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Discussion Starter #1
Fellow sufferers:

I am once again tested to the limit by my Alfa. I had failed smog a year ago and have since done extensive work, including:

- R&R engine, replace all seals and gaskets, incl head gasket
- install new Catalytic from Centerline
- new oxygen sensor, generic, from Autozone, spliced in, Bosch, matched number of one that was in there (it is not the expensive one available from vendors)
- new spark plugs
- new Motronic water temp sensor
- oil change: Mobil 1 15w/50
- tranny fluid drained and refilled
- new fuel filter
- head gaskets are retorqued after 600miles
-new coolant prestone orange
-new oil pressure sensor for gauge
-new ignition coil
-new fuel pressure regulator
-plugged vacuum feed to cruise control (wasn't holding vacuum)
plus a ton of other work that would not be emission related.

- Ignition wires are fairly new, like 5 years and 10kmiles, as is rotor and cap, both don't look bad

I have failed smog 4 times in the past 6 weeks due to high NOX, running lean.
- have tried smogging with different AFM
- have tried sucking water into intake while smogging, did not lower enough
- am using Chevron 91 Octane southern California, with added bottle of Techron fuel system cleaner
- fuel pressure checks out ok
- catalyst seems working, i.e. lower temps aft than fore
- no check engine lights, no codes
- second test procedure does not seem to go past injector test: displaying 1-4-1-1 but not moving on and don't hear much action from injectors
- have installed fan mod so it stays at about 175F while testing
- am driving it hard, done italian tune up method before test
- can't believe that the compression is to high in the cylinders since I passed the NOX a year ago. The problem was different then.


The car performs well, especially in the canyons, and is a blast to drive. Maybe some lack/lagging power from the line unless revved high, but seems always been like that. I get 27mpg on freeway, 80mph, some traffic, and 16 in city, riding it from stop light to stop light.

runs lean, obviously O2 percentages and CO percentages prove that.

Only thing I see is that the Oxygen Sensor is not doing what it should.
Or problem with injectors.

Sheeesh. Doing my head in.

Would hate to bring the car to Uwe since he's soooo cranky.





Smog check 04/28/2009, 100926 miles

%CO2 %O2 HC (PPM) CO(%) NO (PPM)
Test RPM Meas Meas Max GP Meas Max GP Meas Max GP Meas
15mph 2346 9.8 0.4 112 286 321 0.72 2.22 7.55 778 1973 415
25mph 2396 9.6 0.3 86 236 333 0.6 2.1 7.92 717 1773 396

Smog check 03/31/2010 at 101785miles

%CO2 %O2 HC (PPM) CO(%) NO (PPM)
Test RPM Meas Meas Max GP Meas Max GP Meas Max GP Meas
15mph 2362 14.5 1 112 286 23 0.72 2.22 0.01 778 1973 1907
25mph 2404 14.5 0.9 86 236 21 0.6 2.1 0 717 1773 1776
 

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Discussion Starter #2
Smog check 04/28/2009, 100926 miles

%CO2 %O2 HC (PPM) CO(%) NO (PPM)
Test RPM Meas Meas Max GP Meas Max GP Meas Max GP Meas
15mph 2346 9.8 0.4 112 286 321 0.72 2.22 7.55 778 1973 415
25mph 2396 9.6 0.3 86 236 333 0.6 2.1 7.92 717 1773 396

Smog check 03/31/2010 101785 miles

%CO2 %O2 HC (PPM) CO(%) NO (PPM)
Test RPM Meas Meas Max GP Meas Max GP Meas Max GP Meas
15mph 2362 14.5 1 112 286 23 0.72 2.22 0.01 778 1973 1907
25mph 2404 14.5 0.9 86 236 21 0.6 2.1 0 717 1773 1776
 

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Discussion Starter #3
Smog check 04/28/2009, 100926 miles

%CO2 %O2 HC (PPM) CO(%) NO (PPM)
Test RPM Meas Meas Max GP Meas Max GP Meas Max GP Meas
15mph 2346 9.8 0.4 112 286 321 0.72 2.22 7.55 778 1973 415
25mph 2396 9.6 0.3 86 236 333 0.6 2.1 7.92 717 1773 396

Smog check 03/31/2010 101785 miles

%CO2 %O2 HC (PPM) CO(%) NO (PPM)
Test RPM Meas Meas Max GP Meas Max GP Meas Max GP Meas
15mph2362 14.5 1 112 286 23 0.72 2.22 0.01 778 1973 1907
25mph2404 14.5 0.9 86 236 21 0.6 2.1 0 717 1773 1776
 

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But Mad North-Northwest
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Man, you've done a lot of work. Hate to give you more things to check, but maybe:

- Injector cleaning? If they're not flowing well you may have problems.

- Is the cat converter a three-way cat? If it's from CL I'd assume so, but maybe check? If it's a two-way cat it won't have enough NOx reduction.

Good luck.
 

