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Discussion Starter · #1 ·
My Z flunked its CA smog test today (gross polluter), and I'd sure appreciate a tech expert who knows how to diagnose & fix smog problems to give me some advice.

The car sat for over a year and a half in a former own'er's driveway, without being started. It has 166,000 miles, and the engine seems to be original. I removed the head and repaired a damaged manifold, and it runs but I can smell, hear and feel that it doesn't run right.

Here are the test results.

@15 mph (2567 RPM): CO2 12.6%; O2 .7%; HC 2,258 PPM (Max is 231); CO 2.66% (Max is 1.36%); NO 392 PPM (Max is 2,549).

@25 mph (2582 RPM): CO2 12.6%; O2 .5%; HC 2,588 PPM (Max is 181); CO2 2.71%; NO 364 PPM (Max is 2349).

The tech who tested it said the results looked like the car is somehow getting unburned gasoline into the exhaust system. He drove it on the dyno-wheel thing and said it seemed odd to him to have such a bad result, because it seemed to run OK.

His recommendation was to first do a compression test to see if one of my cylinders isn't compressing enough to ignite the fual/air mix. I haven't done that yet (spent the rest of the afternoon at DMV...).

The car was running and had recently passed smog in 1977 when the former owner shut it down, but it had a bad exhaust manifold leak and was 3 quarts low on oil (he misdiagnosed the resulting noises as broken piston rod).

When I took it apart I noticed the old gas smelled really bad, and had gummed up the spark plugs. I ran some naptha fuel system cleaner through it (ran the tank dry to get rid of the naptha), and put in 5 gallons of 93 octane. I changed the cap & rotor, haven't yet changed the plugs & wires (cleaned the old ones on a plug cleaning/blasting machine).

The timing is set at 10 degrees BTDC. It was starting really hard and idling rough, and I adjusted the flow meter (no electronic tools, just did it by ear) till it smoothed out and idled + accelerated smoother.

Any advice on what I should check, and in what priority? It's a hobby car (not my commuter), and I have a very limited budget (what did you expect from a guy who cleaned his fouled plugs instead of replacing them...?). How do I set the flow meter correctly with only common tools? I do have a volt/ohmmeter, if that'll help.

I also noticed that the electrical contacts on all the fuel injectors were badly corroded, but it seemed to me that a corroded contact would cause it NOT to work, when my problem seems to be un-burned fuel.

Sure could use an expert.

Thanks,

Rob
 

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> My Z flunked its CA smog test today (gross
> polluter), and I'd sure appreciate a tech
> expert who knows how to diagnose & fix
> smog problems to give me some advice.

> The car sat for over a year and a half in a
> former own'er's driveway, without being
> started. It has 166,000 miles, and the
> engine seems to be original. I removed the
> head and repaired a damaged manifold, and it
> runs but I can smell, hear and feel that it
> doesn't run right.

> Here are the test results.

> @15 mph (2567 RPM): CO2 12.6%; O2 .7%; HC
> 2,258 PPM (Max is 231); CO 2.66% (Max is
> 1.36%); NO 392 PPM (Max is 2,549).

> @25 mph (2582 RPM): CO2 12.6%; O2 .5%; HC
> 2,588 PPM (Max is 181); CO2 2.71%; NO 364
> PPM (Max is 2349).

> The tech who tested it said the results
> looked like the car is somehow getting
> unburned gasoline into the exhaust system.
> He drove it on the dyno-wheel thing and said
> it seemed odd to him to have such a bad
> result, because it seemed to run
> OK.

> His recommendation was to first do a
> compression test to see if one of my
> cylinders isn't compressing enough to ignite
> the fual/air mix. I haven't done that yet
> (spent the rest of the afternoon at DMV...).

> The car was running and had recently passed
> smog in 1977 when the former owner shut it
> down, but it had a bad exhaust manifold leak
> and was 3 quarts low on oil (he misdiagnosed
> the resulting noises as broken piston
> rod).

> When I took it apart I noticed the old gas
> smelled really bad, and had gummed up the
> spark plugs. I ran some naptha fuel system
> cleaner through it (ran the tank dry to get
> rid of the naptha), and put in 5 gallons of
> 93 octane. I changed the cap & rotor,
> haven't yet changed the plugs & wires
> (cleaned the old ones on a plug
> cleaning/blasting machine).

> The timing is set at 10 degrees BTDC. It was
> starting really hard and idling rough, and I
> adjusted the flow meter (no electronic
> tools, just did it by ear) till it smoothed
> out and idled + accelerated smoother.

