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Discussion Starter #1
After new valve job and change to euro exhaust car runs like (or better) than new. But a month later it failed smog for the first time ever. Results said car was running over-the-top rich. Dan, my mechanic, found that the O2 sensor was non-operational. Put new sensor in. Took car in for re smog test. Failed again. Complete reversal of results: car running way too lean. I've taken it to 2 smog repair places here in San Diego and both just scratch their heads and say "I've never worked on one of these before..."

Smog test guy said if there was a way to adjust the mixture to run richer, the car would pass inspection.

My question is - is there a way to adjust the mixture on Bosch L-Jet? Or can anyone here suggest other solutions? Or is there a smog repair station here in San Diego that knows Alfas? Any and all help/suggestions appreciated.
 

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too lean and it failed? That is odd. Normally they don't like it running rich! hey Ho that's California!

I would test the CAT - this thread has some tips for you and have a look at post #7 here
http://www.alfabb.com/bb/forums/milano-75-1987-1989/159072-verde-failed-smog-how-do-i-fix-adjust-mixture.html

this L-jet page has everything you need to know on the system (....but were afraid to ask:)):
Bosch L-jetronic Fuel Injection Idle Adjustment Diagnostic and Tune Up Technical Article Alfa Romeo Spider Specific
 

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There is an idle air adjustment - but that only affects idle speed emissions. If you car is only being tested/failed at idle speeds consider checking that (info in the L-jet diagnosis/tune up page).

Make sure there are no intake air/vacuum leaks. Known as 'false air' these leaks mess up the L-jet system.
 

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But Mad North-Northwest
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In order to get a good diagnostic, you need to post your numbers.

If the O2 sensor was not working and it was running rich for a while you may have killed the cat. Then once you got the sensor working again and it was running properly, the cat wasn't working well enough to knock down the NOx, which may have resulted in a diagnosis of "too lean". But without the numbers I'm just guessing.
 

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Is the car running at rated temp? 180 190 F?

Lean running could be injectors not delivering enough fuel (part pluggage) per pulse.
Send them out for blueprinting and ultrasonic/solvent cleaning.
Too lean could also be "false" unmetered air leaks.
Check houses of auir intake plenum and OVS hose for cracks.
Elio
 

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Discussion Starter #7
Smog Test Results

First fail before new O2 sensor:
15 mph
HC(PPM)
MAX 124 GP 298 MEAS 250
CO2
MAX 0.78 GP 2.28 MEAS 3.91
25 MPH
MAX 98 GP 248 MEAS 245
CO2
MAX 0.66 GP 2.16 MEAS 4.44

Running super rich, right?!

After new O2 sensor installed:
Everything within specs except NO
15 mph
MAX 815 GP 2026 MEAS 2008
25 MPH
MAX 754 GP 1826 MEAS 2621
CO2
MAX 0.66 GP 2.16 MEAS 4.44

Now running too lean. Any more thoughts on the problem? Cat maybe? Don't think air leaks are the issue - Dan just went through the engine for me.
 

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But Mad North-Northwest
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My guess is the cat. NOx is the first thing that'll go when the cat goes bad. Like I said, it probably died from running so rich for a while.

It's pretty tough to make an EFI car run lean out the tailpipe so I doubt that's your problem. You might be able to tell from the post-sensor HC/CO numbers being *really* low (incidentally, you need all the numbers...even the ones that passed...to diagnose properly).

If you want to make sure there's a few ways to check things: you can check the O2 sensor output voltage to make sure your mixture's correct for starters. If that's okay it's most likely new cat time.

Incidentally, a decent shop with someone who actually knows fuel injection would know this stuff and know how to troubleshoot it. The Spider Bosch FI system is bog-standard. If the mechanics you're going to are scratching their heads, it's time to find new mechanics!
 

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Pretty much what everyone else says...

If it has been running rich for a while the cat will be tired or toast. A new California approved cat will cost you.

To get it to pass with high NOx as is:
- make sure there are no air leaks, consider swapping out any old vacuum hoses for new ones.
- replace fuel filter, make sure in-tank pump is working, and fuel delivery system is working as well as possible.
- put some new spark plugs in, not Bosch Platinum they tend to foul, NGK's are better.
- add some premium gas to the tank
- test it warm not hot, high combustion temperatures create more NOx
- test it at a place where they will open the hood and run a big fan across the engine.
- see if they will run the 25mph test in 3rd gear instead of 2nd, this makes a huge difference.

or last resort pony up $500 for a CA CAT, it will pass but it better to try to deal with the more fundamental issues first.

What is a euro exhaust? 70's 2-piece manifold? these were not as emissions friendly as the one-piece bosch manifold for whatever reason.

Oh and make sure there are no leaks between the exhaust manifold, head and down-pipe affecting the O2 reading downstream.
 

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My last CA cat was $275 installed in the SF Bay area and was needed because the old one was shot. A note, with everything running properly, a Bosch injected car will be about 250 ppm HC before the cat.

Thanks.
 

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Discussion Starter #12
Thanks to the BB

For all the helpful responses. A small tweak to the idle adjuster (3/4) to enrich the mixture and all is well. Car passed with flying colors.
 

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O.K., I will throw this question out: What type of O2 sensor did you install; original style or a 3 wire one? I've noticed on my '83's OEM single wire sensor that the sensor cools down after idling a while, to the point where I do smell it running rich. Once rolling it warms up the mixture leans out.
 

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Discussion Starter #15
O2 Sensor

Installed a Bosch universal sensor. Dan - the magic mechanic I've relied on for years - rewired the ends for the proper electrical fittings. Saved $$$ and works just fine. As I mentioned earlier, the car has since passed smog with great numbers across the board.
 

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But Mad North-Northwest
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I'm surprised, but glad it worked for you. By "idle adjuster" do you mean the idle CO screw on the AFM?
 
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