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94 Lesabre running rough and backfiring


Airsim14
01-16-2013, 01:19 PM
I have a 1994 Buick LeSabre that is running rough and backfiring. I changed the oil, oxygen sensor, spark plugs, and spark plug cables within the last 1000 miles.

The only thing I can think of that might be wrong is the timing.

A month ago, I filled up the tank and drove home. When i tried to start it again, it started up and died immediately. Eventually, I found that the vapor line to the fuel tank had rusted and broken in one spot. So I fixed it. It then started and would run for a couple seconds and die. I took the spark plugs out, and they were all black, so I cleaned them. It ran a little better, but not much. This morning I replaced the spark plug cables, and now it runs really rough, backfires and starts to shake really hard. but I am able to keep it running for a while if I hold the gas down.

Does this sound like timing or something else?

DeltaP
01-16-2013, 05:00 PM
Sounds like misrouted secondary cables. Recheck them and then the timing.

maxwedge
01-16-2013, 08:27 PM
As mentioned recheck wire routing/firing order, can't set timing all computer controlled. Disconnect the maf see how it runs when you recheck the plug wires.

imidazol97
01-16-2013, 08:35 PM
I took the spark plugs out, and they were all black, so I cleaned them. It ran a little better, but not much. ?


What would make the plugs black? Rich mixture if it was a dry black.

What oxygen sensor did you use. Some replacement brands have caused trouble. Do you have the original to put back in?

Also, don't bypass the possibiity of the computer being the problem.

Tech II
01-17-2013, 10:37 AM
Anytime you have a misfire, this causes the engine to run rich, which will cause your plugs to be black, and also contaminate the O2 sensor, if you continue to run the vehicle with a misfire.....

First thing to do, is check coil output at the end of each wire with a spark tester.....If ok, then check fuel pressure, and see if fuel pressure holds....

Airsim14
01-17-2013, 02:36 PM
I'm pretty sure the reason it was running rich is because the vapor line to the fuel tank was broken, and that messed everything up since I tried to run it so many times before I fixed it.

I took the O2 sensor out, and it was all. black. Is there any way to clean it?

Also, I tried to run it again this morning, and I heard a pop and there was a puff of smoke, the car died and I haven't been able to start it again.

I'm pretty sure this is the problem lol.
https://picasaweb.google.com/117158772892782112153/January172013#5834502114480103026https://lh5.googleusercontent.com/-AB_4x4a-2Js/UPhQwrbaHnI/AAAAAAAAAdY/ZxRDOraiZrM/s720/091.JPG

https://lh5.googleusercontent.com/-P-oIB7cS6dk/UPhQwkRiQFI/AAAAAAAAAc8/D0YQ6t_A0Us/s720/092.JPG

https://lh4.googleusercontent.com/-khEY6oGG-ns/UPhQxUM-p3I/AAAAAAAAAdM/t6GWl2WXzBM/s720/093.JPG

What is it? I can't seem to be able to push it back in.
https://picasaweb.google.com/117158772892782112153/January172013#5834502125425436530

Airsim14
01-18-2013, 03:05 PM
Ok, I think that thing has something to do with the exhaust. I kind of put it back in, but it's not staying tight in there so I put a clamp on it to hold it in place until I get things figured out.

I also took the O2 sensor out to clean it last night, and soaked in gasoline to clean it. Not sure if that actually worked. Anyway, I started it up this morning without the O2 sensor, and it ran steady for a few seconds, so I think the timing must be fine. I think I also flooded the engine, so it's not starting right now with or without the O2 sensor.

If it doesn't work, then would I be right in guessing that the problem is the O2 sensor? If so, is there a better way to clean it, or do I have to buy a new one?

Thanks!

imidazol97
01-18-2013, 03:27 PM
Ok, I think that thing has something to do with the exhaust. I kind of put it back in, but it's not staying tight in there so I put a clamp on it to hold it in place until I get things figured out.

Trying to get picture

DeltaP
01-18-2013, 04:13 PM
If it doesn't work, then would I be right in guessing that the problem is the O2 sensor? If so, is there a better way to clean it, or do I have to buy a new one?
__________________________________________________ __________________________________________________ ______________________
In a word.....No.

Airsim14
01-18-2013, 04:13 PM
Thanks. The cloth that's on there has been there for years. I think it's supposed to be some kind of heat shield.

EDIT: I took the EGR valve (I think that's what you said it was) back out, and tried to run it. There is exhaust coming out the hole where the EGR valve goes, and I even had some coming out around the air filter(I don't have it on very tight).

Any idea why the exhaust is coming out the wrong end of the car? lol


EDIT 2: I did some research, and everyone seems to say timing is off, does that sound right?

maxwedge
01-18-2013, 07:03 PM
Or the cat is blocked.

Airsim14
01-23-2013, 05:14 PM
Ok, I can't figure out how to adjust the timing in my car. It seems that mine is different from most other cars. I tried to google it, but I didn't find anything helpful.

I don't think it's the cat.

Does anyone know how to adjust the timing or have a link to something that will tell me how to do it?


Thanks.

aleekat
01-23-2013, 05:39 PM
Like Max said. Timing NON adjustable, computer controlled. I also leans towards a plugged cat.

I don't think it's the cat. How do you know?

maxwedge
01-24-2013, 02:27 PM
Ok, I can't figure out how to adjust the timing in my car. It seems that mine is different from most other cars. I tried to google it, but I didn't find anything helpful.

I don't think it's the cat.

Does anyone know how to adjust the timing or have a link to something that will tell me how to do it?


Thanks.

Did you read my post that it is non adjustable and computer controlled??

Airsim14
01-24-2013, 04:43 PM
Yeah, I read the post, but for some reason I didn't see that part.

It's really cold right now, but I'll try to get the cat off tomorrow.

tempfixit
01-24-2013, 05:08 PM
Yeah, I read the post, but for some reason I didn't see that part.

It's really cold right now, but I'll try to get the cat off tomorrow.

If you do not have a vacuum gauge stop at harbor frieght, without looking it up I am quessing the gauge is under $20.00. Here is a video on testing for a blocked exhaust using a vacuum gauge or remove the upstream 02 sensor and see if that makes a difference.

https://www.youtube.com/watch?v=d-jp1IIJVVk&list=UU_q-UNDJeEBSHqKzAP_8x_A

hope this helps

Check with Autozone or Orielys, they may have one in their loana tool program. Pay a deposit and deposit is returned when tool is returned.

aleekat
01-24-2013, 05:37 PM
Look for a plug normally in front of the cat. You can remove it and test drive and see if the symptoms ease up.

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