90 Camry DX 4cyl. still failing NOx emissions

[scoathy]

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

[atobe]

how's the cooling system and timing of the engine? usually you get high nox with high combustion temp.... it's pretty rare for the cat to fail .. seems like you got most of the other stuff covered... o2 sensor and egr pipings/vavle cleaning

[sam333]

Bad EGR is the #1 cause, are your sure its really working?

What were other emmision #s ? If the cat was bad you should have high HC/CO too.

How many miles on the cat ? 150000 miles is about the limit before you start having cat problems, on a good running engine ( no oil /coolent burning),

Like what atobe said, high combustion temps ( coolent temps .timing(overly advanced) EGR ,overly lean mixture, exhaust back pressure to high.

[scoathy]

Originally Posted by atobe

how's the cooling system and timing of the engine? usually you get high nox with high combustion temp.... it's pretty rare for the cat to fail .. seems like you got most of the other stuff covered... o2 sensor and egr pipings/vavle cleaning

The car is not overheating, coolant was just flushed as well so I believe the coolant system is A-OK. The timing is good too I believe. There are no indications/symptoms that the timing is off at all, though I do not have a timing light or knowledge to check this. The car is running absolutely great, other than the NOx. I'm thinking I should remove and inspect the EGR system myself in case the shop did not actually do so. Then test it. Maybe replace the EGR valve if I find it suspect, then take it for emissions test again before swapping the converter. Assuming the converter is the original, it has 179k on it. thanks for the response!

[DAVIS3903]

ok first you are in the dfw area, right.
on kilf on sat.am's 9-1300 ed wallace talks about using RXP.
i ihave been using this for over 20 years and i tell you it works. it will blow out the carbon and improve our emissions. you will notice a big difference.
my wife notices on her 2005 sienna. i have been running this in my 90 camry for 4 years and the guys at the state inspection have to run it twice because they can not believe the #'s

several parts house carry the little red bottle @ 7.00

run a tank and see what you get

[sam333]

Does the engine knock or ping when accelerating? Does it burn oil ? When you haad your radiator flushed , was it really dirty/ rusty?

[scoathy]

Originally Posted by sam333

Bad EGR is the #1 cause, are your sure its really working?

What were other emmision #s ? If the cat was bad you should have high HC/CO too.

How many miles on the cat ? 150000 miles is about the limit before you start having cat problems, on a good running engine ( no oil /coolent burning),

Like what atobe said, high combustion temps ( coolent temps .timing(overly retarded) EGR ,overly lean mixture, exhaust back pressure to high.

Hey Sam,

I'm not positive about the EGR, to be honest I'll have to doublecheck that once I figure out what size wrench I need to get the pipe off. The biggest I have is 18mm... Hoping the CD-ROM shop manual I purchased on Ebay has the EGR test in it somewhere, I believe it does.

here are both sets of emission test numbers:

1st test

1st Test
High speed
HC (PPM) Standard = 174, current = 14 = PASS
CO (%) Standard = 1.12, current = .19 = PASS
CO2 (%) Standard = blank, current = 14.8
O2 (%) Standard = blank, current = .2
NOx (PPM) Standard = 1258, current = 1972 = FAIL
Dilution (%) Standard = >6, current = 15
Low speed
HC (PPM) Standard = 180, current = 17 = PASS
CO (%) Standard = 1.01, current = .18 = PASS
CO2 (%) Standard = blank, current = 14.7
O2 (%) Standard = blank, current = .2
NOx (PPM) Standard = 1378, current = 1842 = FAIL
Dilution (%) Standard = >6, current = 14.9

2nd Test after the big time tune up

2nd Test
High speed
HC (PPM) Standard = 174, current = 15 = PASS
CO (%) Standard = 1.12, current = .45 = PASS
CO2 (%) Standard = blank, current = 14.7
O2 (%) Standard = blank, current = 0.0
NOx (PPM) Standard = 1258, current = 1769 = FAIL
Dilution (%) Standard = >6, current = 15.1
Low speed
HC (PPM) Standard = 180, current = 16 = PASS
CO (%) Standard = 1.01, current = .41 = PASS
CO2 (%) Standard = blank, current = 14.7
O2 (%) Standard = blank, current = 0.0
NOx (PPM) Standard = 1378, current = 1780 = FAIL
Dilution (%) Standard = >6, current = 15.1


If the timing was off, wouldn't I notice that in the performance? I'm not noticing any of the typical symptoms of a timing issue and the temp gauge is never going above halfway.

Appreciate the assistance.

[scoathy]

Originally Posted by DAVIS3903

ok first you are in the dfw area, right.
on kilf on sat.am's 9-1300 ed wallace talks about using RXP.
i ihave been using this for over 20 years and i tell you it works. it will blow out the carbon and improve our emissions. you will notice a big difference.
my wife notices on her 2005 sienna. i have been running this in my 90 camry for 4 years and the guys at the state inspection have to run it twice because they can not believe the #'s

several parts house carry the little red bottle @ 7.00

run a tank and see what you get

I'll research it and grab a bottle. Yepper, DFW. Thanks!

[scoathy]

Originally Posted by sam333

Does the engine knock or ping when accelerating? Does it burn oil ? When you haad your radiator flushed , was it really dirty/ rusty?

The radiator flush was pretty nasty but the engine has not knocked or pinged at all when accelerating. I've only driven it a total of 100 miles as of this evening so cannot report on the oil burn, yet. Although, I am not smelling it in the exhaust.

[scoathy]

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...

btw, the EGR is testing good and I confirmed it was throughly cleaned at the shop.

Also replaced the distributor and reset timing due to oil leaking from around the distributor. Could the new distributor and timing adjustment resolve the NOx emissions fail, I wonder? Flustered...

[white90dx]

Don't worry about the extra mounting lugs. The stock converter is over-engineered when it comes to mounting.

The lower connection to the exhaust uses studs stock - it sound like the new converter is the same. If the studs aren't in there already, just thread them in there by hand, slide the exhaust on and tighten the nuts down.

-Charlie

[scoathy]

Originally Posted by white90dx

Don't worry about the extra mounting lugs. The stock converter is over-engineered when it comes to mounting.

The lower connection to the exhaust uses studs stock - it sound like the new converter is the same. If the studs aren't in there already, just thread them in there by hand, slide the exhaust on and tighten the nuts down.

-Charlie

Thanks for the info Charlie. One more question and I may be back in the ball game to swap the cat myself... how do you remove the studs that connect the current converter/exhaust pipe?

[white90dx]

Originally Posted by scoathy

Thanks for the info Charlie. One more question and I may be back in the ball game to swap the cat myself... how do you remove the studs that connect the current converter/exhaust pipe?

You don't remove them. Just remove the nuts and pull the exhaust off. If the stud comes out with the nut, that's fine too.

-Charlie

[Doctor J]

Sorry I joined this discussion too late but when I tested my EGR, I attached the vacuum gage to the EGR vacuum hose , taped it to the widshield and drove around at 15 mph. there should be at least 15 inches of vacuum available at the hose end to open the EGR.
I never saw the monolytic (honeycomb) cat failing to reduce only NO (on my car all emissions were higher then max but only a little).

[scoathy]

Finally discovered the culprit. EGR vaccuum modulator. She passed emissions today. Returning the unused converter tomorrow. The original shop supposedly checked this, and I checked it myself and found no issues. Went to a different shop they ran some test and found the problem

I can finally sleep peacefully.

thanks to everyone for the assistance. Invaluable!