Super Gross (polluter) Smog

[jrowell]

Re: Re: Super Gross (polluter) Smog

From RENIX experience, be sure the two vacuum lines at the back of the air box aren't switched and the tubes are clean.

That's a good point. They are hooked up right, but i wonder if that door in the air box is stuck in the "warm up" mode and sucking air right of the exhaust manifold. That would cause high combustion temps i think.

 

[tjmotter]

As I read through this thread I see references to "lean conditions" and "bad O2 sensors". These should be mutually exclusive since the default operation in the event of a bad O2 sensor should be for the vehicle to run rich (exactly like the open loop condition when the car is cold).

Since you haven't looked at the injectors I would start there. Mine would get gunked up and run poorly (bad gas mileage as well) after about 50K. If they are partially plugged, this could create a lean condition. It might be a good idea to pull the intake, clean it, and replace those injectors.....

 

[KENS 87]

Jrowell sounds to me like your egr is not working causing reburn gas to get traped..not circulating possibly raising engine temp...also if your top end feels slugish could be cat is pluged.. seems your 02 sensor is okay but possibly week..
Hc is burned fuel
Co is unburned fuel
high Nox would be EGR & CAT not operating properly

Does it burn oil?

 

[KENS 87]

Just went through the smog crap with my 87'
Got mine to have emissions of new vehicle..

I had the nasty smell too it would gag me...lol
Basically all the burned and unburned gasses are getting through the cat
Probably runnin in open loop ..even when warm ..theres a sensor not working somewhere

Id start with the Egr.. Get the bugs worked out then weld up a new cat..break it in..
get it smogged..take cat off and save it for next time!

 

[jrowell]

I have a hard time believing it's the cat, as it hardly has any miles in it. I do think it is a sensor or injectors causing my problem. Maybe the temp sensor. I will check egr.

 

[KENS 87]

U can put a temp gun before the cat and after the cat..
Should be about 100 degrees hotter before muffler.. Not the best way to check
But it will give u an idea, were its at...sometimes cats seperate from inner honeycomb
to outer layer..especially if its driven hard through the ruff stuff..i would put some injector
Cleaner too..........how does it idle when warm?.......

 

[jrowell]

Re: Re: Super Gross (polluter) Smog

U can put a temp gun before the cat and after the cat..
Should be about 100 degrees hotter before muffler.. Not the best way to check
But it will give u an idea, were its at...sometimes cats seperate from inner honeycomb
to outer layer..especially if its driven hard through the ruff stuff..i would put some injector
Cleaner too..........how does it idle when warm?.......

Idles great. Starts good. Runs good. I'm going to either clean the injectors or put some lower mile ones in. It's going to be a jeep wrenching weekend for me!

 

[GSequoia]

Idles great. Starts good. Runs good. I'm going to either clean the injectors or put some lower mile ones in. It's going to be a jeep wrenching weekend for me!

I'm not sure if 4643 is in Bako or Fullerton. If it's in Bako I'd PM cal and beg him to bring his diagnostics tool with him. Then swing by and hook it up. The live readout really helps pinpoint the problem. I was chasing a failing issue, once I had my MT2500 I was able to see that I had an issue with the O2 wiring, fixed that and I was good to go.

 

[jrowell]

I'm not sure if 4643 is in Bako or Fullerton. If it's in Bako I'd PM cal and beg him to bring his diagnostics tool with him. Then swing by and hook it up. The live readout really helps pinpoint the problem. I was chasing a failing issue, once I had my MT2500 I was able to see that I had an issue with the O2 wiring, fixed that and I was good to go.

It's in Bako, so I'll give that a shot. I'm really interested to see what that diagnostic tool will show.

 

[jrowell]

knock sensor wire. It has a braided wire that is not hooked to anything. What is its purpose? Strength?

 

[old_man]

The knock sensor is nothing more than a high impedance microphone that picks up acoustical noise from the ping or knock. Since it is high impedance, it can easily pick up electrical noise, so they add a shield to the wire. The bare wire runs up inside the foil shield wrapped around the wire to help make the shield work better. If the ping sensor is not connected and working correctly, it will not inform the ECU of the ping. Ping is a symptom of high combustion temps. The ECU tells the EGR to open, feeding a small amount of exhaust gas to mix with the incoming air, lowering the combustion temps.

 

[jrowell]

What controls when this preheater door closes and opens? It's at operating temp and still open. I switched the two hoses and it still opens (sucks air off manifold). What controls the vacuum? Does the little round dohickey inside the airbox sense the temp and close?

