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Lowering NOx with e85?

fl0w3n

fl0w3n

Red Skull Member
Joined
Feb 11, 2022
Member Number
4817
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NorCal
Failed a smog because of high NOx and I’m trying to find the easy way out if there is one.

Vehicle is a 1990 Renix 4.0 in an XJ

Thoughts on adding some e85 to the tank and retesting? Am I going to completely eat away the fuel system with just a couple gallons? Will a couple gallons even make a difference?

Here’s the results if that helps :homer:

0691045F-454E-446C-9633-ACBD3F178CAD.jpeg
 
Don't really see E85 helping to lower the NOx that much. And from what I understand, the increased NOx output can be from several things but I would start with either the EGR system, catalytic converters, or carbon build up in the upper end of the engine.

You could try something like Sea Foam to clean the carbon build up in the upper end of the engine. But I would start with testing the EGR and the catalytic converters. Start with the obvious then work your way from there.

Good luck... :beer:
 
fl0w3n said:
Failed a smog because of high NOx and I’m trying to find the easy way out if there is one.

Vehicle is a 1990 Renix 4.0 in an XJ

Thoughts on adding some e85 to the tank and retesting? Am I going to completely eat away the fuel system with just a couple gallons? Will a couple gallons even make a difference?

Here’s the results if that helps :homer:

0691045F-454E-446C-9633-ACBD3F178CAD.jpeg
Click to expand...
my sons 1997 nissan lowered NOX by pulling the timing back, it wAs a slug but a couple of degrees got it to pass.
 
Will Scarlet said:
Don't really see E85 helping to lower the NOx that much. And from what I understand, the increased NOx output can be from several things but I would start with either the EGR system, catalytic converters, or carbon build up in the upper end of the engine.

You could try something like Sea Foam to clean the carbon build up in the upper end of the engine. But I would start with testing the EGR and the catalytic converters. Start with the obvious then work your way from there.

Good luck... :beer:
Click to expand...
EGR is definitely not functioning well, but I figured that’s why the HC and CO numbers were so low from what I understand. Other than not wanting to fiddle fuck with making the EGR system work since I’d rather just not have it, I was thinking it might raise HC and CO numbers by dropping combustion temp. Could be wrong on that though.

Obviously if I just need to make the system function as intended then I need to do that. Just being lazy and hoping for another way out.
Stingray said:
my sons 1997 nissan lowered NOX by pulling the timing back, it wAs a slug but a couple of degrees got it to pass.
Click to expand...
Interesting, I’d have to check on the Renix but I think from my recollection the distributor timing is locked and only signals to the computer when to send spark, so I’m not sure it’s user adjustable. I’m sure there’s a way around it though.
 
I’ve heard acetone used to pass smog but they never got into details about what pollutant was over what limit.

84 Carbed 2.8
 
fl0w3n said:
EGR is definitely not functioning well, but I figured that’s why the HC and CO numbers were so low from what I understand. Other than not wanting to fiddle fuck with making the EGR system work since I’d rather just not have it, I was thinking it might raise HC and CO numbers by dropping combustion temp. Could be wrong on that though.

Obviously if I just need to make the system function as intended then I need to do that. Just being lazy and hoping for another way out.
Click to expand...
I understand your not wanting an EGR system on your vehicle, but you're in California and there's no easy way when it comes to emissions.

Good luck on finding that work around... :beer:
 
Mike Honcho said:
Move to a free state? :flipoff2:
Click to expand...
You accepting rent applications :homer: maybe you can finish my build for me too :flipoff2:
Clb said:
Blow screwsome for a freedom pass ???
Sorry :flipoff2:
Click to expand...
I tried, the new system doesn’t have a lot of leniency :eek:

Will Scarlet said:
I understand your not wanting an EGR system on your vehicle, but you're in California and there's no easy way when it comes to emissions.

Good luck on finding that work around... :beer:
Click to expand...
Im sure I’m just being lazy and wishful. One thing that gives me hope is the later model 4.0s went away from the EGR so they somehow figured out how to control NOx without it.
 
See how you have low co and hc, but high nox? It is reading averages. Your 02 sensor is reading full rich, then full lean,and bouncing back and forth. Have you tried better 02 sensors? Or watching the o2 voltage?
 
I used to always oil my air filter to limit air in and run 5 gallons of toluene to whatever couple gallons of gas was left in the tank. One time the smog tech asked me to go undo whatever I had done as Sacramento wouldnt believe I even had a car hooked to it. I went and topped the tank off with regular and brought it back and he passed it
 
Your C02 % is at 15.3, that means your cat is doing great, actually its working its butt off. You can do a quick comparison of your 02 vs CO to get an idea of rich vs lean, and your 02 is higher than your CO, indicating slightly lean. A lean mixture = high combustion temp = increased NOx.... So it could have too much air for whatever reason or not enough fuel. Yòu could also have an exhaust leak skewing the numbers.

I would start by ensuring the EGR is in good working order, its sole purpose is controlling NOx. When you apply vacuum to the valve the engine should stall or at least severely stumble. After that, check for vacuum leaks and ensure no exhaust leaks (cracked exhaust manifold) and go from there
 
Fishnbeer said:
Your C02 % is at 15.3, that means your cat is doing great, actually its working its butt off. You can do a quick comparison of your 02 vs CO to get an idea of rich vs lean, and your 02 is higher than your CO, indicating slightly lean. A lean mixture = high combustion temp = increased NOx.... So it could have too much air for whatever reason or not enough fuel. Yòu could also have an exhaust leak skewing the numbers.

