Bad idling and acceleration after o2 sensor replacement

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07-09-2023, 12:34 PM

Vasco Pridat

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Bad idling and acceleration after o2 sensor replacement

I got 1646 error massages for both 02 up sensors and bought a set of four to replace them.
Idling got rougher over months and at some point around 100km/h it sometimes stalled a bit. Acceleration was perfect.
I couldn't get them out so I turned it into the shop and they replaced them and it passed the German mot.
But the car doesn't run well now.
When idling it very Very little changes rpm in a constant sinus like up and down. Like it looses a bit and then throttles back up. Very minor but I notice.
When accelerating normally with a bit more force it does the same. I can't accelerate constantly but I'm 'swinging' more less more less..
Ann suggestions on what's wrong here?
Before this I just had an idle that got worse over a year and sometimes at around 100km/h only with the a on. I lost torque shortly sometimes when giving little gas.

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07-09-2023, 10:24 PM

Vauxi

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Does it ocassionaly run on 7 or less cylinders? Is the car with aj27 or aj26. Aj27 has wideband front sensors.

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07-10-2023, 12:43 AM

Vasco Pridat

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2001 A27... I will read errors again but I think there are no more and it passed the MOT.
It's just so strange that it happened after they changed the sensors

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07-11-2023, 11:18 AM

Vasco Pridat

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Quote:

Originally Posted by Vauxi

Does it ocassionaly run on 7 or less cylinders? Is the car with aj27 or aj26. Aj27 has wideband front sensors.

So I took her out today. Idles rough and accelerates up and down... And I get the same 1646 and 1647.

The sensors have Def. Been replaced.

What else can cause those codes now?
Heater problems..?

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07-12-2023, 11:58 AM

Vauxi

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Does the rough run start immediately or after lets say after a 10s? If it starts later on I'd say rough idle kicks on when lambda control turns to closed loop.

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07-13-2023, 05:06 AM

JagV8

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The DTC guide says all the possible causes of the codes. Work through them one by one, starting with fuses & relays only if you are SURE the new parts could not be bad (cheap, fake, etc).

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