Any honda people familiar with the EGR system?

[ThisIsMatt]

I posted this on a honda forum, but figured I'd try here too.

I have a 92 accord and on light to moderate acceleration there is a stumble, generally around 1500-2000rpm. It also appears to persist at low throttle speeds, but not at idle.

Mechanic says it's an EGR port issue, and wants $335 to "perform egr cleansing". Personally I'd rather spend the money upgrading my tools and do it myself.

How would I go about properly diagnosing this problem to make sure it actually requires port cleaning (and does this require taking the entire intake manifold off?). I'd rather not diagnose by replacing parts one at a time (eg the EGR valve).

Today I pulled the EGR valve off as someone suggested to me. It didn't look too bad at all, just a little buildup that cleaned off easily. Put it back on and the problem persists. If I disconnect the vacuum hose to it the engine runs perfectly. I drove it around a bit with the hose disconnected and it's perfectly smooth like it should be. With the hose connected, if I move the throttle with my hand I can get it to a certain RPM where the engine will stumble and then regain that RPM and then stumble again and go back to that RPM again, continuously. I think this is around 1500-1700rpm. Anyone know what this could be specifically?

 

[Flyermax2k3]

$335 to clean your EGR system?!! What a rip off.... Just run a $3 bottle of seafoam through your EGR valve and you'll be fine (if it is only a cleaning issue).

 

[ThisIsMatt]

Originally posted by: Flyermax2k3
$335 to clean your EGR system?!! What a rip off.... Just run a $3 bottle of seafoam through your EGR valve and you'll be fine (if it is only a cleaning issue).

Hmm, not sure I want to be pooring anything into my intake system. And that is supposed to get rid of carbon deposites?

The place that I took it before (for a tuneup, where they diagnosed this problem) said they would have to pull the entire intake manifold in order to drill out the carbon buildup. Frankly, it didn't look like there was a whole lot near the EGR valve, and I don't putt around town like an old lady for carbon to build up. I think it's something else, but I don't know what...it has been getting noticably worse.

 

[Dulanic]

Seafoam rocks. It works very well at cleaning up a engine. The only downside of it is it can sometimes break up some rather large deposits that can plug up a cat.

 

[ThisIsMatt]

bump

 

[Wingznut]

Cleaning it won't help....

What the EGR (Exhaust Gas Recirculation) valve does is add inert exhaust gas into the cylinder. Since the gas has already been burned, it cannot burn again. Hence, the cylinder temperatures are reduced, causing a reduction in NOx emissions.

Your symptoms are not due to a plugged valve, but due to it opening too far or too soon (or both), and causing an improper mixture. I don't recall your specific setup, but generally there's a solenoid that controls when the valve gets vacuum.

 

[db]

I don't know what all the '92 EGR system consists of, but you could check the performance against specs of the control solenoid valve, the vacuum control valve, the valve lift sensor, and the ECM, in addition to the valve itself.

 

[ThisIsMatt]

Originally posted by: Wingznut
Cleaning it won't help....

What the EGR (Exhaust Gas Recirculation) valve does is add inert exhaust gas into the cylinder. Since the gas has already been burned, it cannot burn again. Hence, the cylinder temperatures are reduced, causing a reduction in NOx emissions.

Your symptoms are not due to a plugged valve, but due to it opening too far or too soon (or both), and causing an improper mixture. I don't recall your specific setup, but generally there's a solenoid that controls when the valve gets vacuum.

That's what I was thinking, but someone suggested I check out the valve to see if it could be sticking or whatnot. Personally I don't believe the prognosis of the mechanic I took it to. Not that I think they're shady, I just don't believe buildup is the problem (their explanation was that the orifaces build up carbon deposits and one could get more clogged up compared to others and cause certain cylinders to run leaner than the others, thus the stumble).

So...how do I diagnose it? I know where the solenoid you're talking about is located...I have a manual

 

[ThisIsMatt]

Originally posted by: db
I don't know what all the '92 EGR system consists of, but you could check the performance against specs of the control solenoid valve, the vacuum control valve, the valve lift sensor, and the ECM, in addition to the valve itself.

h...h...h..how?

 

[Thegonagle]

Although the fact that disconnecting the EGR valve eliminates the symptoms points right to it, this is also a symptom that pops up if you have bad ignition wires/cap/rotor. If those parts are original or haven't been replaced in a long time, you might want to replace those anyway.

