EGR Valve Mystery

[7Freedom7]

The check engine light on my '89 Geo Metro came on and has stayed on for the past few weeks, occasionally turning off by itself for a little while and then coming back on again. When I flash the codes, it comes up 51, which is Exhaust Gas Recirculation Circuit. I did all the tests in the Chilton and all the components: Value, Modulator and VSV seem to be working fine. I checked the vacuum coming from the throttle body which was 0 in. Hg at idle, but went up to 10 in. Hg or so as I pushed down the accelerator.

Should the vacuum be 0 at idle or does this indicate a vacuum leak?

When I put 10 in. Hg of vacuum on the ERG valve itself when running it moves drastically and the engine runs very poorly. When I warm up the car and put the vacuum gauge on the hose going to the EGR valve, I see that it does get about 10 in. Hg when I push the throttle down. However when connected and running warm when I push the throttle down it, the EGR valve doesn't move or barely moves sometimes. This seems strange to me that 10 in Hg. from my vacuum pump moves it drastically but 10 in. Hg from the car doesn't move it hardly at all. What's the deal here?

Is that an indication of vacuum leak?

Would a vacuum leak cause the error code? or would only an electrical problem cause an EGR error code?
I tested the resistence in the Vacuum Switching Valve (VSV), which was 34.5 ohms. One section in the Chilton manual says it should be 33-39 ohms and another section says it should be 20 ohms. Which is it and is this bad?

Would the EGR valve not opening affect my gas mileage or power or is it just the emissions?

[57raceman]

I have the same problem with a 1995, 1.0 3 cylinder. I can clear the 51 code and after 4 or 5 miles it comes on again. Checked everything out seems to working fine. I can see the EGR valve moving when I push the gas pedal. 34 ohms on senser coil. Any ideas???

[iMogal]

I had the same issue guys!

I found that the entire EGR system was properly working(mechanically), but the return port from the EGR valve back into the intake manifold was plugged with carbon.

I got lots of carb cleaner, and a stiff wire(single strand of 14 guage house wire) I feed the wire into the port, and slowly loosened up the carbon. Ocationally removing the wire and rinsing out the port with the carb cleaner. I had to do this MANY times.
(did that make sense? - hope yea understand!)

Eventually I broke through the carbon build up. The bad thing is, the last remaining bit of carbon build up, got sucked into the engine. But the port is now clear. I did all this with the engine running at idle.
(if you do this, do so at your own risk!)
When I finally broke through the port, it startled me, as the engine quickly sucked all the carbon and cleaner into the engine.(just the noise startled me, I wasn't expecting THAT to happen!)

I've had no issues with the EGR system since(been a year or so now)

Hope this helps yea guys!!

[GM Line Rat]

Originally Posted by iMogal

I had the same issue guys!

I found that the entire EGR system was properly working(mechanically), but the return port from the EGR valve back into the intake manifold was plugged with carbon.

I got lots of carb cleaner, and a stiff wire(single strand of 14 guage house wire) I feed the wire into the port, and slowly loosened up the carbon. Ocationally removing the wire and rinsing out the port with the carb cleaner. I had to do this MANY times.

Good advice! I've had to do this 2 times on different Metro EGR Valves (Both return tube clogs).....But I NEVER do it while the engine is running. I remove the EGR Valve from the engine so that the EGR Valves steel return stem (Tube) can be tipped down towards the ground, and as you clean the stem, the carbon deposits and carb cleaner you spray into it can run OUT of the stem instead of inside the EGR Valve. The EGR valves diaphram is made out of rubber and you dont want to risk softening it up or damaging it with the carb cleaner. Besides, it's better to let the excess carbon go OUT of the engine instead of it being sucked inside the engine while your cleaning it! While the EGR Valve is off, you can clean the Vacumn hoses out too! EGR Valves in general are EXPENSIVE to replace! 8 out of 10 times, a good cleaning of them in most any car will reset an EGR Code and the system will run as should again unless their is internal dmg to the valve itself. BTW, Always install a new EGR valve Gasket....Their dirt cheap at the auto store!

[iMogal]

dang, so I didn't quite explain it right, but good points you added there!

Its the return port inside the intake manifold itself that I had to clear out, not the outlet port on the EGV valve.
Unless the intake manifold was removed from the engine, there was no way to prevent the carbon from being pulled into the engine.
So I wiggled the wire through, and flushed out the port the best I could with carb cleaner, but the last bit got sucked ito the engine.

Does that make sense now?

Cheers!

[57raceman]

thanks guys. I check it out and let you know if it worked.

[mostly_water]

This EGR carbon buildup seems to be a popular problem. I'm beginning to think its wise to inspect and clean mine, even though I'm not experiencing problems. Does anyone agree that this should be part of a regular Metro maintenance regimen?

I’ve never had the EGR off before, but it seems fairly simple. Lets assume I don’t know what I’m doing; how badly could I foul things up by giving this a try?

[RossT]

It would be a good idea to clean the two egr ports in the intake/head about once a year. You will need to take the front exhaust manifold off and the egr. It is rather simple to do and hard to mess up. The first time I did this it took several hours. I can now do it in about 10 minutes.

This is the tool that I used to clean the ports;

http://www.teamswift.net/viewtopic.p...ight=egr+brush

[1994 firefly]

so does this take care of the egr code (51)? Because I've had to do the same thing, but it hasn't stopped the code from coming on...

[DOCTORBILL]

I did a thorough job of cleaning out the EGR system using a tool I made from
a small spring pulled out.

First Page of..................."A way to Clean the Carbon out of the IM Passageways !"
http://www.automotiveforums.com/vbulletin/t622536.html

It worked quite well.

I would not advise doing it with the engine running - the carbon might lodge on
one of your valves and keep it from closing. Death sentence....I am told.

DoctorBill

If you have the patience to do it, look thru my thread on how I fixed my '93
Metro three banger:

First Page of..................."NOT the end of my '93 metro...Life after death! RINGS"
http://www.automotiveforums.com/vbulletin/t613410.html

[dookeye]

Okay, here is my theory on the synergystic triangle of malady that plagues the 1.0 Suzuki engine: clogged EGR system+leaking valve seals+burnt valves.

I think that what likely happens is that eventually ( usually somewhere over 100K ) the valve seals start to leak ( I mean how long can those little things last against the constant valve stem movement? ), this causes oil to be burned in the combustion chambers which in turn causes excessive carbonization in the chambers, on the valves, and most importantly throughout the EGR system, which eventually clogs, raising combustion temperatures which eventually burns valve(s).

Make sense? or am I off somewhere?

[1994 firefly]

Ya, that all makes sense, and I'm pretty sure that's what happened to my the last engine that was in this car. The trouble now, is that its a new engine with a clean egr system, and still with the codes...

[dookeye]

is that a completely new engine or is it a dock/JDM engine?

[DOCTORBILL]

Since it only costs approximately $250 to get the Head rebuilt, maybe one should
just pull it off (easy as pie) and have it rebuilt every 100,000 miles.

My Head Rebuilt cost me $230 and that included all the Gaskets (Head Shop asked
me if I wanted the complete set) and I bought new Head Bolts from Shucks for
around $20.

How 'bout them apples...?

DoctorBill

[1994 firefly]

its a re-build, but I know that the passages are clear now because when I move the valve manually, it causes poor running and almost stalling. Still can't figure out what's causing the codes though, always 51 and 46