Bad EGR valve, what can it do

[pierhogunn]

I have a 2001 Saturn SL2, with 160K on it, I know, it's young,

The EGR Valve is not working,

what are the consequences to waiting to replace it?

Dan

[frumper64]

Poor running

If it really gets clogged up, it can cause the car to run really roughly. I had this happen on a Nissan pickup years ago. Simply cleaning all the carbon out fixed the problem though and it was still running fine when I sold the truck 60K+ miles later.

[crokett]

I had one on a Ford Ranger that I delayed replacing. Eventually the truck would start, then quit when it got warmed up.

[pierhogunn]

Okay, so just unbolt it, un-plug it, and spray it full of what?

I have some sensor cleaner that didn't really touch all the black crusty stuff in it, is there something better, like brake cleaner?

and would a fowled plug lead to this sort of non-sense? ( I just changed all 4 of them and the wires)

[dbhost]

EGR = Exhaust Gas Recirculation Valve. This valve is used to lower peak combustion temperatures, and in turn reduce Oxides of Nitrogen.

Wiki link

Depending on the engine, and amount of computer control, this can cause the car to run VERY roughly, or not at all. It can also cause the vehicle to fail an emissions inspection.

I have heard of folks cleaning the EGR valve with carbon removers like Seafoam etc... but I have never done that. A replacement valve is usually cheap enough insurance that it isn't worth trying to salvage the original one.

By the way, I have the same year / model car, but with 100K fewer miles on it. Good to know they go that far...

[master53yoda]

the EGR valve opens when the engine is above idle and ports some exhaust gases into the intake reducing combustion efficiency by lowering the available O2 and combustion temperatures. If it fails open it will cause hard starting and very poor idle. if it fails closed you would notice vary little difference in operation. You could notice some spark knock under load with it failed closed.

It will not pass emmissions if it is failed closed. Cars that do not get emmissions testing done have a number of failed closed EGR valves that are never caught.

[gordons]

I have dealt with www.rockauto.com for many years for parts for my older vehicles. Found most of the items I needed there at excellent prices. For your Saturn EGR valve, they want around $71 for a new OE part.

Only thing to watch for is shipping. They have multiple warehouses and if you are ordering a number of different parts, then you will incur shipping charges from each location. I try to batch my orders accordingly.

As an example, Tire Kingdom wanted $49.95 each for three serpentine belts for LOML's 11 year old Honda Civic plus another $50 to install them (failed annual test for worn power steering belt). I bought all three belts (Gates) from Rockauto for $26 total plus $8.50 for shipping. Fitting charge was free of course .

I hate these annual "scam" tests - heck even Florida stopped doing them!!! But that's a topic for a rant some other time.

Gordon

[Uncle Cracker]

The real purpose of the EGR valve is to make sure that the "Check Engine" light comes on at regular intervals, in the hopes that you will take it to your dealer, who will turn it off for $150 or so...

[pierhogunn]

that is what saturns are all about, not very often do they have serious problems, things leak a little, so you keep an eye on your fluids, and pay attention, you will not have any serious problems. I keep a bottle of antifreeze in the back seat cause some A-hole mixed dexcool with that green stuff, and now, a seal or two is a little worn, and I just have to keep an eye on my coolant level.

My Check engine light is on, and the code is the EGR valve, the car does run rough when not acceleraing, so if that is all it is, I might just order the replacement from rock auto, and spend the 15 minutes replacing it

[mpc]

EGR valves are normally a vacuum actuated "gate" to allow exhaust gasses back into the intake manifold. The already-burned crud won't burn again... but it's got some mass so it absorbs some of the heat of the next combustion cycle, lowering the temperature of the burn. That lowers exhaust temps leading to less NOx formation. NO2 is a natural product of burning gas... but in a hot exhaust manifold or hot exhaust pipe NO2 molecules break down into NOx + O2 molecules. NOx is a prime smog maker.

With the EGR valve in your hand, look for the carbon-encrusted ports. Those are the lines leading to/from the exhaust (typically from the exhaust manifold or a tap in the cyl head) and to/from the intake manifold. The round "flying saucer" portion is a vacuum actuated bit; engine vacuum pulls against a spring-loaded rubber diaphragm. As the diaphragm moves, it lifts the "pintle" valve inside the carbon-encrusted area allowing exhaust gas to flow from one carbon encrusted port to the other. Some EGRs use an electromagnet (solenoid) instead of engine vacuum to lift the pintle.

