Surging
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Surging
Has anyone experienced surging noticable during idling in park after car (1988 Audi 80 - 1.8L no turbo) has been driven and is hot. Speed varies from 900 to 1100 rpm, back and forth. When the engine is shut off and restarted, the surging is eliminated. Mechanic is puzzled and has replaced the idle stabilization valve and the fuel pressure regulator. Thanks
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From: Calgary, Alberta
Re: Surging
try replacing your o2 sensor. if it's been over 40-60k miles since it was last replaced, it's a good bet that will be the problem. not to mention it should increase your fuel economy.
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Re: Surging
This is a reply to archiboy24......
Thank you for your idea. Unfortunately, after replacing the oxygen sensor the surging is still there. I replaced the O2 sensor with a new Bosch OEM brand, not a universal type. The part I can't figure out is why after the car is driven several miles and the surging begins, I can bring the car to a stop, shut-off the engine and restart it and the surging disappears. When the car is surging, the idle is elevated to about 1200 rpm and fluctuates from about 1150 to 1250 rpm back and forth. When I shut the engine off and restart the engine, the engine idles normally at an even 800 rpm. I appreciated your response, thank you again. It was a great idea to try.
From 88audi80
Thank you for your idea. Unfortunately, after replacing the oxygen sensor the surging is still there. I replaced the O2 sensor with a new Bosch OEM brand, not a universal type. The part I can't figure out is why after the car is driven several miles and the surging begins, I can bring the car to a stop, shut-off the engine and restart it and the surging disappears. When the car is surging, the idle is elevated to about 1200 rpm and fluctuates from about 1150 to 1250 rpm back and forth. When I shut the engine off and restart the engine, the engine idles normally at an even 800 rpm. I appreciated your response, thank you again. It was a great idea to try.
From 88audi80
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From: Calgary, Alberta
Re: Surging
hmmm. too bad the O2 sensor didn't solve the problem. as consolation though, you should be getting better mileage. you say that the surging begins after the engine has run for a while and is hot? another suggestion would be to test the thermo-timing switch (sometimes called "temperature sensor" or multi-switch"). i'm not sure where it's located on your car, but on mine it's on the engine block where the upper rad hose feeds in. if this switch is faulty, it may be sending a bad signal to the computer, which will affect things like idle, air/fuel mixture. even if your temperature gauge is reading normally, the part of the switch that sends the signal to the ecu may be bad. i don't think these are too expensive ($40?), but have it checked out, if you haven't already.
if this doesn't solve the problem, then it goes beyond my limited mechanical know-how!
good luck!
if this doesn't solve the problem, then it goes beyond my limited mechanical know-how!
good luck!
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Re: Surging
This is a reply to archiboy24
I had the temperature switch replaced today, however, the surging is still there. Yes, the engine is generally driven several miles before the surging condition commences and is hot. But when I shut off the engine and restart the engine immediately (upon which the surging is eliminated) the engine is still hot. That's the part that baffles me the most. It seems like I am resetting something when I turn the engine off and then restart it. Anyway, I know you have run out of ideas, but I appreciated your input and thank you for sharing your experience.
From 88Audi80
I had the temperature switch replaced today, however, the surging is still there. Yes, the engine is generally driven several miles before the surging condition commences and is hot. But when I shut off the engine and restart the engine immediately (upon which the surging is eliminated) the engine is still hot. That's the part that baffles me the most. It seems like I am resetting something when I turn the engine off and then restart it. Anyway, I know you have run out of ideas, but I appreciated your input and thank you for sharing your experience.
From 88Audi80
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Re: Surging
My '88 80 has the same problem. I finally got tired of looking for a solution since it doesn't seem to effect the way it performs. I've replaced everything that you have said and nothing seems to make it go away.
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Re: Surging
I have the same problem with my 1989 audi 80. The only difference being that if the condition sets in, sometimes it drops to 500 rpm and as high as 1500! i can barely start fro ma stop when the former occurs.
I ahve one idea of what it might be. Listening to my engien the other day, it sounds like I have a vacuum leak somewhere. When the engine idles at 900 rpms (where it should!) i hear a hissing. a little higher and it goes away. I recently changed my 02 sensor and it only got worse (although not from the 02 sensor, it has been degrading steadily.)
So, maybe you ahve a leaky hose too, sucking in air? If anyone finds a solution to this problem drop me an email, please!
thanks,
jim
jmourra@andrew.cmu.edu
I ahve one idea of what it might be. Listening to my engien the other day, it sounds like I have a vacuum leak somewhere. When the engine idles at 900 rpms (where it should!) i hear a hissing. a little higher and it goes away. I recently changed my 02 sensor and it only got worse (although not from the 02 sensor, it has been degrading steadily.)
So, maybe you ahve a leaky hose too, sucking in air? If anyone finds a solution to this problem drop me an email, please!
thanks,
jim
jmourra@andrew.cmu.edu
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Re: Surging--one last thing
One last thing: One factor that i believe is important: I notcied when driving in very heavy rains that the surging same into effect and wouldnt disappear with a restart of the engine. Maybe its sucking in water? forgive any obvious ignorance on my part, im still learning the ins and outs...
--jim
--jim