 

[ThisIsMatt]

Originally posted by: Thegonagle
Although the fact that disconnecting the EGR valve eliminates the symptoms points right to it, this is also a symptom that pops up if you have bad ignition wires/cap/rotor. If those parts are original or haven't been replaced in a long time, you might want to replace those anyway.

The rotor and distributor cap were just replaced, but not the wires. I don't see how disabling the valve points right to it, when it could be something down the line in the intake, or another part of the EGR valve controls...

 

[Pepsi90919]

when you disconnect that vacuum hose are you just letting it leak...?

 

[TechnoKid]

I have a pdf that shows how to clean the egr passaeges on the honda accords. PM me.

 

[Ketteringo]

Anyone ever eat Seafoam the candy? That stuff is awesome! I cant even image using that to clean the engine of your car

 

[ThisIsMatt]

Originally posted by: Pepsi90919
when you disconnect that vacuum hose are you just letting it leak...?

Yes (causes the check engine light to come on when it thinks the egr valve should be engaging)

 

[ThisIsMatt]

bump for...um...someone

 

[TechnoKid]

If anyone needs the pdf, let me know. It is on Matts site too.

 

[CaptainHotbeef]

This might not apply to your problem, but a couple of weeks ago the check engine light in my 98 Accord v6 came on and the reason was the throttle position sensor. I hadn't noticed any problems, so I reset the light and it hasn't come on again. Maybe a loose connection or something (I cleaned the electrical connector and no more problems)

Anyway, I looked up some info on the throttle position sensor and one of the symptoms of it going bad is stumbling at a certain rpm and then recovering as the rpms increase. Something about it being due to an area on the sensor that breaks down and then the engine doesn't know what rpm it is at and the engine control systems get false info. The bad thing about my Honda, and I don't know if this holds for all of them, is that the TPS is non replaceable and you have to replace the entire throttle body.

You can check that the sensor is getting the correct voltage (mine was something like 5v) and then with the ignition on but the engine not running you can open the throttle by hand and see if there is a steady increase in voltage. One site I saw recommended using an analog meter vs a digital meter because you can see the needle drop off where the sensor malfunctions.

Just a little info that I learned and your problem sounded a little similar in some respects

 

[fredtam]

Originally posted by: ThisIsMatt
I posted this on a honda forum, but figured I'd try here too.

I have a 92 accord and on light to moderate acceleration there is a stumble, generally around 1500-2000rpm. It also appears to persist at low throttle speeds, but not at idle.

Mechanic says it's an EGR port issue, and wants $335 to "perform egr cleansing". Personally I'd rather spend the money upgrading my tools and do it myself.

How would I go about properly diagnosing this problem to make sure it actually requires port cleaning (and does this require taking the entire intake manifold off?). I'd rather not diagnose by replacing parts one at a time (eg the EGR valve).

Today I pulled the EGR valve off as someone suggested to me. It didn't look too bad at all, just a little buildup that cleaned off easily. Put it back on and the problem persists. If I disconnect the vacuum hose to it the engine runs perfectly. I drove it around a bit with the hose disconnected and it's perfectly smooth like it should be. With the hose connected, if I move the throttle with my hand I can get it to a certain RPM where the engine will stumble and then regain that RPM and then stumble again and go back to that RPM again, continuously. I think this is around 1500-1700rpm. Anyone know what this could be specifically?

Certain 1990-93 Accords experience a misfire condition or hesitation warm at 1,500 to 2,000 RPM. When vacuum is removed from the EGR valve, the misfire or hesitation goes away. This is usually caused by plugged EGR ports in the intake manifold. To correct, remove the brass plugs in the intake manifold and clean out the carbon. Honda offers a kit with replacement plugs so removal or replacement of the intake manifold will not be required.

 

[Wingznut]

For reference, I was an ASE Master Mechanic of 10+ years in my previous career.

Originally posted by: fredtam
Certain 1990-93 Accords experience a misfire condition or hesitation warm at 1,500 to 2,000 RPM. When vacuum is removed from the EGR valve, the misfire or hesitation goes away. This is usually caused by plugged EGR ports in the intake manifold. To correct, remove the brass plugs in the intake manifold and clean out the carbon. Honda offers a kit with replacement plugs so removal or replacement of the intake manifold will not be required.

With no disrespect intended... That doesn't make sense.

When you unplug the EGR valve, it no longer allows exhaust gas to recirculate into the intake manifold. When the intake manifold ports are plugged, exhaust gas is unable to recirculate into the manifold. Basically, they are the same condition.

Since he has an obvious drivability difference with and without the EGR functioning, it won't be plugged EGR passages in the manifold.

