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2006 Focus 1.6 TDCI Weird Idle / Hesitation Moment


bigshorty
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Hi All

I have a quick query I'd like some help / advice with, hoping someone might have some ideas of what happened.

I had been driving for about 20 - 25 minutes and reached a set of traffic lights. When I brought the car to a stop the rev counter started jumping around erratically between 500 and 1500 rpm, the car was revving in tandem with the movement on the rev counter. As I pulled away from the lights I could feel the car randomly hesitating, although not that severe. This went on for about 5 minutes at the most, and then the car seemed fine again. I got to my destination without any repeat of this, and the 25 mile journey home was ok too.

Does anyone know what might have happened, and whether it is likely that it was just a blip, or the sign of something more serious?

This is the first time its happened, there were no fault codes that came up, and the car has recently had air filter changed, oil and filter changed and fuel filter changed, EGR valve is blanked as well.

Any views, info or advice on this would be greatly appreciated

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10 hours ago, bigshorty said:

erratically between 500 and 1500 rpm, the car was revving in tandem with the movement on the rev counter

The 1st things that come to my mind are the throttle pedal sensor (TPS), or perhaps fuel problems (air or water, or partial blockage). Many other intermittent electrical faults are also possible, all you can do there is wait till they become more noticeable, and just hope it is not too inconvenient!

TPS is a dual redundant pot, bad errors should light a warning light. But wear at the bottom end may cause slight errors that are not detected as a fault, but still affect idle.

Look out for warning lights, get a diagnostic scanner (if you have not got one), & report any additional symptoms here.

If the topic is kept active, it may get noticed by someone with similar experience.

Peter.

 

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5 hours ago, Tdci-Peter said:

The 1st things that come to my mind are the throttle pedal sensor (TPS), or perhaps fuel problems (air or water, or partial blockage). Many other intermittent electrical faults are also possible, all you can do there is wait till they become more noticeable, and just hope it is not too inconvenient!

TPS is a dual redundant pot, bad errors should light a warning light. But wear at the bottom end may cause slight errors that are not detected as a fault, but still affect idle.

Look out for warning lights, get a diagnostic scanner (if you have not got one), & report any additional symptoms here.

If the topic is kept active, it may get noticed by someone with similar experience.

Peter.

 

Thanks for the info Peter, I do appreciate you reply.

I do have a diagnostic scanner, one that I use with Forscan, and a cheapy handheld one, and I will wait and see if it happens again and report any new findings should they happen. I just find it odd that for 5 minutes of a 50 mile journey the car started doing this, yet for the rest of the time it was fine, no problem with idling or travelling at 70 mph down the motorway.

I've heard that sometimes a DPF regeneration can cause some odd issues / symptoms to occur, whether there is any truth in this I don't know, do you think this could have been a possibility? Also, you mentioned wear at the bottom end may cause slight errors that could still affect idle, could you please explain what you mean in regards of wear at the bottom end?

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2 hours ago, bigshorty said:

please explain what you mean in regards of wear at the bottom end

As far as I can tell, these cars all use a pair of potentiometers for the TPS. These have a resistive track, and a wiper that moves along the track. There is usually a 2nd wiper and (non-resistive) track that re-connects the moving wiper to the pot signal terminal. Wear & corrosion (normal atmospheric oxidation may be enough over time), can make the contacts between wiper & track intermittent, especially in parts of the track that are frequently used. On an audio volume control, this will appear as crackles & other noises at certain volume settings. The resistive track can develop cracks or weak points, also.

The Ford pots will be high reliability, long life devices, but they get a lot of use in a hostile environment, and over 10 years may develop problems. That is why the TPS has a duplicate pair. But the comparison will have to have an allowed window.

Unfortunately, there are many other possibilities, the number of possible joints and connections that could cause this is huge. And that is in addition to more mechanical problems like injectors, fuel variations, etc.

My advice is to use your Forscan system regularly. It should give good coverage of the system.  Even if warning lights are not on, DTCs may be present.

Re: DPF re-gen: difficult to see why it should give such a variable, intermittent problem, unless combined with some other, underlying fault. I wonder if Forscan can reveal the time/mileage since last re-gen? I bet this is stored in the car somewhere.

See if anyone else has things to add.

Please keep posting any information/queries here.

Peter.

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On 6/29/2016 at 11:18 AM, Tdci-Peter said:

My advice is to use your Forscan system regularly. It should give good coverage of the system.  Even if warning lights are not on, DTCs may be present.

