power loss

I have a 2000 RS 2.5 sedan manual transmission AWD and basically whats going on is sort of a bunch of problems that may or may not be related. First, I apparently have too much voltage going to my O2 sensor. What should be the normal power readings? The O2 sensor is ok, I got it checked out. I can't remember the readings, I think about 1.6V's, but it's supposedly too high to be "normal."

Another problem is either taking off from a stop or accelerating in town or on the freeway, it has severe power loss. I have to have it right to the floor in order to get some sort of pick up. Could my cat's be plugged? Could this be a sign of O2 sensor failure even though it is said to be fine? As well, my check engine light is on.

Any suggestions?

Did you get the code pulled for the CE light? I don't know if you just jumped to the conclusion it was the o2 since you said that you got it checked out and it was ok.

From the service manual, General Diagnostics chapter, the first things to check for when you have 'Poor Acceleration' are:

Intake manifold pressure sensor
Intake air temp sensor
Intake air temp and pressure sensor
Throttle position sensor
Fuel injection parts
Fuel pump and fuel pump relay
Engine coolant temp sensor
Crankshaft position sensor
Camshaft position sensor
A/C switch and A/C cut relay
Engine torque control signal circuit
Ignition parts

If you can be more specific in what poor accel is, that'd help. How about idling? Smells of gas? Poor gas mileage?

Did you get the code pulled for the CE light?

If you can be more specific in what poor accel is, that'd help. How about idling? Smells of gas? Poor gas mileage?

Well, I am "My Own Mechanic." I do a lot of research before I DIY. The C.E. code is P0172 (Mixture too rich).

Basically, when this power loss occurs, I can push the throttle pedal all the way to the floor and it will be as though I only pushed the throttle a tiny bit. This does this during take off, while cruising in town and on freeway.

Idle seems a bit ruff, Just below 1000 RMP....say 500-900 RMP on a warm idle. I haven't paid attention to the smell of gas but I haven't noticed any smell when checking things out while the car is running.

I should also mention that it performs as per normal when the engine is cold.

I gotta get to washing the roof of my house right now, but I'll go back to the manuals when I'm done and see what it says about that. There was a specific section for diagnostics when problems occured cold vs warm and w/ idle.

Unless you wanted to check the coolant temp sensor in the meanst.

Got the images to appear down below!

"Mixture too rich" could indeed be O2 sensor related. The sensor itself may work fine, but the higher voltage may be sending the ECU an incorrect reading from the sensor.

2tubo thanks for the great post and taking the time to upload the pages, very cool!

Thanks for going through all that time to post those pictures.........but I think IE 7 isn't displaying them properly and all I see is the script that makes the images appear. I can't see any pictures :crying: Can I PM you my email address to send the images as attachments?

Thanks again. Sorry it took my so long to reply, I was away for a few days.

The mechanic said that the wiring "looks" like it's been tampered with. The guy previous did lots of things to the car, like customization, and did it in a half-@$$ed way so the wiring could be at fault. For example, those custom gauge pods on the A-pillar is removed, but the screw holes still remain and they look rather ugly as though he didn't know how to use a drill properly. I haven't paid the chop shop for any repairs yet. Way to expensive and I can do it myself. But I'm a bit skepticle that it's the wiring because it worked fine before.

"Mixture too rich" could indeed be O2 sensor related. The sensor itself may work fine, but the higher voltage may be sending the ECU an incorrect reading from the sensor.

So the wiring could be fine like I suspect?

2tubo thanks for the great post and taking the time to upload the pages, very cool!

hehe, no probs. Hopefully they will help someone out! lol


Thanks for going through all that time to post those pictures.........but I think IE 7 isn't displaying them properly and all I see is the script that makes the images appear. I can't see any pictures Can I PM you my email address to send the images as attachments?

Actually....I finally got the tags to work...woot. If they dont show up for you shoot me a PM and I'll attach them in an email.

http://i126.photobucket.com/albums/p97/Smacksube/P0172%20Code%20Pages/Page1.jpg
http://i126.photobucket.com/albums/p97/Smacksube/P0172%20Code%20Pages/Page2.jpg
http://i126.photobucket.com/albums/p97/Smacksube/P0172%20Code%20Pages/Page3.jpg
http://i126.photobucket.com/albums/p97/Smacksube/P0172%20Code%20Pages/Page4.jpg

Hey, check it out! I can see it, thanks a million!

Hey! I cant read the gauges in the picture!:rofl:

The pillar covers are "snap in"! the yard just GAVE me one so I could mount the guages then if I turn the car I can replace the original. No tools required to fix those unsightly buggered up holes the ahole left ya!

Just unpulg your o2 sensor and see if the power loss remains, then you'll know if it's because of the sensor/related problem or if it's a different problem.

Been a while since new spark plugs/wires?

Just unpulg your o2 sensor and see if the power loss remains, then you'll know if it's because of the sensor/related problem or if it's a different problem.

Been a while since new spark plugs/wires?

I'm not sure actually when the plugs and wires have been looked at. I don't think that's the problem though. The exhaust smell is foul and makes my eyes burn. My 1990 BMW 750iL doesn't do that, nor does my 2006 Expedition Eddie Bauer. My dad is a very good source for automotive repairs, as he worked on race cars that set world land speed records at Bonneville (Steve Green is my uncle, Eagle Machine in Abbotsford, BC, Canada), so you don't get records like that with luck and chance. After doing some research and posting, I finally figured to ask him. The pages you scanned were semi-helpful...as I didn't have time to go through them completely yet so I still haven't fixed the problem, but i'm still pretty sure it's the O2 sensor.

You say 'unplugged the O2 sensor and see if the power loss remains'. Does that mean if the powerloss remains, it's the O2 sensor is bad? Just making sure before I venture off on my own and realize I made a mistake. Thanks a million for your help.

well if i were you, i would replace the Os sensor, they are fairly cheap and quite easy to install, how is you gas milage any change in that? if the o2 sensor change doesn't help anything then start to check the wires back to the ecu to see if anything looks wrong, good luck man

The O2 sensors were quite knackered actually. Did some testing on the old ones and compared them to the new ones and yeah...some new ones were in order. All is fixed, thanx everyone for your help!