[jstarzy]

Hi. I have a 1994 2WD with the 22RE engine and 52k original miles. it's been great since new, however, I've had a bit of running trouble I need to fix as the truck has failed NJ emissions inspection this weekend.

About 2 years ago the check engine light popped on and coded to the ox sensor as one of the choices. Since then, I've replaced the distributor cap, plugs and rotor and air filter. A local garage has inspected it as well, repairing the small crack in the pipe near the forward ox sensor and doing a few other things. They did not recommend replacing the ox sensor. When the truck failed inspection 2 years ago for the same emission problem, this garage did an injector cleaning and passed it for NJ inpsection.....now I'm back in the same situation, 2 years later.

The engine runs with a bit of hesitation until it gets warm. It did not do this prior to any of the problems or work above, so it seems there is something definitly causing trouble related to performance/emissions.

I'm pretty handy and have tools. Any suggestions would be quite welcome...thanks...Jim.

 

[sb5walker]

I would check for codes - the CEL doesn't light for all codes so you have to check. If you post good resolution close-up pics of your plugs, we could tell how it is running. Keep track of what plug from what cyl. See the factory manual, EFI System - Diagnosis chapter for instructions on pulling the codes. You can use a metal paperclip for the jumper.

Also, post your emissions numbers since they can highlight different problem areas and possible fixes.

Emissions threads:
http://www.toyotanation.com/forum/showthread.php?t=327671
http://www.toyotanation.com/forum/showthread.php?t=300515
http://www.yotatech.com/f116/emisions-help-180853/
http://www.yotatech.com/f116/i-need...o-emmision-testing-today-197928/#post51295545

How to read your spark plugs:
http://www.densoiridium.com/howtoreadusedplugs.php
http://www.tuner-junction.com/TJForum/engine-tech/1422-how-read-spark-plugs.html
http://www.autohausaz.com/html/spark-plugs_spark-plug-wires.html
http://aboutkarting.com/plugs/
http://roadstarclinic.com/content/view/70/127/
http://www.theultralightplace.com/sparkplugs.htm

 

[TOYOPARTSMAN]

Have you checked you EGR gas temp sensor or the throttle position sensor?

 

[sometoyotaguy]

sounds like an 02 sensor to me. They aren't that expensive, or hard to change.

It will run rich if the sensor is failing.

 

[jstarzy]

Thanks very much, everyone for this great info.

I reset the CEL before I went for inspection this weekend. It will eventually pop on and I will perform the code test again. If I get the OX sensor code I will replace the front (yes, its a CA-NY vehicle) OX sensor from Amazon.

I presume if this were the throttle body sensor that would send a different code?

Also...I've used non Denso cap and rotor and I think NGK plugs from a local Pep Boys.....any negative issues with that?

I have done no other work (except oil and coolant and air filter) to this engine in the 16 years 52K mi since I bought it new but there are no other issues than the mild rough running and failed emissions.

Thanks...Jim.

 

[TOYOPARTSMAN]

As long as they are NGK plugs, you should be okay. Im not sure if the TPS would set a different code, what got me to thinking was it ran fine until it warmed up. So I was offering places to check that I thought it could be.

If you can't find the O2 sensor on ebay, I do offer TN members 30% off MSRP and I only charge actual shipping costs plus $1.00 - $2.00 for materials, etc.

 

[sb5walker]

Thanks very much, everyone for this great info.

I reset the CEL before I went for inspection this weekend. It will eventually pop on and I will perform the code test again. If I get the OX sensor code I will replace the front (yes, its a CA-NY vehicle) OX sensor from Amazon.

I presume if this were the throttle body sensor that would send a different code?

Also...I've used non Denso cap and rotor and I think NGK plugs from a local Pep Boys.....any negative issues with that?

I have done no other work (except oil and coolant and air filter) to this engine in the 16 years 52K mi since I bought it new but there are no other issues than the mild rough running and failed emissions.

Thanks...Jim.

As mentioned, you do not have to wait for the CEL to "pop on" in order to read codes. Some codes never light the CEL.

Don't just replace the O2 sensor if you get an "O2 Sensor code" Two of the three "O2 Sensor codes" don't indicate a bad sensor in most cases - they indicate either a lean or rich condition which usually have a different cause. So post any codes if you have them.

Bad TPSs usually only cause bad idle test results, but usually don't affect mixture much if at all at higher rpm. Mixture issues tend more to be caused by clogged or leaking injectors, problems with the air meter, vacuum leaks, or ignition issues. Sometimes by exhaust leaks. A bad ECT could cause the computer to never switch to closed loop operation, in which case it will run rich.

Please post your test results so we know what kind of issues are going on with the motor. Also let us know what code you got. Those numbers will point toward the problem.

