Engine fan strange behavior

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Drgz001
Posts: 11
Joined: 29 Aug 2023, 14:37
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Engine fan strange behavior

Post by Drgz001 »

Hi all,
I have a 207 1.6 VTi year 2007 that had an ECU fail.
I replaced the ECU + the BSI + the key and the key sensor.
I programmed the BSI and the ECU with Diagbox.
I had to change many settings because the donor car and mine were very different despite having the same engine and built same year (coupé vs sedan, automatic AC vs. manual, manual gearbox vs. automatic).
I did screenshots of all the settings before I removed the ECU and the BSI.
My problem is that some settings are different with the new ECU and BSI. Especially concerning the automatic gearbox and the AC (mine has a manual AC and the donor car had an automatic one as far as I can see).
Anyway the car works well now. The AC blows warm air but I don't know if it was working before I replaced the BSI.
But it seems that the engine fan has a strange behavior: I find that it turns on very soon, after about 5 minutes at idle as the temperature on the dashboard is only about 70°C.
When I turn the ignition off, the fan keeps turning for several minutes. And strangely when I turn the ignition on it stops, and turns on again when I turn the ignition off.

Can anyone tell me if it's normal or not as it's my first Peugeot.
Thanks for your help!
Gilles
PaulC5
Donor 2024
Posts: 219
Joined: 06 Jun 2023, 15:26
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Re: Engine fan strange behavior

Post by PaulC5 »

There might be a problem with the engine temperature sensor. Use your code reader to look at live data rather than the dash temperature gauge and see if the engine temperature seems right. It ought to be the outside temperature before a first start each day and then increase gradually as the engine warms up, at about 90°C the thermostat should open and the radiator top hose will get hot. About 96°C the radiator fan should start if it gets hot enough and if it then cools the fan should stop about 94°C.
Drgz001
Posts: 11
Joined: 29 Aug 2023, 14:37
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Re: Engine fan strange behavior

Post by Drgz001 »

Thanks for the advice!
I will check that and tell you.
Drgz001
Posts: 11
Joined: 29 Aug 2023, 14:37
x 1

Re: Engine fan strange behavior

Post by Drgz001 »

Hi all,
I checked the sensor values and it's OK.
I think the problem come from the AC.
I can see in Diagbox that the AC requests the compressor to be on but the AC is off and the interior fan is off too.
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xantia_v6
Forum Admin Team
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Joined: 09 Nov 2005, 23:03
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Re: Engine fan strange behavior

Post by xantia_v6 »

In the engine ECU there should be a parameter like A/C disable (I can't remember the exact name) which if true means that the engine ECU is unhappy (perhaps detected a cooling system fault) and has disabled the A/C compressor clutch. If that is the case, you need to sort out the problem in the engine ECU first.
Drgz001
Posts: 11
Joined: 29 Aug 2023, 14:37
x 1

Re: Engine fan strange behavior

Post by Drgz001 »

Thanks for the information. I'm going to check all that!
Drgz001
Posts: 11
Joined: 29 Aug 2023, 14:37
x 1

Re: Engine fan strange behavior

Post by Drgz001 »

Hi,
Here are some news about that problem in case it might help other people.
It took me weeks to sort this out, hence the delay of this post.
I discovered that the ECU of these engines (1.6 VTi) is programmed in a way that when some thing is wrong with a sensor or parameter it shifts to a backup program which is a kind of limp mode. This mode includes turning on the fan on high speed. The fan remains on about 4 minutes after the ignition is turned off.
I guess the purpose is to protect the engine as the ECU doesn't trust the sensors anymore.
In my case, the problem was caused by an intake manifold pressure sensor fault (Diagbox).
Actually, the sensor was OK. But I had a big vacuum leak caused by a broken PCV hose.
After I replaced the hose (which by the way can be done without removing the intake manifold, it just needs to be patient and stubborn) I still had an error caused by the crankshaft position sensor.
Once I replaced the crankshaft position sensor everything went back to normal. No DTC, non abnormal fan behavior.
Important point: things went totally back to normal only after I erased the errors with Diagbox.