I recently purchased a 95 sts with 85,000 miles on it. Shortly after I got it, I noticed a wierd problem under light acceleration(around 1700 to 2300 rpms from a standstill). The acceleration is not steady. You can feel it and also watch the needle jump up and down slightly on the tach. What could be causing this and what should I do. I bought a warranty that covers drivetrain and engine stuff for 3 months or 3,000 miles and I am hoping to fix this under the warranty. Admittedly it is not that big of a deal, but it is annoying and I am wondering if performance could be better.

Sounds like a noisey Throttle Position Sensor, but whatever it is it won't likely get better by its lonesome. Take advantage of that warranty and have it fixed properly.

Oh, and many happy miles. :)

Regards,
Warren

Sounds like a sticky EGR valve to me. Just give me a sec to copy and paste another post of mine here to help you...

here it is:

How to clean a sticky EGR valve

This article pertains to all models with the OBD-I Northstar 4.6L V8.

The symptoms of a sticky EGR valve are surging while trying to keep the throttle steady (not to be confused with surging at idle), and
code P036 (E036). Although it is possible to have a sticky valve with no code (that's how mine was).

First of all, don't do this job when the engine is hot. You WILL burn yourself. Your first task is finding the Exhaust Gas Recirculation (EGR) valve.
It is located underneath the spark plug wire cover near the rear bank of the engine. You will have to move the spark plug wire cover, you
don't have to completely take it off. Just lift it up and lay it sideways on top of the engine.

http://i29.photobucket.com/albums/c296/Krashed989/100_0347.jpg

Now you need to unbolt the EGR valve. To do this, you will need a ratchet with an extension, and a 10mm socket.
Once you know the bolts are unscrewed all the way, don't try to remove them. Instead remove the whole EGR valve with the bolts still in the holes.
This will prevent you from dropping and loosing the bolts.

http://i29.photobucket.com/albums/c296/Krashed989/100_0349.jpg
http://i29.photobucket.com/albums/c296/Krashed989/100_0350.jpg


On the bottom of the valve you will see two holes, one that is plugged with what appears to be a screw and one that is open.
The screw like object is the valve. You should be able to press it in easily and when you let it go, it should close itself again (it's spring loaded).
The one I was working with was sticking in the closed position.

http://i29.photobucket.com/albums/c296/Krashed989/100_0355.jpg


To clean the valve, simply spray carborator cleaner on and in the valve and wipe the dirt off with a cloth. Be very careful not to get it into
the canister, as the carb cleaner is a very powerful deturgent that will eat away the insulation on the windings in the sensor.
The following picture shows what you should not do.

http://i29.photobucket.com/albums/c296/Krashed989/100_0356.jpg

The picture below on the other hand shows the right way.

http://i29.photobucket.com/albums/c296/Krashed989/100_0357.jpg

Once you're all done cleaning the valve, you can reuse the gasket and put it all back together. Just make sure that when you put the
spark plug wire cover back into place that it clears the water pump belt.

What you have just done, should take care of your P036 (also E036) code. You can go into diagnostics mode and clear the code. If by chance it
didn't take care of the code (the code comes back after clearing it and going for a test drive), repeat the process.
If you can't get the code to go away, no matter how many times you clean the valve, replace the valve.

Happy motoring,
Krashed989
__________________

That's a great post. I like pictures.

Great post, Krashed! Thanks very much... I assume this is posted in the Technical Tips section? <cough, cough> :thumbsup:

Great Tip! The same process works on '96 and newer obd-II cars, you just have to move the fuel lines out of the way to get the EGR out. And the code on my '96 SLS was P1406. Thanks for the tips! Oh, its also a good idea to clean the carbon deposit out of the EGR supply and outlet tubes on the engine.

Great post and pictures..!

I know this sounds like a noob question...it actually IS a noob question, but I'm new with Caddys and car mechanics in general...so please bear with me....um....how exactly do you check for codes?? I have a 96 STS

Double post....i cant move the fuel lines out the way....

Double post....i cant move the fuel lines out the way....how do u do it? im scared of breaking something...

