Failed Emissions

I took the truck into emissions testing and it failed due to high HC GPM & CO GPM. This didn't surprise me as the truck was sitting for years before I picked it up a month ago. I put a new weber 32/36 on her and she's running great now but apparently not clean enough for CO. Here are my numbers:

HC GPM = 3.7392 (limit is 3)
CO GPM = 62.6656 (limit is 25)

This is my first time having to go through emissions, and if anyone has any advice on how to tune this to get these numbers down that would be greatly appreciated! Please keep in mind I just put a new weber 32/36 on with a fuel pressure reg., otherwise everything is stock.

Thanks!

Running rich. No idea how altitude effect tuning though. Got extra jets? Are the pulse air pump and EGR working?

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Originally Posted by noahwins

Running rich. No idea how altitude effect tuning though. Got extra jets? Are the pulse air pump and EGR working?

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Yeah, I ordered the extra jets for altitude and they have not been installed yet bc the truck was running great with the stock jets. My first step will be to instal those but I just wasn't sure if it will require additional tuning beyond that. Not wild about taking it in to a shop to have them tune it, but I also don't want to make a dozen trips to emissions, ya know what I mean.

EGR appears to be working properly. Not sure what/where the pulse air pump is though?

Thanks for you input!

Pulse air is the snake pipe running to the exhaust manifold from the air cleaner. It's a weird shape because it's tuned length. The exhaust pulses suck cold, clean air from the air cleaner and inject them into the exhaust stream to help burn any unburned hydrocarbon. I just remembered if you have the Weber, this device is most likely deleted from your emissions system.

There are 2 spare vac line nipples on the Weber carb for devices like the EGR valve.

But simply spending the time to rejet is probably the easiest way to get it through smog instead of getting the PAIR and EGR systems working again. Rejetting the Weber carb is simple. Any competent mechanic should be able to get it running well enough to pass smog in not too much time assuming the truck is in good shape otherwise. The 2.0 is not a particularly dirty engine.

Yeah, Pulse Air has been removed. Thanks for the info on that though. EGR is still in place and hooked up to the weber.

I'm planning on putting the new jets in today or tomorrow. These are the jets weber sold me for altitude, so I'm guessing this should help resolve my problem of running too rich. I'm just wondering if I will have to do anything else that I will have to do? Is it worth just taking the truck into a local mechanic who I trust and has all the diagnostics for testing emissions? I'm assuming they should be able to get this done in 1 hour or less.

Thanks Noah!

I don't know but I'll tell you this: The tech at a local classic BMW shop brings all of his old 2002s to run on our dyno. They are all converted from Solex to the trusty Weber 32/36, like our trucks. He makes adjustments on the fly while I'm driving the car on the dyno and it takes seconds for him to swap our jets in between dyno runs. He brings a handful of jets and a long screwdriver because every car is different. It takes him maybe 5-10 minutes total to get the car running well enough for shakedown runs, and another 5 minutes to get it fine tuned for either lowest emissions to get past smog or max power, depending on what the customer wants. There's more to it than this but from me observing him work and asking occasional questions, it's basically finding the sweet spot on a seesaw between lowering CO, which lowers HC but raises NOx (leaner), and raising CO, which raises HC and lowers NOx (richer). He's an old Hungarian master who's been working on BMWs for 40 years and can probably do this stuff in his sleep. Due to smog laws here, he leaves the emissions equipment on 1976s and takes it off on 1975s and older. Adding smog equipment (air pumps, EGR, cats) give you extra dimensions to work with to cut down tailpipe emissions.

Thanks again for your input Noah. I found a mechanic who has access to all the equipment used my emissions for testing. He's also from MI (where I'm from) so I have extra good faith in him! He may be slightly more than I wanted to pay, but he also takes the truck to the testing station to ensure it passes before returning the vehicle to me.

I should have an update on the status in the net couple hours. I'll keep ya posted (and my fingers crossed)...

Well, thankfully the emissions is somewhat out of my control at this point. As I mentioned in the previous post, I dropped the truck off with a local mechanic who takes the truck through emissions himself. He's been able to reduce the HC #'s but has been striggling to get the catalist cool-enough to pass the CO #. Bare with me on details here, but he said he has to splice in some sort of catalytic converter in order to get the catalyst to cool down to pass the test. Again, this is all pretty new to me, and these #'s don't really mean a whole lot to me, soI'm just going with the flow.

I will say, although this has taken much longer than I had imagined, the mechanic has been very informative along the way and reasonable. They guarantee your vehicle will pass for $80, and they pay for additional tests ($25/ea.). Hopefully his splice technique will pass the test today - I'm getting eager to get Cinnamon back!

On a side note, he did make a comment about how good the truck runs. Now, if we can just get it to run a little cleaner...

So, I've realized that I'm just talking to myself on this thread :(, but I hope this helps someone else with similar issues in the future.

Finally, the truck PASSED emissions!!! The mechanic had to splice in a piggy back catalytic converter behind my factory catalytic converter to get the CO GPM #'s below the mark, then remove it after the test. From what I can understand, the catalyst was too hot in turn not allowing the CO #'s to drop to below the legal limit. According to the mechanic, the weber does not allow you to micro-tune as well as the factory mikuni (which I'm sure we can all agree with). Although he agreed the factory carb is garbage, he did state that they are far more tune-able (for emissions purposes) than the weber. I'm sure not everyone will agree with his comment, but the bottom line (to me) is that she passed emissions!

Although this topic isn't very interesting (at all), I hope this might help someone else who runs into a similar problem as I did. I'm glad I didn't try to resolve this problem on my own, I would have pulled my hair out trying make adjustments, test, adjust, test, etc... not to mention the tests alone would have cost a small fortune. Lesson learned: Don't be afraid to tackle a problem or fix on your own, but know when to turn to the experts for help!

I've been reading closely. I do smog all day long. It's interesting to me. Congrats!

Is your cat toast? How many miles? I have a spare OEM with 106K you can have soon. Should be good for another few 10,000.

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Originally Posted by noahwins

I've been reading closely. I do smog all day long. It's interesting to me. Congrats!

Is your cat toast? How many miles? I have a spare OEM with 106K you can have soon. Should be good for another few 10,000.

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Thanks noahwins - glad someone out there is reading, lol! He didn't say the cat was bad actually - but I will confirm that with him and let you know. He did mention that he's had to do this in the past to a few other vehicles with aftermarket carbs. Maybe a temp solution to replacing the cat?

Regardless, I'm stoked! Just in time to get her plated before times runs out on the temp plates.