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Discussion Starter #1
Hi,

My 95 Escort (1.9) has 162,000 miles on the original engine. It wouldn't pass smog because it was blowing oil and the test shop said it would foul up their equipment. The problem was the apparently the valve seals/guides as it only smoked after coming off extended idle when warm. I put a rebuilt cylinder head on and no smoke. It runs great but now it fails HC and NOX at both 15 and 25 mph. CO is high but passes. They say they tested the cat and it's okay, and that it must be running too rich. But if it was, wouldn't the NOX be normal? In addition, the shop says the rpm is too high at 15 mph because the transmission isn't shifting into 2nd. Yet there's no problem with the tranny when driving, except the 1st to 2nd shift is kind of sloppy at WOT. Repair shops I've shown it to just kind of throw up their hands. The EGR works (at least it stalls the engine when full vacuum is applied to it). Some forums suggest running lean would cause both the HC and NOX to fail, but seems like the HC would be okay if it was running lean. Any suggestions would be appreciated. More details on request. Thanks.
 

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I would assume the check engine light is on?

I would also replace all of the O2 sensors. They report oxygen levels or rich/lean mix to the processor. There wear out over time. Typical replacement would be at 100,000 miles. If these are worn and still send a test signal back to the processor, the processor assumes they are good. However because they are warn, the signal back to the processor is too slow. (Hundredths of a second is make or break for the signal) If that is the case the processor is always doing the wrong thing based on a slow signal about rich or lean exhaust. O2 sensors are key in making the correct fuel trim adjustment. In addition the oil may have done a number on them in as well.

Report back.

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for your info. hc is fuel , too much or too little will cause excess in the exhaust. so high hc's can be caused by rich or lean conditions. (missfire). nox is caused by high combustion temps and or pressures (too much timing, high compression ratio). co is caused by rich conditions. basically not enough o2 for the fuel available in the combustion chamber.
any of these things ring a bell as to the repairs done?
 

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i would recheck valve timing. if off could cause less vacuum(shift points) and mixture changes. i always suspect the most recent repair.
 

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Discussion Starter #5
Thanks for the help. That's another weird thing: the check engine light is not on, and it's not burned out as it lights up during the ignition- on test. I didn't think about the oil killing the O2 sensor (only one on this car). Probably should try a new one. Pretty sure the timing is on as two of us counted reluctor teeth at TDC. The shop that overhauled the junkyard head machined it flat, so the compression could be higher than stock but I wouldn't think it would be by enough to cause all this. The block was not machined. Will also look for codes if my friend can find his OBD-I reader. I've heard some of them don't set the light.
 

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Put in a new O2 sensor and the car runs even better but smog results are the same. The test guy says since all else seems to have failed try a new cat. Could all that burning oil have killed it? Any other suggestions before I cough up $300? Thanks.
 

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Yeah I would shy away from a cat replacement. It is the function of a cat to burn off HC. Oil is a big HC. As long as the cats are not plugged likely they will continue to function. Take a vacuum reading at warm idle. If the reading is slowing dropping then you could entertain cat replacement. Because with a dropping vacuum reading there is an exhaust restriction. If the vacuum holds steady, no restriction.

Can you drive it? Driving it may/will burn - blow out any deposits on the cat. This may take a little driving to do this. And the system is going to re-learn normal with the new O2 sensors.

Is the check engine light on?
Have you pulled any codes?

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Discussion Starter #9
Sorry I didn't get back to you sooner. No, the check engine light is not on. The code reader is still MIA, and I'm not sure I follow the instructions for reading codes with a blinking test light; e.g. the code reader makes the computer go through a diagnostic routine (clicking relays, fan starts and stops etc.) before it will spit out the codes. The car is drivable and gets driven plenty. It seems to have more power now than when I bought it, when it only had 60,000 miles. At warm idle the vacuum gauge reads steady 20" in Park and 17" in reverse, with a slight jiggle. I have attached a file which is (sort of) a copy of the smog test results. It has been tested three more times since, and each time the readings are higher, though CO is still passing. And that's even after replacing the O2 sensor.
 

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Based on your vacuum readings there is no exhaust restrictions.

The diagnostic things that happen (Sounds) when the reader is connected is typical for Ford EEC IV system when it is doing the self test.

I need to think about this a bid. In the mean time disconnect the battery for greater than an hour then reconnect. I realize this is a pain as the clock and radio settings will be lost. However it get's rid of the operating history.

Glad to hear it has more power.

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A good read. http://www.discountconverter.com/tech-tips/news_page.cfm?Key=catalytic_converter-&News=216

Questions -
Is cooling system maintenance up to speed?
(with the head change I would assume yes. Don't like assuming)
MAP sensor issue?
(Not sure how to check this yet)
With the new cylinder head, I assume you got a new timing belt & water pump.
Make sure the cam/crank timing has been set correctly. ESPECIALLY if the non-passing emission test only occurred after the cylinder head replacement.

You have checked EGR & have new O2 sensors.

Just some thoughts
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Discussion Starter #12
Wow, this stuff can get complicated. Cooling system is good. Water pump and timing belt were replaced at 156000. Will look into the MAP sensor. The idle has been rough (although even) for quite a while. After the head replacement it still idles rough but it's a stronger rough if that makes sense. There's just a lot of vibration at idle, and all the mounts have been replaced. My friend (who is the actual mechanic) and I used the procedure in the Haynes manual to set the timing by counting teeth on the crankshaft position sensor reluctor at TDC. I don't have the book with me right now.

Something else to add to the mix from the Ford Escort Owners Association: a guy with a 94 with the 1.8 engine had a similar smog failure pattern and a new cat made it pass, though his HC was still fairly high: https://www.feoa.net/threads/smog-stumble.77577/

Thanks for your help.
 

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Nice old thread. However the guy didn't come back and post 2 years later.

In your test #s above the HC is definitely too high. Almost double passable at 25MPH. The NOX is too high at 15 MPH and passable at the higher speed. The CO is passable.

Either the engine isn't burning enough fuel. (The rough run would be an indicator) Or you are still getting oil into the combustion chamber. Or may be some of both. I think if you replace the cat there will be new material in the new cat. The numbers will be lower which is OK for the CO & NOX. Will the numbers be low enough for the HC?

Disconnect battery for an hour and reconnect
Re-Check coolant level make sure topped off
Re-Check cam to crank timing
Run compression test dry and wet on a warmed up engine
When the plugs are out snap pictures of them and post
Make sure throttle body is clean, mounting is tight with a clean air filter
Make sure all hoses are connected
Get an IR thermometer and measure exhaust pipe just before cat and just at the end of the cat on a warmed up engine

Post back.

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Discussion Starter #14
Finally replaced the cat and it passed. Still idles rough though. Will be working on a whole new engine for the future; for now we just wanted to get it legal. Thanks for all the effort. BTW, I see that when a cat is advertised as "exact fit," uh, not really.
 

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Interesting.

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