Failed Smog, high HC at idle

[Infamax]

I've searched and tried various things. I've changed spark plugs, O2 sensor, CTS, vacuum lines, cleaned the maf, new air filter, changed cap and rotor, checked timing and set idle multiple times, and I still haven't been able to pass the sniffer.

The HC and CO are high at idle. Once the rpms starting going up, the smog numbers go down. As soon as the smog tech lets off the throttle and the motor gets to idle speed, the HC start shooting up. The numbers are fine anytime besides right at idle.

I'm at a lose, any help would be appreciated. I've included a pic of my smog sheet.

[nismolvr]

has any one messed with throttle screw settings? Have you cleaned Throttle valve of any gunk or carbon deposits ?maybe certain air passages in TB are clogged and your engine starves for air at idle, runs rich. New air filter? High HCs with High COs at idle are a sign of not enough air . Will bet some one messed with throttle screw settings....Hope this helps..

[Infamax]

It's a SOHC engine BTW.

I'm not sure I know where the throttle screw is located. I've owned the car for 5 years, and it's had the same SOHC since last time I smogged, which passed just fine. I pretty sure the throttle screw hasn't been messed with.

I'll pull and cleaning out the throttle body and see if that helps any.

[qoOp]

ah, CA smog sucks! i'm still trying to get my car to pass. >.>

[Wookie384]

Check EGR. It's probably clogged.

[mnmax]

Check EGR. It's probably clogged.

^^Yes definitely, check your EGR. With it clogged, you're not getting the right (or any) recirculation of unburnt HC and CO back into your combustion chamber.

I used to be a smog tech back in the day and it always sucked that CA law prohibited us from explaining what might be the possible issue with their car when it doesn't pass and customers would come back in saying that they had spent up to thousands of $ trying to rectify the problem.

[mxexux]

^^^ ya but how would a clogged EGR cause high HC's and CO? The numbers seem to say that it is running rich to the point of misfiring at idle.

OP, the pic shows that you failed visual on "other related emissions components." And also it says that the timing was "defective." Do you have any mods on the engine? What is the spark timing set at?

[mnmax]

^^^ ya but how would a clogged EGR cause high HC's and CO? The numbers seem to say that it is running rich to the point of misfiring at idle.

The amount of HC and CO exiting out the exhaust is basically regulated by the EGR either before or within the catalytic converter to be routed back into the engine to be burned. Whatever is left over is supposed to be trapped in the cat. If either of those fail, then the result will be too much emissions exiting the exhaust. So, it could be a couple of reasons:
1) clogged EGR valve or recirculatiion tube
2)catalytic converter failure
3)EGR valve not recieving signal or vacuum(depending on what type of EGR)
4)faulty EGR valve

Any of those could be the reason. Since you said that he also failed a visual inspect, it may be that his EGR may have been unplugged for whatever reason.

EDIT: Nevermind on that last statement. Just looked at the sheet, it says that EGR passed functional test

[Infamax]

I tried removing the egr pipe, It was rusted on and I couldn't break it loose. I'm gonna try again in the evening after it cools down and I get back from class. I'll give the egr valve and throttle body a good clean.

The smog tech had checked the egr solenoid, and said it appeared to be working properly. He also checked the egr valve and said it seemed to be working like it should.

The reason it said I failed visual was because the smog tech thought my timing was off. He thought the timing mark furthest to the left was 0* BTDC, when it's actually the second from the left. After that test, I've been going to a different smog station.

Could my problem be a faulty injector? If so, is there a way to check the injectors? I had previously read of a way to check the injectors using the ecu's self-diagnostic system, but I couldn't find anything on that again.

[mnmax]

should be able to just google the year, make, and model of your car with trouble code chart and it should give a break down on how to read the trouble from the little blinking led's that you see on your ecu. unless you know someone that has nistune or consult to read it on a computer direct from your diagnostic port.

[Infamax]

I don't have a CEL, I know how to check the codes.

One of the 5 modes in the diagnostic system is used to test the fuel mix ratios. I tried looking up the thread that described how to check for improper working injector using the ecu's diagnostic system.

