Running rich

[DR7740 Lurker Find all posts View Profile Close DR7740]

Hi all, new to the world of Prado,s & Pradopoint. Did have this posted somewhere else but no response so trying here.

90 series petrol prado 2000 model

Hi all, looking for some info please on my 2000 model prado 3.4v6 petrol.
At idle the exhaust smells to me to be very rich?, a bit like after mowining your lawn with a 2 stroke mower? your cloths smell fuelly.
A blip on the throttle & she puffs back smoke.
no check eng light on
idle seems ok
plugs/air filter all new (plugs removed and were very black???)
no inlet manifold or vacuum leaks detected
exhaust seems ok(standard) no leaks
I read a few articles re the maf sensor/cleaned it-no change
now replaced it with a new 1(genuine purchased off ebay) but the car wouldn,t pull at all so had to put old 1 back(old maf seems to drive car fine?)
Is the fault only at idle??
I suppose i need to have a probe stuck up its bhind to really know?
Would be happy to have a good tech check it out but where???-live in the hills district sydney
Any comments appreciated .

Regards,
Bruce

[marknatasha89 Lurker Find all posts View Profile Close marknatasha89]

There should be an idle mixture screw. This really needs a gas analyser at a workshop to tune.

If you get an LPG conversion, then the entire petrol system (MAF, mixtures, etc, etc) is bypassed when running on gas. Instead LPG has 3 simple adjustments which can be tuned each 20 000km via a gas analyser if you are keen. The payback period should be around 30 000 km at far less CO2 and other pollution emissions. The only mild drawback I have experienced so far is a slight reduction in range to around 900 - 1000km including the sub-petrol tank. All good.

[Leethal Advanced Member Find all posts View Profile Close Leethal]

Hi Bruce,

Sounds very much like a dirty/faulty MAF sensor, the Ebay "Genuine" sensor may have been for a Hilux 3.4 which I believe is a different sensor to the Prado one.
It is possible to adjust the mixture via a "control" pot in the engine bay (behind the air cleaner), you may have another sensor reading incorrectly (say the IAT reading colder than actual temp) as long as the sensor gives the ECU a signal, it will not generate a fault code so it might be worth getting the ECU checked by Toyota.
The most likely cause is the MAF sensor though and I would clean it again with CRC MAF Sensor cleaner or try and source a known functioning sensor first.

Lee

[DR7740 Lurker Find all posts View Profile Close DR7740]

Ok, many thanks for the reply.
I here what you say about that MAF(trying get get a known good 1 isn,t easy unless i knew of someone with the same?)
Does the Hilux sensor have the same numbers stamped on the MAF?)
What about the ecu system temp sensor-any known checks/measurements to test?
Regarding the idle mixture adj any idea how to do?
Many thanks again for your help.
Regards,
Bruce

[michaeGa Lurker Find all posts View Profile Close michaeGa]

Hey Bruce,

Similar prob with mine (1999 3.4 V6 petrol); only owned it 6 months. Very "rich" smelling on start up; also appalling fuel economy (~20L/100km town driving). Mechanic adjusted mixture screw which is located on inside of engine bay above drivers side front wheel. If you look hard you can see a R (rich?) and L (lean?) at the base of the balck plastic screw. Adjustment was done with a gas analyser, turned the screw about 4-5mm toward the L.
Rich smell gone, no noticeable decrease in engine power when driving and latest fuel economy 16.4L/100km town driving (some while towing trailer).

Pretty happy, looking forward to a longer road trip to try for better fuel figures. Hope this helps.

Mike.

[rthy Lurker Find all posts View Profile Close rthy]

Would you happen to have a pic of the mixture screw?

[Evo's 90 Lurker Find all posts View Profile Close Evo's 90]

Hey Bruce,

Similar prob with mine (1999 3.4 V6 petrol); only owned it 6 months. Very "rich" smelling on start up; also appalling fuel economy (~20L/100km town driving). Mechanic adjusted mixture screw which is located on inside of engine bay above drivers side front wheel. If you look hard you can see a R (rich?) and L (lean?) at the base of the balck plastic screw. Adjustment was done with a gas analyser, turned the screw about 4-5mm toward the L.
Rich smell gone, no noticeable decrease in engine power when driving and latest fuel economy 16.4L/100km town driving (some while towing trailer).

Pretty happy, looking forward to a longer road trip to try for better fuel figures. Hope this helps.

Mike.

I might need to look at this on mine too, I always thought mine smelt a bit rich and economy is around 20L/100km around town as well. I would be interested to see if this a common adjustment point in toyota's that do not run o2 sensors as I have the same problem with my 2.7L hilux.

Pat.

[DR7740 Lurker Find all posts View Profile Close DR7740]

Hi Mike, many thanks for the info, found the sensor but does not have a screw ? only a hole?-could see the R & L so must be the sensor you are talking about?. Tried to turn towards the L but it only moved 1/4 of a turn-may be that this sensor is faulty???
Just to confirm-sensor is black, 3 wires to conector, mounted on rhf engine bay guard area by a phillips head screw.
Regards,Bruce