commodore airbox to fit and has new air filter.

should i be expecting this fuel economy is there anything i should do to make it better ?

i could change the diff ratios but im looking $1000 each to buy the new centres and currently it drives pretty well the ratio is a little out cause it does shift up gears early.

any advice from people who have owned or done the conversion beforee would be awesome ! , i plan to get it on a hoist soon and il work out what ratio centres are in it now.

thanks hope some people can shed some light on it !

Post by **Struth** » Tue Dec 08, 2009 11:36 am

They are not known to be an economical conversion but that fuel economy is pretty bad.

Where does it pick air up from, under the bonnet or have you got some kind of cold air intake. If it's under the bonnet then sucking the hot air from the engine bay will effect economy as will any unnecessary bends or restrictions in the intake pipes.

Are the 02 sensors connected?

Cheers

Post by **booflux** » Tue Dec 08, 2009 11:53 am

As Struth said check the 02 sensor, but I also feel that the ratios will be part of the problem, unfortunately bad economy is a given with this conversion in a Lux, the other option is to get it put on gas, or imo pull it sell it to some sucker who thinks its a good conversion and throw a 3rz in

Post by **Frankenyota** » Tue Dec 08, 2009 1:24 pm

Mine used a lot of feul when it wasn't going into 4th gear, where the torque
converter locks in.
What size tyres do you run?

I have got 35" MTRS with 4.88 gears and get about 320 km out of 40 odd litres.

Matt

Post by **mates85** » Tue Dec 08, 2009 2:08 pm

hey guys thanks for the replies ,

well basically its standard commodore intake i just shortened the plastic intake tube to the airbox , it does suck air from the bay and not cold air intake althoug i can mod it easily for c0old air intake so it sucks it from in front of the inner guard i might do that anyway.

i will check the O2 sensors as well !

when i bought it , it wouldn't select 4th gear and slipped so i pulled it out and sent it for rebuild , fixed that issue.

thanks guys il check some things and get back to you !

Post by **HUSSLN** » Wed Dec 09, 2009 8:41 pm

dam 320 from 40 odd litres is mad economy, i got 450 highway with shit plugs an leads, everything leaks on the motor i suspect its done some serious k's. mines 4.11s with 35s last full tank i got 360 with a little freeway some country and around town. i run standard fuel tank im keen to move upto 4.88s though. but i run a modded 80series rear diff an need a low pinion front to stop it hitting the sump so think lockers will be first.

Post by **Struth** » Wed Dec 09, 2009 8:48 pm

mates85 wrote:hey guys thanks for the replies ,

well basically its standard commodore intake i just shortened the plastic intake tube to the airbox , it does suck air from the bay and not cold air intake althoug i can mod it easily for c0old air intake so it sucks it from in front of the inner guard i might do that anyway.

i will check the O2 sensors as well !

when i bought it , it wouldn't select 4th gear and slipped so i pulled it out and sent it for rebuild , fixed that issue.

thanks guys il check some things and get back to you !

Mine was posting 104rwkw drawing engine bay air, then 130 rwkw drawing snorkel air, so it makes a big difference to the engines performance.

If the 02 sensors are not working the computer will run a basic compensation map as opposed to altering fuel delivery live based on what the engine is doing at the time.

Also get your fuel pressure checked, preferably under driving conditions, lack of fuel delivery from the pump will also add to poor fuel economy.

Look at your plate under the hood on the firewall, there will be a section called trans/axle, what are the numbers on that, ratio can be worked out from these numbers.

Cheers

Post by **HUSSLN** » Wed Dec 09, 2009 9:11 pm

booflux wrote:As Struth said check the 02 sensor, but I also feel that the ratios will be part of the problem, unfortunately bad economy is a given with this conversion in a Lux, the other option is to get it put on gas, or imo pull it sell it to some sucker who thinks its a good conversion and throw a 3rz in

settle down. Im thus far happy with the conversion. Pulls hard up hill, beats patrols landcruisers deisel petrol whatever. It is what it is. Maintenance costs are good i wouldnt say you'd need to be a "sucker" to think its a good conversion.

Saying that. A ls1 conversion is something i want to do in the not to distant future.

Post by **crankycruiser** » Thu Dec 10, 2009 5:51 am

not sure on the commy v6's, but on my LS1 i didnt have the air intake temp sensor connected... and it used crap loads of fuel until i put it in.... might be something simple like that.