EDIT: The NGK plugs should be fine. I've found my 3VZE runs better on Densos than any other plug, even NGK, but the NGKs are good too. They may not run well for as long as the Densos will, but should be fine new. To be honest, I haven't noticed much difference with the caps, but the Denso rotors have some kind of carbide coating that makes them last much better than non-Denso rotors. I've noticed a couple other probably Japanese-made brand rotors also have a similar coating and probably last just as well. Again, any rotor when new will probably work okay, but cheap ones won't last near as long as a Denso.

 

[jstarzy]

Thanks again. I'll secure the codes and report back on the numbers when I can get some time on the vehicle again.

The emission failure occurred during both the low and high RPM test and were for 2 types of gases for both low and high. I will post the details as soon a I can.

The engine hesitates during load when warm (no apparent problem cold or hot). It seems to run ok at temp except for the emission failure.

Thanks...Jim.

 

[jstarzy]

More info......

I cancelled the check engine light prior to inspection. The diagnostic connector is now posting a continuous 2 blinks per second, which I believe is a "normal" indication. I presume the system needs to detect the fail again before it will post the code?

Per the NJ inspection report:

Mode: Idle: Fail

Gas Reading Standard
HC ppm 384 (220)
CO% 6.52 (1.2)
CO2% 11.1
02% 0.0

Mode: High Idle Fail

Gas Reading Standard
HC ppm 356 (220)
CO% 6.87 (1.2)
CO2% 10.7
02% 0.0

The "reading" is the truck, the standard is the norm. The baseline norms are in parenthesis. My truck's figures are not.

I can't remove the plugs to post pics just yet, my 13/16 socket is in the boat at the dock!

I hope this will shed some light on the repair I need to make.

I would consider just using a good local shop if I had confidence in one. The dealer is fairly far away and a hassle.

Thanks...any help is much appreciated.....Jim.

 

[sb5walker]

The CO readings indicate your engine is running rich. Common causes of rich running include tired O2 sensor (or corroded O2 sensor connector), leaking injector(s), including possibly the cold start injector, exhaust leak upstream of the O2 sensor (allows air/oxygen to be drawn into exhaust stream - fooling sensor), out-of-range air meter, bad engine coolant temp sensor (so ecu never switches over to closed loop operation), high fuel pressure (rare, could be caused by obstructed fuel return line or bad pressure regulator). Possibly the PAIR (Pulsed Air Injection) system is malfunctioning, but that's not real likely either. There are simple instructions for troubleshooting the PAIR system in the factory manual.

There may be other possible causes of rich running but those are all that come to mind at the moment.

The plugs will probably be flat black, but if there are any that are not that would be of interest.

I would try replacing the O2 sensor with a factory spec direct fit Denso, check the ECT, TPS and VAFM per factory manual specs, check for exhaust leaks, pull the cold start injector but keep it connected and make sure it doesn't operate for more than 10 seconds when motor first started. Plug the CSI's hole in the plenum with duct tape or some such.

If you don't find anything with those checks, or replacing the O2 sensor, a fuel pressure test would be a good idea. Testing the injectors for leaking isn't easy - there are procedures in the fsm but an easier alternative would be to send them to witchhunter.com - they do a great job cleaning and flow-testing injectors. They're affordable and turnaround is very quick.

It's a common misconception that a bad sensor will give a code. Actually the computer will only flag a sensor if it's shorting out or has an open circuit. But if a sensor is worn and is giving bad readings, the computer has no way of knowing that the information it's receiving is wrong, so you have to test the sensors, either by checking the resistance of the sensor's terminals, or by checking the voltage on the ecu terminals when ignition is on. Vicoor, one of our professional tech members, recommends the latter. There are target volts in the EFI - TROUBLESHOOTING section of the factory manual. The VS voltage from the air meter tells the computer how much air is going into the motor. If it's reading out of range, that could cause the computer to inject too much fuel.

If the back of the throttle plate is dirty, I'd clean the throttle body with a throttle body specific cleaner. Be sure to get no solvent on or in the TPS as that would kill it.

I'd also run through a bottle of an injector cleaner that contains polyether amine, the only truly effective ingredient for the in-the-tank cleaners. The only two products that still have it are Red Line SI-1 Complete Fuel System Cleaner (most PEA) or CRC's "Guaranteed to Pass Emissions Test Formula" (less PEA than Red Line's product but still a good amount). Once you've found and fixed the cause of the rich running, replace the plugs for the repeat emissions test as carbon can cause spark to short out and it's difficult to clean all the carbon out of the plug.

EDIT: see this post for some tips: http://www.yotatech.com/f116/black-sooty-tailpipe-222388/#post51575732 The specs mentioned are for a 22RE but you can look up the specs for a 3VZE. Many of the tips apply to either engine.

 

[jstarzy]

SB5Walker...thanks very much.....!

I have my work cut out for me.......Jim.

 

[Vicoor]

As sb5walker said, you are obviously running very rich with the CO% that high. He mentioned the coolant temp sensor, but you should first make sure your engine is reaching operating temperature. A cold engine (or a bad coolant temp sensor that makes the ECM think it is cold) will certainly make it rich.