I would start by ensuring the EGR is in good working order, its sole purpose is controlling NOx. When you apply vacuum to the valve the engine should stall or at least severely stumble. After that, check for vacuum leaks and ensure no exhaust leaks (cracked exhaust manifold) and go from there
Click to expand...

Fancy way of saying to oil his air filter and run toluene to greatly increase his octane and lower his combustion temps like I said above.

:flipoff2:
 
My bad, I just read the numbers on the inspection report and not the replies.

Maybe I will have to start checking for that during inspections
 
Fishnbeer said:
My bad, I just read the numbers on the inspection report and not the replies.

Maybe I will have to start checking for that during inspections
Click to expand...
Haha, no its cool to see the reasoning behind it from someone who actually knows what thier talking about. (I dont. Just know its worked for me)


Since your in the know more then 99% here, what are some questionable tricks you have seen that work?
 
1. Place it on non op.
2. Get a P.O. Box in a smog exempt county.
3. Google homes for rent and take the two addresses to dmv and register said car to the home in smog exempt county but tell them it’s a cabin and you don’t live there permanently but your car stays there. Also tell them to send your mail to the P.O. Box. Once it’s taken care of take car off of non op and register.
 
NorCalJalopy said:
1. Place it on non op.
2. Get a P.O. Box in a smog exempt county.
3. Google homes for rent and take the two addresses to dmv and register said car to the home in smog exempt county but tell them it’s a cabin and you don’t live there permanently but your car stays there. Also tell them to send your mail to the P.O. Box. Once it’s taken care of take car off of non op and register.
Click to expand...
I’ve done this with a PO Box and my regular home mailing address. Doing it through AAA is a key I think, they aren’t scrutinizing like DMV typically is

Still need to smog on transfer of ownership, unless non-op somehow skirts that.
 
Fishnbeer said:
Your C02 % is at 15.3, that means your cat is doing great, actually its working its butt off. You can do a quick comparison of your 02 vs CO to get an idea of rich vs lean, and your 02 is higher than your CO, indicating slightly lean. A lean mixture = high combustion temp = increased NOx.... So it could have too much air for whatever reason or not enough fuel. Yòu could also have an exhaust leak skewing the numbers.

I would start by ensuring the EGR is in good working order, its sole purpose is controlling NOx. When you apply vacuum to the valve the engine should stall or at least severely stumble. After that, check for vacuum leaks and ensure no exhaust leaks (cracked exhaust manifold) and go from there
Click to expand...
Good info. I wouldn’t be surprised if there’s an exhaust leak, these 4.0s are infamous for cracking.

I have some different Volvo injectors instead of the stock ones, so I’d be a little surprised if it idles lean. I have an Arduino custom data monitor some dude made for the Renix, I’ll check again what my AFR is reporting at idle.

Last time I did a dump of the data these were the values - if there’s a 2nd or 3rd value for an item it is after it warmed up, whereas the first number is right off the bat cold

16-17 Hg of vacuum
12.8 Hg of MAP vacuum
1.6-1.8 V at MAP
30.0 Hg BARO
90* Water - 180 * Water - 210* Water
65* Air - 108* Air - 138* Air
13.5 Battery
13.8 V O2 Heater - 13.6 - 13.3
1.9-4.8 V Oxygen - 2.4 - 1.78
14.8-16.0 Air/Fuel - 14.9 - 14.7
Rich Exhaust - Rich - Rich
Closed Exhaust Loop - Open - Open
Off EGR - Off - Off
590-700 RPM idle - 590-650
116 IAC Turns - 109 - 64
17% Throttle
0.88 V Throttle
Closed TPS mode
5.6-6.0 Injector M/S - 5.8 - 5.5-6
0.6 Cold Enrich - 0.0 - 0.0
70-120 Short Term FT - 128 - 128
128 Long Term FT - 128 - 128
0 knock - 0 - 0
14-15* spark advance
0 retard
 
fl0w3n said:
I’ve done this with a PO Box and my regular home mailing address. Doing it through AAA is a key I think, they aren’t scrutinizing like DMV typically is

Still need to smog on transfer of ownership, unless non-op somehow skirts that.
Click to expand...
Have to non op it before its due for smog
 
Are all your vacuum lines in good shape? I had broken ones on the passenger side near the firewall.


Edit: the internet says a bottle of ISO HEAT into a 1/4 tank could work some magic after you drive around polluting the earth substantially.
 
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I ran the lambda calculator for you based on the numbers you are running at 14.9:1 (lean). Again, these numbers could be skewed from an exhaust leak. If you have an exhaust leak you can hear the exhaust coming out of a crack, but what is also happening is it draws air into the exhaust as each 'pulse' goes through. So that 02 number may not be accurate.

If you run the calculator again and replace the o2 reading of .3 with .01 (same as CO reading) the ratio is 14.7:1.

Check exhaust for leaks and verify proper egr operation
 
Fishnbeer said:
I ran the lambda calculator for you based on the numbers you are running at 14.9:1 (lean). Again, these numbers could be skewed from an exhaust leak. If you have an exhaust leak you can hear the exhaust coming out of a crack, but what is also happening is it draws air into the exhaust as each 'pulse' goes through. So that 02 number may not be accurate.

If you run the calculator again and replace the o2 reading of .3 with .01 (same as CO reading) the ratio is 14.7:1.

Check exhaust for leaks and verify proper egr operation
Click to expand...
That’s cool data man.

Any insight on how the 4.0 from later generation was able to get by with no EGR from the factory?
 
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