Toyota Repair: 1990 Camry ERG Modulator Valve & Alternator, shade tree mechanic, combustion temperatures

Question
Hi Ted,

Thanks for taking our questions.  Evidently, I couldn't get in quick enough on your previous response so here is a summary:

1990 Camry 3sfe EGR valve

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This is a summary of a previous question:

Just found your column and I am looking forward to getting your input on several items. However, my baby just failed her NOX emissions test in TX so this will have to be the first question. The levels have been rising noticeably in the last year or so. The High/Low numbers in 2002 were 532/864; 2003 415/399; 2004 1136/1223 and now in 2005 they are 1759/1806. Passing levels are 1258/1378.

The EGR valve seems to be the popular culprit so I plan to remove it and clean it out. Do you have any cautions or recommendations in doing this? Is there anything else that I should address?

Is there any shade tree mechanic method to determine if the catalytic converter is working as it should?

Thanks,
Kep

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from Ted:

The cat converter is the least likely cause, High NOX readings can be caused by a malfunctioning EGR system but this will turn the check engine light on, Is that the case?
If not, the EGR system may not be the problem so let me know if the light is on, it's very important, another cause of high readings is that the combustion temperatures are too high, the EGR system was designed to reduce combustion chamber temperatures to reduce NOX emission, that's it's only purpose.
If the engine is running too hot it will have a direct effect on emissions so make sure there is no overheating problem. Please get back to me with this additional information, and if there is a check engine light on I will need the trouble codes from the computer

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Reply:

Thanks Ted,

Since then I have cleaned out the EGR valve and my NOX numbers went down to 700 or so.  

While completing this I noticed the Erg's exhaust outlet to the EGR Modulator was also clogged as was the hose. I cleaned these out and would now like an idea on how to clean the Modulator. I believe the exhaust side of its diaphragm is clogged too. The diaphragm seems lethargic. Do you know of a solvent for carbon that I could soak the Modulator in?  The support team for SEA FOAM feels their SF-16 motor treatment would be safe (Sea Foam or Deep Creep are NOT compatible with the electronics because we are a 100% petroleum product so do not use there, but we ARE safe for rubber, plastic, gaskets or metal surfaces.)but I want to be certain that I don't damage the diaphragm, is it rubber? Is there a way to take the Modulator apart, clean it, and reassemble it? Would some silicone spray in both the top and bottom of the diaphragm chamber help?

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Since I couldn't get in to you soon enough I went ahead and inspected it (Successfully!) without cleaning the Modulator but I still would like to clean it if I won't hurt it.

Another situation:

Two miles out of the inspection three of my indicator lamps ("Brakes", "Battery", "Lights") came on at the same time.  Curiously, they would all go out when the engine revved up enough.  Also at the end of the day (after the car cooled) they didn't come on for about 5 miles.  Then, same behavior.

Would a bad alternator do this?  The quick check showed the output at 12.46.  Three lights at a time is befuddling me.


Thanks Ted,
I'm looking forward to this forum,
Kep

Answer
We normally don't clean the modulators, they are fairly inexpensive(about$70), if it's working properly I would not tamper with it.
But if you do want to clean it it can be taken apart, the top comes off and there is a fiber type of filter inside, it can be removed and cleaned as well as the interior of the valve, to me, dish soap and water would probably be the safest, just make sure everything is nice and dry, maybe a can of cpmpessed air would be a good idea.
I almost forgot you second question, the alternator is a typical cause for this problem so the solution is to replace it, the OEM from the dealer are expensive, you can use aftermarket as long as you deal with a reliable source.