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Loss of power and shaking because of oxygen sensor..

14K views 28 replies 9 participants last post by  astroturf 
#1 ·
Hi,

My van started acting strange again. It's a 1993 Astro 2WD CL EXT. Symptoms: random shaking (going like this: chug-chug-chug), reduced/loss of power, specially uphill or in overdrive (low RPM, high load). In the beginning it was almost unnoticeable, but then it got worse. At the end, I thought the engine would jump out from under the hood...

Six months ago it had the same symptoms, caused by a busted/loose plug. This time it turned out to be the oxygen sensor. It had rusty connectors.

Questions:

1. I drove around with a half-working oxygen sensor. Is that bad? Can this cause permanent damage? Should I have parked and had it serviced right away?

2. Where is this sensor and what does it actually do? It was not me who fixed it, but I'd like to know in case it happens again.

Allman
 
#2 ·
The 02 sensors are in your exhaust pipes. I'm not sure how many are on a 93, 3 maybe. One on each pipe coming down from the engine and one at the back side of the CAT.
It's not good to run like this, the computer get's the wrong information and tries to compensate, but is still delivering the wrong fuel/air mixture.
It sounds like you might also have a bad CAT.
The 02 senors monitor how efficiently the engine is burning the fuel and how well the CAT is burning up the waste. The computer takes the readings from all the 02 senors and then adjust the the engine so that runs cleaner.
 
#3 ·
He only has one sensor and its in front of the CAT. Now that you have a new 02 sensor you should be fine. If you drove it around with the computer dumping a lot of fuel into the cylinders to compensate for the bad 02 sensor then you may have fouled the plugs, but if its running just fine now I'm sure your OK.

How is your gas mileage? Any black smoke or smell of fuel while idling?
 
#5 ·
It really is only one, on the exhaust pipe in front of the cat. You need the special offset oxygen sensor socket or just a big effin' wrench to get it loose - space is kinda tight there.



If you didn't see black smoke coming out the tailpipe, I wouldn't think you damaged the cat.
 
#7 ·
Hi again and thanks for all the info/help!

Here is what happened:

The service took out the oxygen sensor, cleaned the connectors and put it back again - they said it was working, just a little rusty (they did it for free). The van was OK for about 2 weeks (no shaking or loss of power). However, yesterday it started again. It's really frustrating, same symptoms as before so I'm 99.9% sure it's the oxygen sensor again (more precisely, the connections to the sensor itself).

Is it possible to remove/check it without that "special offset oxygen sensor socket"? I'd like to investigate the problem myself, specially 'cause the service doesn't have a slot for 9 days and now I'm driving around chug-chug style and reduced power...

Thanks again for all the help.

Allman
 
#8 ·
You can remove it with a 7/8" wrench if you can get to it...I don't have a test procedure handy. It's possible that the sensor itself is operating intermittently. Is the sensor the original, and how many miles are on it, and your van? If you could take a few minutes to fill out your profile it'll help now and in the future. Thanks, Les.
 
#9 ·
Hi,

I think it is the original sensor. Around 230 000 miles on the van. I'll update my profile shortly (thanks for the tip).

I have taken some pictures. Could you tell me if this (see below) is the O2/oxygen sensor or not?

DSC07172.png


DSC07174.png


Could the problem/symptoms be caused by a hole in the exhaust system?

Thanks again.

Allman
 
#10 ·
Yep, that's the O2 sensor. Is it the problem? I doubt it. Could it be the Cat Converter? Likely not if there's a hole in the pipe before the Cat Converter, the hole would reduce the backpressure.

Go to your local mom and pop muffler shop and have 'em test the backpressure. That will tell you if there's a problem with the converter/muffler assembly.
 
#11 ·
Hi,

I am not aware of any hole in the exhaust system. I was just wondering if the same symptoms could be caused by a hole / leakage.

What's funny now is that the van runs almost OK (I think the shaking / chug-chug almost disappeared). It came back about 2 weeks after they cleaned the O2 sensor connector (for a day or two), but now it seems to be almost OK again. However, it doesn't feel like before (less power). I'm still scratching my head...

Allman
 
#15 ·
Yes, that's the OEM sensor. Whether or not it's original, who knows. I have one just like it in a box outside I bought just last month.

Yep, that's all. 7/8 wrench or the offset oxygen sensor wrench. If it doesn't have the copper anti-seize on the threads already, put it on before you install it. I'd put a little dielectric grease (same as spark plug boot grease) in the connector before I hooked it up, too.

Oh, and don't get a Bosch. They're just not right for our vans - AC Delco or Delphi.
 
#16 ·
Leeann_93 said:
Yes, that's the OEM sensor. Whether or not it's original, who knows. I have one just like it in a box outside I bought just last month.

Yep, that's all. 7/8 wrench or the offset oxygen sensor wrench. If it doesn't have the copper anti-seize on the threads already, put it on before you install it. I'd put a little dielectric grease (same as spark plug boot grease) in the connector before I hooked it up, too.

Oh, and don't get a Bosch. They're just not right for our vans - AC Delco or Delphi.
......Or Denso ( My OEM sensors are Denso's), and I'm pretty sure that all 3 aforementioned sensors are made by the same company. :mrgreen: NO Bosch!!
 
#17 ·
rev_les said:
Leeann_93 said:
Yes, that's the OEM sensor. Whether or not it's original, who knows. I have one just like it in a box outside I bought just last month.

