3FE Emissions woes

[CO92FJ80]

Hello all, been fighting Colorado emissions testing with the old 3FE. First try, it failed miserably. I then gave it a full tuneup, plugs, wires, cap, rotor, air filter, replaced all the vacuum lines and new thermostat so that it now actually gets to normal operating temperature. I found the temperature switch for the cold start injector was messed up and disconnected that, ran it again and just failed on only CO this time. Was tested with a 50/50 mix of E85 and regular unleaded. Previous owner (member of this group) had to get an emissions exemption last go round. I am so close to passing. I think there’s a way, but could use some advice from you all. Any ideas? Last two test results attached.

 

[Rzeppa]

Looks like you've already done most everything I can think of. On a 3FE is timing electronic or mechanical? I know on my 60, I have to set the static timing back to factory 7° BTDC to pass, then after it passes I set it back to 11° where it runs better and gets better fuel economy. The only other thing I can think of for your 3FE is maybe clean (or rebuild/replace) your injectors. Oh and make sure your smog pump is working properly. The last time I had to get my 60 smogged I discovered that the pump was working but either the ABV was stuck or was leaking and the air wasn't getting to the rail. I just bypassed it and ran the outlet of the pump directly to the air injection rail and then passed.

The biggest problem our old rigs face is that our state legislators and the bureaucratic drones they hire to set the rules keep moving the emissions goalposts on us. Originally the standard was ppm CO and HC, now it is gpm on the rollers, which was never required when our rigs were manufactured.

 

[Cruisertrash]

@CO92FJ80 I’m not a 3FE expert by any stretch, but whenever anybody posts about emissions troubles I always post this graph. It was very helpful in getting my 2F to pass.

The hard part is on you: finding out what widgets, valves, and circuits affect the mixture in your motor. My best guess is that you’re running a touch rich - that would make NOx and HC low, but get you into the part of the CO curve that is high. Does the 3FE have any accommodation for thinner air at altitude like the 2F, or is that handled by the MAF? Did you clean or replace the MAF? Can you neck down or partially choke off your EGR? I live in the world of the carburetor so take that guess with a grain of salt.

 

[subzali]

Air pump working properly?

O2 sensors check out?

Cat converters operating ok?

 

[CO92FJ80]

Air pump working properly?

O2 sensors check out?

Cat converters operating ok?

Cats are new, 300ish miles. O2 are a couple years old, air pump is definitely sucking if I pull the tube off the air cleaner housing.

 

[CO92FJ80]

Looks like you've already done most everything I can think of. On a 3FE is timing electronic or mechanical? I know on my 60, I have to set the static timing back to factory 7° BTDC to pass, then after it passes I set it back to 11° where it runs better and gets better fuel economy. The only other thing I can think of for your 3FE is maybe clean (or rebuild/replace) your injectors. Oh and make sure your smog pump is working properly. The last time I had to get my 60 smogged I discovered that the pump was working but either the ABV was stuck or was leaking and the air wasn't getting to the rail. I just bypassed it and ran the outlet of the pump directly to the air injection rail and then passed.

The biggest problem our old rigs face is that our state legislators and the bureaucratic drones they hire to set the rules keep moving the emissions goalposts on us. Originally the standard was ppm CO and HC, now it is gpm on the rollers, which was never required when our rigs were manufactured.

I haven’t checked timing yet, it’s a pain in the butt to see the timing mark. I will check it this week. I’ve read about guys swapping the air tube on the 60’s but can’t seem to figure out how to do so on the 80. I think the egr ducting was different between the two models, but am not sure of that.

 

[Rzeppa]

EGR only affects NxOx, not CO or HC

 

[subzali]

Just thinking about incomplete combustion…timing could have an effect.

Also thinking maybe weak spark or something harder to diagnose. Proper plugs and plug gap? Coil going bad? Not to send you down a rabbit hole but maybe there are some checks to do to verify proper function.

Fuel injectors come to mind too-want to make sure there is good fuel atomization.

 

[CO92FJ80]

Just thinking about incomplete combustion…timing could have an effect.

Also thinking maybe weak spark or something harder to diagnose. Proper plugs and plug gap? Coil going bad? Not to send you down a rabbit hole but maybe there are some checks to do to verify proper function.

Fuel injectors come to mind too-want to make sure there is good fuel atomization.

As far as I know injectors the the factory set. You could be on to something there. Plugs, cap raptor and wires are new, NGK plugs and wires, factory gap. I was thinking maybe it’s time to adjust the valves? Definitely gonna try retarding timing as well.