[Ekin_s13]

i don't know why people are telling you to check the erg when the test is two speed idle. if you look at your co2 is low and o2 is high that show your cat is not work at 100%. i think you should change the cat and o2 sensor.

[mxexux]

The amount of HC and CO exiting out the exhaust is basically regulated by the EGR either before or within the catalytic converter to be routed back into the engine to be burned. Whatever is left over is supposed to be trapped in the cat. If either of those fail, then the result will be too much emissions exiting the exhaust.

I'm going to have to strongly disagree with you there about what the EGR does. You are partially right about it reciculating exhaust gasses back into the intake, but its purpose is NOT to burn left over HC's and CO...Its only purpose is to reduce NOx by lowering combustion temps when it dillutes the intake charge with inert exhaust gasses.

OP, leaky injector is a definite possibility. Or, like MNMAX said, the CAT is another possible cause. I would lean more towards the injector though since the numbers show that the HC's are way too high, higher than the CAT is supposed to filter out any way.

Also, take a look at the vacuum lines that go to the fuel pressure regulator. If there is a vacuum leak there, the regulator may be leaving too much pressure in the rail at idle.

[nismolvr]

This guys problem is only at idle ! EGR operates only off idle and cruise. If it was stuck closed he'd show high [email protected] 25 mph but its NoT!If it was opening slightly ,not seating correctly all the way @ idle it would misfire throwing your a/f ratios off . I bet it's just your idle air control valve Or throttle valve and not your EGR.

[zerodameaon]

Change your cat!! I had this exact issue almost the same numbers and i changed my cat to a Magnaflow 36306 i believe and i passed. Just barely but it passed. These idle tests are sadly harder to pass then the enhanced tests. My car would pass pretest enhanced but fail the regular test.

[nismolvr]

Change your cat!! I had this exact issue almost the same numbers and i changed my cat to a Magnaflow 36306 i believe and i passed. Just barely but it passed. These idle tests are sadly harder to pass then the enhanced tests. My car would pass pretest enhanced but fail the regular test.

Now that I saw his o2 @ idle High O2 at Idle is Maybe a Vacuum leak causing a lean missfire Is Idle higher than normal RPMs?,If no Vacuum leak . I'd have to agree with this quote. Change the cat like the he advised.

[Wookie384]

Cleaning out the EGR costs nothing but your time and brake clean, a cat, injectors, and/or O2 sensors cost money, start with the easiest cheapest shit before you throw your money into it. Even though EGR passes visual and functions, how are you sure the pipe itself isn't clogged/ restricted?

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[nismolvr]

i don't know why people are telling you to check the erg when the test is two speed idle. if you look at your co2 is low and o2 is high that show your cat is not work at 100%. i think you should change the cat and o2 sensor.^^^^^^^ Exactly the guy failed in HC and Co @ idle!!!!!Why in the hell are people telling him to clean his EGR? High NOX readings are signs of bad EGR system ,period!EGR does not open @ idle !It only opens @ off idle and cruise not @ idle!!!! therefore stop telling the guy to clean his EGR.He failed @ idle people. !

Some of you sound like you know what your talking about but in reality dont know anything , look at his results Study them before you assume its an EGR problem! So much misinformation.

[nismolvr]

Cleaning out the EGR costs nothing but your time and brake clean, a cat, injectors, and/or O2 sensors cost money, start with the easiest cheapest shit before you throw your money into it. Even though EGR passes visual and functions, how are you sure the pipe itself isn't clogged/ restricted?

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Dude the test results show its working!!!If he Had high NOX @ 15 MPH and @ 25 MPH it would show on his print out copy! Thats how you know the egr system is faulty. Here is a easier cheaper way of testing the EGR , Apply Vacuum directly to valve while engine is Idling .If it stalls and engine turns off , hello! it works.Sytem is unrestricted cause gases are getting by and his egr pipe isnt clogged.
Getting off way off subject , his problem is NOT EGR related.

people need to study how and when and why we have EGR systems in our vehicles .




The guy most likely has a vacuum leak causing a lean missfire , take carb cleaner and spray around intake and find your leak ,look for unplugged vacuum hoses.

[LeaS13Zenki]

yup somg alaways sucks same problem with my sohc i had vaccum leaks my car failed nasty.