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C4 - DS4 Owners :: Forums :: Coupe and Hatch Pre 2011 cars :: C4 Coupe Hatch and General Questions

Idle problem after exactly 30 seconds from ignition on

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Tue May 10 2016, 05:11am
Member No: #31871
Joined: Jul 28 2013
Location: Italy
Goodmorning everyone,

I'm an old joined the forum, not active but very attentive reader. : D

I have a problem with my C4 1.4 16V 88CV of 2005.

Abstract: Motor ET3J4, 92840km, work carried out last month because of the fateful "problem antipollution system" and that the machine would not start more (1200 € approximately):

1) new Coil;
2) new lambda probe upstream;
3) new engine control unit;
4) Distribution and water pump;
5) General Cutting (candles, oil, various filters, tablets etc.).

The current problem is this: with the engine cold (5-6 hours after the last "round" performed) when I turn on the machine, the idle is ok as usual for 28-30 seconds. Arrived at the 30th second after the engine starts to mumble / sweat / choke / wince slightly as if it were flooded before recovering around the 40th second of the approach (sometimes just he does not have it on and off).

Please note:
1) The problem did it in the past, but much more sporadically and only in particularly "cold days."
2) Already used acetone as an additive to gasoline, no result;
3) already cleaned and polished throttle body and air pressure sensor;
4) When the engine is hot (with more than one notch lit on the instrument panel display), the problem does not occur;
5) Coupons always carried out on a regular basis;
5) The diagnostic detects some problems, but before I tell you what I would like to have your opinion just based on the symptoms described as not to influence any hypotheses (because of errors that detects only one, and I'm not sure, can hit something!)

What do you think it can be?
I look forward to any suggestion / solution! Thank you so much for your attention and sorry for the bad English.
Tue May 31 2016, 04:13pm
Member No: #6926
Joined: Jan 06 2009
Location: France. Loire valley. (retired )
If it was flooding then you would have black smoke from the exhaust at the time it is running rough.

Could be the mass air flow sensor not giving the correct signal to the ECU.

If there is no smoke from the exhaust then it's probably running weak.

This will cure itself as the engine warms up and vapourises the fuel correctly.
1 User said Thank You to COLVERT for this Post :
 DavidTwister (01 Jun 2016 : 01:12)
Wed Jun 01 2016, 01:11am
Member No: #31871
Joined: Jul 28 2013
Location: Italy
Thanks for the reply!

This is the video of my problem: Citroen C4 1.4 problem
Sound is bad and it's not how you really feel but it is enough to understand the problem. You can see the engine vibrations during the problem.

Last week i changed:

coolant sensor
thermostatic valve
maf sensor
crankshaft position sensor
camshaft position sensor
coolant liquid.

Nothing has changed, the problem remains.

No black smoke from the exhaust at the time it is running rough, and never.

What else could it be??
Fri Jun 03 2016, 03:39am
Member No: #31871
Joined: Jul 28 2013
Location: Italy
News about, please help me!

by connecting the car to the Diagbox, and checking the live parameters, I found this strange behavior of the oxygen sensor downstream (the one not changed, the original). This is the video with the behavior described:
- Click Here -

Practically this happens:

1) until the controller is in "open loop" (in the video from the fourth to seventeenth second, ie for the first 13 seconds from the ignition of the cold engine) the minimum is regular and the values ​​of the oxygen sensors are not updated;

2) from the seventeenth second of the video, the adjustment goes into "closed loop" and the reading of oxygen sensors start: the upstream (the new one) immediately begins to give updated reading of the values ​​expressed in millivolts, the downstream remains at "zero" up to the 27th second of the video.
Just start the reading of the downstream oxygen sensor (totally wrong- 3.8 volts when the value should be between 0.1 and 0.9 volts-) the minimum almost dies and begins to "drown" and then recover a dozen seconds later, though the value of the downstream oxygen sensor does not change for another minute or so, and then begin to detect "suitable" values.

Now my question is: the problem is the downstream oxygen sensor which probably does not immediately reach the right temperature, and until he does return wrong values?
Or the wrong values is a symptom of something else, and then the cause is not directly the downstream oxygen sensor?

Fri Jun 03 2016, 10:53am
Member No: #35215
Joined: Apr 20 2014
Location: Russia
Hi, David! Have you ever seen a catalytic converter? May be it destroyed. You have to disassemble and check out it.
- Click Here - is ok
- Click Here - faulty
1 User said Thank You to Honest for this Post :
 DavidTwister (03 Jun 2016 : 14:18)
Fri Jun 03 2016, 02:47pm
Member No: #31871
Joined: Jul 28 2013
Location: Italy
Thank you for reply!

The values of the two oxygen sensors are both ok after about 1-2 minutes so i don't think in the malfunction of the catalytic converter, isn't it?

However, the two images you uploaded are the same; can you please fix it?

And a news, if i disconnect the downstream oxygen sensor the value still remains 3,8 volts as if it's a default value from the ECU when the oxygen sensor does not transmit the data; and the strange idle problem at the 30th second still remains with the downstream oxygen
Sat Jun 04 2016, 12:21am
Member No: #35215
Joined: Apr 20 2014
Location: Russia
Updated. After about 1-2 minutes ECU sends the value. Are you the first the owner or not? If not than may be the catalytic converter have been removed. in any the case the catalytic converter need to check out about damages.
Thu Mar 23 2017, 01:12pm
Member No: #31871
Joined: Jul 28 2013
Location: Italy
Update to nearly 10 months since the last post:

-The catalytic converter Has Been removed: it's ok;
-I changed the downstream o2 sensor, but the problem still remains;

- I tried to disconnect the Map sensor, and the idle was perfect tmbweed !
This forced the Ecu to stay in open loop mode; changed the Map sensor, checked the map sensor wires but if i connect it the problem return, Because after about 10-12 seconds from the cold start the ECU change in Closed loop.

So the idle problem is when, only in cold start mode, the ECU change from open loop to closed loop.

Any ideas?!? Is the Ecu software that does not handle well the cold starts?
Mon Mar 27 2017, 06:55am
Member No: #8798
Joined: Apr 13 2009
Location: Cyprus
Hi David,
I have a similar issue as you have, albeit from a 2008 C4 1.6 VTi engine. The idle is dropping almost to a stop for the first few minutes, when engine is cold. However, this problem has been manifesting after I had the car for about 4 years from new. I haven't diagnosed it so far, but I doubt it is a software issue, because it would have been there since new. I guess something must have changed/degraded in the electronics/sensors, that gives the ECU erroneous readings.
Is there any schematics available of the ECU input/output and the arrays of sensors used in the C4?
Fri Jun 18 2021, 01:20am
Member No: #58354
Joined: Jun 18 2021
Location: Greece
And me i have another problem

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