L28 02 sensor reducer part? (please help!)

[PhilbertZ]

Hi all,

 

So, I failed smog, and have been doing some tune up things to the car to improve my chances on the second pass.

 

Removing the 02 sensor didn't work out - in a BAD way - the hex bolt started to strip so I stopped and took to my mechanic to finish the job, along with my new O2 sensor.

 

He could not get it off - it was fused or something...it broke. The O2 sensor is screwed into some kind of a "reducer" - A larger hex bolt threaded piece that screws into the manifold (similar to aftermarket sender unit mounts for guages - oil pressure, etc).

 

So now he has the reducer out, with the broken old O2 sensor fused in it. He's tried a vice and breaker bar- and heat - nothing is breaking that thing loose.

 

He's trying to locate a reducer piece that will fit where the old one did (and will fit the new O2 sensor), but is coming up short.

 

Any of you guys had this happen and if so, how did you resolve it?

 

Until I find a fix, I'll have a hole in my manifold and am unable to drive it

 

Thanks

[PhilbertZ]

well, my mechanic ended up burning/grinding the old one out and was able to utilize the old reducer with the new O2 sensor.

 

Now timing and valve adjustment and crossing fingers for smog!

[woldson]

Are you familiar with the afm?

[Guest Rolling Parts]

That is normal for a 30 year old part on the exhaust system.

The "fix" I did last year on an 83 turbo was to removing the down pipe, drilling out the old part, and then welding on a new O2 "bung" to the down pipe.

 

You're right. The old parts simply "fuse" to where there is no way to separate them.

[PhilbertZ]

Are you familiar with the afm?

 

The air flow meter? I'm learning about it through the EFI Bible I downloaded (70+ pages!).

 

What does it have to do with the O2 sensor being fused on though?

 

I was surpirsed that it was fused on (indicating it had not been changed in 20+ years) - the previous owner took meticulous care of the car since new - $20,000+ in receipts when I got it.

[Guest Rolling Parts]

I was surpirsed that it was fused on (indicating it had not been changed in 20+ years) - the previous owner took meticulous care of the car since new - $20,000+ in receipts when I got it.

 

I'm not surprised.

The car without the O2 feedback can work well enough to pass previous slack smog checks. The O2 feedback is only a "narrowband" anyway so it's not a very advanced control mechanism. What ususally happens is that something else causes a smog faillure (vacuum leak, bad sensor connectors, old injectors, leaky valves, stuck thermostat, fouled spark plug, clogged EGR, etc). I don't have the FSM in front of me but I don't believe that the O2 correction factor on the ZX engine for fuel mixture was a very high percentage control adjustment factor for trimming the mixture time.

 

A couple of questions:

1) Is the mechanic younger than the age of your EFI system and

2) What state are you in that it requires a smog check on a car over 25 years old?

3) When it still fails smog after swapping the sensor, will he give you a refund?

[PhilbertZ]

Thanks RP for the feedback on this.

 

1) He's about twice the age of my car

2) CA (ugh) - my registration says "High emitter profile"

3) Don't know....it will cost $20 more to test again (didn't charge me the full amount when I failed - subtracted $20 out from total

 

Since failing, I replaced plugs, wires, cap/rotor, O2 sensor.

 

I will do timing and valve adjustment before going back.

 

I also have on order BOSCH replacement connectors for my injectors, cold start valve, etc ($10 each with free shipping - can't beat that!). Once that's all done, I will take it back for re smog.

 

Not sure how best to check for vacum leaks?

[Challenger]

I would work on checking all your vacume lines. Also is your egr working?

[PhilbertZ]

I would work on checking all your vacume lines. Also is your egr working?

 

Thanks Challenger.

 

I haven't done an EGR test - not sure how to but can look in the FSM.

 

I did the ECU/EFI system resistance test with an ohmmeter over the weekend and things seemed to all work correctly, according to the FSM tests.

 

Dumb question, but what is the best way to test vacuum lines? and if bad, can I just replace with generic silicon ones (are the thicknesses relatively the same across the board in the engine bay)?

[Guest Rolling Parts]

My mistake, I did not read the "CA" in the sig line & profile(Doh!).

 

Checking vacuum leaks can be done (in a gross, overall way) by running the engine at idle and removing the oil cap. If the engine keeps running fine then you have a vacuum leak. If the engine stumbles and almost dies, then you probably don't have a leak.

 

A better approach might be to go through the FSM http://xenons130.com/reference.html

Read Section EC and it lists the steps to test individual components.

