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Hello there , I love my 91 Volvo 240 and recently something happened and I would need your help to diagnose the problem.
i can explain everything that I have done to the car in the previous month :
i changed the thermometer and radiator hoses. Previous owner cut thermometer open so it was always opened.
I changed all battery cables as well as the crankshaft position sensor etc.
after I changed the thermometer the car started idling roughly when I would slow down , come to a stop, basically 4-5 rough idle as soon as I slow down - stop.
i checked all cables and saw that the AIC was unplugged. I thought I unplugged it when I took off my battery cable but now I realize that previous owner left it that way.
so today I clip the AIC cable back in the car doesn’t start or stall. I take it off again the car starts fine. I put it back again and push on the accelerator (while being parked ) I take it for a drive and magically everything seems resolved the car doesn’t idle strange etc. 2 hours later I drive again and the strange idling when I stop / slow down is back. I pull to the side of the road and take off the AIC cable and then put it back in car won’t start again or stall. I take it off and drive home.
i don’t know what’s the issue really could the rough idling when I slow down be due to this ? Or something else and I’m on the wrong track? Any help would be really appreciated and let me know what part I should order and change. Thanks for reading all of this! Engine bay
Not sure what you mean by the AIC. Are you referring to the idle air controller? The idle air controller sits just below the intake manifold.
Your symptoms sound to me that you are actually referring to the Air Mass Meter (AMM) or sometimes called the Mass Air Flow (MAF) sensor. This sensor sits near the battery. Generally if the car runs fine with the AMM disconnected it is an indication that the AMM is bad.
Not sure what you mean by the AIC. Are you referring to the idle air controller? The idle air controller sits just below the intake manifold.
Your symptoms sound to me that you are actually referring to the Air Mass Meter (AMM) or sometimes called the Mass Air Flow (MAF) sensor. This sensor sits near the battery. Generally if the car runs fine with the AMM disconnected it is an indication that the AMM is bad.
thank you for answering! It’s the cable behind the IAC idle air control valve. When unplugged car runs when plugged car doesn’t run.
And always idling strange when slowing down / stopping
Certainly the car will not idle as it should with it unplugged. It sounds like the idle air controller was not functioning properly so the previous owner probably adjusted the throttle body so it is opened enough to idle. Since the system was not designed to operate that way it doesn't run properly when decelerating, etc.
First I would remove the idle air controller and make sure it is clean and operating properly. Take a look at the link below. It is for the 700/900 series but the engine is the same:
a warmed up B230 with all accessories off and the IAC unplugged, should idle at 500-600 RPM, and things like the AC pump or even putting it in drive can make it stall. With the IAC plugged in, it should idle about 750 RPM even with the AC running, in gear, etc. its not unusual for the rpm to momentarily dip when the AC pump comes on, but it should return to the 700-750 idle RPM.
a COLD engine, with the IAC connected, might idle around 1200 rpm, but should drop pretty quickly as it starts to warm up.
05-31-2020, 09:36 PM
IAC cable
