Smog not Passing.

[jshjuarez]

Hello again. So I took my car to get a smog check a while ago in order to get plates for the car and it did not pass smog. I really need help. So I've changed spark plugs, oil and filter, distributor cap ,ignition rotor, alternator, all 3 belts, valve cover gasket, battery,air filter,O2 passed and the catalytic converter passed . People tell me to use sea foam to bring the carbon build up down . Two major problems I'm facing is vacuum line sensor/switch says disconnected and ignition timing says mech problem. PLEASE HELP. I want to get the car running . It's a 1986 mk3 automatic supra 3.0 7mge

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[fox74]

You did not mention the mileage, I have the same supra with 157000 miles on it, a few years ago I really had hard time to pass smog, it was the O2 sensor, now it passes smog close to what it was when she was brand new. Check the timing, and make sure the car is at full operating temperature by driving on freeway at high speed for few miles on the way to the testing station, I also run on super unleaded when it is getting close to smog test. The old trick was to add alcohol to gas to pass smog but today's gas already has %10 alcohol that makes passing smog easier. Compare your last year test number to the recent test if you find a big deviation it might give you some clues. Let us know how it goes.

 

[jetjock]

The engine appears to be in fuel control. The EGR doesn't look like it's working though.

 

[jshjuarez]

I actually bought the car from Ohio and it hadn't passed smog for 3 years and had been sitting for two years that is why I've done a full tune up.


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[jshjuarez]

It has 216,XXX p miles with a rebuilt engine on 60,000 miles


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[jshjuarez]

I only use premium but as well I can not drive the car around because of no plates the car had custom plates ZOHARA the seller kept the plates I live in California


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[fox74]

EGR has to be in good working condition to pass the smog, if the EGR value is stuck, which normally do, it is an easy fix you need to clean the valve, apply vacuum to make sure it is operating correctly., The are many videos on youtube to show you how to do it. If the gas in thank is sitting for two years is no longer good, need to be replaced. it is strange to rebuild the engine at 60,000 miles, my supra still does not use a drop of oil.

 

[jshjuarez]

I meant the engine was rebuilt and had 60,000 miles when I got it with the original miles before 216,XXX on the cluster


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[jshjuarez]

I looked online and the price of an egr is quite expensive does anyone have an egr that they are willing to sell


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[fox74]

Did you try to repair the one you have ? unless the diaphragm is damaged you should be able to clean it up. Mark the vacuum hoses first, remove it from the car and give it a good cleaning. You high NOx definitely indicates EGR is not working. Let me know if that didn't work, I will know who might have one.

 

[mirage83]

If all else fails I'm sure someone on here will sell you one they have laying around. Check the Want to Buy/Parts Wanted section, shouldn't cost much at all if you end up having to get one. I've had mixed results cleaning up EGR's on various vehicles.

 

[Busted_Knuckles]

Also, replace the O2 sensor with a Denso brand only. I tried a Bosch O2 sensor, but had to pay a mechanic $279 to tell me it wasn't working right. He put in a Desno sensor straight from the dealer and it immediately passed. It passed for 6 more years until I grandfathered out of emissions here in Georgia.

 

[3p141592654]

There's no need to waste money on an OX sensor when its clearly in fuel control as it is. The slightly high HC measurement needs to be tackled after the ridiculously high NOX is taken care of.

The EGR has three main parts, the EGR valve, the vacuum modulator, and the EGR VSV. After 25 years any of these are suspect. Before you throw parts at it, and as you note they are expensive, do some diagnostics to figure out what is wrong. It's all spelled out here.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EC&P=13

 

[jshjuarez]

I ordered an EGR from tubbie and it clearly says on the paper that the O2 passed as well as the catalytic converter passed. We're do I buy the filter for the EGR vaccum modulator


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[Busted_Knuckles]

Look, I'm not trying to start a flame war or nothing like that, I'm sharing my experience. The O2 sensor does not set the value for tail pipe O2 emissions, it is used to set final fuel trim. That Botched (Bosch) sensor was not sending a proper signal, but also did not set the CEL. The ECU responded with a slightly rich mixture. A Denso sensor from the Toyota dealer sent proper signal and corrected the fuel trim. Even if the EGR tubing was completely blocked up, it is not going to affect the fuel mixture. You may have an EGR issue, but, until you fix the fuel mix problem, you will not pass emissions.

The fuel mix is controlled by the AFM, the CTS, the IAT, which is in the AFM, the FPR, and the O2 sensor for final fuel trim. Believe me or not, a Desno O2 sensor fixed my problem, which was the same as yours.

 

[jshjuarez]

Dam I wish I knew how to check all of that I'm only 19 barely starting my mechanical career with this car and friends help.


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[jshjuarez]

I will change my EGR once it get here


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[jetjock]

Follow 3p's advice. It's the best given thus far. Anyone capable of properly interpreting your emissions report can see the O2 sensor is working. As for Bosch sensors I've used them with with zero problems. Hell, they invented the damn things...

 

[jshjuarez]

Ok cool . Will install the things I purchased radiator ,oil cooler, EGR valve . The stock Radiator is leaking so I got a mishimoto one at a good price. So three main things to check is the EGR valve , the filter on the EGR vaccum and what is the EGR VSV


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[3p141592654]

The EGR is a royal pain to replace, and trivial to test. The book says use a vac pump, but a piece of vinyl hose and you mouth will work just as well,. It does not take much vacuum to actuate a working EGR. Engine idling, apply vacuum to the valve and it should stall or run very rough. Takes about 5 minutes to do that test. The vacuum modulator can also be tested almost as easily with a piece of vinyl tubing.