 

[Cruisertrash]

EGR only affects NxOx, not CO or HC

EGR is recirculating unburnt hydrocarbons. It affects NOx, but also alters the HC content. Not that it will solve an incomplete combustion scenario, but nonetheless…

 

[Crash]

For an in depth discussion google 3FE high CO emissions and find the Ih8mud thread from years ago. Speaking from hard earned experience, every single thing about your engine has to be functioning as well as you can possibly get to pass today’s standards. Requirement numbers are stricter than when your truck was built which doesn’t seem fair, but there it is. It’s the reason I went with five year collector plates, just to less often deal with the drama you are experiencing now. You are really close, numbers-wise. Good luck!

 

[Rzeppa]

EGR is recirculating unburnt hydrocarbons. It affects NOx, but also alters the HC content. Not that it will solve an incomplete combustion scenario, but nonetheless…

No, EGR dilutes the fuel/air mixture with exhaust, thus reducing combustion temperature and production of NxOx. If there is any unburned hydrocarbons in the exhaust then there is a problem that needs to be fixed. I got schooled on that whole business by the head of the Colorado Air program when I was getting my exemption for my non-USA FJ45, which had no smog equipment whatsoever. I forget the guy's name, but he was a PhD chemist by training and took an interest in my rig when I brought it in. I had to take it to their headquarters rather than one of the regular Air-Care places to get the exemption, and he personally fiddled with my carb and timing to get the lowest readings. He also said that at our elevation, there's hardly any need for EGR, but the feds keep on the state over ozone readings.

 

[Cruisertrash]

No, EGR dilutes the fuel/air mixture with exhaust, thus reducing combustion temperature and production of NxOx. If there is any unburned hydrocarbons in the exhaust then there is a problem that needs to be fixed. I got schooled on that whole business by the head of the Colorado Air program when I was getting my exemption for my non-USA FJ45, which had no smog equipment whatsoever. I forget the guy's name, but he was a PhD chemist by training and took an interest in my rig when I brought it in. I had to take it to their headquarters rather than one of the regular Air-Care places to get the exemption, and he personally fiddled with my carb and timing to get the lowest readings. He also said that at our elevation, there's hardly any need for EGR, but the feds keep on the state over ozone readings.

Interesting. I’d love to talk to somebody like that in any field. I always thought EGR was for “more complete combustion of HC”.

I once knew a chemist with Kwal paint when I ran the warranty department of one of the largest painting businesses in the state. Really interesting dude to talk to, especially when figuring out oddball problems.

 

[subzali]

Interesting. I’d love to talk to somebody like that in any field. I always thought EGR was for “more complete combustion of HC”.

I once knew a chemist with Kwal paint when I ran the warranty department of one of the largest painting businesses in the state. Really interesting dude to talk to, especially when figuring out oddball problems.

You might be thinking about the air pump injection. It helps complete the combustion of any unburned HC coming out of the engine.

 

[SteveH]

air pump is definitely sucking if I pull the tube off the air cleaner housing.

Be sure the air pump is actually pushing air out the exhaust side into the head.

Jeff Zepp's comment: The last time I had to get my 60 smogged I discovered that the pump was working but either the ABV was stuck or was leaking and the air wasn't getting to the rail. I just bypassed it and ran the outlet of the pump directly to the air injection rail and then passed.

is very valid....try to arrange this.

 

[CO92FJ80]

air pump is definitely sucking if I pull the tube off the air cleaner housing.

Be sure the air pump is actually pushing air out the exhaust side into the head.

Jeff Zepp's comment: The last time I had to get my 60 smogged I discovered that the pump was working but either the ABV was stuck or was leaking and the air wasn't getting to the rail. I just bypassed it and ran the outlet of the pump directly to the air injection rail and then passed.

is very valid....try to arrange this.

Are they the same setup on the 60 and 80? I was under the impression they were different.

 

[Rzeppa]

They both have smog pumps and thus they both have to an air bypass valve (ABV). In one position it sends the smog pump output to the injection rail, in the other position it sends it elsewhere (back to the air cleaner?). But yeah, this system probably has more affect on CO readings than anything else, and if it isn't working properly there's no way to pass CO.

 

[CO92FJ80]

They both have smog pumps and thus they both have to an air bypass valve (ABV). In one position it sends the smog pump output to the injection rail, in the other position it sends it elsewhere (back to the air cleaner?). But yeah, this system probably has more affect on CO readings than anything else, and if it isn't working properly there's no way to pass CO.

I’ll look more into this. Thank you.

 

[AdamKFarmer]

Is there an emissions supplement to the repair manual? I have one for my 82 that steps through each system with tests, I also have to get it to pass smog.

 

[Rzeppa]

There are normally 3 FSMs:

• Chassis/Body
• Engine
• Emissions