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Old 05-14-2021, 06:54 AM   #1
Deadwrong33
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Default 740 code 321

Any help is appreciated CEL came on it drove fine but I came up with code 321? I noticed a slight rough idle upon stopping at a light. Other than that no clue? I read a few items it could be this forum has been good to me thx in advance, I’m new to this motor but not Volvos lol.
My exact model is a 90 740gl automatic.
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Old 05-14-2021, 07:40 PM   #2
dl242gt
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Do you know what engine management your car uses? It could be one of two types. Either Bosch LH2.4 Jetronic or Regina/Rex system. A fast way to tell is the Bosch system uses a mass air sensor on the intake hose and the Regina/Rex uses a small intake air temp sensor in the intake hose. The ignition coils are different as well. Bosch is a typical round cylinder coil. But the Regina/Rex has a big square coil/amplifier setup.
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Old 05-14-2021, 09:24 PM   #3
lookforjoe
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If it's Regina, pretty sure 3-2-1 is throttle switch/ idle motor related. If you can't hear a 'click' when you crack the throttle open by hand under the hood, your throttle plate is prolly gummed up & not closing all the way, or the linkage is out of adjustment. It is rarely the switch adjustment. Get a new TB gasket, remove the TB, soak w/ carb clean & put it back.
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Old 05-15-2021, 01:45 AM   #4
MasterBlaster
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3-2-1 - Signal to cold start valve short to ground or missing

For many (including my 90 740GL Rex/Regina), this is a normal code and can be ignored.

As I understand it, the original operation had the valve always powered, along with the rest of the injectors, and only grounded for more enrichment when the engine was below -18c and under 600 RPM.

Somewhere back in time Volvo issued some kind of service bulletin that rewired the valve so that instead of being connected to constant power, power is only supplied when cranking. The rest of the time (like just before cranking) the ECU sees it as an "open circuit" and sets code 321.
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Old 05-15-2021, 10:45 AM   #5
Deadwrong33
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Thx some said it could radio suppression relay? New to this motor I know my way around the 5 cylinders
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Old 05-15-2021, 10:47 AM   #6
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I will check that out thx
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