Hello everyone. I have been lurking this site for many years. Very new to a forum setting as well. I have owned my 97' Saturn SC2 for almost 7 years. It is a family car, I purchased it from my parents who purchased it from their parents. I didn't want it to end up going to some weirdo when they were done with it, so I snatched it Anyway... Will try to keep this as close to the subject as possible. I'm not a gearhead so excuse my ignorance, and if there is any information I am lacking please let me know and I'll do my best to provide it. Also if this has been covered before I apologize for the double post.

Quick background history on the car: The car had an engine swap done to it about a year ago, it now has a 96' motor (96' motor in very good shape, came from a college, GM donated it to the college so it lived on a motor stand until I got it. Lucky me!). 1997 Saturn SC2 DOHC 1.9l with a 1996 motor (same spec).

About 2 weeks ago (this engine now has about 4000 miles on it) check engine came on, Autozone tells me it was the EGR valve (P0401 and P1404 to be exact). I watched Richpin and someone elses video on how to clean it. It was already very clean, so that was worry some. This one would be the 1996 EGR that came with the 1996 motor. I ended up just putting the EGR from the original '97 motor back on after cleaning it. The check engine light went away upon start up with the replacement EGR (without me resetting the codes). Today, (it's been about 2 weeks) the check engine light came back while I was driving in town in moderate traffic. Same diagnosis from Autozone, codes P0401 and P1404. I had the codes reset today and I will see if that fixes anything (lol)... however... I highly doubt the EGR valve itself is the issue, to my unprofessional opinion, and I'm sure it will come back on soon.

Why would the check engine light go away after replacing it and me not resetting the codes, and then come back on 2 weeks later? Does anyone have any idea on what to look for/what could be causing it to throw the codes? Should I really just go buy a new EGR valve from the auto store? My roommate thinks it has something to do with the wiring. If that is the case, can I just replace the wires/wiring harness, if that's even an option (if so, how do I go about doing that)? It seems to be running fine with or without the codes on, so I do not know what to think... I really am thinking something else is causing it to throw a false code. What do I know though, that's why I'm asking ya'll... thanks!

 

I'm not sure, but it MIGHT take so many drive cycles before the computer resets the codes. Derf is our resident S series guru and the super moderator, so he'll be along shortly with a better answer. Just be patient.

 

Ah, joyous egr codes.

How much oil does the new engine burn?
If it has done nothing but sit bone dry on an engine stand for decades, I'm going to guess that some of the internal seals are passing oil into the cylinders. Same deal w the oil control rings in each piston. If it was started dry for the first time, oil may be slipping past the rings.

pull the plugs, wipe them clean, and reinsert. Let it warm up for a few, then shut it down. Pull the plugs? Are any oil soaked or fouled? They should also be the stock copper NGK BK...listed as oem equip on RockAuto.com .

My best guess is that the new engine is burning oil. You won't see it out the tailpipe until it is too late. The carbon in the exhaust deposits inside the egr passages AND in the exhaust pipes leading to and from the egr valve. Especially the input.

Deposits will form inside that exhaust pipe leading to the EGR input, likely before or at the same time they start to build up in the EGR valve itself. I have two s cars from the mid-90s and they didn't start having EGR flow issues until they started burning oil.

The most obvious reason to me why switching EGR valves would lead to a delay but re-emergence of the codes is that the EGR valve swapped in had freer flow and more complete pintle movement before you put it in.

​​​​​ After removing the EGR valve, fill it with carb cleaner and let it sit for about 15 minutes. Pour out the carb cleaner then repeat about 10 times. Seriously. 10 times. Then put a torx screwdriver into the bottom of the pintle and slowly work it up and down to see if it is sticking. The gap between the pintle and the passage it sits in is very narrow, so it does not take much for buildup or particulate crap to muck up the motion.

Every time the PCM commands the EGR to the closed position, it monitors the amount of time it takes the pintle to reach the closed position or what it thinks is the closed position. If the pintle is not moving freely, it cannot get there in a short enough amount of time and it throws a code.

Back back to where all of this crap is coming from to clog up your EGR. The answer is the exhaust tube that is feeding the intake to the EGR. After you clean the EGR but before reattaching it, put towels down to cover everything under the hood that doesn't move. Most definitely cover the input pipe to the EGR with a towel, but not before spraying a decent amount of carb cleaner on all walls of that pipe. Let this soak for about 15 minutes. Works best if the vehicle is already a little warm.

USE HEARING PROTECTION. YOU WILL BE LISTENING TO RAW EXHAUST WITH NO SOUND DEADENING. IT IS LOUD AND IT WILL DAMAGE YOUR HEARING IN SHORT ORDER.

With that pipe covered and anyone or anything you care about NOT in front of the vehicle, crack the engine and let it run for about 10 seconds. Then go look at the disgusting crap that has been blown out of that pipe onto the towel you covered the pipe with. If you are more about free-forming it, do some driveway painting with it by leaving the towel off.

Keep the rinse soak run crud removal cycle until you get everything out that you can.

Before reinstalling the EGR, clean it again being extra careful to work the pintle up and down to generate truly free movement. Also hold up the EGR valve and spray in my chamber or another and you will see how they are connected. No tools to clean this unless there is baked on stuff which there shouldn't be.