Yep, that's all. 7/8 wrench or the offset oxygen sensor wrench. If it doesn't have the copper anti-seize on the threads already, put it on before you install it. I'd put a little dielectric grease (same as spark plug boot grease) in the connector before I hooked it up, too.

Oh, and don't get a Bosch. They're just not right for our vans - AC Delco or Delphi.
......Or Denso ( My OEM sensors are Denso's), and I'm pretty sure that all 3 aforementioned sensors are made by the same company. :mrgreen: NO Bosch!!
Yup, I just got a box from RockAuto with a Denso O2 sensor for my Bravada inside (the AC Delco box outside is for the Astro) - it does look quite a bit different than the OEM sensor, however ;)
 
#18 ·
Leeann_93 said:
rev_les said:
Leeann_93 said:
Yes, that's the OEM sensor. Whether or not it's original, who knows. I have one just like it in a box outside I bought just last month.

Yep, that's all. 7/8 wrench or the offset oxygen sensor wrench. If it doesn't have the copper anti-seize on the threads already, put it on before you install it. I'd put a little dielectric grease (same as spark plug boot grease) in the connector before I hooked it up, too.

Oh, and don't get a Bosch. They're just not right for our vans - AC Delco or Delphi.
......Or Denso ( My OEM sensors are Denso's), and I'm pretty sure that all 3 aforementioned sensors are made by the same company. :mrgreen: NO Bosch!!
Yup, I just got a box from RockAuto with a Denso O2 sensor for my Bravada inside (the AC Delco box outside is for the Astro) - it does look quite a bit different than the OEM sensor, however ;)
hmm, Maybe dey's not da same maker den... :lol: The originals on my '99 had Denso printed on 'em though, ( I think they were the originals, anyway...It only had 74K on it when I bought it) I guess someone might have changed them. :shrug:
 
#19 ·
rev_les said:
hmm, Maybe dey's not da same maker den... :lol: The originals on my '99 had Denso printed on 'em though, ( I think they were the originals, anyway...It only had 74K on it when I bought it) I guess someone might have changed them. :shrug:
They're the same overall length, but the outer metal cylinder that's on the OEM isn't on the Denso. Maybe that's the only difference?
 
#20 ·
Hi,

Hah, the one I have right now (which I suspect is defect) is actually BOSCH, I checked it last night...

Image from PartsTrain.com, I think this is the exact type:

bosch_o2_sensor.jpg


How come they are "no good for our vans"? :geek: I always try to get AC Delco parts, but seriously.. should I avoid BOSCH when it comes to the O2 sensor?

Thanks again.

Allman
 
#22 ·
allman said:
Hi,

Hah, the one I have right now (which I suspect is defect) is actually BOSCH, I checked it last night...

Image from PartsTrain.com, I think this is the exact type:



How come they are "no good for our vans"? :geek: I always try to get AC Delco parts, but seriously.. should I avoid BOSCH when it comes to the O2 sensor?

Thanks again.

Allman
I've always liked Bosch O2 sensors, and until I got my Astro, I never had any problems with them. Ever since I put them on my '99, I constantly have HO2 codes. I have about 150K on them now, and I'll be going Delco or Denso when they get replaced.
 
#23 ·
Hi again,

I bought a new oxygen sensor and replaced the old. First attempt: the shaking / sluggishness was almost worse than before. I disconnected the sensor and squeezed the female connectors a little so that they get a better grip on the male ones. Put it back in, result: it's somewhat better but far from perfect. The van is still shaking and there is little power / acceleration when I push the gas. Sometimes it "awakes" and behaves normal, but only for a few seconds... (not fun with other cars right in front of me and suddenly the van decides to accelerate).. but then in the next moment, it's back to sluggish / chug-chug...

I'm banging my head into the wall... :banghead:

Sometimes it sounds/feels like if there were "small explosions" in the engine...

What can it be? Plugs, cables, rotor and distributor cap were changed 6 months ago, same goes for the air filter. The service says they have measured/checked and didn't find anything wrong the the ignition. Fuel filter hasn't been changed for at least 4 years, but I don't think it's that since the problem is coming and going (I suspect a bad connection / electrical disturbance somewhere, but where?). I *think* it was better when it was colder outside (less shaking), but now I'm not sure anymore.

Please share your thoughts / suggestions on this one...

Allman
 
#24 ·
It does sound like a possible electrical problem,I would recommend, however, that you spring for the 8 bux on a new fuel filter. Make sure the coil wire is on the posts good. Try starting it at night (or in the dark somewhere) with the engine cover off, and look for any arching within the ignition system. What brand tune-up parts did you use?
 
#25 ·
Hi,

Thanks for the tips. Where is the coil located on the Astro? I don't think I've seen it yet, but then again I'm not a mechanic. :) Plugs, wires and such were replaced with AC Delco parts. I bought a new fuel filter already last Friday, but I'm not sure if I dare messing with that alone. I haven't dealt with flammable liquids before. Also, a guy at a drop-in service told me he doesn't want to do it 'cause he has bad experience with changing these kind of filters (something about the procedure being painful, risk of destroying the connections/nuts, etc.).

Allman
 
#26 ·
New observation, this morning:

Shaking / power-loss becomes worse when in Overdrive. I'm pushing the gas but response is slow. Sometimes I have to shift down to Drive manually (or aggressive kickdown) to gain power. In other words: it seems it's better with high RPM, worse with low RPM.

Allman
 
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