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Discussion Starter · #1 ·
Apparently I need a new catalytic converter on my '94 164LS. Can't get the car through emissions due to high NOx, and the repair shop noted that my cat is not heating up properly I'm not seeing any on the usual suppliers websites. Any suggestions? I read that someone successfully used a Magnaflow 94008. Anyone have any experience with this? Welcome your thoughts.
 

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1991 164L
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If your car is not heating up properly does that mean you engine thermostat is stuck partially open when engine cold? How quickly does it warm up and at what temp does it operate at when driving?

Is your O2 sensor and sensor heater working correctly?

Do you have any codes in ECU memory?

Check for error codes: Alfa 164 Motronic M1.7 Self-Diagnosis

Report your findings.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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I doubt that the cat is the problem, as they are pretty darn long lasting and reliable. The one in my 94LS is still doing it's job so well the tech at the testing station told me he hadn't seen a car this age do so well.
 

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Discussion Starter · #4 ·
OK, let me clarify a couple points. The car has 167,000 miles of city driving on it. Just about everything conceivable has failed in the past year or so. <sigh>

Now, the shop I took the car to is a certified emissions repair shop. I have to use one in Virginia in order to get a waiver in the event I can't get this puppy through emissions. What they told me was that the catalytic converter is not heating up as would normally be expected. The air coming out of the cat is the same temp as the air going in - not a normal situation. They tweaked the mixture and when the HC levels went up, so did the NOx levels. They are convinced that the cat is exhausted after 167k miles.

The car itself is running at normal temp. That's not the problem. The O2 sensor is relatively new. I do get a code 1223 from the ECU, but O2 sensors normally start sending mixed up signals when a catalytic converter fails.

So, back to my original question. Does anyone have a recommendation on an aftermarket catalytic converter? Anyone have experience with a Magnaflow 94007?
 

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I remember the old trick of stepping on the meter's hose when they're doing the test. Worked every time.

Don't know how inspections work there, over here there are some inspection centres with less zealous inspectors that will hardly fail a car on small issues. Last time I took the C15 van there, the inspector noted the glass on the left headlamp was getting loose (old silicone) and I just told him I'd fix it. He didn't even put it on the report.

About the emissions, I accidentally stepped on the meter's hose...
 

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Cat

I have a cat that was just installed on a car to get it to pass smog. The cat didn't fix the problem and I parted the car out. The cat already has the flanges on it to bolt in to a 164LS. $100 plus shipping and it'is yours. Shoot me you email address and I'll get you a picture.
 

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So high NOx comes from high combustion temperatures.
If Steve was correct then we would have high CO etc. If CO is normal, then its probably the catalytic converter. Who knows, maybe someone ran leaded fuel through it or something.
What about Alfaguy35? It would be interesting to see which gasses he failed the smog test. If he also failed NOx then what's the use of buying his converter?
 

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Apparently I need a new catalytic converter on my '94 164LS. Can't get the car through emissions due to high NOx, and the repair shop noted that my cat is not heating up properly I'm not seeing any on the usual suppliers websites. Any suggestions? I read that someone successfully used a Magnaflow 94008. Anyone have any experience with this? Welcome your thoughts.
Catalytic Converters, Smith Brothers

They do a good work. Send it to them for rebuild
 

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The O2 sensor is mounted in the front of the cat so it is not likely to be affected by the cat actually. A 1223 means you have some other mixture related problem, not actually a faulty O2 sensor itself. The code is a little misleading and misunderstood by many. 1223 comes up when the computer has reached a point where it can go no further to try and fix the mixture problem and thus results in your failed emissions test. May or may not be a fault of the cat. Mine has 197,000 miles on it and passes easily. Get the 1223 fault fixed (false air leak, idle air control in-op, or something along those lines) and you are likely to fix the E test failure without replacing the cat. The cat could have been damaged by a head gasket (coolant) leak or something along those lines in the past, it is possible. If the car's thermostat is getting up into the 195*F to 212*F range like it should be getting to when fully warmed up, the cat really should be heating up too. If your thermostat is stuck open (like they do when they go bad) than your cat, even if actually good, may not heat up fully. DO confirm you car's engine warms up properly before condemning the cat. Too many get replaced unnecessarily and the Alfa OEM cat is a better one than any replacement you will find. If you do buy a new cat and still run the car with the 1223, you will likely damage the new cat in a short time and end up back at square 1 next time around. The high NOx would suggest a lean mixture is happening, which supports my hypothesis of a false air leak (maybe at the large air intake hose, is yours cracked?). Take Alfaguy35's situation for instance, he replaced the cat and still didn't pass, so something else was the cause of the failure. Find the actual failure, save money on the cat, keep the car original and pass this year and the next.
Charles
 

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Further proof is that although there are thousands on this forum, there is not a single thread about replacing the cat, and even this thread nobody has replied positively. This cat just doesn't seem to break.
 

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1991 164L
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There are some threads about getting your cat rebuilt but not many on using aftermarket replacements.

Miller was one but can't find onfo on it now.