Basic tests:
* Find a clean piece of fat vacuum or coolant hose that'll just wedge into either of the carbon encrusted ports. BLOW into the other end of the hose. If the EGR is sealed, you won't get any flow out the other carbon encrusted port. If the EGR leaks... scraping the carbon off or dousing it with spray carb cleaner (let it soak a bit) will usually fix it. Soaking it in gas or diesel fuel works too. Usually a car with a EGR valve that leaks this way will have a lousy idle and will probably be hard to start.

* For EGRs with vacuum actuation: there will be 1 (or more) small vacuum nipples on the flying saucer part. If you have multiple ports (often on turbo cars) you'll have to ID the various ports. The ones on the "top" of the flying saucer (opposite the pintle valve and carbon ports) typically are the ones that open the EGR valve; any ports on the bottom side of the flying saucer are "reference pressure" ports - they connect to the air filter typically or a computer controlled solenoid that bypasses the EGR when the engine is stone-cold. Ignore all lower ports for now - leave them open, and cap/plug all but one upper port. Apply vacuum to the remaining upper port and verify 1) that the vacuum doesn't leak down (if it does, the diaphragm is torn and the EGR valve is junk) and 2) that the pintle lifts - you should be able to blow through the carbon encrusted ports now. If the valve doesn't lift, either the diaphragm is bad (or you've got a blocked vac port) or the pintle itself is jammed.

* For EGRs with electric solenoid operation: most are 12 volt but there is no guarantee of that... and using a too-high voltage will burn up the solenoid. Using an ohmmeter, you can measure for continuity across the two wires going to the solenoid. You should see a bit of resistance... somewhere between 10 ohms and 1000 ohms typically.

Other "EGR" failures:
* The pipes to/from the EGR's main ports (carbon encrusted ones) also get blocked by carbon. This was a common problem on Nissan Sentras. Many cars have a small orifice in the pipe leading to the intake of the engine (or inside the intake manifold itself) that easily clogs with carbon. Use that fat vac/coolant hose to blow into the ports where the EGR mounts... you should be able to blow air into both of them. If one is blocked, spray carb cleaner and a soft wire brush might save you.

* Leaking vac hoses.

* The hose from one of the "top" ports on the EGR valve should (eventually) go to the intake manifold somewhere between the cylinder head and the throttle plate or right to the throttle body/carburetor for "ported vacuum" on older engines. I.e. it gets intake manifold vacuum. Find that port and, with the engine idling, make sure there is vacuum. Rev the engine up to 2000 RPMs or so to see if vacuum builds up on "ported vacuum" installations.

* If any vac hose from the EGR valve goes to some sort of vacuum switching solenoid gizmo, that solenoid may be bad. Modern computer controlled EGR setups work this way: the computer turns the solenoid ON or OFF to control when the EGR functions. So if a solenoid fails, the computer will toss the EGR error code.

Note/warning: when using the fat vac/coolant hose to test the EGR valve, remember to always blow towards the valve - never suck. You'll get a mouthful of nasty/toxic exhaust crud for your troubles if you suck on the hose.

mpc

[jcjrsmith]

Yeah, some of the older Saturns are hard to kill. I got a 1997 Saturn SC2 for my son. It has 172,000+ miles on it and runs great. It does, however, leak oil. My sister-in-law bought the car used for my nephew, but he never really liked to drive it. I traded her a laptop I got for $75 and an old digital camera for the car about three years ago. We decided then (Josh was almost 14 at the time) that it would become the Josh-mobile. We had the car painted last summer for his 16th birthday and now he is almost 17 and drives it every day.

[Uncle Cracker]

Yup, LOML had a Saturn SC-1 with about 175K on it, and in great shape. She drove it to work every day, 60 miles RT. Then she got a wild hair and bought a new one, giving "old faithful" to our (then) 30-y.o. son. It lasted exactly 3 weeks with him at the wheel, and it was over... Dr. Destructo strikes again...

[Habe]

The fault code is really pointing to the EGR system not just the EGR valve. You could have a bad vacuum or electrical signal to the EGR valve itself. I would trouble shhot the system to find the real fault before you buy any parts that you may not really need.