Slant Six Forum
https://www.slantsix.org/forum/

02 sensors; this may be a job for superdan
https://www.slantsix.org/forum/viewtopic.php?t=33079		 Page 1 of 2
Author:  bob fisher [ Thu Jan 01, 2009 8:02 am ]
Post subject:  02 sensors; this may be a job for superdan
happy new year dan and sages - i may be a heretic but here goes. i have a88 buick lesabre with the 3.8 v6. i understand this is a legendary engine. it is the only engine other than the sl6 which i put in a class by itself in terms of durability, economy and reliability. it may prove out tobe the next sl6 in terms of reputation. my problem- the service engine soon light has been on for a week with no change in engine behavior. autozone puts a scanner on cars for free but only back to 95. dealer wants to clip me for 85 just to put their scanner on it. car has 182k with no serious work, no oil consumption and still gets 18mpg in town even with hydramatic . here is my analysis. first i plan to unscrew the 02 sensor from the manifold near the firewall and install a new bosch for 21.95. dealer wants 150 part and labor in addition to scan clip. then i will disconnect battery hot wire cable for 20 seconds to reset the computer. hoping that will be problem solved and light out. here is my research- uncle moe first told me 90% of those service engine light problems mean the 02 sensor has crapped(never replaced in 10years and 50k miles). moe also says dealers use this as a profit enhancement scam. here is my 2 cents/question- if the cat is clogged (the engine is not stalling ,puffing or missing which is a tipoff) or partially clogged couldnt that reduce the 02 in the exhaust and trip the sensor? would appreciate dan or another sage giving me a critique of my analysis. thanks tons bob f
Author:  SlantSixDan [ Thu Jan 01, 2009 8:17 am ]
Post subject: 
GM didn't make it as convenient to check codes as Chrysler did with the keyflick procedure, but you can get a tool for a buck or so that looks like a car key with a forked end. It connects two terminals on the car's underdash diagnostic connector and causes the stored codes to flash out on the Check Engine light. If you know which terminals to connect, you can make do with an unbent paper clip.

Definitely replace the O2 sensor (you're long overdue and it's costing you gas mileage) but don't use a Bosch sensor, they're junk. Get an NTK or a Standard-BlueStreak or an ACDelco. Shouldn't cost more than about $25 or $30.

Clogged catalyst would result in very noticeable symptoms — low power and poor gas mileage, pinging, etc.
Author:  bob fisher [ Thu Jan 01, 2009 8:44 am ]
Post subject:  02 sensors
thanks dan- all i meant by the hot wire cable was, after the new sensor is in, disconnect the positive battery cable for 20 seconds which will cause the computer to reset itself and presumably the light will go out. is that correct? also what do you think of my clogged cat thinking? thanks again. bob f
Author:  Reed [ Thu Jan 01, 2009 9:33 am ]
Post subject: 
My sister drives a 90 Buick Riviera with the 3800 engine and 4 speed auto tranny. The car has 181,000+ on and still drives and idle very nicely. Pulls down decent gas mileage too.

Dan is spot on with the paper clip suggestion. years ago I was a dope and spent $40 on a special Gm "Code Reader" from napa. It is a plastic box with two metal prongs sticking out of it that plugs into the under-dash diagnostic connector. Hit a couple GM sites and find out which terminals to jump to read the code.

I don't know about the cat being clogged. As far as I know, the cat on my sister's car is the original 28 year old cat and it seems to be doing fine. If it was clogged it might mess up the signal to the O2 sensor, but again, I doubt that is the problem. It is far more likely that the O2 sensor needs to be replaced.

Clogged cats are bad.

Image

But if your cat was clogged you would have some noticeable driveability problems. If the car still drives fine and gets good mileage then i doubt the cats are clogged.
Author:  Rust collector [ Thu Jan 01, 2009 10:03 am ]
Post subject: 
http://www.troublecodes.net/GM/
Author:  SlantSixDan [ Thu Jan 01, 2009 10:37 am ]
Post subject: 
Image @ Reed's clogged cat pic
Author:  bob fisher [ Thu Jan 01, 2009 11:14 am ]
Post subject:  dan and reed
reed- your clogged cat metaphor is funny as hell. never thought of that. thanks i needed it. will let you know what happens with the new sensor. soaking the thread in blaster juice right now. so dan if the sensor solves the light problem , does the light automatically go out or do you have to disconnect the battery for a moment to reset the computer? dont want to risk a dealer ripoff to get the light off. moe says so and my engineer friend says most car computers hes seen work like that. never heard that one until this week. regards bob f
Author:  Reed [ Thu Jan 01, 2009 11:48 am ]
Post subject: 
Thanks. I have been looking for a good "clogged cat" picture for awhile, and finally found one this morning. I have been waiting for an excuse to use that joke... :wink:

Disconnecting the battery will clear the trouble codes from the computer's memory, so the light should go off. of course, if the new sensor doesn't solve the problem then the light will come back on. Before you clear the codes you should check them and write down what they are. These can be very helpful in diagnosing any problems.
Author:  63d100sixer [ Thu Jan 01, 2009 1:00 pm ]
Post subject: 
OK. I have a 95 LeSabre with the 3800. It has 144,XXX on the clock, and has the check engine light on. It runs great, minus a hiccup once in a while. I know why my check engine light is on. I was about 15 miles from home when the water pump took a crap. I didnt have the money for a tow. It was free 7 miles, then 15 bux a mile after that :shock: . THATS 120 bux, then Id have to buy a waterpump still @ 40 bux. So thats 160 bux. I was near the safehouse I volunteered at (I stopped going because they changed staff) so I parked it in the parking lot. I walked the 3 miles to autozone, and bought a waterpump. I was on my way to the PAP, so I had all of my tools with me.