Moral of the story. If you do not clean out the pipe that feeds the EGR, you can clean the EGR valve every 3 weeks if it's your thing but it's much easier to get rid of the biggest source of EGR issues while you have it apart.

Also, do not submerse the entire EGR valve in liquid

Please let us know how it works out.

 

It doesn't get more detailed than that. Thanks for letting him know what to do, derf. Now, you can take the rest of the day off!

 

derf, (and Rubehayseed, thank you as well) thank you so much for such a detailed and quick reply! Wow.

The new engine burns/leaks no oil yet (see last entry at the bottom). Or, if it does, it is so miniscule that it doesn't show visibly on the dip stick hardly at all. It's still "green" so to speak.

The previous engine certainly burned/leaked oil as was evidenced visually. I put full synthetic in this engine after having it swapped and have no problems to report yet regarding loss of oil or performance.

I read your amazing reply shortly after you posted, and I have not wanted to post quite just yet until some time has passed. Didn't mean to ghost such a great response. Figured a decent amount of time/driving has passed since then to report that no codes have re surfaced after clearing them. I am hoping it is back to normal (we'll see). So far the car has been through at least 10-15 drive cycles, and perhaps around 200 miles since I had the codes cleared. A balance of freeway and in town driving, leaning more towards short trips to the corner/grocery store, etc. Seems to run the same as usual (good)...

If the codes come back, I will do as you have mentioned, and share the results. Will also give an update as time passes if the codes don't come back. Again, thanks so much for the information.

(Small horror story, not really relevant to EGR, rather to the engine) About a week after driving when the mechanics were through swapping it, they didn't clamp the heater core hose on all the way (doh!), and it completely detached while I was on the freeway! Was running with no coolant in the system, it all leaked out on the freeway. Coolant gauge slightly hit red line (I pulled over as soon as I could when I noticed it was starting to get hotter than usual, any later and it probably would've been done for) and made a nice crack in the radiator plastic (so I put the radiator from the 96' car on and hooked up an external transmission cooler); I am so lucky that the new engine survived, glad I pay attention to my gauges and had the opportunity to pull over when I did. Limped it home after letting it cool with engine off/driving on the shoulder (rinse and repeat)/relying on the grace of in town traffic to just let me get the hell home. Luckily I wasn't too far from home at that point. The point of that story being, despite that specific hard ship on it, the engine seems fine so far. I don't think any seals were damaged, etc. that would cause it to leak/burn oil, just yet.

 

Mr Derf, semi bumping an old thread just to make sure I have this clear,, in laymans terms. I too am getting the p0401, not burning any oil( she old, 320k) . I changed out the EGR valve since it was cheap, code went away for about 30 miles.

I watched a video about trying to fish a flexible something or other through the port to scrape the walls, but it didnt work. so before I remove the damn engine to clean it, im gonna try your tip..

So, remove the egr,,,, fill the exhaust side port with carb cleaner... any tips on getting more in? I only seem to be filling a small bit...
Let that sit and then start the car.... seems this will blow massive amounts of crap everywhere? ( thats a good thing as long as its clean )
is it increased flow rate or something that allows this to blow out?

When you say cover the input pipe the the egr, you mean the smaller hole that goes to the intake?

 

Cover both ports to catch the goo. The port leading to the EGR is the one you're spraying..
It comes out b c you've loosened it off the side walls of the port.
340 k on an original OEM EGR? Not bad at all must be a SOHC.

 

yes, just a regular ole SL SOHC. still runs like a champ so i refuse to give up on it. im about to go tackle this in a few hours....
did you take of off the air filter while doing this or did you leave that all attached? I can get to the valve with it on, but all of that is in the way and most certainly in the direct path off all the crap thats gonna come out.

Also, how did you get lost of carb cleaner into it? All i did yesterday was fill the opening. i am not sure any went into the passage way. add hose and fill from top?

Thanks again for all your help, i am glad there are still some saturn forums around!

 

of course at this point, second guessing everything i am about to do...

my intake port to the EGR is pretty damn clean. I cleaned the hell out of it yesterday, but did not clean the newly installed EGR that was likey cruded up a bit.

I am worried that the blockage is in the passage way through the engine block itself. Ive seen videos about trying to fish a cable through. otherwise a guy in youtube " richpin) basically has his engine apart, intake and exhaust manifolds off and was cleaning it. I DONT WANT THAT>
Does this ( your method) blow out that passage way a bit too?

 

Apologies. I don't think I was being clear but I'll go back and read my initial post with directions to see if I effed it up.

In the previous step you cleaned the EGR valve itself.

In this step, you are trying to get as much crud out of the pipe that leads to the intake port of the EGR. The reason being all of that carbon will eventually migrate and clog up your pristine EGR. A lot of people just clean the valve but don't address what's coming down the pipe, literally which then just clogs it up again. You may not have as much issue with that if you are not burning oil, but the dohcs clog their egrs at a pretty good clip.

Yes, of course take off the ducting because it is in the way. When doing this step, the EGR is completely removed and you are looking at the flange with two holes in it where the intake exit ports matchup to the exhaust gas input and output from the EGR. That is the port you want to cover with a rag to catch all of the skuz and that is where the skux is coming from.

Make sure you are wearing hearing protection, as with the EGR removed, you are getting raw exhaust coming at you through the intake pipe that meets up with the intake port on the EGR. It's freaking loud as expected. Just want you to know what to expect and how to be safe in doing this.