If you would like a confirmation that the ports aren't plugged, Matt... Open the EGR valve with the car idling. You can do this by either applying vacuum to it (presuming it'll still open with little backpressure), or better yet, reach under it and push the diaphragm up.

If the ports are plugged, nothing will happen and the car will idle normally. If the ports are allowing exhaust to recirculate, the engine will idle very poorly and probably even stall.

 

[fredtam]

Originally posted by: Wingznut
For reference, I was an ASE Master Mechanic of 10+ years in my previous career.

Originally posted by: fredtam
Certain 1990-93 Accords experience a misfire condition or hesitation warm at 1,500 to 2,000 RPM. When vacuum is removed from the EGR valve, the misfire or hesitation goes away. This is usually caused by plugged EGR ports in the intake manifold. To correct, remove the brass plugs in the intake manifold and clean out the carbon. Honda offers a kit with replacement plugs so removal or replacement of the intake manifold will not be required.

With no disrespect intended... That doesn't make sense.

When you unplug the EGR valve, it no longer allows exhaust gas to recirculate into the intake manifold. When the intake manifold ports are plugged, exhaust gas is unable to recirculate into the manifold. Basically, they are the same condition.

Since he has an obvious drivability difference with and without the EGR functioning, it won't be plugged EGR passages in the manifold.

If you would like a confirmation that the ports aren't plugged, Matt... Open the EGR valve with the car idling. You can do this by either applying vacuum to it (presuming it'll still open with little backpressure), or better yet, reach under it and push the diaphragm up.

If the ports are plugged, nothing will happen and the car will idle normally. If the ports are allowing exhaust to recirculate, the engine will idle very poorly and probably even stall.

With all due respect you can find this info all over the net posted by people with similar or better credentials than you. Example..

"Wayne Pasicnyck, an IDENTIFIX Asian specialist, is a Honda electrical, SRS, brakes, air conditioning, Toyota master, ASE master and L1 certified technician. His 15 years of experience includes 12 years as a Honda line technician."

 

[ThisIsMatt]

Originally posted by: Wingznut
For reference, I was an ASE Master Mechanic of 10+ years in my previous career.

Originally posted by: fredtam
Certain 1990-93 Accords experience a misfire condition or hesitation warm at 1,500 to 2,000 RPM. When vacuum is removed from the EGR valve, the misfire or hesitation goes away. This is usually caused by plugged EGR ports in the intake manifold. To correct, remove the brass plugs in the intake manifold and clean out the carbon. Honda offers a kit with replacement plugs so removal or replacement of the intake manifold will not be required.

With no disrespect intended... That doesn't make sense.

When you unplug the EGR valve, it no longer allows exhaust gas to recirculate into the intake manifold. When the intake manifold ports are plugged, exhaust gas is unable to recirculate into the manifold. Basically, they are the same condition.

Since he has an obvious drivability difference with and without the EGR functioning, it won't be plugged EGR passages in the manifold.

If you would like a confirmation that the ports aren't plugged, Matt... Open the EGR valve with the car idling. You can do this by either applying vacuum to it (presuming it'll still open with little backpressure), or better yet, reach under it and push the diaphragm up.

If the ports are plugged, nothing will happen and the car will idle normally. If the ports are allowing exhaust to recirculate, the engine will idle very poorly and probably even stall.

I understand what you're saying, but I think you're missing the fact that only some of the passages are blocked, which is what my mechanic suggested, and what I've also seen online. I think I'm going to do the port cleaning myself. Take a look at the PDF on my site (in sig).

 

[Wingznut]

Originally posted by: ThisIsMatt
I understand what you're saying, but I think you're missing the fact that only some of the passages are blocked, which is what my mechanic suggested, and what I've also seen online. I think I'm going to do the port cleaning myself. Take a look at the PDF on my site (in sig).

Originally posted by: fredtam
With all due respect you can find this info all over the net posted by people with similar or better credentials than you. Example..

"Wayne Pasicnyck, an IDENTIFIX Asian specialist, is a Honda electrical, SRS, brakes, air conditioning, Toyota master, ASE master and L1 certified technician. His 15 years of experience includes 12 years as a Honda line technician."

There is one part in that article that is intriguing... "...often it is a lean run condition or an EGR distribution problem with EGR going to one or two cylinders, rather than all four."

If the EGR system is designed where it has separate passages that distribute to separate cylinders... Well, then I can certainly see how it can cause what you are describing... And I stand corrected.

(I don't recall ever seeing an EGR system that doesn't just dump into the manifold plenum. *shrugs*)