But o2 sesors would be my first guess

Post by **booflux** » Thu Dec 10, 2009 7:22 am

HUSSLN wrote:
booflux wrote:As Struth said check the 02 sensor, but I also feel that the ratios will be part of the problem, unfortunately bad economy is a given with this conversion in a Lux, the other option is to get it put on gas, or imo pull it sell it to some sucker who thinks its a good conversion and throw a 3rz in
settle down. Im thus far happy with the conversion. Pulls hard up hill, beats patrols landcruisers deisel petrol whatever. It is what it is. Maintenance costs are good i wouldnt say you'd need to be a "sucker" to think its a good conversion.

Saying that. A ls1 conversion is something i want to do in the not to distant future.

Mate I stand by my comment it is crap conversion, for the cost and power a 3RZ is simply a better conversion. If you want to spend a little extra you can have a 5.0L or 1uz so why anyone would bother is beyond me.

A commo conversion would be reason enough for me not to buy a 2nd hand truck, Id rather buy a cheaper one with a 22R

Post by **Frankenyota** » Thu Dec 10, 2009 10:25 am

Hey hussln what size is your feul tank?

Around town i get 280km from a tank, 320 on the highway.
Maybe it has to do with the 4.88 gearing?

It's coming off the road for some christmas repairs so may check the tune then.

Matt

Post by **HUSSLN** » Thu Dec 10, 2009 7:07 pm

only 60 litres factory lux tank.

Post by **Rory** » Thu Dec 10, 2009 7:38 pm

I will say tho, id never DO a v6 conversion, or buy a hilux with one, iv seen to many with poor fuel eco, bad cooling systems, and performance not much greater than a 3rz conversion.

But,most ppl that have them love them n thats their thing, imjust a tight ass n like 4cyl rego!

Post by **optima** » Thu Dec 10, 2009 7:54 pm

my mates got v6 in his hilux with turbo 700 his fuel gauge doesn't work . so he has been filling it up every 300k's an hasn't run out of fuel yet . an thats around town driving. as for bein a crap conversion anything is an upgrade from standard power.

Post by **bracar80** » Thu Dec 10, 2009 8:06 pm

i was getting bored with this forum but thanks to hussln i think its about to get interesting again.
I have a vs v6 in mine with 4.11s and 35's and get a bit over 300 out of standard tank regardless of driving conditions.
Generly speaking if you get the same k's on or off road there is something wrong with a number of things,I.e. speed sensor, o2 sensor, map sensor and so on. I know mine's shagged but i've given up caring.
As for Boofs statement i have mates with 3rz's and there not much better on fuel, and when something goes wrong there more expencive to fix, thats the beuty of the commo conversion, commo motors and gearbox's (if you run an auto) are cheap and easy to get. My 2c

Post by **booflux** » Fri Dec 11, 2009 6:54 am

bracar80 wrote:i was getting bored with this forum but thanks to hussln i think its about to get interesting again.
I have a vs v6 in mine with 4.11s and 35's and get a bit over 300 out of standard tank regardless of driving conditions.
Generly speaking if you get the same k's on or off road there is something wrong with a number of things,I.e. speed sensor, o2 sensor, map sensor and so on. I know mine's shagged but i've given up caring.
As for Boofs statement i have mates with 3rz's and there not much better on fuel, and when something goes wrong there more expencive to fix, thats the beuty of the commo conversion, commo motors and gearbox's (if you run an auto) are cheap and easy to get. My 2c

They may be cheap on parts but how often do you see a 3rz needing repairs or parts? In my experience very little, granted most of the ones I know of have been factory fitted, but they easily see 450 a tank and run reliably. I have had a few commodores, non ecotec, ecotec and the current one is the alloytec, all have been rubbish, I personally cant stand the engine in the commodore, as they are nothing but trouble, and the economy sucks.

Granted they are a power increase from a 2.8 diesel in a Lux but then so is a 22R

Post by **smaddock** » Fri Dec 11, 2009 5:31 pm

booflux wrote:but they easily see 450 a tank and run reliably.

Not that I've seen. My 3rz conversion gets between 400-420kms on either approx 60ltrs of petrol or 70ltrs of gas, and thats regardless of driving. Its got an interceptor ecu so is running more efficiently that standard and a little bit leaner at cruise, and I still get that economy.