If you have had the fuel rail recall done, then you have a stainless steel fuel rail. There is no flex in it like the nylon rail. You must remove the rail and injectors.

I got it out of the way and cleaned it today...thanks to this post i got a clean EGR valve...

If I was to put the EGR valve in carb cleaner overnight would it be ok? How about doing the same to the throttle body?

It may be risky, but I do not see a problem with putting the egr valve in a pan of carb cleaner. Just make sure the level of carb cleaner does not go higher than the valve stem where the rubber boot is. It probably isn't good for the gasket though. However, when I remove my egr valve, the gasket stays on the engine. In Krashed's pics, his gasket is still on the valve.

I've been watching this thread for awhile and the whole time I've wondered just how much could this part cost to justify all the work to clean it. Wow, was I surprised! $200 at the parts store alone, how much would it be at the dealer? I now have a copy of this cleaning procedure folded neatly into my factory service manual! Thanks!
lrry99eldo

Great tip, but I see this cleaning tip is specific to the OBD-I Northstar 4.6L V8.
I have a 98 Eldo ETC. I believe that would fall into the OBD-II, correct?

I have similar gas pedal sticking problems and slight RPM movement when the car idles when cold.
Could this same tip be used to clean my EGR valve, or is it different on a 98-Eldo?

Thanks
Tim

Your symptoms could have another cause. You might want to start another thread in the Eldo/Seville section.

As far cleaning the EGR valve goes, this procedure is the same for your year. Removal of the valve from the engine may be slightly different.

I just recently bought a 96 sts and the guy had all the receipts from the all the work that had been done to it. He had a mechanic put on a new EGR valve and it costed about $250 (parts and labor).
Glad the previous owner put one in before I bought, saves me some dough.:cool2:

In Krashed's pics, his gasket is still on the valve.

Yes it is but I didn't document that I also changed the gasket afterwards. I changed it because that's actaully half of the gasket on the valve and the other half is still on the engine. The layers of it just split apart.

Great tip, but I see this cleaning tip is specific to the OBD-I Northstar 4.6L V8.
I have a 98 Eldo ETC. I believe that would fall into the OBD-II, correct?

I have similar gas pedal sticking problems and slight RPM movement when the car idles when cold.
Could this same tip be used to clean my EGR valve, or is it different on a 98-Eldo?

Thanks
Tim

Yours is probably about the same, I just wasn't sure if the locations, or bolt patterns were different.

If your gas petal is sticking, you have a totally different problem. My gas petal has never been sticky, but when I tried to keep the gas petal steady to keep a pace up a hill, my car would surge instead of going steady. For me, the surging never happened at idle, but I'm not sure if it's possible or not for the EGR valve to cause suging at idle.

If I was to put the EGR valve in carb cleaner overnight would it be ok? How about doing the same to the throttle body?

Just remember that the objective is to keep the carb cleaner out of the canister. Otherwise it might eat away at the insulation on the windings.

I cleaned out the EGR valve. Man--removing it and installing it was a bear.

Although I don't have a steel fuel rail (recall only goes up to 1997), I have the metal bracket atop the EGR valve. I dropped a fastener (nut that fastens the metal plate to the top of the EGR valve) into the engine valley--and lost it.

My carb cleaner was misplaced--so I tried electronics cleaner and to my surprise a slurry of black water came out and the valve was squeaky clean. Nice surprise. The valve did not seem to be getting stuck before or after, but the shaft did have a lot of carbon deposits on it, which I successfully removed with the electronics cleaner and a small brush.

I scraped the old gasket off with a razor blade, and it was a bear all over again to put the EGR valve in, with that thick bracket in the way.

Man, I had alot of fun with my dad's 99 deville at 97k miles today. Symptoms: stall at low speed, misfiire P300 code, and surging on moderate/heavy acceleration. Heavy acceleration to 4000rpm would cause it to stall. No other code than P300. And my father babys the N*

Cleaned out the throttle body, and cleaned out the EGR valve. Both were filled with crap. On the 99 deville, there's no spark wire cover, but there's a different kind of headache, a bracket that attaches between the fuel lines and one of the EGR screws. Take the nut off, then gently push the fuel line away from the EGR to clear the bracket off that screw, then proceed to remove that screw.

