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EGR Frequency Solenoid Not Working/ Failed SMOG

 
Old 02-19-2019, 12:00 PM
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Icon4 Failed SMOG - HC's too high

Hey everyone,
I've got a '92 Civic VX as my commuter car, have to renew registration and it's smog year so took it down to the shop to get it tested and it failed massively. The Hydrocarbons are in the gross polluter range at 2500 rpm. My EGR failed the functionality test as well so that's where I started.

As soon as I took it off I knew something was wrong because some previous owner had put a strip of aluminum tape over the ports in the manifold blocking off the EGR. Took that off and moved on. The EGR works, I applied vacuum straight from the manifold and the engine stalled pretty much immediately.
I get vacuum signal all the way up to the inlet of the EGR Frequency Solenoid up on the fire wall, but no vacuum past it. I have 12v at the plug which I'm not sure is right, I thought it was only supposed to have 12v over 2000rpm? I tried it with it plugged in and not plugged in and still no vacuum signal. I took the solenoid out and tried it on the workbench and the solenoid does click but the ports must be clogged or something.
Since they're not made anymore has anyone repaired one of these? Is there a substitute available?

Last edited by Notmyusername; 02-22-2019 at 03:35 PM.
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Old 02-19-2019, 03:47 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Most solenoids have one wire connected to a constant source of +12 volts and the ECU pulls the other wire to ground to activate the solenoid. When the solenoid is not active you will measure +12 on both wires.

You may have the wrong ECU. Also the hoses could be hooked up wrong. It's clear that someone else has been in there before and who knows what they did. A VX requires a complete set of VX parts to work properly. You can't mix and match from the non-VTEC-E models. Identify what you have.

The main effect of the EGR is to reduce NOx. Gross amounts of HC are likely some other problem entirely.
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Old 02-20-2019, 08:55 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Okay I'll check on that, does the service manual show correct part numbers in it? I've got a PDF copy of that I can go through.

Vacuum hoses are hooked up correctly according to the manual, but I will do some more testing of the solenoid. I'll try and hook up my little hand vacuum pump to one side and a vacuum gauge to the other and apply power to the solenoid.

Since all this was caused by needing to get smogged, what would the HCs come from? Where should I look to repair that?

All the ignition is pretty new, just replaced at the end of last year new wires, plugs, rotor, cap, ignitor, and coil.
Valve adjustment was just set with the last oil change.
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Old 02-20-2019, 09:04 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

you'll need to verify if the egr is working and go from there. You might need to clean out the egr passageways as they can get gunked up. We had a member 5yrs ago take his HX to a mechanic to clean out the passageways because the regular stuff he used from parts stores weren't working.
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Old 02-20-2019, 09:05 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

You might try replacing the oxygen sensor, it is important to the D15Z1 running properly especially under light load. Expensive though.
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Old 02-21-2019, 01:52 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

The EGR Valve works, when I applied vacuum to it at idle the engine stalled. I cannot get vacuum signal from the solenoid so I believe that to be faulty but want to test it more thoroughly first.

Due up this weekend is a new PCV valve, cleaning the IM (new gasket ordered and egr valve gasket ordered.) and setting/confirming spark timing.

Hopefully I can get the solenoid working and it'll be all good, has anyone repaired one of these solenoids before?
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Old 02-22-2019, 03:40 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Alright so ran through the factory manual EGR system test and it seems like it's all working good. Got 8" of vacuum to the EGR valve hose, and applying 8" of vacuum to the EGR valve made the engine bog down. There is a little bit of gunk under it in the IM but certainly not blocked.
Timing was a bit advanced so reset it to stock.
PCV valve is new and operational.
Cleaned the filter housing and hose to the TB, and replaced the air filter.
Spark plugs are the correct type with correct gap, they were a nice light tan but the edges by the threads had some black carbon looking deposits.

The smog place re-tested and I'm doing a lot better but still not enough to pass yet.
Any other thoughts?
When I have time I'll clean the IM still, but didn't get a chance to do it today. It's got welded plugs so I'll have to drill it out.
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Old 03-14-2019, 10:48 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Another update. EGR system is all functional as stated above. Cleaned the IM as best I could, it wasn't super bad to start with but got all the deposits off and cleaned out the second straight PCV under the IM and the hose to it as well as all attached sensors and the TB etc. Got it all back together and then had to replace the thermostat as it got stuck open at some point (unrelated to IM but still worth mentioning I figure) bled coolant afterwards.

Took it to smog again and it was even worse than the first time?!

Now I smell gas occasionally at idle so I need to check for leaks from pulling the IM. I also still sometimes get an unsteady idle even though I've bled coolant a few times and cleaned out the IACV again when the IM was off.

I put a new O2 sensor in (proper NGK 24300 model) and have not noticed a change in driving yet but hasn't been smogged since I put it in.

This is getting frustrating so any help would be appreciated!
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Old 03-14-2019, 12:24 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

So you ignored the high HC and thought fixing the egr valve would magically solve that? Did you do any research into what causes high HC levels before you wasted money failing smog again?
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Old 03-14-2019, 12:30 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Originally Posted by Chrisfrom1986 View Post
So you ignored the high HC and thought fixing the egr valve would magically solve that? Did you do any research into what causes high HC levels before you wasted money failing smog again?
HC's and EGR not directly related but the EGR system got failed the first time in the functional test so it needed fixing anyways.

HC's are from too rich or too lean a mixture if I've been reading right. Or possibly oil/coolant leaks. Also possible is weak spark, but distributor components are all new as of last summer and shouldn't be failing that soon. Other suggestions included cleaning the IM, making sure both PCV's and their hoses were clear and working.

I've read through all the threads I could find related to the VX and smog and did everything I could from those.
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Old 03-14-2019, 05:10 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

HC emissions is unburned fuel. You need to post the entire results if you're seeking help as you cannot diagnose an emissions problem without looking at the entire gas analysis. It could be anything from a leaking injector to loose valve clearances.
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Old 03-15-2019, 07:23 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Alright the first test is as follows.


The next two times the just ran the pre-test, but they did give me a printout of the latest one (The worst one, second time was the best but didn't get a printout).


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Old 03-16-2019, 05:45 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

1) Compression test the cylinders.
If compression is good and nearly identical in all 4 cylinders...

2) Install new plugs, wires, cap and rotor and set the ignition timing.

Then have engine emission tested again.
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Old 03-16-2019, 08:11 AM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Originally Posted by muellersfan View Post
1) Compression test the cylinders.
If compression is good and nearly identical in all 4 cylinders...

2) Install new plugs, wires, cap and rotor and set the ignition timing.

Then have engine emission tested again.
Less than 10% difference on the compression test: 185, 183, 182, 193. All plugs out and TB open, and tried keeping the cranking time as close as possible as well.

I'll try that and report back.
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Old 03-16-2019, 01:09 PM
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Default Re: EGR Frequency Solenoid Not Working/ Failed SMOG

Just got back from smog, they've been nice enough to just run the pre-test real quick and let me know numbers without charging me an arm and a leg every time.

Drove around for a bit before stopping at smog, and with new OEM cap and rotor and new good quality wires and new plugs last week still horrible numbers. About 400 at idle and 300 at 2500.
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