Ava

Now that I have my head gasket and tranny problems solved, there's more...

In the part of the world I live in there are not much new (or even used) parts available. One of the former owners of my Toyota Hilux Surf 3.0L V6 (known as 4Runner in the US) had apparently no choice but to use what he could get. He mixed three original injectors with three injectors from a Toyota Corolla. The cylinder displacement difference is 100cc (400cc against 500 cc per cylinder) so I could imagine the computer has no choice either and gives one side of the V6 too much and the other side too less petrol in order to find a balance. Currently I'm running at or below 9.4 mpg.

I've looked around but cannot find three Hilux injectors so I was thinking, if I can find them, to put in three extra Corolla injectors in place of the originals so I have a matched, but possibly too small, set of six injectors.

A. Would that help getting fuel consumption down to a reasonable level? Would the EFI computer know how to handle this situation?

B: What would I loose in terms of horsepower, accelerating, etc.

C. Should I look for specifics on the (used) injectors like special codes? For instance, I now have two Corolla injectors 23250-16150 marked "DD" and one marked "BB" (also marked 15 and 17 respectively). I suppose that these codes tell us something about how much fuel they'll inject at a given number of milliseconds. I also have three standard 4Runner/Surf injectors 23250-65020, one marked 09 and ‘K’ and two marked 12 and ‘J’. These also have the imprint 230, which could be the number of cc/min according to R.C. Engineering’s info on http://www.rceng.com/technical.htm .

Ava.

Gadget

Wow. What a mess that is.

All six injectors shoudl be the same size or you are asking for serious problems, but you already know that.

If you can find out what size or capacity the stock injectors are we might be able to pull our resources and help you out.

I might be able to get my hands on a set of stock injectors from a 3.4 which are 238cc.

Anyway try to find out what size they are. Check with Corey. I think he had is cleaned and flowed and that might help.

Gadget

www.GadgetOnline.com

FattyCBR

a- Theoretically the ecu should be able to add fuel in closed loop operations based on what the O2 sensor is telling it, however, once in open loop it will revert to preprogrammed maps and that is probably when you would damage the engine. Since your mileage is so low have you ever changed the O2 sensor, that is one possible cause of poor mileage, but I understand your engine is probably a bit out of whack from the different injectors.

b- I'm not sure specifically, but it would probably be significant once the injectors can no longer supply enough fuel and that's when you would hurt your engine.

c- The code you need to look for is this part number: 23250-65020. As far as what I've been able to determine there are no other codes on Toyota (Denso) injectors that give any indication of their size.

If you want I can look around up here and try and find you some 4Runner injectors if you're interested.

Ava

Any thoughts on how to check for a broken O2 sensor? That could be one thing to check before doing anything else.

I've put in a thermostat when I replaced the almost dissolved water pump. I'm finally operating in closed loop, but seeing the speed my fuel gauge is going down, it was no great help.

Ava.

MTL_4runner

That O2 sensor(s) could definately be a problem if it hasn't been done in a long time. You will need to probe it with a multimeter so verify its operation. Otherwise like any part you can just replace it and see what happens. If you test it, get a good service manual for working on the car (if you don't already have one by now) that will give you the senor specs. That way you can test all the sensors in the air/fuel delivery system to help you get the best gas mileage. Any sensor out of spec, replace it.

I would also suggest to have someone get a full matching set of injectors from the boneyard up here and mail them down to you. They are not that heavy and should be cheap enough to mail. Not sure where in S.A. you are?

Ava

I have the Haynes manual, but I don't think I've seen values for the O2 sensor in there. If you have any measurement figures, don't hold back.

If all else fails I might need a few injectors.

If you read the text under my avatar you'll see I live at place the Dutch traded for New York. :pat:

Ava.

FattyCBR

The O2 sensor produces an oscillating signal that varies between 0-5 volts. The thing is though that even when it's bad it can still produce an oscillating signal that will tell the ecu the wrong thing and the ecu will inject too much fuel and your fuel mileage will go to crap.

Have you replaced your plugs and wires? Also if you have a distributor a new cap and rotor would help. Also try removing your catalyttic converter, it may be clogged and that can kill your mileage as well.

Do you want New York back? They have a senator I can't stand.

MTL_4runner

It should be about 0 to 1 volt on an O2 sensor in general. Some do vary slightly more. The highest I have seen them go was about 2V and MAF sensors are generally more the range you are talking about at 0 to 5V.

I don't have a manual for your year 4runner to verify but the sensor should oscillate around 0.3 to 0.7v (but be relatively stable in that range) if the sensor is ok. There should be a section with a bunch of tables in the manual where it gives all the resitance and voltage values for testing all the sensors. Most manuals also have a sensor troubleshooting section to them too. There are other conditions which can push the O2 sensor out of the range so you need to be thorough about checking all of them and not replace a good sensor by mistake.....like a bad converter! If you have no regulations down there then you could just gut the converter and know that is not the problem for sure. Otherwise you will need to be a bit more vigilant in your testing skills.

Check out this page for info:
http://www.autoshop101.com/asetest/asetest12.html
It is a test but it will help you learn quite a bit about them and what situations can cause what.

I can't stress how bad mixing the injectors is for computer controlled engines......simply may not run ight without them. Trouble is that the computer will adjust injector pulse time based on the assumption all the injectors are identical....if they are not then some cylinders will run rich and some will be lean so that the O2 sensor sees the best fuel ratio possible.