I just look at them and there are a LOT of things to test.

 

Did they just give you a "fail" based on any particular emission (COx or NOx) or maybe a fail at a particular RPM? This is one of the systems I hate to troubleshoot!

[PhilbertZ]

My mistake, I did not read the "CA" in the sig line & profile(Doh!).

 

Checking vacuum leaks can be done (in a gross, overall way) by running the engine at idle and removing the oil cap. If the engine keeps running fine then you have a vacuum leak. If the engine stumbles and almost dies, then you probably don't have a leak.

 

A better approach might be to go through the FSM http://xenons130.com/reference.html

Read Section EC and it lists the steps to test individual components.

I just look at them and there are a LOT of things to test.

 

Did they just give you a "fail" based on any particular emission (COx or NOx) or maybe a fail at a particular RPM? This is one of the systems I hate to troubleshoot!

 

Thanks for the oil cap tip!

 

They test at 15 MPH (1657 RPM) and 25 MPH (2674 RPM).

 

The "MAX" legal limit for CO is 1.35% @ 15 MPH, and 1.15% @ 25 MPH. I was *Just* under at 25 MPH with a 1.14% reading, and *way over* at 15 MPH with a 2.82% reading.

 

So basically, it looks like I'm running rich and have too much CO coming through - right?

 

My NO readings were very low - no issues there.

 

I've read that you can change the air/fuel mixture on the AFM when removing a factory installed screw cover and turning a screw, but honestly, I'm nowhere near that level of confidence/expertise, and I would do more damage than good there (plus I don't have diagnostic equipment to do changes on the fly).

[Guest Rolling Parts]

They test at 15 MPH (1657 RPM) and 25 MPH (2674 RPM).

 

Interesting,

It's only too rich below 1675 rpm?

There is a "Throttle Switch" (on the throttle shaft) that richens up the mixture below 1,000-900rpm but does not at mid-rpms. It's adjustable with a screwdriver. Look on page EF-41 on the manual.

 

Run the engine with the cover off the Throttle Switch and make sure that the center contact is not touching either the idle or WOT (the outer 2 contacts) when the car is running at 1650 rpm. When they touch at idle or wide open, it sends in some extra fuel....

 

Hope it's that simple....

[PhilbertZ]

Interesting,

It's only too rich below 1675 rpm?

There is a "Throttle Switch" (on the throttle shaft) that richens up the mixture below 1,000-900rpm but does not at mid-rpms. It's adjustable with a screwdriver. Look on page EF-41 on the manual.

 

Run the engine with the cover off the Throttle Switch and make sure that the center contact is not touching either the idle or WOT (the outer 2 contacts) when the car is running at 1650 rpm. When they touch at idle or wide open, it sends in some extra fuel....

 

Hope it's that simple....

 

I just checked out the pages you're referencing (I have the same FSM at home too).

 

Are you talking about the Throttle position switch (TPS)? I did have an issue with the TPS last year when it got wet during an engine cleaning (car went into "limp mode") - I had to blow dry it to make the car work again...maybe it's corroded and causing extra contacts like you mentioned above?

 

I'll see if I can run that test - is it as simple as taking off the TPS cover and using a tolerance tool (like I use for valve adjustments) to measure the gap, and then adjust it?

 

 

Phil

[Guest Rolling Parts]

Are you talking about the Throttle position switch (TPS)? I did have an issue with the TPS last year when it got wet during an engine cleaning (car went into "limp mode")

 

is it as simple as taking off the TPS cover and using a tolerance tool (like I use for valve adjustments) to measure the gap, and then adjust it?

 

Not trying to be rude here, but it's NOT a throttle position sensor(TPS) but it's simply a switch that is closed only when the throttle is not at cruise. That difference in terminology/function is why it makes sense that the switch is not adjusted correctly and can cause an over-rich at the low RPM side. Adjustment is as simple as loosening the phillips head screw and sliding the whole switch to where it needs to be. Yes, remove the cover to see the switch contacts and adjust per the FSM.

 

There is also not a "limp mode" on these cars, no ECU memory, no "codes". This EFI system is crude and that's why attention to the basics is required. Adjust the valves, the throttle switch, inspect vacuume lines, timing, temp sensors, etc. When you adjust it to spec, it will run in spec.