I got back and proceeded to work on the car. I had to remove the motor mount, and while doing so, i smashed the coil pack holder. When I was done, I went to PAP and got a used one. I damaged the coilpack, and didnt know it until I got home and changed the holder. @ 90 bux a pop, Im waiting until I can afford all 3. Thatll be when I get my tax refund.

And right after that happened, I recharged my AC and the compressor exploded, so I replaced it. Since the controls are the stupidly designed digital ones, It failed resulting it to go into "SAFE" mode, which is always on :? . So I unplugged the compressor so it wouldn't be constantly on

I know, I know long post, but, with these cars, the engine is SOLID, but in my experience, its the accesories that fail.

This IS the 2nd engine in the car. While going through vegas, the engine decided to go, um, elsewhere, lol


you would be surprised at what fails on these engines.

I THINK on your engine, you have an electronic EGR. Ive heard those fail as well. I have no experience with your year. Mine is a 1995, which I think was the last year before they switched to the series 2.

good luck 8)
Author:  Charrlie_S [ Thu Jan 01, 2009 2:00 pm ]
Post subject: 
Bob, DO NOT change any parts, or disconnect the battery, until you check the codes. There are many, many reasons the CEL is on. Don't waste time and money just throwing parts at it. Jumper terminals A & B in the diagnostic conector, with a paper clip to flash the codes. I'm not sure of the years (would have to check) but some of the early sequential FI motors had a magnet on the cam gear, that triggererd the cam sensor. These magnets have been know to fall off, and cause loss of cam sync signal (will light lite). You will not see any difference in performance. The computer uses this signal to switch from the default batch fire to sequential mode (strictly an emissions thing). Not saying this is your problem, just using it to illustrate, it may not be something that can be fixed by throwing parts at it. You really need to check codes before doing anything.
Author:  SlantSixDan [ Thu Jan 01, 2009 2:34 pm ]
Post subject: 
Quote:
Bob, DO NOT change any parts, or disconnect the battery, until you check the codes. There are many, many reasons the CEL is on. Don't waste time and money just throwing parts at it.
I agree with you in principle, but he is way overdue for a new O2 sensor, which will pay for itself very quickly in saved gasoline. O2 sensors slow down as they age, and they can get very slow and wasteful without setting a code, so in this specific case, telling him not to replace it is sort of like saying "Hey, don't replace the spark plugs just 'cause they have 50,000 miles on them and the electrodes are worn down…wait til the engine stops running, and then you'll know you need new spark plugs!".
Author:  sandy in BC [ Thu Jan 01, 2009 2:59 pm ]
Post subject: 
Id read the codes first.....

Then change the O2 sensor and clear the codes.

Those codes are very useful information.
Author:  bob fisher [ Thu Jan 01, 2009 7:35 pm ]
Post subject:  02 sensor
getting a bit confused sages- if i change the sensor , then reset the computerand the light goes out, isnt the problem solved? if there is another problem or if the new sensor is stinko then the light willcome back on right? if the light comes back and i do a scanner check then what harm is done? the old sensor is most likely dead or weak and should be replaced anyway. the dealer will soak me 85 for the scan and i risk being lied to about a laundry list of unnecessary expensive repairs. sure the dealer will say the sensor i put in is no good and try to triple charge me for his sensor plus additional alleged defects. could this also be caused by a map sensor? moe told me if that crapped engine would stall and not restart. invite your critique of my thinking. regards bob f
Author:  steponmebbbboom [ Thu Jan 01, 2009 7:51 pm ]
Post subject: 
just friggin jam a paperclip into terminals A & B and read the code thats tripped the light in the first place.

Image

its not
that
complicated

and yes replace the O2 sensor, 18mpg is low for that engine.
Author:  Charrlie_S [ Fri Jan 02, 2009 5:08 am ]
Post subject: 
Quote:
Quote:
Bob, DO NOT change any parts, or disconnect the battery, until you check the codes. There are many, many reasons the CEL is on. Don't waste time and money just throwing parts at it.
I agree with you in principle, but he is way overdue for a new O2 sensor, which will pay for itself very quickly in saved gasoline. O2 sensors slow down as they age, and they can get very slow and wasteful without setting a code, so in this specific case, telling him not to replace it is sort of like saying "Hey, don't replace the spark plugs just 'cause they have 50,000 miles on them and the electrodes are worn down…wait til the engine stops running, and then you'll know you need new spark plugs!".
I am not saying not to change the sensor. I am saying don't do anything before checking the codes. By your logic, he should also change the EGR valve, and clean the passages, they get old, also.

PS: a scanner can show live data, such as the switch rate of the O2 sensor, which will tell if it is lazy or not.

PPS: Bob, if you want to travel this far, bring the car up to me, and I will scan for codes and live data, for you, no charge.
Page 1 of 2 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/