I have a 4.3 TBI engine that just isn't putting out the power anymore. It also has dead spots at about 1500 rpm. I have replaced plugs and wires and cap and rotor. I have also replace the EGR valve. These have helped (I could tell that they were in need of replacement), but not much. What are the symptons of a bad oxygen sensor? What else should I look for?
It's a 93 GMC 1500, 185,000 trouble free miles - if that makes any difference.
Fuel filter
Yeah, a $5.99 fuel filter and a $19.99 O2 sensor would likely do that truck wonders. To the original poster, if the O2 sensor that is in it has more than 75k miles on it, it's shot anyways and needs to be replaced.
Doc
Replaced less than 5K miles ago - did not make a difference.
as I mentioned in the previous post - the Fuel filter was just replaced. The O2 sensor, however, is another story. It's original, so I guess it's about 110K over due. I'll get a new one on it and see what happens.
Thanks.
BTW - where is that sensor located on my truck? I looked it up, and it may be a 1 wire or a 3 wire sensor, so I gotta locate it before I even order the part.
Don't forget your knock sensor.
Robert Marshall
Michael Rothwell wrote:
If it was his Knock sensor or anything to do with the ESC system he'd have a code 43 and the SES light would be on. Crappy performance as a result of ESC failure results in full spark retard and code 43.
Doc
In the exhaust manifold, just before it meets up with the crossover pipe. Looks like a giant, ugly spark plug.
Doc
I guess it wouldn't have to but wouldn't a O2 sensor set a code also?
Adair
O2 sensor has to hit a threshold before the ECM spits a code. It can be failing and not set a code as it hasn't hit the threshold voltage required to set a code yet. The Knock Sensor on the other hand has no threshold or operating paremeters like an 02, it either works or it doesn't, so when it pukes the ECM always spits a code.
Doc
That may be but I have a 1994 Chevy 1ton with a 454 and I lost power and a loss of gas milelage. The book told me it could be the fuel pump filter, the fuel pump, the nock senser, sticky brakes, fuel presure reg,or the fuel injectors. I replaced the nock sensor and got back my old truck and it never showed up on my computer.
Robert Marshall
"Doc" wrote:
The O2 sensor can be way off before it sets a code, especially the ones after the cat or the single wire ones. I only found a bad one after I hooked my laptop up (with OBDII connection and program), and watched the O2 sensor readings in "real time".
One of these days I am going wreck and kill my self if I don't stop going down the road watching my laptop and my GPS. I would like to have some "night vision" capability to play with though.
Thanks for everyone's input. I put a new O2 sensor on the truck this weekend. It was huge pain in the butt to get the old one out.
So far, it looks like it is making a sizable difference. I dont have the surging at around 1500 to 2000 rpm anymore, and it pulled the hill at speed again. I used to drop to 55 to 60 mph going up a grade that I hit all the time, I pulled it at 70 on Sat. It is still is weaker than it was 100K miles ago, but it's not bad.
Michael
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