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check engine blinks during idle

J Volvo

New member
Joined
Dec 17, 2018
Location
Oregon
Hello all,

I am thinking of buying a friends 244 1990 2.3L 4-cyl N/A everything looks good runs as it should, however, when the engine idles it will momentarily slow down (sounds like it could stall, but never actually stalls) and the check engine light will blink on for a split second and than it goes off again and it will do this a few times a minute. I was wondering if anybody was familiar with this behavior. I asked a trusted Volvo mechanic who is familiar with the 240's and he said not to worry it just happens when the rpms get low and he said not a big deal. Is this a common thing in 240's? Is there a remedy to this little hiccup?
 
Make it idle correctly and see if it goes away, even if its applying a touch of throttle as a test, weird dash light stuff often comes from low voltage, and if the battery is weak and the alternator is spinning slowly, its possible.
Pull the engine codes and see whats there, if anything. It doesn't give great info but its easy and can point you in the right direction.
 
The check engine light will light briefly when the idle drops way too low. It does not set a code. I'd look into whatever is making the RPM drop.

Clean the throttle body, adjust the throttle plate and TPS, clean the MAF, and check for vac leaks are my suggestions. The accordion hose from the maf to the throttle body is also a known failure point.
 
The old thin plastic accordion hose is awful, it gets a lot of holes worn through the bottom. I had an '88 240 that had a million holes worn through, replaced it with the later style thick rubber unit.
Everything esmth suggested is should be done regardless, all very good ideas, part of stage 0. I would add clean the idle air motor to that list, and maybe test it, that can be done with a simple multimeter.
 
the check engine light will blink on for a split second and than it goes off again and it will do this a few times a minute.
Pull the engine codes and see whats there, if anything. It doesn't give great info but its easy and can point you in the right direction.

To read the codes (if any are stored) I'd normally link to pictures of the OBD box, and then copy/paste the whole procedure and a list of possible codes, but........ meh.
It's already over there -> http://www.volvohowto.com/how-to-read-the-codes-on-1990-1993-volvo-240/
 
I went ahead and cleaned the Throttle Body and MAF and I'm still getting the inconsistant idle. I'm thinking maybe it could be Idle Air Control. If anybody else has ideas I'd appreciate the input.
 
I went ahead and cleaned the Throttle Body and MAF and I'm still getting the inconsistant idle. I'm thinking maybe it could be Idle Air Control. If anybody else has ideas I'd appreciate the input.

pull the IAC and clean it. You can put 12v across the two terminals to verify it moves quickly and freely. Also pull the accordian hose and be 100% sure there are no holes/splits. They can be hard to spot
 
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