Go in the underhood diagnostic connector and check the voltage at the Oxy terminal while the engine is hot and running about 2000rpm. it should switch quickly back and forth from about 0.2V to 0.8V. If it is pegged over 0.8V that would tell you that the O2 sensor is correctly reporting a rich condition. Then you should look for a leaking cold start injector, bad fuel pressure regulator (leaking diaphram, or to high fuel pressure) Or other problems that would make it run rich.

If it hangs lower than 0.4V then the O2 sensor is incorrectly reporting a lean condition and you need to find out why . Could be a bad sensor, a wireing issue, or air getting in the exhaust up stream of the sensor.

Hope this helps

 

[jstarzy]

Thanks very much, Vicoor!

 

[jstarzy]

Thinking this over a bit, I'm certain that the area near the front O2 sensor on the front pipe may be leaking. The bolts for the sensor broke apart years ago and a local tech jery rigged the sensor to the shafts on the pipe and patched the leaky pipe with sealant near the sensor. It very well could be leaking. (is this common for this truck?)

From your notes, I see this could be tricking the sensor to think the mixture is lean and therefore have it report this to the ECU. The ECU would react by making what was otherwise an ok mixture more rich than it should be to compensate. All happening with a properly functioning O2 sensor. A .4 reading from the Oxy terminal would prove this and rule out the sensor? Is this correct? Can a fairly small (meaning not loud but noticeable) leak cause the state above?

I now see a new pipe is about $100 plus the labor. If this is the problem, I guess trying to repair the area around the O2 sensor is a waste of time. Is this better left to a shop for install considering access, tools, rusted manifold bolts, etc?

Am I heading in the right direction? The hesitation is only during warm up under load but the emission issues are at idle and speed....all the time.

I have no reason to think the engine isn't operating at temperature. The gauge goes to 1/3 as it has done from new and the heat gets good and hot as it always has.

Thanks again.....all this expert help is great...Jim.

 

[sb5walker]

I think a muffler shop would probably be the easiest way to repair the O2 sensor mount. They could weld in a new piece of pipe, assuming the front pipe isn't TOO bad. It is common for that mount to get very rusty - it's a PITA.

Depending on how bad the leak, that could definitely be the cause of your rich running. Good luck with it and please let us know how you make out.

 

[Vicoor]

If you have an air leak into the exhaust the O2 sensor reading could be anything from what might appear normal to pegged close to zero.

Basically if you have a leak, you should consider the O2 sensor reading to be unreliable until you can fix the leak.

The front pipes are prone to leaking (gosh, why do they only last 15-20yrs anyhow) but be aware that the studs sometimes pull out of the head and leak at the manifold gasket.

So get that exhaust tightened up and see how that helps.

 

[TOYOPARTSMAN]

Oh gosh, are they ever prone to exhaust leak. As some have stated, tighten up the studs as much as you can. If they back out, as they do, I would reinstall them with time certs and not heli coils. heli coils will work, but Time certs work better and longer.

 

[Vicoor]

Timecerts??????

Really it doesn't matter, I've use both (alot) and they both give good results, Just make sure you do them right, as they both can be boogered and then you'll have a real mess.

Any how the real reason I'm back is I was thinking I could give you (and everyone else a tip on finding small exhaust leaks.

Use a length of small diameter hose (like vacuum hose) and hold one end real close to your ear (don't stick it in your ear) then run the other end all around the exhaust. you'll hear a "fluttering" noise when you find a leak. Sometimes it helps to have an "assistant" hold a wad of rags over the tailpipe.

 

[jstarzy]

A bit more info.....

I got under the truck when running just now. There is a smelly, mild leak exactly at the front CO sensor mount. Everything is so corroded, a sealed fit is just not happening. The puff of air is mild but it is there, escaping right at the point the sensor fits into the pipe on the passenger side of the sensor.

At the diagnostic connector:

While cold and warming up: the front CO sensor is reporting -8.5v (yes, minus, I had to swap the VOM leads to get a reading. - at ox1 and + at the ground connector). It reaches -11 at hot.

The rear CO sensor is reporting -11 cold or hot.

Reving to 2k RPM causes very little fluctuation around the readings above.

The connection points at the cat are very corroded. I'm not sure how much repair could be done to this exhaust system outside of replacing just about everything.

Any more thoughts? and thank you....Jim.

 

[Vicoor]

When you test the O2 sensor at the diagnostic connector (it's actually OX1 not Oxy like I said before) you'll want to have the + lead to the OX1 terminal and the - lead to ground.

Like I said before It should fluctuate between 0.2V to 0.8V fairly rapidly (8 times or more in 10 seconds) when hot at 2000rpm. If it is reading really rich it could go as high as just over 1V and hang there.

11V is a problem.