Rough running
Thread Starter
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
From: Woodlands TX
Rough running
This car is driving me insane. After replacing two of the O2 sensors, first with Bosche then again with AC Delco the SES light returned. I figured it had to be a wiring issue so I checked the wires and everything "looked" fine. I noticed the negative battery cable was a little loose at the battery so I tightened it.
The SES light is gone now but the car is running rough starting about 20-30 seconds after start up. I also noticed that the lights on the dash would dim or brighten when I pressed the gas. She runs fine down the street but I can smell that she is still running rich when I pull her in the garage.
The SES light is gone now but the car is running rough starting about 20-30 seconds after start up. I also noticed that the lights on the dash would dim or brighten when I pressed the gas. She runs fine down the street but I can smell that she is still running rich when I pull her in the garage.
Thread Starter
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
From: Woodlands TX
I really don't know. How would I check? The codes that were stored on the SES when I had the O2 problem were all related to no activity from Bank 2 sensor 1. Now that the SES light is off I don't know. At idle you feel it run really rough but down the street it seems ok.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
You can pull the plugs and look for gas...would point to a leaky injector. You can get a fuel pressure guage and see how fast the fuel pressure drops after the engine is shut off. You can also ohm the injector coils hot and cold to see there resistance. Is the only code you get for the O2 sensors? What is the code rich or lean.
Thread Starter
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
From: Woodlands TX
The codes that were present were:
P0151- O2 Bank 2 Position 1 weak signal
P0154- O2 Bank 2 Position 1 Insufficient Activity
P0300- Random System Misfire
P0174- Bank 2 Lean Condition
The SES light is back on at this point. I don't have a scan tool, I will have to take it get the codes read again.
P0151- O2 Bank 2 Position 1 weak signal
P0154- O2 Bank 2 Position 1 Insufficient Activity
P0300- Random System Misfire
P0174- Bank 2 Lean Condition
The SES light is back on at this point. I don't have a scan tool, I will have to take it get the codes read again.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by hman1987
The codes that were present were:
P0151- O2 Bank 2 Position 1 weak signal
P0154- O2 Bank 2 Position 1 Insufficient Activity
P0300- Random System Misfire
P0174- Bank 2 Lean Condition
P0151- O2 Bank 2 Position 1 weak signal
P0154- O2 Bank 2 Position 1 Insufficient Activity
P0300- Random System Misfire
P0174- Bank 2 Lean Condition
BTW, you can get your error codes quite easily without a scan tool. Just follow the directions detailed here, and goto the link pertaining to your '87 vin#:
http://www.troublecodes.net/GM/
***********EDIT***************
and the 'P0174- Bank 2 Lean Condition' will make your PCM "Richen up" your Bank2. How does you engine run when cold??? Is your rich problem only noticable when the engine has warmed up?
Last edited by MikeC4; Jul 9, 2006 at 07:30 PM.
Thread Starter
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
From: Woodlands TX
I thought the problem was a bad replacement O2 but this is the second one I put in there. The first one was a Bosche and when that did not solve the problem I went to the dealership and got an AC Delco O2 sensor....problem returned.
My baby is a 96 with OBD II so I can't do the PIN out and flash codes. When the problem first started the she would run fine when she was cold from sitting up over night. The SES would even go off for awhile. But now the light stays on all the time unless the codes are cleared. Now when I start her, she runs good for about the first 20-30 seconds and then starts running rough at idle.
My baby is a 96 with OBD II so I can't do the PIN out and flash codes. When the problem first started the she would run fine when she was cold from sitting up over night. The SES would even go off for awhile. But now the light stays on all the time unless the codes are cleared. Now when I start her, she runs good for about the first 20-30 seconds and then starts running rough at idle.
Thread Starter
Instructor
Joined: Feb 2006
Posts: 144
Likes: 0
From: Woodlands TX
I also think I may have a problem with the alternator as the I mentioned in the orignal post. The lights on the digital dash seem to get slightly brighter when I step on the gas at idol. This has me thinking as the shop told me that the O2 sensor seem to funtion (switch as it is supposed to) when the RPM's are above 2500.
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Burning Brakes
Joined: May 2006
Posts: 904
Likes: 0
From: Boynton Beach FL
hmm.
I know this isn't going to help, but I just got rid of my 96 Yukon (5.7L) because I was running down all these same codes. (o2 sensor codes, and then the dreaded P0300 code that I was never able to resolve fully). Fixed it by replacing cats, all O2 sensors, camshaft position sensor, injectors cleaned, tune up, and then the head gasket blew on me.
I just hope you're not going where I was headed in the Yukon. Same exact codes though, just brought back (bad) memories, and had to comment.
Good luck!
I just hope you're not going where I was headed in the Yukon. Same exact codes though, just brought back (bad) memories, and had to comment.
Good luck!
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
Ok, the O2's only start woking after the car reaches a certain temp, if it starts happening 20-30 sec. after startup, it is not the O2. The code you are recieving is an effect, not the cause. You need to look farther, mine was a combination injectors, stuck IAC and vaccuum leak.
Get an OHM meter and check your injectors, clean your throttle body and IAC, do not drop the IAC as I did and check for vac. leaks.
Get an OHM meter and check your injectors, clean your throttle body and IAC, do not drop the IAC as I did and check for vac. leaks.
2nd Gear
Joined: Jul 2006
Posts: 2
Likes: 0
Randy93 is correct...if you receive the code within 20 to 30 seconds after start up it would be because of un-spent fuel vapores...this is caused mostly by stuck or leaky fuel injectors. Test them first and you will most likely find one on bank 2 side.
