SES Light & EGR Valve question

[Crazy Canuk]

Hi

My car is sick again but I don't know how sick it is.

About a 1/2 a week ago my SES light comes on for 2-3 mins then blinks out. So I asked around at work and they said don't worry about it. However this weekend after I had the low coolant sensor replaced, the fly wheel cover tightened (it was loose?) and I drove ruffly 150miles it came on again. I shut off my car and restarted it, and it came on again. I let the car sit for half an hour and the light was off so I took it to the shop then.

Today I called the shop and they told me it was throwing the code for the EGR valve, they reset it and told me to see if it does it again.

My question is how many times or how often the SES light comes on untill I shoulde take it back, I haven't notice anything wrong with my car, no ruff idle or anything. I think it could be throwing out a false code out?

Also how bad is a bad egr valve if I don't notice anything wrong with my car? If the SES light comes on should I take it to the shop in the next couple of days or drive there right away?

Thanks.

[TraceZ]

The EGR valve is a simple device that is easy to replace. It is held to the back of the intake manifold with 2 nuts. It has a vacuum line running to it.

While cruising under part throttle it will open and allow some exhaust gas back into the intake manifold to lean out the mixture a little, lower emissions and increase fuel economy. As it gets old it can clog up with carbon and stick. The valve is actuated by an electric solonoid on the vacuum line, which is also very easy to replace.

Finding a replacement is easy on the forums "for sale" section, also try looking in the "for sale" section over at camaross.com, you could even post a "wanted" ad. I would guess you'll pay $10 - $15 plus shipping for a good working LT1 EGR valve and electric solonoid.

Here is a picture of the back of the LT1 intake manifold, courtesy of Shoebox.

[Injuneer]

First, get the exact code.... there are two possible in OBD-I. One is for electrical continuity on the EGR vacuum solenoid. The other is for low EGR flow. Obviously, you don't want to replace the EGR valve if the code is for the solenoid.

Most likely its DTC 32 for low EGR flow. That could be several different things, including the problems described above - Valve broke, passages plugged up. But it could also be the solenoid not actually opening, or a leak in one of the vacuum lines from the intake manifold to the EGR valve.

Dont panic... its not a major problem. The EGR flow is intended to dilute the cylinder's air charge with non-combustible exhaust gasses, not to lean the cylinders out. Leaning it out would promote the formation of NOx. Displacing some of the air reduces the O2 content and lowers the combustion temperatures. With the valve not working, there is a small chanve you might see some detonation (knock) if you were to lug the engine up a hill at low RPM in the wrong gear, but you still have the knock sensor to counteract that problem.

[Crazy Canuk]

Ok thanks alot

I didn't see the light go on today and I will keep my eyes open for it, I am just collecting some information about it so I can fix it if the problem is comes back on and turns out it isn't just a random code. I will also find out which code came up if it comes back on.

It's nice to know that I have enough time to get a replacement part if it is the EGR valve.

I read the shoebox site to get some background on the valve too which helps.

Thanks

[Crazy Canuk]

A continuation of this question,

I dropped the car off at the shop after shopping around for a new egr valve and o2 sensor (o2 sensor is just going to be a maintaince thing) and while driving it to the shop I got on the gas a little from a low rpm (maybe 3500-4000rpm) and I herd a horrible horrible noise that sounded like someone was hammering hard from under my gear shifter (I have an automatic) I felt like I was going to be sick, it stopped once I decreased the rpm and the car ran smooth, later when I slightly accelerated from a stop to turn it did it again (but only like 2-3 hits). Also I have notice my engine temp going up to about 100 on the gage (and if I ran it more it would continue to increase).

Could both of these be caused by the EGR Valve/solenoid misbehaving? I have had a bad miss fire in my car b4 but I dont think I have ever had a engine knock so I dont know what that sounds like and this noise was totaly different. I am hoping my car isn't getting cranky again and wants some more new parts

[TraceZ]

The noise you heard is your transmission mount failing. You'll need a new one of those also. The good news is they are cheap and easy to replace.

[Injuneer]

A continuation of this question,

I dropped the car off at the shop after shopping around for a new egr valve and o2 sensor (o2 sensor is just going to be a maintaince thing)

You have 2 O2 sensors. Both should be replaced, if you are doing it for "maintenance"...... but these things can last 100K miles easilly. Unless you are having a problem that can be traced directly to the O2 sensors, you may be replacing them prematurely. A dealer or shop is going to charge you $70-80 per sensor for the parts, and then a lot to install them. You can buy genuine Delphi replacements online for 1/2 of what a dealer would charge you, and replace them yourself. Same with the EGR valve. I bet the shop nicks for $120 for an EGR valve.... $40 if you do it yourself.

Also I have notice my engine temp going up to about 100 on the gage (and if I ran it more it would continue to increase).

Do you mean 100deg Centigrade? Does is only do this when you are driving at high speed? Is it less of a problem when you are sitting still or driving slowly?

Could both of these be caused by the EGR Valve/solenoid misbehaving? I have had a bad miss fire in my car b4 but I dont think I have ever had a engine knock so I dont know what that sounds like and this noise was totaly different. I am hoping my car isn't getting cranky again and wants some more new parts

The clunking is the tranny mount, not related to EGR. There's a chance the EGR could contribute to a slightly higher engine operating temp if you tend to lug the engine a lot at low RPM in the wrong gear, but tell us exactly WHEN it reaches 100degC and we might be able to suggest a cause.

[Crazy Canuk]

I am not sure if it is 100 C or F, but it is 1/2 on the temp. gage (it isn't listed on the gage).

I have had it go that high on a long trip in the past but in the last 2 days it has been doing that on the drive home (ruffly 10-15mins) in the city but 1/3 of my trip is up a slight incline hill where I go about 70k but the temp. climbs at a steady pace thru my trip home. It hasn't climbed like that in the past and usully stays at just past the 1/4 mark on the gage or 85.

Thanks for telling me about the transmission mount, I was freaking when I herd it and it only happened 2 times and I was almost at the shop. I bought the replacement parts myself fairly cheeply and I thought I only had 1 o2 sensor because my car is OBI 1.

Thanks for the help, maybe this will also solve the rattle that dosn't seem to be going away.

As soon as I start catching up on the little problems with my car, I always have big problems right behind

[Injuneer]

OBD-I has two pre-cat sensors, one at the bottom of the exhaust manifold on the drivers side and one in the Y-pipe right below the manifold on the passenger side. OBD-II has 2 pre-cat sensors and 2 after-cat sensors.

"100" is degC. = 212degF for those of us south of the border. Is your front air dam (plastic scraper under the bumper) in place? If that i missing the temps will rise as the vehicle speed goes up.

[Crazy Canuk]

Hi just a update

My trany mount is toast but I have to wait untill next week to get it fixed because it is the long weekend up here and they didn't have time to get the part and fix it today so I drove it home slowly

I want to beat my mechanic sometimes though because he left my car unlocked and unarmed with the keys in the car. I went to disarm it and it arms

But he's honest and fair and gives me alot of free service all the time. I am going to wait till I have to do emissions next year to get the o2 sensors switched, I read here b4 that its a good maintanice thing to do and my car is around 120 kilimeters.

With the temp, the gage is in C, on the way home (a longer distance from the mechanic to my home then work to my home) the temp stayed at around 87.5 C where is usully goes too. So I am thinking the slight increase in temp was the bad EGR valve and me just being paranoid or 'extra careful'

Thanks again for the info, I think I am the only customer at his shop who buys his parts and tells him what is wrong with the car when I drop it off to get it fixed. I should fix it myself but I am always too scared to do something wrong and brake something