After cleaning both TB and EGR out, topped out the gas tank (11 gals) of Shell 93, I went to a backroad and floored it. Problem solved... now I need to do a couple more WOT's before giving it back to the old man.

My EGR valve has been causing a rough idle and stalling lately. I recently took it out, cleaned it with carborator cleaner and replaced it and now the vehicle won't turn over. It just keeps cranking. My question to Krashed989 (http://www.cadillacforums.com/forums/member.php?u=16457) or anyone else was: could this mean i messed up the EGR valve while cleaning it? I sprayed the carb-cleaner inside the two holes and put a paper towel in there to wipe out some of the carbon build-up... I didn't get any cleaner on the black electrical cylinder I don't think... Before I tried to clean out the EGR valve, the vehicle started and ran, though rough and with some stalling, but after the cleaning, won't start.

Did you check it before reinstalling it? Did the pintle valve move freely without sticking (opened or closed)? Did you pull any electrical connections and forget to plug them back in?

I cleaned mine with electronic contact cleaner, and a toothbrush. The electronics contact cleaner was extra insurance in case it managed to get inside the windings.

The thing is I still got the code a couple of times after putting it back together.

I performed the "carbon cleaning" via the intake vacuum with GM Top Engine Cleaner aerosol, then raising RPMs to 2000 and turning the car off when the smoke begins to come out.

A few WOTs later, no more EGR code. I think my pinging with cheap gas could have possibly been related to the EGR.

Would it be unwise to take some Seafoam or GM TEC and put a bit into the intake of the EGR while the car is running in order to clean out the hoses and the whole system? And if it is unwise, is it only unwise because it would damage the valve and nothing else? If so, I think it'd be a good idea to do before changing one (which I think I am about to do...).

How are you going to do that? Where are you going to put it? Besides that, there is no EGR flow at idle. Just pull it and clean it the conventional way if you need to.

Well was thinking of holding the throttle lever open a wee bit...unless it has to be in drive, wasn't sure. I saw a vacuum line going to it...but calling up the diagram of the valve in my head, that might be bad for it and cause it to stop working, you're right. Might just put it in the return line with it off though.

Well was thinking of holding the throttle lever open a wee bit...unless it has to be in drive, wasn't sure. I saw a vacuum line going to it...but calling up the diagram of the valve in my head, that might be bad for it and cause it to stop working, you're right. Might just put it in the return line with it off though.


Hey wait a minute. Are you talking Northstar? Different beast altogether. Pre Northstar you have to clean out the "mouse holes" inside the throttle body with an old wire hangar. Your proposed method is more orthodox, in that case. Do a search under the correct engine forum. There are plenty of posts on how to tackle the EGR code on a pre-Northstar.

Wait a minute. "Mouse holes" are on '93/'94 Northstars. He has a 4.5. Mtflight, I believe you are thinking of the EGR "tubes" in the 4.9 tb bore.

That vacuum hose tailfin is discribing goes to the vacuum side of the EGR diaphram (no carbon there). Besides that, the pre Northstar EGRs rarely need cleaning.

Wait a minute. "Mouse holes" are on '93/'94 Northstars. He has a 4.5. Mtflight, I believe you are thinking of the EGR "tubes" in the 4.9 tb bore.

That vacuum hose tailfin is discribing goes to the vacuum side of the EGR diaphram (no carbon there). Besides that, the pre Northstar EGRs rarely need cleaning.


Ahhh! I stand corrected. :)

Yeah in retrothought, this doesn't seem like a bright idea. So I'm just going to crawl up the exhaust and...ok no...:bang2:

I Am Reading Pcm;po171&po174 On The On Board Computer.my Problem Is Rough Idle Or Surging During Idle.what Does The Codes Mean.i Cleaned The Egr Valve But Only Used Carb Cleaner Around The Opening Of The Valve.how Far Do I Go?should I Push The Spring Loaded Valve Al The Way In?i Have A 2001 Deville.

