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Discussion Starter #1
I'm having an absolute bear of a time getting my 2000 Avalon w/78K smog-approved. The last remaining unpassed item is CAT NOT READY. I have replaced 3 oxygen sensors (2 qty upstream in the exh manifolds and 1 qty downstream, near the cat converter) and the MAF sensor. Prior to this replacement, I was getting P071 and P1130/P1135 fault codes. Those have been apparently fixed by the sensor replacements. Yay!

But the CAT NOT READY indication remains and kills me for smog.

Here's my question and maybe it's a dopey one: The car drives fine, operating temp seems stable and unremarkable, a skosh below midpoint on the temp gauge. I've completed several run-throughs of the various "drive cycles" suggested by folks and even #4 of the Toyota manual.

here: http://www.22rte-trucks.com/public_files/TSB_EG003-02.pdf No dice. But the Toyota manual says the operating temp has to be 176 degrees F.

Question: If it happens that I have a 160 degree thermostat installed, then the engine temp would NEVER reach 176 degrees and I can NEVER (with said thermostat) achieve the operating conditions req'd for the Toyota reco'ed drive cycle?

My next strand of spaghetti on the wall is to borrow a pal's laser thermometer, check (1) the coolant temperature once the engine is thoroughly warmed up, and (2) checking pre and post CAT temperature just being sure that input temp is roughly 300 degrees and outputs temp is 500 degrees.

Anyone?
 

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Most OBD2 readers can output the coolant temperature. Or, what the ECU thinks the coolant temp is. Get that number and report back.
 

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Discussion Starter #5
I've driven at least 500 miles working to get this thing set. I've sat in idle @ 3000 rpm (2000 rpm is 55 mph, 3000 would be 75-80 mph) for 5 real minutes. No go.

I just buzzed over to my friends house to borrow the thermo. Not fully warmed up, but close. Quick zap while I was there; 135 degrees. I can't do this at fully warmed up as I write this post until later today. And still, I want to check input vs output temp on the CAT.
 

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Quick zap while I was there; 135 degrees.
Where are you pointing the gun at? That seems awfully low.

What brand is the 160 deg 'stat? There are some garbage brands out there for 'stats. A lot of them open waaaay too soon, at too low a temp.
 

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Discussion Starter #7
The car only has 78K on it, despite being 20 years old. I would imagine (but do not know for sure) the thermostat is as supplied with the new vehicle. I do not know its temp rating. It could be working fine and be a 160 degree thermo. It could be a broken 160 degree thermo. From what I have seen, although the thermostat is a near nightmare to change out, I am hoping that this is my issue with regard to not being able to get the CAT ready. At least I would know and there would be the glorious option of being to re-install the several pieces of interior trim and then bolt my passenger seat back in....those had to be removed to get to the downstream oxy sensor connector. With any luck (not that I have had much so far) I am hoping I can tie-wrap a partial sheet of cardboard over the radiator, get the engine heated up more than it now heats up, drive to complete a drive cycle, and get past my smog exam for which I am overdue.
 

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My scanner will show real time data, including coolant temp.. it isn't expensive ($50). Shooting temps with an IR gun doesn't tell you what the sensor is sending the ECU. A bad sensor could tell the ECU the coolant temp was -40 in the middle of July in Death Valley. The cat monitor will never run if the ECT is bad.

Why would you put a 160 T-stat in an Avalon? Mine routinely shows 195 degrees when the engine is hot. That is the correct opetating temp.
 

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I would imagine (but do not know for sure) the thermostat is as supplied with the new vehicle.
Oh, I thought you implied that you put in a 160° 'stat. My mistake.

So it's likely the original thermostat then. Which is a 180° thermostat. With it being ~20 years old, there's a pretty good chance it's opening too soon at too low a temp. That's typically how they fail.
 

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Discussion Starter #10 (Edited)
Bad news. Coolant temp 181 degrees.
CAT input temp 211 (at extended idle, was a little higher earlier, but engine is plenty warmed up)
CAT output temp 272
= Bad cat converter, thermostat is OK.

(#&(&&*(^$P_)@#

Output temp should be about 100 degrees and sometimes 200 degrees hotter than the input, from everything I've read. Not at idle, but at or after high speed running.

As for what the various sensors are sending the ECU, the P071 got fixed, the P1130 and P1150 got fixed; on battery disconnect a pending showed up and then self-cleared. I find it hard to believe that all the other sensors would send updated data but this one single one would not.Besides, the CAT sensor is genuine Denso and the others are....whatever.

