Hey VX owners - I need your help by looking at your own egr system - Fuelly Forums

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Old 05-30-2010, 07:35 AM   #1
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Hey VX owners - I need your help by looking at your own egr system

My 92 VX has been acting up lately. I'm getting a hesitation issue right after it warms up, mostly in the morning after it has been off for 8 hours or more. Some days the behavior is worse than others. Might be the gasoline I'm using. I was using Shell for about three years and did not have any issue while cruising at 70 mph but the VX idle was bad - misfiring like crazy. When I switched to Mobil in March this year, the idle is smooth but I get the strange hesitation (misfire?) at 65 to 70 mph - but not all the time.

While troubleshooting what can cause this, I found that the egr valve will not hold static vacuum with a hand vacuum pump. As soon as I release the hand pump, air rushes back into the pump. It will only hold vacuum drawn from the running engine at 5 inches Hg at the EGR a idle. Is this normal?

I put a vacuum gauge in the line from the egr solenoid valve to the egr valve and test drove it. I only get vacuum to the EGR valve at 3000 rpm or higher at a steady speed which is about 55 mph in third gear. That tells me everything is functional - the ECU is grounding the EGR solenoid when the conditions are right.

Thing is - I'm not sure if this is normal or not. I get no EGR vacuum when below 3000 rpm. That rules out 5th gear. Why would egr be needed only at 3000 rpm or greater? Does the VX engine cylinder temps stay low enough at cruising speed in 5th gear to not require egr?

Anyway, I'm looking for VX owners who can test the egr in their cars to see if they have the same symptoms. According to the helm manual, the egr valve is supposed to hold vacuum when running at idle. It does not say if the vacuum source is the engine or a hand vacuum pump like I have. My egr valve will maintain the engine vacuum - I switched to the evap purge solenoid out of the CVC valve to avoid the egr solenoid duty cycle. When I apply vacuum this way, the egr valve lifts and rpm drops - like it should.

Anyone willing to look at this? I'm mostly interested if someone else with a hand vacuum pump can see if the egr valve in their VX holds vacuum or not.
I'm having some difficulty understanding why the valve won't hold vacuum this way. What allows the air to return to the vacuum pump and zero the gauge?
Does the air escape through the diaphragm or the pintle shaft? Who knows.
I don't want to buy a new egr for $150 for no reason. Sometimes used egr's pop up on Ebay but none right now.
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Old 05-30-2010, 08:03 AM   #2
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Usually its a bad diaphragm in the pump that leaks and causes it to not hold vacuum.
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Old 05-30-2010, 11:23 AM   #3
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No, it's not the hand vacuum pump itself - it works fine - holds vacuum all day.

Ross (djenyc) said he had three VX egr valves that leaked air. See his thread below. He did not specifically test with vacuum though.

http://www.gassavers.org/showthread.php?t=9505

I can get the egr valve to open with the hand pump - it just won't stay open. It loses vacuum almost immediately. Weird (or not) that it "holds" vacuum with the steady pull of the engine vacuum. It seems to be the way it was designed. I haven't been able to find detailed info on the egr valve yet. I would be interested (fascinated) to see the schmatic.
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Old 05-30-2010, 06:47 PM   #4
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I think there is a small crack in the rubber EGR valve diaphragm.

It may not be the whole problem though- it sounds fishy that your EGR valve never sees vacuum below 3K rpms.
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Old 05-30-2010, 07:19 PM   #5
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There might be a small crack in it, that's true. I'm fairly sure the EGR valve has never been removed from this car and I don't want to try removing it to inspect it more closely unless it's really necessary.

It's unclear if egr is active at low rpm or not. Many VX owners never rev their engines often, if at all. This is the first time in 15 years of ownership I've ever actually monitored any vacuum signal while driving. In the age of instant information on the Internet, certain information remains proprietary to the auto companies. I have not been able to find any data from Honda yet regarding the input signal levels that trigger the ECU to ground the EGR solenoid. The VX, unfortunately is OBD1 - oh well. Serial data from the DLC connector can be read by a Honda scan gauge but they are rare.
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Old 05-31-2010, 02:40 PM   #6
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I have a used EGR valve with about 10,000 miles on it from my '95 VX. It was replaced in 1996, about 10 months after I bought the car (new) because it made a "fluttering" noise once the engine reached operating temperature. My Honda mechanic friend researched it and determined the noise was completely normal. The only reason it was audible inside the car was because the EGR valve was mounted on the firewall, and the noise transferred through the wall into the interior.

If you need it, I'll sell it to you for $50.
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Old 05-31-2010, 03:46 PM   #7
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No, not interested in buying an egr valve (new or used) at this time.

Still waiting for another VX owner to test their egr valve and post what they find.
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Old 06-05-2010, 06:03 PM   #8
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I have a good news, bad news story tonight.

The good news is that the hesitation issue at cruising speed has been resolved. Replacing spark plugs was all it took. So it wasn't the egr system after all. It might be a problem later but I expect a code 12 when trouble strikes.

The bad news is three of the four Bosch Platinum Plus spark plugs I was using were bad. The center electrode was missing on two of them - I cannot see the platinum wire at all, it's buried deep in the insulator - somewhere. The other bad plug had the platinum wire still in place but it was sticking out of the insulator halfway to the grounding strap. Only one appeared to be "normal". They were in my VX for 50K miles. Clearly too many miles/hours.

That's it - I will stick with NGK ZFR4F-11 (4043) plugs from now on. I will have to change them out every year to year and a half but it's what I'll need to do.

So, the egr will remain a mystery, unless.........
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Old 06-05-2010, 09:50 PM   #9
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I had a spare EGR that I tested off of the car with a hand pump...it held vacuum once I got it to open (it was stuck shut from crud).

A theory as to why the EGR won't stay open with the hand pump while on the car (running I'm assuming):
The vacuum created by the air going into the chamber from the intake maybe pulling the EGR valve closed. At idle my VX pulls about 22hg/in of vacuum so the hand pump needs to pull more than that to open the EGR valve while the car is running.

I might not be making any sense though as it's late and I'm tired.

Glad you got those nasty platinum plugs out of there. Those things are trouble for lean burn and turbo cars. So expensive too. The NGK V-Powers are cheap enough to replace every year for a few years and still not add up to the price of one set of platinum plugs (that will cause problems as you have found out).
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Old 06-06-2010, 10:20 AM   #10
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Thanks, TomO for checking your spare egr valve.

Now I know the egr in my VX has a diaphragm leak. It's not bad enough yet to set a code 12. I will replace it if/when the code 12 occurs.
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