CITROEN RELAY 2.0 Hdi No throttle response

TWICKS

Have a Citroen Relay 2002 with 2.0 (1997cc) HDI engine. Has a Bosch EDC 15C 7 Ecu. It only has a 3 pin (older style?) diagnostic socket coming out of ECU.
Current problem i have is engine starts ok. running at idle speed but throttle will not respond at all when depressed the red management light (looks like the injector spray ) is on.
Prior to this complete failure, van could be going around the corner, pulling offf from traffic lights or going round a roundabout and would be unresponsive on throttle for a couple of seconds (just idle revs) and then pick up. This then included intermittently on flat road also. Didnt seem to happen more whether engine cold or warm.

Previously with van have been unable so far to pick up a diagnostic fault code am still trying?

Any suggestions /ways of testing advice would be gratefully received. Thanks

Marktheshark

Air flow sensor fails and usually, ups voltage to the power on the throttle pot to 10v and it thinks its on tickover as it is 5v full throttle 10v no throttle.

If its not the Maf (unplug it and see if it revs) , the Air vacuum pump is next suspect.

TWICKS

Thanks Marktheshark shall give that a try and report back.

TWICKS

It didn't make any difference whether MAF sensor
(Siemens 5WK9 623) plugged in or not as to throttle response


These were the readings from plug disconnected from MAF sensor. Ignition switched on engine not started (A)Engine was just idling (B)Throttle depressed half way(C)
( A) (B) (C)
PIN * Ign turned ON * Engine Idling * EI Throttle half down


1 5.03V 5.03V 5.03V
2 12.4V 14.12 V 14.12V
3 0V 0 V 0V
4 Blank Pin Blank Pin Blank Pin
5 0V 0V 0V
6 0V 0V 0V
I removed the MAF sensor it was very dirty (maybe never been cleaned) with fragments of old air filters caught on the mesh guard and gently cleaned it with a MAF cleaner. Should I break into wire from plug to ECU to get a reading (as not exposed and cant get a test probe into plug when attached to MAF sensor) and take same readings or is there another way to check if MAF is faulty . Curious to know what the voltages to the pins signify. You also mentioned about the vacuum as next suspect, where is this located and what does it do. Am on an interesting learning curve here help and advice is much appreciated.
Also am trying to source somebody with an older style (3 pin ?) diagnostic pre current OBD (14 pin) that will read the fault codes. Have seen the name Lexia mentioned as current Bosch seemingly unable to pick anything up. nearish toNorth London N4 based.

arcon5

Look at the throttle position sensor.
some live data would be perfeft

atrixblue.-MFR-.

In my experience of the fly by wire on the pug citroen's is that the pedal sensor on the accelerator is what I'd be looking at as its the cheapest to replace and most common to fail, it has spade male connectors when the plug is removed so easily tested with a multimeter, and a single pedal not connected to a full box cage so a few bolts and its out. my suspicion would be the pedal first before going to the throttle and ECU. I replaced at least one per year on my ex works pug partner 2005 van.


Look here then look for ODB2 port (glove box or under dash drivers side) and have a live read of the sensors.


just be glad you don't own a Renault form 2003-2008, those throttles were not fit for purpose.

TWICKS

Thanks. Have checked voltages on throttle pedal sensor assembly.


IGN ON Pin1 - 5.04Volts Pin2,3,4,5 - 0Volts Pin 6 - 0.36Volts


Engine
IDLING Pin1 - 5.05Volts Pin2,3,4,5 - 0Volts Pin 6 - 0.36Volts


Engine
IDLING
Throttle Pin1 - 5.05Volts Pin2,3,4,5 0Volts Pin6-0.36to2.29Volts
depressed
varying to
max

Does this indicate that TPS sensor is functioning ok? Ishall break into the MAF sensor feed cable then to check on idle and half throttle ?

atrixblue.-MFR-.

TWICKS wrote: »

Thanks. Have checked voltages on throttle pedal sensor assembly.


IGN ON Pin1 - 5.04Volts Pin2,3,4,5 - 0Volts Pin 6 - 0.36Volts


Engine
IDLING Pin1 - 5.05Volts Pin2,3,4,5 - 0Volts Pin 6 - 0.36Volts


Engine
IDLING
Throttle Pin1 - 5.05Volts Pin2,3,4,5 0Volts Pin6-0.36to2.29Volts
depressed
varying to
max

Does this indicate that TPS sensor is functioning ok? Ishall break into the MAF sensor feed cable then to check on idle and half throttle ?

https://www.youtube.com/watch?v=3k6cOC81OvQ

One thing to note is that you should isolate the pedal from the battery and ECU as a "base test".

TWICKS

Do you mean by "Base Test"to check the resistance of TPS seperately ?

atrixblue.-MFR-.

TWICKS wrote: »

Do you mean by "Base Test"to check the resistance of TPS seperately ?

explained via PM, yes isolate form car battery unplugged from car wiring harness, your base testing it isolated to prevent potential wiring issue form causing a false test reading giving the impression the unit is faulty when it isn't.