Here is one from web: http://smithcat.com/inventory.htm
 

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Don't ignore the 1223 CEL, the cat not heating up is just a symptom and not the cause, most likely. You not only could have a false air problem, you could just as likely have a fuel starvation problem. If your not at stoichiometric, your not going to pass the E test and the cat can't do its job either. These mechanics your talking to are just looking for the "easy fix" it seems. What have the "certified emissions mechanics" done to look into fixing the 1223 CEL code??? What did they do exactly to "tweek" the mixture?
Charles
 

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Don't ignore the 1223 CEL, the cat not heating up is just a symptom and not the cause, most likely. You not only could have a false air problem, you could just as likely have a fuel starvation problem. If your not at stoichiometric, your not going to pass the E test and the cat can't do its job either. These mechanics your talking to are just looking for the "easy fix" it seems. What have the "certified emissions mechanics" done to look into fixing the 1223 CEL code??? What did they do exactly to "tweek" the mixture?
Charles
I agree. Something else is probably wrong. These cats are very good. Although I have seen a few go bad, one I replaced on a LS was totally shattered inside. But I kept it because I will have smithcat rebuild it. I would never want to use an aftermarket Cat.

I hate to say this, but it might be work checking timing as well as what Chazzy suggested.
 

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Bob at AutoDelta had the cat replaced on our 1991 164L with 165,000 miles. The Midas aftermarket cat, they welded on, lasted only two years before it failed the emissions test again.
Our '92 164-S still has the original cat and just passed its test with flying colors today.
 

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Aftermarket cats don't have near the "precious metal" content of the OEM cat. That's why you don't want to get rid of it if you don't really have to. I put a cheap one (Bosal) on my Volvo 240 because the original (with probably 300,000 miles on it or more (the odo was broken when I bought it)) had just pieces of honeycomb in it and some that had gone downstream. It has passed at least four times, but I don't expect it to last nearly as long as the OEM one did. It was cheap though and it's not hard to bolt another one on should it fail. The car is in very good tune though, so that should help it last. I also installed a new head gasket and valve seals, along with a complete tune up, lambda sensor, fuel pump replacement and timing belt to name just a few things I did to it. It passes very easily, as it should even though it suffers from severe piston slap at idle. :eek: :(
Charles
 

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Discussion Starter · #16 ·
Don't ignore the 1223 CEL, the cat not heating up is just a symptom and not the cause, most likely. You not only could have a false air problem, you could just as likely have a fuel starvation problem. If your not at stoichiometric, your not going to pass the E test and the cat can't do its job either. These mechanics your talking to are just looking for the "easy fix" it seems. What have the "certified emissions mechanics" done to look into fixing the 1223 CEL code??? What did they do exactly to "tweek" the mixture?
Charles
Chazzy, you are both right and wrong. The cat was likely toasted when the car started backfiring. I'm not sure what was causing the backfiring, but when we fixed the broken drainback hose from the vapor canister, the backfiring stopped. When the mechanic richened the mix, both the HC and NOx readings went up. Not something that should happen with a good cat. I replaced the cat with a generic magnaflow and the NOx readings at 25 mph went from 2257 to 1099 (1167 is passing).

However, you are right that the 1223 is something else that needs to be fixed. The car still did not pass emissions because the NOx reading at 15mph was still too high, almost double the limit. The fault code is still periodically showing up, and the car sometimes feels like its dragging, possibly from fuel starvation. High NOx would suggest the mix is too thin.

So here's the part I can't figure out. At an idle or at a constant pressure on the gas peddle at a low speed, the fault light will come on and the car will feel like its dragging. Then all of a sudden without changing anything, the engine will suddenly return to normal power and the fault light goes off. It does not appear to happen at high speeds/high rpm, only at low rpm. The only thing I can figure is that something is sticking, but I'm not sure where to start. What would cause a too thin mix which could correct itself?

Recent engine work included fiddling with the idle actuator. The fuel filter is relatively new (<10k miles). Checked the air filter at the last oil change 2k miles ago and glanced at it again recently. It looks clean. Any suggestions on where to start?
 

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When was the last time the short fuel hose in the in-take fuel pump was replaced? This hose has been the culprit on more than a handful of fuel-related issues.
 

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IAC or false air leak at the large black intake hose, etc. I still think the new cat wasn't necessary as you have another problem causing it to not pass and the new cat is in danger of being damaged by the real problem (again). A cat can "revive" itself when you correct the real problem by burning off the contaminants once the real problem is fixed (after putting some good "Italian tuneup" miles on it). The new cat is only masking the issue somewhat for now. That's OK though, you don't have to listen to me. I'm not even a "real" mechanic. :D
Charles
 

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Discussion Starter · #19 ·
IAC or false air leak at the large black intake hose, etc. I still think the new cat wasn't necessary as you have another problem causing it to not pass and the new cat is in danger of being damaged by the real problem (again). A cat can "revive" itself when you correct the real problem by burning off the contaminants once the real problem is fixed (after putting some good "Italian tuneup" miles on it). The new cat is only masking the issue somewhat for now. That's OK though, you don't have to listen to me. I'm not even a "real" mechanic. :D
Charles
You're probably right, but I was kinda screwed. I couldn't get my plates renewed without either fixing the problem or spending $$ at a Virginia certified emissions repair facility. Well, the certified guy said that's what I needed. If I walked away, I had no plates for my daily driver. If I did what he said and he was wrong, I got a waiver and got my plates renewed. Now that they are renewed (on wavier), I took it up to DiFatta Brothers so they can fix the real problem. If they can't figure it out, no one can.

I do appreciate your input and help. I'm far from a "real" mechanic, but you guys seemed to know a whole lot more than the "experts" around here.
 

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Paul can probably find the problem I am sure.
 
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