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Rich Condition

  • Mahdi
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14 Mar 2020 09:15 #38332 by Mahdi
Rich Condition was created by Mahdi
Hi Mr Pual\ guys

I have been working on a suzuki CIAZ 2015 (Map type) ,, showing on the LTFT
- 17% without saving a fault code and the engine keep misfiring and running up normal, the O2 sensors had passed the lean test when pulling a vacuum hose and rich test when spraying fuel through throttle , Map sensor giving reading 49KPA at idle

But the non sense which happened to me that the car runs perfectly when unplugging the O2 sensor !!!!!! And LTFT tends to zero !!

Any explanation ! I'm getting crazy !

Note : the car has just finished a head gasket job .


Thanks,

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14 Mar 2020 11:02 - 14 Mar 2020 11:08 #38338 by Tutti57
Replied by Tutti57 on topic Rich Condition
Possible the 02 is contaminated if it was chugging coolant from a bad head gasket. What is the downstream sensor reading?

Does the car have a MAF sensor too? Not sure if that map reading is normal but someone else will.
Last edit: 14 Mar 2020 11:08 by Tutti57.

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14 Mar 2020 14:00 - 14 Mar 2020 14:41 #38346 by scannerjohn
Replied by scannerjohn on topic Rich Condition
So we are understanding your data correctly as this was an issue with another member, are you reporting a negative 17 LTFT.


Last edit: 14 Mar 2020 14:41 by scannerjohn.
The following user(s) said Thank You: Tutti57

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14 Mar 2020 14:03 #38347 by Mahdi
Replied by Mahdi on topic Rich Condition
Yes -17%

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14 Mar 2020 14:06 #38348 by Mahdi
Replied by Mahdi on topic Rich Condition
But it still switching lean and rich... between .1 to .9 normally!

I heard about a working lazy sensor causing issues , could it be in my case

Lazy sensor ! But in case it is , what is the normal frequency for a normal O2 ( min , max) Values !?

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14 Mar 2020 14:50 #38351 by scannerjohn
Replied by scannerjohn on topic Rich Condition
Your 02 is oscillating normally, between 1 and 9mv is normal. Your engine is running rich, getting too much fuel so the pcm is taking away fuel. By unplugging the 02 you are taking away the 02 data from the pcm so it goes into open loop. You showed that the 02 is responding via vacuum leak and fuel, so the 02 seems Ok but as Tutti57 said, it could be contaminated with coolant.

You say the idle is rough. Is it also high?


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14 Mar 2020 20:04 #38366 by Tutti57
Replied by Tutti57 on topic Rich Condition
I believe Paul said he is happy when he sees .2v to .8v when switching. You won't be able to tell frequency without a scope. I think the ECM is pretty good at detecting a slow response, so follow scannerjohn here.

Nissan Technician

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15 Mar 2020 12:48 #38380 by Tyler
Replied by Tyler on topic Rich Condition
49 kpa at idle isn't fantastic. :unsure: I'd suggest rechecking that reading with a hot engine at idle with no loads on.

If the 49 kpa reading remains, I'd consider a mechanical timing problem. Especially since it just got a cylinder head job.

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