So, could a bad O2 sensor...

[daeron]

Could a bad O2 sensor be bad in such a way as to cause poor low idling, as well as a major hesitation on throttle when cold? My car cannot br driven until it warms up a little, and when you hit the gas cold the engine just TOTALLY stumbles over itself. This is a problem that arose alongside my intermittent sputtering issue that I resolved by replacing my missing gas cap..

 

I had thought it was a CTS issue, because I had come away with the misconception that this was a common problem with the SPFI, but now I am finding its more of a turbo issue.. Knowing what I do about FI in general, this is DEFINITELY behaving like a CTS issue, but my say-so doesn't mean much more than saying "it runs like crap when its cold."

 

I have no CEL, but I *do* return an O2 sensor code in d-check mode. I am going out to check for at least 0.1 volts between the O2 sensor plug and the vehicle body now.. for that matter, could it be a grounding issue with my exhaust pipe?!??

 

Im trying to take all of the reading, thinking, and discussion I do here, and actually DO something for a change... and if this O2 sensor would just die (as I think it may finally have) it would force my hand.. At the same time, the more subtle misfires that I DO get to track down, the more I learn about how the system works.

 

EDIT

 

Okay, I verified proper voltage with the key on (0.25V) but got to thinking about the condition of my exhaust manifold (holey) and grabbed a crappy kinda rusty old set of jumper cables.. spritzed the clamps with deep creep, and grounded the exhaust to the alternator and the sensor bung to the battery, and tried to start the car again.. and it SEEMED like it might be running a little less poorly.. I couldnt run for too long without losing my control on the experiment though (problem drastically reduced at operating temperature)

 

Has anyone else experienced poor grounding of the O2 sensor? I've got to find time to get up to the shop and swap in a spare, but I wonder if a new y-pipe might not be in order.. there are four or five other reasons (broken angle on one side of engine, rust hols on the weld lines from the gutted cat) BUT I already have a gutted cat, so I dunno..

[Skip]

The ECU ignors the 02 sensor until it enters closed loop.

 

Coolant temp sensor ("thermosensor" as it's called in the FSM) tells the ECU the H20 temp.

170 deg F is around where your car goes into closed loop.

 

So the cold start stumble and the 02 sensor are probably

unrelated.

 

For the 02 grounding issue. I use a small worm type hose clamp (like for a heater hose) to fasten a wire to the 02 sensor body then run the wire to a chassis ground point.

[hooziewhatsit]

sounds like a sticky Idle air controller to me. Do some searches for "IAC " and you should find more than enough info on it.

 

I also had bad stumbling off idle when cold until I cleaned mine up. Since then it's been just about perfect

 

-Dave

[Prospeeder]

throttle positioning sensor did that horrible hesitation from a stop also untill the car got hot

[daeron]

The reason I phrased the question as I did, was the O2 sensor code thrown by the D-check. Thats a fact that merely needs to be dealt with, my dad has two O2 sensors that should fit, and are known to be functional.

 

Well, I myself had come to the conclusion that my next step was the be the IAC.. I was already looking at how to take that thing off. Would it be a simple affair to unbolt the throttle body from the intake so that I can access those screws easier? Otherwise it looks to be a PITA to fit a screwdriver onto them, what with my power steering pump in the way :-\

 

Every vehicle needs it ALL done, or at least checked through, once in a while.. When it works right, this SPFI is a great thing. When it fails, at least theres reliable, simple, and accurate testing procedures for each bit... if only I had a real garage (tools-wise) at my house!!

[hooziewhatsit]

use a pair of vice-grips to break the bolts loose. After that you can usually get them by hand.

 

When I cleaned mine, I also took off the solenoid (two small screws), shot some silicon into it, then actuated it a couple times (jumped 12v to it).

 

Then I used carb cleaner on the inner portion of it, and spun the valve around to make sure nothing held it open.

 

You may be able to get away with just taking off just the solenoid portion, and leave the valve body attached to the throttle body, but would be best to clean everything at once.

 

-Dave