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

[SkintKnuckles]

Hi all,

ok, I've repeated all measurements I've made to date using the best earth I can find.

Egr position sensor block connector disconnected, ignition at pos II:

Pin 1 (yellow) = 10.83 V, pin 2 (green/white) = 3.32 V, pin 3 (green/grey) = 11.86 V, pin 6 (brown) = 10 mV

The same measurements were repeated using pin 6 as the earth:

Pin 1 (yellow) = 10.88 V, pin 2 (green/white) = 3.30 V, pin 3 (green/grey) = 11.83 V


Next I repeated the measurement for Pin 1 (against chassis earth and also pin 6 earth):

Ignition off - pin 1 vs earth = 10 mV; pin 6 vs earth =0.00V; pin 1 vs pin 6 = 0.00 V

Ignition on - pin 1 vs earth = 10.89 V; pin 6 vs earth = 10 mV, pin 1 vs pin 6 10.87 V.


Then repeated the measurement for Pin 3 (against chassis earth and also pin 6 earth):

Ignition off - pin 3 vs earth = 70 mV; pin 6 vs earth =0.00V; pin 3 vs pin 6 = 40 mV

Ignition on - pin 3 vs earth = 11.85 V; pin 6 vs earth = 10 mV, pin 3 vs pin 6 11.83 V


Finally, I did the KBB EGR actuator test using the best earth:

Voltage at pin 3, ignition on = 11.76 V

Voltage at pin 3, pin 2 earthed off chassis = 11.76 V. EGR actuator made normal noise when pin 2 was earthed (grinding). Thus, no voltage change when the EGR actuator is live.

Ok, that's me for the day. Weather is just too bad. I'll keep an eye on this thread but cannot make further measurements until things improve here.

NB It is worth noting that the voltage drop I've reported here that is symptomatic of the limp mode etc, was made using the battery terminal as the earth, so this observation remains solid.

Apologies for any confusion this has caused. The last thing I want to do is put out information that is misleading, or waste your time with spurious readings.

cheers
Neil

[SkintKnuckles]

Hi mike,

I replaced the ETM 25 K ago I did this in response to an ETM related DTC. On the basis that I got a code when the ETM had failed (stripped cogs due to gunked up ETM), my guess is that the cogs are fine.

nonetheless, i'll check this when the weather improves as its a quick thing to do and I'll need to move a few things about to do the extra checks that Chris recommended (i.e. test the voltages to other components fed by the green/grey wires).

cheers (and thanks)
Neil

[KBB]

Well in one of your earlier posts I did think we were onto something when you reported the voltage at pin 3 dropped when you energised the EGR on pin 2.

I'm looking at diagram TP 3989202 for 2006 Page 57 15D system. The origins of this supply wire from fuse B15 via the main relay FMA3 dose power some key components Engine pad vac valve, vac valve for EGR cooler, turbo control actuator motor. If voltage drop is showing with just the EGR valve loading the circuit then when the other components are activated then the will be no power available.

[SkintKnuckles]

Hi KBB,

thanks for the explanation. My gut feeling is that the measurements I've made most recently - with the most stable ground and highest apparent voltage change - are likely to be the most believable. Thus, these measurements showed no delta voltage upon energising the EGR valve.

I meant to ask this question when Chris has mentioned the shared green/grey supply to a number of components ( a test I hope to try tomorrow). If we assume that there is an upstream issue and dodgy voltages are supplied to these multiple components via the green/grey wiring, would I normally expect a DTC for these events?

cheers
Neil

[Symes]

Have you driven the car since your post at 13:42 yesterday? I need to look back to see if pin3 is the actuator, and pin2 is the position feedback, but if they are then they look like they'll result in 'full' power mode.
I suppose what we need is a similar set of results when in 'limp' mode to compare, as has been mentioned, if the actuator supply is dropping then the position can't be sensed either.
I share your confusion regarding that if the source of supply is shared then why are the other modules not throwing codes, but the shared 'feed' will split into individual wires to the modules at some point and it may be the the problem is only on the egr one. The wiring diagram should show where the 'taps' are from a logical perspective, and hopefully denoted with a connector number. Finding the connector might be fun though!

Hope the weather is better for you today, it's a glorious morning here... ;-)

[Chris_Rogers]

I'm coming to the view that the voltage testing prior to 13:42 yesterday maybe compromised due to poor earth references.

I think it would be wise to start from scratch to diagnose the problem given the standing fault code 44B0 (i.e. EGR position sensor faulty signal).

It seems that testing via vida showed the EGR valve position data is not changing in spite of activation of the EGR valve.

KBB's post No.57 made some suggestions about monitoring the position feedback which is believed to be on pin 1 (yellow) of the connector.

It would be very useful to have the pinout and signal data for the engine ECU, usually this is available in vida, maybe someone with vida could post this info.


I'd suggest:

With the EGR valve connected.

connect a voltmeter between pin 1 & 6 of the connector.

Ign at position 2, ground the pin 2 to activate the EGR valve and note the effect on pin 1 DC voltage.

I would expect whatever the method of monitoring EGR position this voltage should show some variation in a working system.

[SkintKnuckles]

Morning Symes,

weather today is looking a bit better. It was wild yesterday. Must have looked like a madman standing outside working on the car in gales force winds. The glassy stare of a man with EGR valve problems....

