can I

[oolbreeze]

Hey finaly beat the ranger issues except I have no 02 sensor reading but the plug is still in the motor. So no check engine light until truck warms up still runs good. Until you run it hard and let up but fuel mixture does not and you loose 1/2 tank in 59 miles. So would I be better to unplug the 02 sensor from motor so it does not read and put motor in failure mode. or how do I bypass the issue?

 

[RonD]

What year and engine?


You have no O2 sensor reading, not sure what that means?

But with no "reading" then it is already in "safe mode" or limp mode, and MPG will be in the toilet.
Computer has to run engine Rich in that mode, because Lean will burn up pistons and valves.
Rich can also cause Cat failure.

You need to get O2 system working

Using a carburetor is the only way to "by pass" it

 

[oolbreeze]

it is a 91 3.0 v6 and was given to me with all kinds of issue. right now the 02 sensor is plugged into motor but has no sesor actually attached. it runs fine fo awhile sometimes days then goes into safe mode. it was in failure until replaced the coolant tempature sensor with all test passed code 41 is all I get not 98 just out of range. my dad runs his sonata without 02 and has for years just little worse gas milage.
I dont drive it once it starts running rough but it has dropped up to 5 gallons gas in 50 miles but I mean from 45 to 50 it dropped alot of fuel before parked it.

 

[oolbreeze]

has no cat so no worries there

 

[RonD]

Don't really get that, O2 sensor is maybe $40-$80.
Gasoline is like $3+ bucks a gallon............so you are looking at 25 gallons of gas to break even on O2 sensor cost at $80

Why in the "wide world of sports" would you not replace a bad O2 sensor, it would pay for it self in a month even if you only drove it a few miles a week

Yes you can drive it for years without one, but really don't see the logic in it, I guess I am just cheap

 

[oolbreeze]

Like I said free with a lot of stupid ass issues such as jb welding the back brake lines into the drums, welding half the cat to a home made exhaust and cutting the other half off and then the mechanic I told to plug into the flex pipe until I can finish the new exhaust took that to mean zip tie to the exhaust pipe and watch it burn. The 02 sensor is actually 44 dollars but I dont get why it is only sometimes that it acts up sometimes after days. And it had this problem when the 02 sensor was still in the y pipe of original exhaust.

Today when the thing started running rough and rocking like a fuel injector was misfiring or something it did not show fail mode or limp mode or safety mode just out of range or low voltage. It seems to happen after I get in it like it does not stop sending the amount of fuel after I let off. And this issue has gotten increasingly better with every new part or adjustment including cutting the orginal sensor off.

So that is why I am so confused. I mean I hear you when you say it can't be running without 02 sensor but I have actually got 25 mpg out of a tank ans I have gotten 15mpg. It has only been in fail mode once and that was the coolan sensor and a used computer out of my other ranger because mine has a pin mising. Turns out a missing pin is better than another trucks PCM.

 

[oolbreeze]

by only showing the 02 code I mean got pass codes on the ignition on motor off test and all the computer memory test both read 11. All the actuators and relays activated and all sensors where found. The reason I have not replaced it yet is because I have no where to plug it into the exhaust as of yet.

There is not any factory opening for the sensor and I do not know how to put some thing like that into the new y pipe. Best I can think of is to cut a groove at the end of one of the pipes I am using to replace the flex pipes and stick it in there. Plus it is a single sensor made to go before the cat I thought those sensors relayed message but did not dictate to the PCM how to mix the fuel but the coolant temp and warm air sensors did that. Thats why they call it the master sensor on this year truck.

 

[det107]

There is not any factory opening for the sensor...

Any el cheapo muffler specialist worth his salt should be able to put a bung hole to take an 02 sensor -

 

[Rex2nr]

...the new exhaust took that to mean zip tie to the exhaust pipe and watch it burn...

Just needs the zip tie replaced

Might not want to hit any "el cheapo" place again

 

[RonD]

What you are describing now is an engine problem and the O2 voltage(code) is just a symptom of that problem not the cause of it.

I would clean and test MAF(mass air flow) sensor.

Also the fuel pressure regulator(FPR) on the fuel rail has a Vacuum hose attached, the vacuum pulls open the FPR while engine is running.
If FPR leaks this vacuum hose can pull extra fuel into the intake, causing drop in MPG and rough running.
Pull off this vacuum hose and check it for fuel.

 

[Tedybear]

We're going to wind up crossing posts and getting confused. This is also in urgent help needed. Need to stick to 1 thread to avoid issues.

 

[oolbreeze]

Can I

Ron D
please evaluate because I have put another mass airflow on it as well as a new 02 sensor and coolant temperature sensor. The vacuum hose you talk about is it the one on inline fuel filter? because I smell gas and motor is choking and knocking on the rich mix,

 

[RonD]

No vacuum line on a fuel filter.
Fuel filter is in the frame rail below cab, under drivers seat area.

You have a 1991 Ranger 3.0l

There will be TWO fuel lines connected to the engine.
One will be the IN fuel line coming from the fuel pump in the gas tank, through the fuel filter then to the Fuel Rail just above lower intake.
The OTHER fuel line is the OUT, it is connected to the Fuel Pressure regulator, it may "look" like a filter, a can, but it isn't.
Picture of it here: http://www.ebay.com/itm/1991-93-For...tor-/271340603567?vxp=mtr&hash=item3f2d2908af

 

[oolbreeze]

Can I

there was no fuel in line. the whole thing is just awkward. With each new part it clears up for a day