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Discussion Starter #7 (Edited)
mileage is 101789, rebuilt 8 years ago, 15k miles ago. Model is 1991 Manual 164L

valve clearances:
valve clearance check: all intakes:0.018(0.457mm), cyl 6 fits barely with that gauge. Specs call for 0.0187-0.0197"(0.475-0.500mm)
valve clearance check: all exhaust: 0.08 (0.209mm), cyl 5 tight, adjusted to 0.08" Specs call for 0.088-0.098"(0.225-0.250mm)

sperry stage one head job, am pretty sure he did not put in s cam

timing checks out ok, also
 

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I'd say you have put some effort into it. Why are you trying to cool it down while testing though? It will test better hot. In fact the closer to 210*F the better. Are all the injectors spraying right? Maybe take them out and have the flow tested/cleaned.
Charles
 

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Discussion Starter #9
yeah have feeling that it's the injectors. Everything else is new or fixed tight. cooling it down was recommended by smog tech.
Better be the injectors. What a PITA.
 

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But Mad North-Northwest
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Charles,

In general hot testing is better. But too high temperatures can cause high NOx, so in this case he's doing the right thing.
 

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If the injectors are clogged bad (and even if they aren't), I would be going into the fuel tank to retrieve the fuel pump and see if the in tank filter is full of crud and replace the short hose and even just throw a new pump in, just because you don't want to do that job again. I will say again, I think most 164 running/starting issues are related to fuel pump/tank maintenance. The right work done there will be rewarded. Most of the other Motronic stuff under the hood is long lasting and almost bullet proof. On a 164, when someone says "lean running"/starting problems and I don't have false air/vacuum/IAC issues, I'm going into the tank to investigate. I know you said, good fuel pressure, but I'm still going into the tank to clean crud out and replace hoses/fuel pump. Same with any old car, this stuff just gets old and needs attention from the years of filling up and inattention. It should be able to pass at well over 175*F, temp is not the problem here (but I do understand what you are saying).
Charles
 

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Incorrect ignition timing can also cause high NOx. I don't remember if the Motronic on the 12V 164's allows you to set ignition timing though...
 

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running lean...not getting enough fuel. I am with the group, sounds like the engine is starving even though it runs great. Lean runs hotter, making more NOx. Take the injectors out and have them professionally cleaned. I would bet with a car this old you have some issues with spray patterns. The nozzles are virtually pin holes and any crud on the pintels will alter the spray pattern significantly. Hope this helps.
 

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catalyst seems working, i.e. lower temps aft than fore
I thought that the outlet side should be hotter than the intake if the cat is operating correctly.
 

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I would change the o2 sensor with a correct one. I had an Accord fail with the same type of problems after I put a new generic o2 sensor it failed I then got the correct style of o2 sensor and it passed with really good readings.
 

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Check 2 things:

Voltage reading of O2 sensor with:
1) O2 Sensor is connected to the ECU ( you need to somehow tap into the signal)
2) O2 sensor is disconnected from the ECU

In both cases make sure the O2 sensor heater is connected.
 

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Discussion Starter #20
Ok,
Put rebuilt injectors in a while back and finally made it today to my smog tech guy. He put it on the dyno and did a test without the CA DMV system. Test only basically. I do not have a read out but it still runs lean and will not pass. He injected Windex (ammonia) also and it wasn't enough. Basically I have practically zero HC when it is running, and high NOX.
Now the injectors are rebuilt from Alfissimo and seem splendid. The car runs not 100% fine, though. When it is hot out, in 90 plus degree weather, and I am sitting in LA traffic, running the AC, it has a bit of an irregular heartbeat at idle, sitting in traffic. This is obviously with a full load on the alternator and AC running, with fan belt coming on and the voltage gauge dropping to little over 12V. Also, jackrabbit starts from red light are not perfect, slight stumbling and hesitation (shag you, M3!).
So, now: I am suspecting the OX sensor. After all, I did miser and not buy the expensive one. I am gonna go and spend the money and buy the proper one, maybe even the $250 one. The one I have right now is for a early 90s Ford Taurus(Bosch)and spliced in. Next item would be that the after market cat which is practically brand new just ain't doing it. I looked at the original cat again today with the smog tech and the combs look intact. However in 2009 when I first failed due to lean running it was with that original cat also.
Other items include: intake runner rubber sleeves. They are money, so I have skimped. Maybe worth it to get new ones.
And, off course, the tank. It was replaced with a new one about 10k miles, 5 years ago after I skidded and hit the curb in a fast curve with my rear wheel. Possibility of crud on the fuel pump filter in tank seems minimal though. That will be last one to do.

Approach is as follows:

- install an OXS as close to OEM as possible, no matter the cost
- test again
- put original cat back on
- test again
- remove fuel pump and check for dirt, clean it
- test again
- drive in reverse for a while until I find a latrine, then hit the latrine, and be done with it. This may be out of state. Possibly Arizona. Never mind, I have nothing against Arizona, it's just FAR away.
No check engine light BTW, and no codes.
 
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