When the car was next driven (i.e. after the most recent voltage tests you mentioned) it was indeed in full power. It remained in full power for an outward and then a return journey. It then dropped back to limp mode upon arrival. My theory is that it is just doing this to wind me up

I, too, wanted to do a set of comparison voltage measurements when the car was in limp mode, but the conditions were too challenging (or I'm just too wussy to stand in torrential rains doing voltage readings). I'll take it for a belt later and if it goes into limp, I can immediately do these measurements and report back.

That said, when I did this sort of test before (with the car in limp mode) I got a massively reduced voltage via the single EGR position sensor pin I could measure a voltage on. However, I'll feel happier if/when this test is repeated and confirmed across all pins. I have a nagging doubt that a bad earth may have contributed to some of what I have seen. If true, this still begs the question as to why an earthing point can be 'reliable' for one set of measurements and then unreliable for another.

I've already mapped out and identified the various connectors for the green/grey wires, so hopefully I can riingfence this down to a single component or see a more widespread problem. Either outcome would move us one step closer to a solution. I'm also going to have a look at the end of the actuator when its live, to see what is actually happening at the business end (that drives the EGR valve). At the least, I should be able to see if its turning, what the eccentric cam does in response, and which component is making the god awful noise (think coffee bean grinder!).

cheers and have a nice Sunday
Neil



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[SkintKnuckles]

Hi Chris,

thanks for the comments. I've just posted a reply to Symes, where I basically speculate exactly what you've just said. i.e. that a bad earth, at least during one set of measurements, may have muddied the waters in terms of the symptoms, and therefore the diagnosis.

Its no problem at all to repeat the test that you mentioned. However, since your thread yesterday made me start to doubt my earlier earth references (excluding those determined using the car battery earth, which have to stand by until I know different), I've now done the test 4 separate times, all with consistent answers (within mv of one another). The only time I've seen a voltage drop was using an earthing point that our combined views suggest is dodgy.

Thus, my gut feeling is that the no voltage change during EGR actuation is the correct answer for my car, even if its not the right result expected for a working circuit.

Since I'm a scientist, we have an old adage "don't waste clean thoughts on dirty data". This situation feels a bit like that. I can totally understand your rationale about remeasuring, and share some of your concerns, but I think the collated data I put up yesterday is the most reliable I've made to date. This is frustrating, as I'm doing the measurements to the best of my ability, they seem consistent and reproducible, and yet you/I aren't sure if we can trust them.

However, I do feel that we've moved forward yesterday in establishing that earlier earths in the engine bay were perhaps not solid. However, the most recent ones reported, I do believe to be the best and most reliable. Do you think an auto electrician is the way to go? These measurements are very simple, but if I'm throwing noise into the mix, then it sure ain't gonna help diagnosis.

cheers
Neil

[Chris_Rogers]

I think you have now established a reliable chassis earth point for future measurement and that pin 6 is a reliable ECU earth.

I'd move forward on this basis and confine measurements to using these known earth points.
Paying an auto electrician (of unknown skill) to confirm what you already know doesn't seem a good plan to me.

If we had the pin out signal data for the ECU this would take some of the guesswork out of it as wee'd know what was a good position feedback signal, maybe some kind soul will post it up for you.

[SkintKnuckles]

Hi Chris,

thanks for the words of encouragment and thoughts

I just did a control set of measurements for yesterday's ones. This time, I rigged up an extension lead for the battery earth. It was 4.5 m long. This was to extend a bombproof earth lead up to the engine bay and to repeat KBB's EGR test.

Before I used it, I measured the voltage at the battery terminals with the ignition off (12.55 V) and on at pos II (13.84 V). This gave me two voltages that confirmeded alternator function. Then I re-measured these parameters using the earth lead extension. The values with the extension were 12.63 V (ignition off) and 13.94 V (ignition off). Thus, the lead gave consistent results to the battery terminal, except the latter measurements were ~0.1 V higher (no idea why).

Anyway, this proves the earth extension was reliable and that the extension lead wasn't attenuating measured voltages i.e. it was a reliable earth to use.

Then i did the EGR energisation test recommended by KBB. I did this three times, each time disconnecting the leads and reconnecting them (to allow for readings skewed by dodgy connections etc).

The results were:

Test 1, Voltage at pin 3 (ign @ pos II) = 12.06 V; this voltage was 12.02 V when the EGR was energised. Again the usual coffee grinder sound. Delta voltage = -40 mV.

Test 2, Voltage at pin 3, (ign @ pos II) = 12.06 V; this voltage was 12.03 V. when the EGR was energised. Again the usual coffee grinder sound. Delta voltage = -30 mV.

Test 3, Voltage at pin 3, (ign @ pos II) = 12.06 V; this voltage was 12.02 V. when the EGR was energised. Again the usual coffee grinder sound. Delta voltage = -40 mV.

These results didn't change when using an alternative point on the chassis to energise the EGR.

Conclusion - using the battery earth yielded a slightly higher voltage than the chassis earth (i.e. 11.76 V yesterday for chassis, 12.06 V today using battery earth. Thus, a minor difference, with battery earth a bit better than the chassis one. My opinion is that both are fit for purpose. Any criticisms of this logic, folks?

Second, across multiple tests, it seems possible to energise the EGR valve actuator without a significant voltage drop to pin 3 (i.e. no measurable change yesterday using the chassis ground vs a maximum of 40 mV drop today using the battery ground).

given the above control for the effects of the extension lead, correct alternator voltages at battery, and concurrent results using the battery vs chassis earths, I think we have to trust these data.

OK, now to build on this.... My new fancy meter will be delivered tonight so am good to go with new tests from tomorrow onwards. I'll also do the voltage checks on the other shared components using green/grey wires tonight/tomorrow.

cheers
Neil