P0171 - Fuel Trim System Lean Bank 1
P0174 - Fuel Trim System Lean Bank 2

Vacuum leak maybe.

Yes, press the spring loaded valve all the way in. It should move freely and not stick anywhere along its travel. Clean the shaft as well as the opening, but don't allow carb cleaner to run into the "can" as it can destroy the insulating varnish on the windings.

Ok let me clarify or can you elaborate a little more. You want us to protect the canister by putting rag over it or by not spraying too much carb cleaner in the valve?

Ok let me clarify or can you elaborate a little more. You want us to protect the canister by putting rag over it or by not spraying too much carb cleaner in the valve?
When cleaning the EGR, hold it in the upright position as it is when mounted. Holding it inverted allows solvent to run down the shaft and into the "can". That is what you want to avoid.

GUYS........Once you have cleaned the carbon chunks out of
that EGR valve install one of these GM linear clean screen
gaskets with a screen to keep the carbon build up out of the EGR
Best $7 bucks I have spent!

I have used them in my older GM vehicles..................

http://www.tomco-inc.com

I would not put that thing on my car on a bet. I can see the screen getting clogged and causing all sorts of drivability problems. The EGR passage is large enough so that it should never get plugged or need cleaning. That screen is not. That thing is a problem waiting to happen.

RANGER..........from all the posts I see here with clogged EGR valves
that gasket may well be a cure................

I used it successfully on my girls 4.3 Blazer which had many clogged
EGR issues because of the factory programming which didn't fully
open the EGR all the way thus causing carbon buildup and driveability
issues...............

My local indy repair shop now uses these screen/gaskets in several
different applications for older GM/Ford vehicles to cure carbon
clogged EGR issues..................

A good fix for $7 bucks IMO and experience and have NEVER had another
clogged EGR in her vehicle in the last 2 years!
Me thinks she need to BEAT on that vehicle a little to "clean" it out!
LOL!!!!!!!!!............geo

I cleaned my EGR valve thanks to the pictures in this post.
I had failed HC on the yearly inspection so I tried to clean everything in the enginecompartment. Did this, TB and plugs. No I'm back on the road again.
Thanks :thumbsup:

Hey Krashed989,

Thanks for the excellent post on how to clean the EGR Valve. I am a new caddy owner ('95 Seville SLS) and just pulled a few codes which brought me to this forum. (PO36 - PO39 - PO94)

THANKS!

edited: dont post questions in tech tips, please see sticky - urbanski

Guys.......If your tired of cleaning the carbon chunks out of your
EGR valve as I was from Grannys carboned up ride.
Check out this replacement EGR valve gasket that has a screen
moulded into it. Cost about $5 bucks.........geo

http://www.tomco-inc.com

I used electronic contact cleaner spray, instead of carb cleaner. It's a solvent that does not damage sensitive electronic parts.
That way if it does happen to get in the can, it won't harm it.

I kept getting PC1406 in my 96 Concours so I cleaned out the EGR valve today and it fixed it. Thanks again for the tutorial (I also used it ~40,000 miles ago). On the 96 Deville with the stainless steel fuel rail, I had to remove the manifold cover, unscrew the 4 bolts that hold the fuel rail down, pop out the fuel rail/injectors. After the fuel rail moves freely, then you can flex it enough to get access to one of the EGR bolts. I cleaned the EGR valve out with carb cleaner but the pintle was still sticking REALLY BAD. I then went to a wire brush...still sticking. I had my neighbor take a look and he used his flashlight to look inside. Around the rrim where the pintle valve sits closed (flush with the surface that touches the gasket) I had nasty carbon build-up. I had to use a flathead screwdriver to scrape out the carbon. After that, the pintle moved freely and my code is gone. Thanks again!

Sounds dangerous; fuel lines next to a HOT EGR valve; catastrophically dangerous.

You better start working on cars and trucks to get an idea of just where fuel lines really run. The proximity to the top (not the exhaust side) of an EGR valve is the least of your worries !!

Not to mention that it has a heat shield on the fuel line side.