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90 Camry DX 4cyl. still failing NOx emissions

  #1  
Old 05-22-2011, 01:26 PM
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Default 90 Camry DX 4cyl. still failing NOx emissions

Good afternoon everyone,
This Camry I purchased is running like a top. The only problem I have now is that I cannot pass emissions, therefore cannot drive the car, legally... Below I have posted the initial NOx readings, followed by all the stuff I replaced that may/may not contribute to the problem, and that is followed by the follow-up NOx readings. I'm hoping someone on the forum reads this and can help point me into the right direction. My wife sells her car tomorrow, at which point I have no choice but to drive the Camry illegally... the catalytic converter seems easy enough to replace, sitting in front of the motor as it does, but it is very expensive. I will replace if recommended but want to be sure before I sink $300-$400 more into the car.

Any assistance is very much appreciated! I'm between a rock and hard place at this point.

Initial Emissions Test
Passed all except NOx
NOx test =
High speed standard 1258
High speed reading 1972
Low speed standard 1378
Low speed reading 1842

Replaced/cleaned the following that may/may not be a factor:
Plugs
Coil
Cap
Rotor
Clean EGR paths (So I am told, and paid for, at least J)
Clean EGR vacuum assembly
Fuel filter
Air filter
O2 sensor
Coolant Temp sensor
Changed all fluids and filters

2nd Emissions test took place after driving around town a total of 60+ miles:
Passed all except NOx
NOx test =
High speed standard 1258
High speed reading 1769
Low speed standard 1378
Low speed reading 1780
 
  #2  
Old 05-22-2011, 05:06 PM
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Basically N0x is caused by high combustion temps.

Lean fuel mixture-check for leaks on intake side of engine, cracked vacuum hoses, etc.
Retarded ign timing. Typically not a problem the distributor was somehow moved.
Cooling system problem resulting in engine running hotter.
EGR system failure, lack of enough exhaust gas being routed back to intake.
02 sensor problems.

and

Bad converter
Leaks in exhaust system before converter. Bad gasket, holes, etc. Or crushed pipe.

Did the shop test the EGR system after cleaning it?
 
  #3  
Old 05-22-2011, 05:42 PM
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Thanks for the response Toyo. Ya know... i did not ask them if they tested the EGR system after cleaning. Yep. I know... should assume nothing... haha.

I believe the shop manual I have on CD-ROM details the EGR test and I can check/replace the vacuum lines myself... fthey are cheap enough I imagine and I could probably replace them as quick as I can check them for leaks...

If that does not work then I'll purchase a $$ converter and install it... looks simple enough.

Thanks again!
 
  #4  
Old 05-23-2011, 12:45 PM
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In theory the check engine light should come on if there was a problem with the EGR or the converter was bad (tested indirectly via the O2 sensors). However not always so.

If you have the manual testing the EGR system is straight forward enough. Another typical problems besides carbon build up is a failed VSV valve. A DC electric solenoid valve that turns vacuum to the EGR system on or off via computer input.

For a good selection of converter brands and good prices suggest the internet site Rockauto. Make sure you get the exhaust gaskets if they don't come with the unit. If you car is located outside of California you can use any converter you want.

Used converters are worth scrap money, check around for prices. Don't just trash it.
 
  #5  
Old 05-23-2011, 02:52 PM
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Originally Posted by toyomoho View Post
In theory the check engine light should come on if there was a problem with the EGR or the converter was bad (tested indirectly via the O2 sensors). However not always so.

If you have the manual testing the EGR system is straight forward enough. Another typical problems besides carbon build up is a failed VSV valve. A DC electric solenoid valve that turns vacuum to the EGR system on or off via computer input.

For a good selection of converter brands and good prices suggest the internet site Rockauto. Make sure you get the exhaust gaskets if they don't come with the unit. If you car is located outside of California you can use any converter you want.

Used converters are worth scrap money, check around for prices. Don't just trash it.
I'll follow your advise, test the EGR, VSV (This must be what the manual refers to as the BVSV), if needed, rock auto for the converter/gaskets and scrap the old converter.

Thanks so much Toyo!
 
  #6  
Old 05-31-2011, 05:30 PM
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Another hurdle in this emissions endeavor. I received the converter today. I purchased the walker brand, model Walker 16097. I pulled it out the box and immediately realized it does not have the side mounting lugs that the OEM converter has on the passenger side. I also discovered that the three lower bolts, where the converter attaches to the lower exhaust, do not have heads... they are threaded on both ends and not enough threads to use two bolts to make a head I can put a socket on.

Called the local muffler shop (www.richs-performance-mufflers.com) and he said it would be a couple hundred bucks, but since I purchased an aftermarket, he could not guarantee that price until they saw the converter I purchased. Then went into why OEM was best for converters.

has anyone swapped converters on a 90 Camry and ran into issues with Walker aftermarket converters.

I'm pretty much to the point where I feel like the best thing is to just hand him the car and let him fix it.

At present this $500 purchase has become over $3k total and still can't drive it legally due to failed emissions... one of those days...
 
  #7  
Old 06-01-2011, 12:38 AM
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Suggest you call Walker customer service and or the place you purchased the converter and ask about fit up issues. This converter P/N states it is supposed to be a direct fit, obviously it is not.

Any of these converter at the link below look like your converter?

1990 TOYOTA CAMRY LE Catalytic Converter

Suggest you post these questions at the Toyotanation website in the forum section appropriate for your year where members have most likely dealt with the same issues.
 
  #8  
Old 06-01-2011, 07:04 AM
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Hi Toyo,

Yes. WALKER Part # 16097 is the unit I purchased

I also posted this in the Gen 2 forum @ Toyota Nation. got a message on that forum last night stating that the Walker will fit fine citing that the OEM converter was perhaps a bit overbuilt with the side support lugs. Hoping the same member will explain how he removed the three threaded studs that connect the converter to the exhaust pipe.
 

Last edited by scoathy; 06-01-2011 at 07:15 AM.
  #9  
Old 06-19-2011, 08:40 AM
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Forgot to post an update on this. After testing the entire system, another shop doing the same, it was still failing. I ended up taking the Camry to another shop, just not convinced the converter was the issue (Only failing NOx but passing the other emissions). Rich's Performance Muffler in Wylie Texas discovered the EGR vacuum modulator was indeed failing. It was cleaned up twice and tested twice by me and the other shop... shows how much I know... LOL they replaced the modulator and the car passed with flying colors. The NOx tested in the low 500s and the car is running really well. Lesson learned = Don't assume everything you know about other vehicles makes you a pro on any specific vehicle, and don't assume all mechanics/shops are created equal.
 
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