[PhilbertZ]

Not trying to be rude here, but it's NOT a throttle position sensor(TPS) but it's simply a switch that is closed only when the throttle is not at cruise. That difference in terminology/function is why it makes sense that the switch is not adjusted correctly and can cause an over-rich at the low RPM side. Adjustment is as simple as loosening the phillips head screw and sliding the whole switch to where it needs to be. Yes, remove the cover to see the switch contacts and adjust per the FSM.

 

There is also not a "limp mode" on these cars, no ECU memory, no "codes". This EFI system is crude and that's why attention to the basics is required. Adjust the valves, the throttle switch, inspect vacuume lines, timing, temp sensors, etc. When you adjust it to spec, it will run in spec.

 

Thanks - no rudeness taken at all - I really appreciate the detailed feedback and your patience with my level of knowledge here - I really am learning a lot as I go here.

 

In good news, I tried the oil filler cap while running removal and it killed the engine in seconds - so that would imply my vacuum system is not leaking, correct?

 

I'm going to try to do timing, valves, switch adjustment tonight. I've also ordered some new Bosch connectors for the injectors, cold start valve, etc, since mine were brittle and falling to pieces.

 

Thanks again

[HowlerMonkey]

That's amazing......I've never seen anybody actually get out that "reducer" from any nissan turbo elbow.

 

That must have been a horrible pain.

 

You owe him a six pack of tasty beer.

[PhilbertZ]

That's amazing......I've never seen anybody actually get out that "reducer" from any nissan turbo elbow.

 

That must have been a horrible pain.

 

You owe him a six pack of tasty beer.

 

Yeah he's done me a lot of favors - I think he stll feels bad because my truck's drive shaft fell off 2 blocks from coming to see him about a strange noise (after he installed a new transmission for me)....that's another story.

 

It's actually not a turbo - just a normal manifold. Once the O2 sensor was ripped mostly out, it he could fit a socket around the reducer. Getting the destroyed O2 sensor out of the removed reducer was the hard part....

 

RollingParts: I adjusted the Throttle switch last night - easy job - and it was out of spec. I checked the timing too, and it was 10 degrees, plus or minus 1 - right on spec. I'll do valves tonight, and check timing again.

 

Bosch injector plugs come today in the mail too.

 

Thanks everyone!

[renatodato]

Don't forget the catalytic converter. If it's the original cat, most likely needs replacing. This could cause a failure in CA smog test no matter what you do to the rest of the car. What I did was to buy a CA legal cat from Autopartswarehouse.com for about 130. dollars. Since it's a bolt on, I switched the old one on for driving around, then, the new one gets bolted on when test time comes around. This way, the new cat will last indefinitely,lol.

Also, would have been easier to get the female bolt at the junkyard and tossing the old one. Besides, it's free at the junkyard, hehehe. Just finished my strut/suspension rebuild job. I learned a lot tricks, so if you have any questions let me know. I get most of my parts online on Rockauto.com. Everything at Autozone and Kragen is twice as much.

Renatodato

South San Francisco

[PhilbertZ]

Thanks Renatodato - The cat will be my last resort, if I fail again.

 

I was doing my valve adjustment this weekend and am now confused.

 

The FSM says to adjust the first batch of valves when the number 1 cam lobe is pointing straight up, then rotate the camshaft so that the same lobe is pointing straight down to do the other batch of valves.

 

However, for TDC in cylinder 1, wouldn't the timing mark be at "0 degrees" on the crank pulley (I just did my timing so I know when this is lined up)? The reason I ask is, when the lobe is pointing straight up or straight down, the timing mark is NOWHERE near "0" on the crank pulley.

 

Should I be adjusting valves when the lobe up straight up/straight down, or when the timing is at "0" (then do a full rotations, and adjust second set...)?

 

Apologies if this is a noob question, but I don't understand which is the proper position in which to make the adjustment?

 

Thanks

[Guest Rolling Parts]

However, for TDC in cylinder 1, wouldn't the timing mark be at "0 degrees" on the crank pulley (I just did my timing so I know when this is lined up)? The reason I ask is, when the lobe is pointing straight up or straight down, the timing mark is NOWHERE near "0" on the crank pulley.

 

You don't need to worry about TDC when adjusting the valves; all you need to do is fully unload the valve (cam lobe straight up) and then adjust the clearance.

 

As far as TDC with 0 degrees on the timing mark, the #1 cam lobes should actually be splayed out to both sides equally (neither the exhaust nor intake should be trying to open a valve at that time!). So yea, the cam lobe should be no where near pushing a valve rocker when the timing make is at 0.