MAF sensor readings

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
yoseff
Posts: 139
Joined: 29 Nov 2010, 01:34
x 16

Re: MAF sensor readings

Post by yoseff »

PaulC5 wrote: 31 Dec 2023, 13:08 As well as MAF values, have a look at the MAP values. The MAP should be atmospheric pressure before starting the engine and once running using the accelerator pedal the values will change. If not then the MAP and/or its tapping point might be bunged up with carbon. Whilst not important, if you can, get the values in bar or mbar rather than psi.

Whilst not mentioned in the posts, I assume it is a C5 you are having problems with.
I've cleaned the MAP before, and will try to get its readings in mbar to see if they are near the expected ones. Will have a deeper look into that.

And yes - i've should specify what is the car - It is an 2011 C5 2.0 Hdi 163 , my personal one.
I currently "have" two - one is my personal one , and the other (not exactly mine , but from the company) , same engine but from 2010 , that is my working car.
The current problem is in my personal one. The working one have been with another set of issues described in another topic :mrgreen:

I realized already that i use less throttle at lower speeds with mine that in the work one (1-4% vs 6-8% @ 20 ish km/h) , and that the roughness happens mainly in that initial area. Bad contacts in throttle pedal sensor? Unsure if it can be opened to clean...

Found a topic here that seems to be from someone with similar issues in the past and i'm seeing what i can learn from there. Clutch pedal position sensor and anti stall mode seems also a possibility , need to check that sensor in Diagbox.
viewtopic.php?t=65340
User avatar
yoseff
Posts: 139
Joined: 29 Nov 2010, 01:34
x 16

Re: MAF sensor readings

Post by yoseff »

darbuck wrote: 01 Jan 2024, 19:45 To clean it you take it off the car and very carefully and liberally spray the sensor itself. Make sure you don't touch the hotwire with anything solid it will almost certainly snap if you do. Gentle is key
That's how i did with MAF sensor cleaner from Liqui Moly (https://www.liqui-moly.com/en/gb/air-fl ... 00537.html). Also sent a lot of cleaner inside the MAP sensor
In this engine it is so easy to take out that i dont mind cleaning it regularly. :-D
User avatar
yoseff
Posts: 139
Joined: 29 Nov 2010, 01:34
x 16

Re: MAF sensor readings

Post by yoseff »

Doo wrote: 02 Jan 2024, 16:03 As a further, the MAF also controls the use of the EGR on a diesel engine so if you are unsure of the state of it, might be worth a look as they can & do suffer from a build up of carbon.

On that note, when I did my wife's 2007 C4 1.6hdi engine not that long ago, I was pleased to note the EGR was if not immaculate, then as close as you can get for a valve that spends it's life in the exhaust system.

I am pleased to announce I am certain this is due to the prolonged use of BP Ultimate (or it's equivalent) diesel. That and regular oil & filter changes.
MAF seems to be working relatively well , specially after cleaning it
I always use "premium" diesel in my car. Currently from Repsol (10e+)
Oil and filters changed every 15 - 20k km
EGR behavior currently under analysis , but apparently seems to be working properly (at least from the sensors point of view)

Been driving with FAP app and Torque Pro (constantly swapping between those 2 apps to see several parameters, as they cannot be working at the same time)
User avatar
darbuck
Donor 2023
Posts: 1070
Joined: 25 May 2014, 16:45
x 151

Re: MAF sensor readings

Post by darbuck »

Hopefully that's it sorted now
Darren
User avatar
yoseff
Posts: 139
Joined: 29 Nov 2010, 01:34
x 16

Re: MAF sensor readings

Post by yoseff »

darbuck wrote: 08 Jan 2024, 20:49 Hopefully that's it sorted now
Regarding to MAF , it seems that the cleaning sorted it out. It's now near the expected values.
However, randomly i continue with my rough low speeds acceleration as mentioned here: viewtopic.php?t=80383
Something i've realized is that it coincides with the throttle body (or Air mixer , as appears in FAP app) not working randomly
In one trip is ok , then it stops working and car gets weird,
I'm driving most of the time with FAP app working & Logging , but no conclusion yet. Would it be a good idea to share some of my FAP Logs?
User avatar
yoseff
Posts: 139
Joined: 29 Nov 2010, 01:34
x 16

Re: C5 X7 "Rough" engine response & some Jerking @ low accelerator

Post by yoseff »

Still the same - In some travels throttle body (it appears in FAP as air mixer) , works and car is smooth , but then randomly it will stop working and then the roughness starts once again...
Air mixer instruction seems to correlate with what is asked. The not working part seems to be that air mixer movement stop asking to work. EGR movements also look a bit suspicious sometimes . Could a bad / clogged EGR provoke that behavior?
User avatar
myglaren
Forum Admin Team
Posts: 25695
Joined: 02 Mar 2008, 14:30
x 4970

Re: MAF sensor readings

Post by myglaren »

Topics merged.
User avatar
yoseff
Posts: 139
Joined: 29 Nov 2010, 01:34
x 16

Re: MAF sensor readings

Post by yoseff »

Adding a bit more info from the discovery journey, i realized that EGR is open (Around 50%) at Idle and from what i've read around it wasn't supposed to do that. It doesnt seem stuck , as the instruction fits close to what it is doing. Maybe the juddering i'm feeling randomly is EGR related afterall?
I'm tempted to blank it in order to test if it changes something , but probably that will throw out some error immediately... What would be the best way to test it without disassemble too much things?
20240118_212144.jpg
User avatar
darbuck
Donor 2023
Posts: 1070
Joined: 25 May 2014, 16:45
x 151

Re: MAF sensor readings

Post by darbuck »

Try blanking it off it shouldn't throw a code for a while.
Darren