Hi Peter

Just used Forscan to check DTCs and have got code P2458 (DPF regeneration duration) code come up. This isn't the first time this has come up, a few weeks ago my mechanic mate found this code after the EML came on. It was the EML that is red in colour and has an exclamation mark in a round cog (if that makes sense). We found out that the Eolys additive tank was empty. I have had this refilled, the counter reset and the DTC cleared and the EML hasn't come on since, but the P2458 code has shown up again. I have heard that the exhaust gas temperature sensor can become faulty, and when it does there could be DPF over fuelling issues that happen. Do you think this could be a cause for odd moments of erratic idling? I have to admit, I haven't noticed any visible signs of a DPF regen happening lately, such as plumes of smoke, burning smells, fan running, slight increased engine revs or different engine tone that are supposed to occur during a regen.

Didn't know if you or anyone else had any thoughts on this, I would appreciate any views / ideas.

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13 hours ago, bigshorty said:

used Forscan to check DTCs and have got code P2458

In your 1st post, where you stopped & revs were jumping, it could have been doing a regen then. Had you been driving fast enough (>50mph) prior to the stop, to allow the active regen to start? If so then it all points to dpf problems. If the Eolys tank was empty for some time (and this may be undetectable, the level is calculated by guesswork on fills & use, not by a level sensor!), then dpf blockage is more likely.

Note: Passive regen happens unaided, in normal driving. Active regen happens under pcm control while driving, with elevated exhaust temperature. Forced (or Static) regen happens when started by a scan tool.

If the duration is too long, this is likely to be because either the indicated exhaust temperatures did not rise high enough, or because the indicated pressure drop over the dpf did not reduce. So there are 3 main reasons for this:

DPF is too badly clogged, perhaps with unburnable ash, and will not clear.

Temperature sensor (or wiring/connector) faulty. (2 are fitted, I have heard, one each side of cat and/or dpf.)

Pressure (DP) sensor (or wiring/connector) faulty.

Wiring or connector faults are likely to raise another error as the signal will be out of allowed bounds. Major sensor failures (open/short circuit), ditto. It would have to a partial sensor fail, so it read an allowed, but wrong, value.

So, sadly, dpf failure may be most likely. But it is worth doing other investigations first.

Forscan should be able to initiate a Forced regen. This is done on the driveway, and uses high rpm for 15 minutes (all automatically controlled). See Tom's topic:

There is a video of a forced regen near the bottom of page 1.

This can fail (be aborted) if the various sensors indicate regen is not possible. It may result in a re-occurance of P2458, if the regen does not clear the dpf. It did not help in Tom's case, but still worth a try, just to see what happens, or if any other DTCs occur.

It should be possible to monitor exhaust temperature & DPF DP live using Forscan, or log them over a drive cycle. This could indicate if the readings seem sensible, or are just silly, which would indicate a sensor failure.

Numerous other engine signals are needed for an active or forced regen to happen:

" With regard to the sensors for regeneration all the engine sensors are used, the EGR valve must be closed, the turbo vanes are usually set at a low boost, the EGT sensors need to read correctly, the IAT and ECT are measured, the DPF sensor,  the MAF and MAP are checked, & the CKP (crank sensor) for engine speed. "

(From:http://www.justanswer.co.uk/ford/8v2eg-june-2014-dpf-filter-blocked-2009-1-6tdci-ford.html )

 

However if the problem continues, and the sensor readings seem right, then a new dpf may be the only answer. Removing the dpf insert may allow confirmation that this is the problem, but is likely to be an MoT fail these days.

A 75k mile lifetime for these dpfs is quoted by some, though there are many examples of much longer life.

I am Not an expert on DPFs, so please look around for other (Better?) advice. I guess this is not the advice you hoped for! But the P2458 DTC seems quite specific.

Peter.

 

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9 hours ago, Tdci-Peter said:

It should be possible to monitor exhaust temperature & DPF DP live using Forscan, or log them over a drive cycle. This could indicate if the readings seem sensible, or are just silly, which would indicate a sensor failure.

Thanks for the info Peter

I would like to monitor what you mentioned using Forscan, however I'm rather novice when it comes to using it and what to look for as far as results go. Do you know if there is a guide I can follow to get live data, or would you be kind enough to go through the procedure to do this for me please, if its not too much hassle?

