Hmmm... trying to figure this out. Just threw in a new air filter, new t-stat and cts. After the car has been warmed up and been on the highway for let's say...at least 10 minutes. This is when the problem starts?

So I'll be cruising down the highway and let my foot off the gas to slow down from roughly 70 to 55 or so, or even jumping off the highway onto an exit. It's then that my "Service Engine Soon" light flips on. Problem is, the car is a 93', so my mechanic can't scan it, since it's an OBD1. He has a scanner for cars at OBD2 and above.

My pops thinks it's an O2 sensor but I'm just not sure. I'm about to swap out my EGR valve gasket and fuel filter this weekend/later this week. Anyone else have any ideas, or cheap parts I could throw at it to make it run smoother?

 

Not sure you if you can do this with your computer, but it is the only year that it can be done when equipped with the LT1 engine. Otherwise, I would say to invest in a scanner that is OBD-I capable (maybe consider one that does I and II to make it more versatile). It will save you money in the long run, if you work on your own car.

 

I do work on my own car usually, unless it's something a bit more complicated like engine mounts, where I don't feel too safe doing them.

Unfortunately, I don't have any extra cash to foot for a scanner right now. By the way, I own the 6 cylinder, not the LT1, haha.

If this helps at all...it only does it once I get off the highway from a normal cruising speed and SES light shuts right off when I turn the car off and then back on.

 

Yes, I noted that yours was the V6. Scanning is the only way you are going to find out what the light is for. That's just the way it is. You can't work on a modern car without a scan solution.

 

Have you tried flashing the codes using the link in post #2? It doesn't cost anything to try it. Until you know the cause of the ses light all you can do is guess.

Your description sounds like an egr problem to me, but that's just a guess. Throwing parts at a problem without knowing the cause can get expensive, and still not fix it.

 

I may see if the local parts store can help me scan it, if anything. Thanks for the replies by the way guys.

As for the EGR...well the valve itself is incredibly expensive, so I'm just gonna throw an EGR valve gasket on it for now, since it's cheap and can only help improve my gas mileage. Hopefully that's where the problem lies but if not, the improved MPG is gonna be nice, since I'm getting right around 21 city/highway mixed right now, if I'm granny driving it.

Idle tends to be a tad rough, more once it's warmed up rather than cold. I'll keep you guys posted.

 

On another note, I just ran through that link he posted earlier.

Looks like my 93' is the only year that's able to do this, go figure. I've done it before on older cars I've owned and I may just run up to Autozone and grab one of their little "keys" or something that press into the DLC.

 

You realize that you don't need a "key".... you just short the two pins with a paper clip.

 

Eh yah but the key is free and it's unlikely I'll find any paper clips lying around the house anyhow.

I'll run up there tonight and see what they can do to help me out...

 

It doesn't have to be a paperclip. A piece of wire will work.

 

No paper clip? No problem, use a pair of scissors, a fork, two keys, etc etc... I know you have the two keys ;-)

 

Excellent! Now I just need to look through the manual and find the code patterns. Injuneer, on that book you sent me, would you happen to know what page has the code banks on it?

 

There are two volumes, Parts 1 and 2. The engine is covered in Section 6, which is in part 1. Sections 6 through 6D5 cover the details of the engine's construction and operation. 6E covers "driveability and emissions" - that's where the code descriptions and cures are located. There is a separate area for the 3.4L V6, starting on page 6E3-A-1. That page is a table of contents for the 3.4L, showing where each topic/code is covered. Also take a look at Section 6E3-B, showing common problems/symptoms, and possible cures.

 

Ok, looked through it and had it scanned by a newer scanner with an adapter. Turns out I've got some kind of "too lean" bank 1 emissions problem.

So I'll start with the EGR gasket as planned and move on from there. Thank you so much for the help so far!