grosso

All standard SW20 3sgte will have a narrow band with one wire.

Not all 3sgte, Gen 3 oxygen sensors are (4 wire)

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Carmikey

grosso

All standard SW20 3sgte will have a narrow band with one wire.

Not all 3sgte, Gen 3 oxygen sensors are (4 wire)

Sent from my SM-J320ZN using Tapatalk

And the reason for this that a Gen 3 has a MAP senor instead of an Air Flow Meter and I suspect it has a wide band in it.

Mr2, 3sgte ... 80s-90 (design days of sw20) o2 sensors were narrow band ... gen1-2 different number of wires to gen3-5 as later design send power (called heater in the wiring diagram) said to assist sensor response. The gen3-5 is not a wideband as per today’s Bosch 4.9.

This is separate operation / signal to a MAF/MAP.

Hi,
 
Hope you get it sorted. I'm new to this forum and want to start a new thread but can't find the button. Where is it please?

Well I finally got back to my MR2 problem, and after checking with a couple of contacts, it seems the little things always trip us up.
 
The suggestion of a FPR was thrown around and it was suggested that the return line to the tank should be checked to make sure it's not blocked or restricted. After taking the return line off, I tried blowing through the hose, and I couldn't, it seems to be completely blocked.
 
So just as an experiment, I hooked up a temporary hose from the return hard line, into the filler neck and immediately it ran like I always expected it would. 

I drove it around our 200 metre driveway, and it happily lights up the rear wheels!
So my question now is, if the rubber hose in the engine bay is not blocked, and it isn't, is there another rubber hose further down toward the tank?

I'm trying to eliminate the possibility that when the tank was dropped to fit a fuel pump, that the mechanic may have kinked or squashed another rubber hose further downstream.
I'll try to back it up onto ramps tomorrow, but thought someone here may know of another rubber section which I will try to find and test first.
 
Then I need to find a water leak which shows on the ground under the passenger seat, I hope it's not the hose from hell!
 

Hey mate, I just had a similar issue with running rich, mine was O2 sensor. Replaced that and it was all good. Also I would check your inside your ecu for leaking or expanded capacitors. (Just another problem I ran into after Restoring one back That had been sitting a while)

@ 92, my 1992 3SGTE runs a 2 wire o2 from factory

Tony Brown.
As stated earlier, the O2 sensor is really only actively controlling mixture during closed loop operation.
Regarding the steel hardline (Return line to tank). From where it exits the engine bay on the forward  bulkhead I think it is a continuous steel line along the top of the tank and into the tank via the fuel pump access /hanger. It certainly goes to the bottom of the tank right adjacent to the pump pickup.
Maybe try a little compressed air but gently ? Might be an idea to change oil too if it's been badly contaminated with fuel.
 
 
 
 

Hi Falcon, thank you for the info regarding the fuel line, I tried compressed air but no luck with the fuel filler cap on or off. Might be time to push a wire through it....
 
Your suggestion of changing the oil is a good point, I don't think it will be an issue since it has barely been driven until now but it is still cheap insurance and will be done.
 
Thanks again, Tony.

I should also mention, I did find a Denso single wire 02 sensor and fitted it in March, and as predicted it made no difference to how it ran.
 
I do believe that it was simply a fuel return issue, artificially raising rail pressure to the point where it would run excessively rich.
 
It now runs very well if I bypass the hard line back to the tank, no smoke, no fouled plugs, no blubbering.
 
Fixing the coolant leak is now most important since I am unable to drive it while it's leaking coolant.
 
 
 
 

If you want to save having to remove the fuel tank you could cut out a section of the filler vent steel pipe and insert a " T " piece to take that fuel pressure regulator return line back to the tank.
Make sure to cap the existing hardline on the front bulkhead.
Ask me how I know it goes to the bottom of the tank ?!!