As for the commo motor, I have owned a few and think the power delivery would suit a hilux, even more so than a 3rz. They don't need to be revved like crap to get them up and moving, and they actually rev out further than a 3rz if you want that lil bit extra. Even a statesman with a ecotec v6 gets better economy than my 3rz, and a statesman would weigh similar, and yes I'm talking around town driving, not highway so aerodynamics doesn't come into play. Bout the only prob I can see on most commo conversions that get crappy economy is the setup, and the fact people don't understand fuel injection and how to fix issues, ie oxy sensors must be fine as must afm, and all other sensors for that matter.

But then again, some people have just had bad experiences with them, so each to their own

Post by **bracar80** » Fri Dec 11, 2009 6:33 pm

I have to agree with Struth this is not solving mates85 problem the motor he has is what it is, there cheap easy to fix and in my case reliable.
The 3rz's do have valve problems and I could buy a complete motor and gearbox for a lot less than fixing the head on a 3rz. But anyway to try and solve your problem this is from a gregory's manual for a vn.

(1) incorect fuel pressure: check the fuel pressure with a fuel gauge
(2) leaks in the fuel system: check the connections and components for leakage
(3) faulty coolant temp sensor operation
(4) faulty manifold air temp sensor (mat sensor)
(5) faulty manifold absolute pressure sensor (map sensor)
(6) faulty fuel injector operation
(7) Vacuum leaks
(8) faulty thermostat operation
(9) faulty cooling fan operation

Hope this gives you something to work with?
Cheers Brad

Post by **MrSparkle** » Fri Dec 18, 2009 9:59 am

bracar80 wrote:I have to agree with Struth this is not solving mates85 problem the motor he has is what it is, there cheap easy to fix and in my case reliable.
The 3rz's do have valve problems and I could buy a complete motor and gearbox for a lot less than fixing the head on a 3rz. But anyway to try and solve your problem this is from a gregory's manual for a vn.

(1) incorect fuel pressure: check the fuel pressure with a fuel gauge
(2) leaks in the fuel system: check the connections and components for leakage
(3) faulty coolant temp sensor operation
(4) faulty manifold air temp sensor (mat sensor)
(5) faulty manifold absolute pressure sensor (map sensor)
(6) faulty fuel injector operation
(7) Vacuum leaks
(8) faulty thermostat operation
(9) faulty cooling fan operation

Hope this gives you something to work with?
Cheers Brad

This was by far the most helpful post yet. mates85 if i was you id be following this checklist and im sure you will see a drastic improvment in your economy.

I had a 3rz lux and it was a good car. I got over 400 out of a tank and that was on 33's all the engine had changed was a set of extractors. I personally dont like the commodore engine conversion either but i can see why people would do it. Its cost effective, easily sourced and repaired, And being thick on the ground means parts are cheap for it too.

Post by **Dents LN65** » Sun Dec 20, 2009 12:13 pm

I would also check diff ratios 84 4runner had
4.875 for petrol or
4.55 for diesel

I recently removed a Holden V8 253 from a 4runner which had 4.1 diffs fitted.

(my 3RZ gets 420 - 450kms / 55 - 57ltrs approx mostly highway driving) my 2c!

Post by **taps** » Sun Dec 20, 2009 3:41 pm

I had a v6 commo in a 84 4 runner, th700, 4.88 on 35's and loved it......

Heaps of power, good on road and off......but

It was a thirsty beast, 300 to 350 km of 70 lt was about the norm, it was also hot to ride in with no air con, could and would not stop, and i used to feed it a fair few C.V,s but it was a good truck, would not go back there thou.

Post by **stock 4runner** » Sun Dec 20, 2009 4:39 pm

i had one years ago with a lux manual and got told you had to run the speed sensor to solve this problem witch ment i had to buy an adapter for my speedo cable not sure if its the same with an auto. but i never ended up doing it , just put it on gas

Post by **taps** » Sun Dec 20, 2009 7:42 pm

stock 4runner wrote:i had one years ago with a lux manual and got told you had to run the speed sensor to solve this problem witch ment i had to buy an adapter for my speedo cable not sure if its the same with an auto. but i never ended up doing it , just put it on gas

Marks Adaptors sell those speed sensors, i think they trick the ECU to think its in a commodore and then able all the fuel settings to be used, i never had one in mine either, there about $350 from memory ???