> Any advice on what I should check, and in
> what priority? It's a hobby car (not my
> commuter), and I have a very limited budget
> (what did you expect from a guy who cleaned
> his fouled plugs instead of replacing
> them...?). How do I set the flow meter
> correctly with only common tools? I do have
> a volt/ohmmeter, if that'll help.

> I also noticed that the electrical contacts
> on all the fuel injectors were badly
> corroded, but it seemed to me that a
> corroded contact would cause it NOT to work,
> when my problem seems to be un-burned fuel.

> Sure could use an expert.

> Thanks,

> Rob
Is the cat still on the car or did the previous owner removed it? also check to see if all the vac.lines are hooked up still (none disconnected)
 

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Discussion Starter · #3 ·
> Is the cat still on the car or did the
> previous owner removed it? also check to see
> if all the vac.lines are hooked up still
> (none disconnected)

The converter is still on, but I didn't check it to make sure it works (don't know how to, really). I bought new vacuum lines and went to a junkyard, found a car nearly identical to mine (same emissions controls), and spent about an hour making a drawing of all the vacuum connections. I re-ran all the vacuum lines. There's one that I had trouble running (goes through firewall, into a thing-a-magig hooked to the heater core), so I plugged it (the heater core apparently had a previous leak, so I bypassed it with my cooling lines).

I'm no expert to say the least. I might've screwed up the lines. If I could find a clear diagram (only have a Haynes manual) of the emission control vacuum lines I'd feel more confident. The under-hood stickers are all gone.
 

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Discussion Starter · #4 ·
>Year ago I didnt pass the smog test in Texas. My HC readings were over 21,000. I found out my air flow meter was from a BMW. Replaced it and the HC went down to 3500. I then replaced the Cat. and
found out that my timing chain was off. After a
major tune up, I passed the test. To adjust the
air flow meter go to auto shop because they have CO meter to adjust it. Check your PCV valve,
EGR valve,Thremal vacuum valve, O2 sensor, carbon
canister, and vacuum controller on your distributor. The items help control emissions.
Good luck.

My Z flunked its CA smog test today (gross
> polluter), and I'd sure appreciate a tech
> expert who knows how to diagnose & fix
> smog problems to give me some advice.

> The car sat for over a year and a half in a
> former own'er's driveway, without being
> started. It has 166,000 miles, and the
> engine seems to be original. I removed the
> head and repaired a damaged manifold, and it
> runs but I can smell, hear and feel that it
> doesn't run right.

> Here are the test results.

> @15 mph (2567 RPM): CO2 12.6%; O2 .7%; HC
> 2,258 PPM (Max is 231); CO 2.66% (Max is
> 1.36%); NO 392 PPM (Max is 2,549).

> @25 mph (2582 RPM): CO2 12.6%; O2 .5%; HC
> 2,588 PPM (Max is 181); CO2 2.71%; NO 364
> PPM (Max is 2349).

> The tech who tested it said the results
> looked like the car is somehow getting
> unburned gasoline into the exhaust system.
> He drove it on the dyno-wheel thing and said
> it seemed odd to him to have such a bad
> result, because it seemed to run
> OK.

> His recommendation was to first do a
> compression test to see if one of my
> cylinders isn't compressing enough to ignite
> the fual/air mix. I haven't done that yet
> (spent the rest of the afternoon at DMV...).

> The car was running and had recently passed
> smog in 1977 when the former owner shut it
> down, but it had a bad exhaust manifold leak
> and was 3 quarts low on oil (he misdiagnosed
> the resulting noises as broken piston
> rod).

> When I took it apart I noticed the old gas
> smelled really bad, and had gummed up the
> spark plugs. I ran some naptha fuel system
> cleaner through it (ran the tank dry to get
> rid of the naptha), and put in 5 gallons of
> 93 octane. I changed the cap & rotor,
> haven't yet changed the plugs & wires
> (cleaned the old ones on a plug
> cleaning/blasting machine).

> The timing is set at 10 degrees BTDC. It was
> starting really hard and idling rough, and I
> adjusted the flow meter (no electronic
> tools, just did it by ear) till it smoothed
> out and idled + accelerated smoother.

> Any advice on what I should check, and in
> what priority? It's a hobby car (not my
> commuter), and I have a very limited budget
> (what did you expect from a guy who cleaned
> his fouled plugs instead of replacing
> them...?). How do I set the flow meter
> correctly with only common tools? I do have
> a volt/ohmmeter, if that'll help.

