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3.2 idle question......again.
Backgound: I have a hunting/surging idle on my 3.2. I just had the engine out and replaced almost everything. CHT, O2, hoses, fuel lines, seals, intake gaskets...etc. Before it went under the knife it had a surging/hunting idle, usually only when the engine is cold. It still does this now.
I did this: ![]() When I put the jumper on the idle just smooths right out. What is that telling me? I bench tested the ICV. It goes click/clack when you put 12V on it. It had the correct resistance as per bentley. It hums when it's plugged in. Could it still be bad? I've been reading idle threads for the last couple of hours. |
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Hi ,what was the last time you have checked you fuel mixture?
You do have an oxygen sensor right? Try to disconnect it and see if the humming problem is still there .If the set up is to rich the oxy sensor is trying to correct it. Ivan
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1985 911 with original 502 191 miles...808 198 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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I can't say I have ever checked my mixture. Not sure I have the instrumentation for this.
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well? it is kinda important to know your CO adjustment.
Did you say you do have an oxygen sensor right? Try to disconnected it and see what is the idle doing...let me know Ivan
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1985 911 with original 502 191 miles...808 198 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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I just played with it. When I started it surged as per normal and then settled out quickly because the engine was still warm. Idled fine. Unplugged the O2 sensor. Idled fine.
I have a univeral 3 wire o2 sensor. I have the black wire going to the green wire. I am hoping this is correct and this is also the only wire I disconnected. Correct me if I'm wrong but doesn't the car ignore the O2 sensor when it is cold? |
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.well the circuit goes trough the oxy sensor and fuel is corrected all the time.You have to disconnect all 3 wires for adjsuting the fuel mix and if you have a catalyst you should measure before cat.
I do not know what do you have as an universal oxy sensor .Maybe a picture? Basically there is no need to have it plugged in at all.In Canada you do not have a smog inspection or do you? i suggest you go and check your fuel mix.... Ivan
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1985 911 with original 502 191 miles...808 198 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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Quote:
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do you have an air-condition?
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1985 911 with original 502 191 miles...808 198 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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Try turning down the idle air bypass. That usually cures the problem.
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usually yes ..in this case the OP never checked the Co mix ...i bet the AFM box still have the original plug in it...
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Quote:
Based on your tests, it sounds like the ICV itself is OK.
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Dan '87 Targa Carrera 3.2 - Fabspeed Cat Bypass, M&K Muffler, SW Chip Venetian Blue |
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i would tell you how to check your basic CO adjustment ..but you did not answer my questions...
Ivan
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Just for kicks I looked investigated my DME. I wanted to see where the fuel quality switch was. I played with it, I am 90% sure it was on setting 1 before I touched it. I made sure it's on setting 0 now.
No appreciable change. Thing still surges. I think I played with the idle screw too much and now I have a hard time getting it to stop surging when warm. This car is depressing me. |
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well if you would have the a/c..you did asked how to check your fuel mix without the c/o machine,right?
Since you do not have a/c this test is not for you. --------------------------- stlrj..to check if your fuel mix is too rich you run the warm engine on idle , you put your a/c on and using your hand(or Foot in the car) you step on the throttle to five some high rmp for a second or 2. If the engine dies ,going to idle, the mix is too rich....little trick i have learn in my 911 practice years;-) There is also one trick i leaned back in the 1970 by an oldtimer mechanic.In those day there were no gas analyzers...for this you just need a single match which you place behind the exhaust.....too long story .................. Ivan old man...did you disconnect the oxygen sensor -all connections? Ivan
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Pete 79 911SC RoW "Tornadoes come out of frikkin nowhere. One minute everything is all sunshine and puppies the next thing you know you've got flying cows".- Stomachmonkey |
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Hi Pete..i think he said his Idle control valve is working properly...
Ivan
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If it were a mixture problem, it never would have passed smog or at least, at some point it must have passed.
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