Engine: D5: A puzzle for the EGR valve expert/masochists out there...

[Jetmech]

I have a copy of Vida on my laptop, but cannot find an illustration of the ECM plug pin layout.
This is what it says about the values at the pins concerned' A28 = Grnd. A66 = egr position sensor 0-5V. A71 = egr control signal 0-12V.

[Jetmech]

Originally Posted by SkintKnuckles

Hi all,

Then Kenny did a manual drive of the EGR valve using his cool software. This repeatedly gave rise to a noise that lasted for 2-3 seconds and came from the EGr housing, but no change in valve position. This suggests the electric motor is working on the EGR valve, or at least responds to requests for movement.

Are you sure the egr valve is actually opening? From the above statement I wonder if there is an internal mechanical fault in the valve its self.

[KBB]

Simon,

Many thanks for the ECM pin data, if in VIDA you then look up any diagnostic code appertaining to an EGR fault and then select the test procedure it should show the front face of the connector with pin numbers.

The EGR activation test with engine at idle is the one to do to confirm valve response and EGR flow. The valve position feed back circuit is the method used to move and stop the EGR pintle to various positions, the actual monitoring of the ERG Gas flow is monitored by the MAF as it detects a drop in inlet air volume as the space is taken up in the manifold by EGR gas.

[outnumbered]

post 35
http://www.volvoforums.org.uk/showth...=230529&page=4

[SkintKnuckles]

Hi Simon,

nope, I'm not sure that the valve is actually opening. At the time we did the test (engine off, VIDA on, ignition at pos II) I had the hunch that the EGR pos sensor was fine, and that the motor for the EGR valve was dead, or the mechanism slipping etc. Thus, the test we did showed that something was moving/making a noise when we sent a command to the EGR valve to move. However, I completely agree that noise from EGR valve motor does not equate to movement

Hopefully I can do this test soon.

cheers
Neil

[KBB]

Neil,

Dose you digital voltmeter have a setting for duty cycle and frequency?

[SkintKnuckles]

Hi KBB,

no, it doesn't. Its a very basic one to measure basic volts, resistance etc. Is this likely to be a dealbreaker in terms of a finding a solution and executing a test plan, as obviously I will source what I need in the quest for a fix?

For what its worth, I've attached an annotated schematic of the EGR valve/position sensor block connector. This way, we are all using a common map for whatever follows. All credit goes to Mike for getting this from VIDA (as per his post above). I merely annotated it with the information that has been supplied today. Thanks guys!

I also tried the disconnection of the MAF multi-plug during running. This threw up the following codes , 44B0 (EGR position sensor fualty signal), 6720 (EGR flow too high). In addition, I also got some new ones

CEM - Central electronic module (D2):
0x1A62 - Communication with ECM control module Signal missing
0x8F09 - ECM wake up signal Signal too high

I assume that these new codes are just down to the MAF connector being disconnected during the code reading, and hopefully nothing to do with my EGR issue. I'm open minded tho'

cheers
Neil

Edit - due to a quirk of fate/ignorance on my part, the only wire I've got voltage through (when the car is in limp mode) is the green/grey one (pin 1). This oscillates from ~30 mV (limp mode) to 12.8 V (full power). However, this wire, based on Simon's feedback is the sole wire that doesn't feed directly into the ECM. I'm hoping that this is good news, as it may suggest that whatever the origins of my flaky voltages are, it isn't the ECM

[KBB]

Looking at the wiring diagram the seems to be a discrepancy with your diagram.

Wiring diagram denotes:

Pin 1 Yellow to ECM A66 Position feedback voltage.
Pin 2 Green/White to ECM A71 Ground side control.
Pin 3 Green/Grey live feed via Fuse B/15 and relay FMAS 3 live with key at position 2.
Pin 4 Not Used
Pin 5 Not Used
Pin 6 Brown/Black to ECM A28 potentiometer feedback position circuit ground.

Worth checking before proceeding further!

[SkintKnuckles]

Hi KBB,

whoops, mea culpa! There is a perfectly rational explanation for my mistake - I was being an idiot!

Attached is the revised, correct scheme. Apologies, all of this stuff has been going on in the background of a house move and move between countries. So I'm doing all this stuff in the background, and I'm not a little harrassed.

p.s. I'm just off to do the EGR valve operation test using VIDA, and with Kenny's help. will report back later with the outcome.

cheers
Neil

[KBB]

If you can give an approximate UK time Kenny will be on scene the will be some very useful voltage readings to take whilst bidirectional control is being applied to the EGR circuit.