> I also noticed that the electrical contacts
> on all the fuel injectors were badly
> corroded, but it seemed to me that a
> corroded contact would cause it NOT to work,
> when my problem seems to be un-burned fuel.

> Sure could use an expert.

> Thanks,

> Rob
 

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Re: Advice

Rob,
You are running in a grossly overrich condition that is generally caused by corroded connectors on your engine temperature sensor. You have three sensors on the front of your thermostat housing. The 1-wire goes to the gauge in the car. The small of the 2-wire sensors is your engine temperature sensor. If it has continuity problems it makes your ECU think that the engine is at the North pole and hugely increase the pulse duration of your injectors - thus the cloud of black smole and rough idle. Take the connector off the sensor and mechanically clean all the green-white corrosion off the sensor and the connector. Then fluch with battery terminal cleaner, thoroughly dry, coat with dielectric grease and reassemble. follw the leads from your sensor connnector about 16 and you should see a lump in the wiring. Remove the insulation and you'll find some barrel style connectors there where the sensor pigtail ties into the main harness. Pull these apart, clean, grease, and reassemble.
The other 2-wire sensor is your thermotime switch. It sends a signal to your cold start injector which is injector #7 located on your intake mainifold -follow the fuel line. Clean this sensor and it's connectors that same as the engine temperature sensor. Now pull all your plugs and thoroughly clean and dry them. They are probably badly fuel fouled by now.
Once this is done -crank the car up - it should run much better.
Now - take the car to a old Z knowledgable mechanic that has an exhaust gas analyzer and have hime set your throttle switch and AFM to factory specs. Don't let him use any shortcuts - make him do it right. Your correct CO should be 0.5% with about 50 PPM at 2,500 rpm.
Good Luck,
Phantom
 

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I'm no expert, I'm just a teenager but me and my dad had the same problem trying to smog my car. We were in the same situation, we bought a car that had not been run for over a year and a half. We took it to a guy and he ran a test and told us that it was just the air-fuel mixture had to be adjusted but once he tried it still didnt pass. It was running to rich and the catalyc converter wasnt working at all, but that wasnt a problem. After some tests we found out one cylender was running to lean and another was running to rich. At first we thought we would have to rebuild the moter but when we did a compresion check things didnt lokk so bad. We used all sorts of fuel ingection cleaner and replaced the two ingectors. We really didnt think it ould make a difference on the test but we had it tested anyway and it passed. We never did hae to replace catalyc converter.

Hope this helps.
 

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Discussion Starter · #7 ·
Great Advice, Phantom

> Rob,
> You are running in a grossly overrich
> condition that is generally caused by
> corroded connectors on your engine
> temperature sensor. You have three sensors
> on the front of your thermostat housing. The
> 1-wire goes to the gauge in the car. The
> small of the 2-wire sensors is your engine
> temperature sensor. If it has continuity
> problems it makes your ECU think that the
> engine is at the North pole and hugely
> increase the pulse duration of your
> injectors - thus the cloud of black smole
> and rough idle. Take the connector off the
> sensor and mechanically clean all the
> green-white corrosion off the sensor and the
> connector. Then fluch with battery terminal
> cleaner, thoroughly dry, coat with
> dielectric grease and reassemble. follw the
> leads from your sensor connnector about
> 16 and you should see a
> lump in the wiring. Remove the
> insulation and you'll find some barrel style
> connectors there where the sensor pigtail
> ties into the main harness. Pull these
> apart, clean, grease, and reassemble.
> The other 2-wire sensor is your thermotime
> switch. It sends a signal to your cold start
> injector which is injector #7 located on
> your intake mainifold -follow the fuel line.
> Clean this sensor and it's connectors that
> same as the engine temperature sensor. Now
> pull all your plugs and thoroughly clean and
> dry them. They are probably badly fuel
> fouled by now.
> Once this is done -crank the car up - it
> should run much better.
> Now - take the car to a old Z knowledgable
> mechanic that has an exhaust gas analyzer
> and have hime set your throttle switch and
> AFM to factory specs. Don't let him use any
> shortcuts - make him do it right. Your
> correct CO should be 0.5% with about 50 PPM
> at 2,500 rpm.
> Good Luck,
> Phantom

Phantom, I want to thank you for the good advice, and for taking the time to write out a very understandable troubleshooting/fix solution. It's posts & replies like yours that keep me coming back to this page, and that make this page the first thought in my mind when I run into a Z-problem that I can't figure.

I haven't worked the Z over yet, but I've read and re-read your post and I have a feeling you've saved me a lot of money, time, and frustration.

Thanks again,

Rob
 
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