I am going to do a 5 minute high-speed rev-up test and then recheck the input/output temps before making the final death pronouncement. P'ed off.
 

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Yeah, not what anyone would hope for. But at least you're going in the right direction, I think.
 

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Discussion Starter #12
Well, there was about a 70 degree difference after the high-rev test. Argggggh. That seems like it should be OK.
But a new pending P1130 and a P1150 showed up.

I think what I'm going to do is to get genuine Denso oxygen sensors for the #2 (firewall) sensor and even replace the #1 sensor w/genuine Denso (even though it doesn't seem like I need it as I have not seen P071 since changing it) and throw those in. From Rock, two of those are a tad under $100.

It's been mentioned several times on this site and I should have listened. The cost of Denso oxy sensors (from Rock) is
about $45-48. The cost of unknown aftermarket ones on ebay is $20. While a genuine Denso sensor from Autozone or O'Reilly's is about $100, or I have seen them priced up to $160, there's no better example of stupid false economy than buying a no-name.

The cost of an installed CAT [email protected] $1500 is 1/2 the value of the whole car.
 

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Discussion Starter #14
Well no doubt I'll have to be dragged kicking & screaming to replace the CAT. I agree, the input/output differential on the CAT seems nominal. That's why I am thinking "get the right 02 sensors for the big extra $100. before the $1500 tsunami hits. Even if I've already replaced them.....but with suspect parts.
 

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Is that $1500 cost from a dealer, or?? That sounds really high. An aftermarket cat runs about $250, add another 50% markup and a couple 100 for labor, and it should total about $600. If you’re in CA, make sure a CARB-compliant cat gets installed.
 

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Discussion Starter #16
To be honest, I haven't priced the full treatment from a real repair joint. I've heard up to $1800 and a low of about $1300. Maybe I am mistaken; I hope I do not have to find out.
 

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Ah... yes. Just checked on a Toyota parts site, and they sell the complete “Center Pipe”, which includes the cat and most of the piping from the cat all the way back to the muffler, and it’s $1200 - p/n 17420-0A130, if you’re curious. So $1500 would be about right then.

No way on earth I’d go that route.
 

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Some shops can rebuild your oem catalyst, there were exhaust specialty shops in NY doing them when I left 6 years ago, the mil stayed off and they passed emissions testing, also they had to give a 3 year warranty for converter replacement.
 

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Discussion Starter #19
I would hesitate to get a rebuild; for one thing I'd be skeptical (but have no idea whatsoever and have made zero inquiries) that's allowed in CA. Second, I'm already 30 days past due on getting smogged and thus am driving around without a reg. I'm just kind of reluctant to do anything but the "normal" thing. In the interim I shall check it out, though. Thank you for the suggestion.

As it turns out, I am revising my input/output temp differential assessment. Yes, it is true that the output temp HAS TO BE hotter than the input temp, now the questions is, "by how much"? I have seen videos and estimates and perhaps wild-a** guesses of between 25 degrees F and 200 degrees F. The output of my CAT is definitely hotter than the input. Therefore the CAT is working.....some.

What I'm doing NOW is to get genuine Denso sensors for the no-names I already replaced. Too bad they only cost 4x as much as the no-names but that's life. Of course, I ordered and received two DOWNSTREAM sensors = numbnut ordered the wrong parts so I have to return those. At least numbut NOTICED the rubber gaskets (characteristic of the downstream sensors because the output wires feed through your car floor) in time NOT to open tha packages so they can be returned.

Here is my thinking: Suppose the no-names sort of work. They work enough to extinguish any error codes. But they (or one of them) is/are intermittent or flaky. Error P1130/1150 DID show up again. Huh. How did that happen? IF they are intermittent then the CAT will NEVER "learn" whatever it needs to learn to be READY. I am getting no CAT error (P420 or similar) I DO get the higher output temp than input temp. The CAT at least works somewhat. So maybe one or the other sensors upstream are flaky and the CAT condition NEVER gets learned.

It's all I got without shotgunning a replacement CAT which is the last thing anybody would want to do.

More to follow, guys. Thanks for the encouragement and helpful suggestions!
 

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NY is a CARB compliant state, the catalytic converters meets emissions, California may prohibit it but I can assure you it’s legit in NY state Inspection emission repairs.
 
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