Car stalls / hesitation question
07-13-2003, 09:21 PM
#1
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Car stalls / hesitation question
My car (89 S4) has been experiencing some hesitation / stalling problems recently. It starts fine and then when I drive for a short time (maybe a few minutes) it is very down on power and wants to stall. It surges and inevitably, stalls out. I can start it right away again.
At first I thought it might be the fuel filter, so I replaced that and I also replaced the fuel pump relay (just in case), but it still stalls. Sometimes when just sitting in the garage, I will run the engine and the idle sometimes wavers badly. I have done the temporary (I know) fix of lubricant into the line going to the idle stabilizer and that seems to help there.
One item that I don't know if it has anything to do with my car's stalling problem. Right before all this has started I was doing some cleaning up in my car and discovered a disconnected line / wire under the fuse panel. It is fairly thick, black in color and has a round connector with 3 pins (2 male, 1 female). I posted about this before and someone thought that it might be the oxygen sensor ? Evidently, it was disconnected since I bought the car and has run fine without it (passed emissions with flying colors) but since it looked like something that neither of the PO's had put it... I connected it back up. It's probably just coincidence, but this stalling problem started happening since then.
Does anyone have any ideas ? I would like to tackle the problem myself, but am getting closer to bringing it to a shop to let the pros check it out.
Rob
<img border="0" alt="[crying]" title="" src="graemlins/crying.gif" />
At first I thought it might be the fuel filter, so I replaced that and I also replaced the fuel pump relay (just in case), but it still stalls. Sometimes when just sitting in the garage, I will run the engine and the idle sometimes wavers badly. I have done the temporary (I know) fix of lubricant into the line going to the idle stabilizer and that seems to help there.
One item that I don't know if it has anything to do with my car's stalling problem. Right before all this has started I was doing some cleaning up in my car and discovered a disconnected line / wire under the fuse panel. It is fairly thick, black in color and has a round connector with 3 pins (2 male, 1 female). I posted about this before and someone thought that it might be the oxygen sensor ? Evidently, it was disconnected since I bought the car and has run fine without it (passed emissions with flying colors) but since it looked like something that neither of the PO's had put it... I connected it back up. It's probably just coincidence, but this stalling problem started happening since then.
Does anyone have any ideas ? I would like to tackle the problem myself, but am getting closer to bringing it to a shop to let the pros check it out.
Rob
<img border="0" alt="[crying]" title="" src="graemlins/crying.gif" />
07-15-2003, 04:08 AM
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sounds like the o2 sensor is bad. with the black wire connected does the car run ok (ie go like stink) at wot? 02 sensor is bypassed at wot....
02 sensor is not expensive - here c. 150 bucks
did you disconnect the battery when reconnecting black wire? this might be worth doing, and let the LH go through the idle stabilisation routine on reconnection.
HTH
e
02 sensor is not expensive - here c. 150 bucks
did you disconnect the battery when reconnecting black wire? this might be worth doing, and let the LH go through the idle stabilisation routine on reconnection.
HTH
e
07-15-2003, 02:12 PM
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Hi Robert,
When it cuts out, check of the ignition protection realy has activated. It is mounted on the same plate as the two brains. If it activates either a red or a green LED comes on. That shuts one bank of cylinders down.
Maybe the PO disconnected the O2 sensor to hide some other fault.
When it cuts out, check of the ignition protection realy has activated. It is mounted on the same plate as the two brains. If it activates either a red or a green LED comes on. That shuts one bank of cylinders down.
Maybe the PO disconnected the O2 sensor to hide some other fault.
07-15-2003, 03:05 PM
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That disconnected wire may be the low octane plug. If so it should remain disconnected.
If your car is running in "limp home" mode you'll find that four fuel injectors have been shut down. If you use a pair of insulated pliers and pull each plug in turn you'll find that the middle two on one side and outer two two on the other don't make any difference in the way the car runs and the opposites make it even worse.
That happens when the temperature sensors at cyllinders 3 and 7 read a significant difference in temperature. If that's the case you can look for a bad injector, plug, plug wire, or injector plug.
If your car is running in "limp home" mode you'll find that four fuel injectors have been shut down. If you use a pair of insulated pliers and pull each plug in turn you'll find that the middle two on one side and outer two two on the other don't make any difference in the way the car runs and the opposites make it even worse.
That happens when the temperature sensors at cyllinders 3 and 7 read a significant difference in temperature. If that's the case you can look for a bad injector, plug, plug wire, or injector plug.
Last edited by ErnestSw; 07-15-2003 at 03:11 PM.
07-16-2003, 10:21 PM
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I think I may have it...
Hey gang,
I was talking to Tom at 928 International and he confirmed what I was thinking, that it might just be a bad O2 sensor. When I unplugged the line (underneath, by the fuse panel) the car ran better... not great, but better. No stalling. I did the lubricant spray into the idle stabilization line and the next morning the car idles noticeably smoother, except that now it idles very low, almost sounding like it will die at any moment.
Another thing that I thought was very strange (Art Bell strange...) was that the car would stall within 50 feet of the same place on the way to work. That to me was odd until I read that it take a while for the O2 sensor (and that area) to get up to operating temperature. Now, it makes sense. The temps finally came up at about that point at which I was about 2 miles away from home.
I should be getting my new O2 sensor tomorrow and since I will be taking my car in to get it aligned (after adjusting my ride height to correct specs... Can you say amen brothers and sisters !!!) I will have them put it in as well as a new set of plugs and an oil change.
Now, finally I may be able to start on that repaint of the nose...
Rob
I was talking to Tom at 928 International and he confirmed what I was thinking, that it might just be a bad O2 sensor. When I unplugged the line (underneath, by the fuse panel) the car ran better... not great, but better. No stalling. I did the lubricant spray into the idle stabilization line and the next morning the car idles noticeably smoother, except that now it idles very low, almost sounding like it will die at any moment.
Another thing that I thought was very strange (Art Bell strange...) was that the car would stall within 50 feet of the same place on the way to work. That to me was odd until I read that it take a while for the O2 sensor (and that area) to get up to operating temperature. Now, it makes sense. The temps finally came up at about that point at which I was about 2 miles away from home.
I should be getting my new O2 sensor tomorrow and since I will be taking my car in to get it aligned (after adjusting my ride height to correct specs... Can you say amen brothers and sisters !!!) I will have them put it in as well as a new set of plugs and an oil change.
Now, finally I may be able to start on that repaint of the nose...
Rob
07-18-2003, 02:16 PM
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Elemental,
Today, followed your advice and did a disconnect of the battery and now everything is running fine once again. Maybe I'll just wax the car today...
Rob
Today, followed your advice and did a disconnect of the battery and now everything is running fine once again. Maybe I'll just wax the car today...
Rob
07-19-2003, 01:28 AM
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Check caps and wires?
Solved my similar problem.
Jeff
'87 5-spd
RMB, Ott, 993 wheels
"Its not whether I get a ticket, it's whether I choose to pull over and receive one."
ps: Now that I'm paid up, how do I go from "user" to "addict" etc?
Solved my similar problem.
Jeff
'87 5-spd
RMB, Ott, 993 wheels
"Its not whether I get a ticket, it's whether I choose to pull over and receive one."
ps: Now that I'm paid up, how do I go from "user" to "addict" etc?