 

[jrowell]

Re: Re: Super Gross (polluter) Smog

The knock sensor is nothing more than a high impedance microphone that picks up acoustical noise from the ping or knock. Since it is high impedance, it can easily pick up electrical noise, so they add a shield to the wire. The bare wire runs up inside the foil shield wrapped around the wire to help make the shield work better. If the ping sensor is not connected and working correctly, it will not inform the ECU of the ping. Ping is a symptom of high combustion temps. The ECU tells the EGR to open, feeding a small amount of exhaust gas to mix with the incoming air, lowering the combustion temps.

So if that shielding has deteriorated (foil wrap missing) over a section of the wire what should i do? I was just going to throw it in some split loom and call it good.

 

[BulletMaker]

Ya, in reading the hundreds of High Nox threads, I've came across a couple that say bypassing it made the results better. Maybe it'll make a little difference either way, I just don't see it causing a 3000 nox number. Of course, that is my uneducated in smog equipment opinion. I could be totally wrong!

The EGR system recycles exhaust gas into the cylinders, this has the effect of cooling down the burn temp of the fuel. The HO engines got around this by having a slightly larger head that essentially held back some of the exhaust gasses as a way of making the engine "EGR-less". I suppose it does work at the expense of compression.

Generally speaking, high NOx is the result of high cylinder burn temps, this can also be happening if you're dumping too much fuel into the cat which tries to burn all the HC into CO2, but energy is evolved in this process, which means NO can also be evolved during this process.

FYI, NO2 and NO smell like chlorine and burn the nose and eyes. Not sure if this is the "smell" you're getting from the tail end or not.

IMO, if you're running too rich, your O2 numbers will be low (burning gas in the cat). I tend to think this is a lean-run condition, which EGR and cleaning out the fuel system and possibly thinking about new injectors will become critical to passing smog.

 

[jrowell]

Re: Re: Super Gross (polluter) Smog

The EGR system recycles exhaust gas into the cylinders, this has the effect of cooling down the burn temp of the fuel. The HO engines got around this by having a slightly larger head that essentially held back some of the exhaust gasses as a way of making the engine "EGR-less". I suppose it does work at the expense of compression.

Generally speaking, high NOx is the result of high cylinder burn temps, this can also be happening if you're dumping too much fuel into the cat which tries to burn all the HC into CO2, but energy is evolved in this process, which means NO can also be evolved during this process.

FYI, NO2 and NO smell like chlorine and burn the nose and eyes. Not sure if this is the "smell" you're getting from the tail end or not.

IMO, if you're running too rich, your O2 numbers will be low (burning gas in the cat). I tend to think this is a lean-run condition, which EGR and cleaning out the fuel system and possibly thinking about new injectors will become critical to passing smog.

Chlorine... That may be a better description... I have found that my egr solenoid is not activating when vacuum is applied. I think that is part of my problem. I think the air box pre heater being stuck open sucking air of the exhaust manifold is another part.

 

[jrowell]

Ran seafoam through it. Didn't really get as much white smoke as I expected.
Anyone know if a 88 egr solenoid will work on an 87? They look a little different.

 

[jrowell]

Put a scanner on it tonight and it showed no signal from knock sensor/ open loop. It's a new knock sensor and the wire looks good all the way to the C101. Going to pop that connector open tomorrow and clean it out.

What would the "no signal from knock sensor/ open loop" do to my smog test and MPG's?

 

[Hellbent]

FWIW...
I've owned several renix xj's, none of them have ever had a plugged in & working knock sensor(they've always seemed to run better without it-never had any ping issues). They've all passed ca smog with flying colors, running good ol' crap ca 87 octane.

Put a scanner on it tonight and it showed no signal from knock sensor/ open loop. It's a new knock sensor and the wire looks good all the way to the C101. Going to pop that connector open tomorrow and clean it out.

What would the "no signal from knock sensor/ open loop" do to my smog test and MPG's?

 

[Hellbent]

I'd be looking very carefully at the whole egr system, it's main purpose in life is NOX reduction.
I did have my '87 PASS smog years ago with a non-functioning egr valve, I guess the guy only checked it visually-not actually functionally. NOX numbers were quite a bit higher than with it working, but it still passed. It does help a lot.

 

[GSequoia]

You need to get into closed loop. OPen look doesn't pay attention to things like the O2 sensor. It would probably be best to start by carefully looking at all wiring. When mine wouldn't hit closed loop it was a short in the O2 heater circuit, perhaps start there.