Post by **wacky** » Tue Jan 05, 2010 3:51 pm

Coolant temp sensor, O2 sensor and airbox intake temp sensors would be the ones I'd be looking at, nab a few spares off ebay and swap them over - the beauty of these engines is they're easy to work on, and cheap to find bits for.

O2 sensors and coolant temp sensor can combine their issues to give a fuel-hungry pig of a thing, I'd start with them first.

Post by **33boxer** » Tue Jan 05, 2010 9:31 pm

ive heard that the map sensor might contribute i also heard that if you shorten the hose to it it will give you a power gain i had a vn an the temp sensor was stuffed and it ran like crap swapped it over and never had a drama best be checking you sensors

Post by **longlux** » Wed Jan 06, 2010 6:57 am

Thread cleaned.

If it happens again, I will be recommending bus rides.

Post by **Vulcanised** » Wed Jan 06, 2010 2:39 pm

a screwed up O2 sensor will stuff your mileage up.

you could poke this one it.....

http://cgi.ebay.com.au/Supercharger_W0Q ... 414bc2a017

a guy at J7 had one on a V6 conversion in his hilux and it was un-catchable. He said it ran out of puff at about 5,500 rpm, but a pulley change to increase the speed of it would have helped. Other than that he said it had mounds of torque and didn't really need to go over those revs.
I am told that the standard holden MAP sensor will handle up to about 8psi..... but an after market one wasn't expensive.

Post by **mates85** » Tue May 18, 2010 9:54 pm

Been a while since ive been back on here !

so i put new plugs , leads, O2 sensor, fuel filter and VR coilpack

it overall didnt seem to do much better for fuel economy did run a little better although sicne the coilpacks my tacho doesnt work anymore not that it matters but strange it doesnt work.

im thinking diff ratio might be my problem it changes gears way too fast i tihnk it changes to 3rd at 30km/h (turbo 700)

i have to check what ratios i have now but what diff ratios would best suit this appkication

VN V6 - Turbo 700 - 31" A/T tyres

and can anyone recommend a place to get new ratios or can they be sourced from another model hilux ?

also my front diff seal that stops the oil from leaking from the axle has gone on my drivers side, if im changing my ratios would it be easier to change this seal at same time ? my mechanic quoted $600 - $700 to change the seal its a bitch of a thing for an old truck one expensive seal but i know its a prick of a job !

cheers guys ! thanks for all replies !

Post by **brad 93hilux** » Tue May 18, 2010 10:39 pm

mates85 wrote:
and can anyone recommend a place to get new ratios or can they be sourced from another model hilux ?

also my front diff seal that stops the oil from leaking from the axle has gone on my drivers side, if im changing my ratios would it be easier to change this seal at same time ? my mechanic quoted $600 - $700 to change the seal its a bitch of a thing for an old truck one expensive seal but i know its a prick of a job !

cheers guys ! thanks for all replies !

Look around on this site, or ebay... you will pick up a bargain if you look.

That price is unbelievable

for the mechanis to charge that much just for the seal... You would be getting ripped off to the max... By the way it is a very easy job not hard at all

To do that seal you are saying is no more then $80 for a seal kit and less then 3 hours labour to do it.

You could do all the seals, bearings, greases and diff oil for $250-300... the price he is charging i would hope he is doing both sides.

Buy a repair manual, it is very straight forward and will save you a sh*t load... offer someone a case of beer and they would prob do it with you...

And yes you do these at the same time as changing the centres... (they will be pulled apart any way)...

Brad

Post by **mates85** » Thu May 20, 2010 9:52 pm

sh!t hey , i got another quote from a 4x4 specialist they want $500 jsut for changing 1 sides seals ?

any advice as to where to buy new diff gears at a better ratio i dunno what ratio i sohuld get a 3.9 or maybe 4.11 ???

if im gonna keep this 4runner i have to do something about economy costs like $70 to fill and around town im getting 250-280km a tank and its daily driven lol.

anyone on here wanting to do a cashy ? i have a tint workshop all work can be done in in sutherland shire in south sydney.

im going to see if repco can order in new diff gears in diff ratios cause i get a smokin price from repco cause i know a store manager but would be good to know other places that i definately can get them from for a good price !

thanks guys appreciate all the help ive had thus far !

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