I know its a lot to ask but I would appreciate it.

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1 hour ago, bigshorty said:

using Forscan, however I'm rather novice when it comes to using it and what to look for as far as results go

Hi Paul,

To be completely honest, so am I (rather novice!) I used Forscan to help solve a nasty problem with my Instrument Cluster, and saw that it was a (relatively) easy tool to use, and a very powerful tool. I did play around with the live monitoring a bit, but not for any serious work, so I know it is there, but am not an expert.

The term used for these monitoring functions is "PID", and there should, in one of the menus, be a list of the PIDs (quite a long list I suspect), that are valid for your car. Read the list, looking for terms like DPF, DP, Pressure Drop, Exhaust temperature, EGT (Exhaust Gas Temperature), or similar. You then select a list of PIDs to monitor, and I think an icon then appears at the bottom of the screen to start monitoring. (You probably need to be connected to the car even to read the list of PIDs, so the software knows what is is dealing with.) (DP means Differential Pressure, = Pressure Difference)

Some other PIDs that May appear are: mileage when the last regen was done (DSLCR), mileage when last regen attempted (DSLRT) and time in minutes since last regen (TESLRT).

As far as values go, I would start with the engine not running (ignition must be on), and cold. Then EGT values around ambient and a DP near zero would be right. Then start the engine, see if the EGT values rise, I would expect around 80C to 150C to be reasonable for idle. The DP should rise, a few kPa at idle, rising smoothly as the revs rise. I suspect values much over 10kPa indicate a blockage. (1Bar = 14.5PSI = 100kPa, so 10kPa is 1.5PSI)

Really you are looking for unexpected jumps, or significant errors (silly readings). Small calibration errors would be hard to find without special equipment, but are much less likely.

After my last Post, I did see that Tom had answered your other entry. He is very knowledgeable, and has the same engine as you, so he may be able to give you more, or better information.

All I can think of at present,

Peter.

 

 

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That's some great advice thanks Peter. I've been meaning to use Forscan more, and the info you've given will definitely help me do that and hopefully show up, or preferably not, any issues.

I'll let update this with any finding from the Forscan results.

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Hey Peter

Sorry to keep bugging you but I just wanted your view on something.

I plugged Forscan in however could not find a PID for EGT sensor. Do you know what else it could be described as? What I did find was a PID for pre particulate exhaust temperature (PPFT) which had a starting value of 100'C. I found the DP DPF PID fine so started monitoring. When the car warmed up under idling to normal operating temperature the PPFT went up to 108'C and seemed to stay there. The DP DPF stayed steady at 0.8kPa whilst idling and as I increased the revs steadily the DP DPF value went up steadily, I revved up to 3500rpm and got a reading of about 4.0kPa.

Can you tell me what you think of these readings please? To me it sounds like a DPF blockage isn't the issue.

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6 hours ago, bigshorty said:

PID for pre particulate exhaust temperature (PPFT) which had a starting value of 100'C.

I would say EGT and PPFT are names for the same thing. Any sign of a Post particulate exhaust temperature PID? I seem to recall hearing it had two, but might be mistaken.

More importantly, a starting value of 100C on a cold engine sounds very dodgy. That definitely needs more investigation. It should be possible to monitor the exhaust pipe temperature, ideally with a thermometer, but a hand will do if it starts cold. "Ouch" temperature is about 60C, and "sizzle, that is going to hurt", temperature is over about 80C. (i would advise stopping the hand test at Ouch!)

It is just possible the system only starts to read at above 100, and just freezes at all readings below 100, this should be evident on further tests.

The DP readings sound good, and that is good news.

Peter.

 

 

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Hi Peter

Final update with some findings I've discovered using Forscan, which I was hoping you could give your views on if you don't mind.

Had to drive today, so thought I'd plug in Forscan and get some live data, see if I noticed anything. During the drive I had to pull up at some traffic lights and noticed the weird idling again, as I pulled away the car seemed to hesitate a bit. My partner was in the car looking at the Forscan data when this started and noticed the PPFT temperature reading started to climb quite quickly. Over the period of the next 6 or 7 minutes the temperature reading was in the mid to high 400'C range, peaking to 560'C, I'm presuming this was a regen as when the temperature reading went back down to normal operating temp the reading for 'distance since last regen trial' (or something like that) reset itself to 0.0km. The whole process lasted between 9 and 10 minutes. I also noticed that the DP DPF reading went up during this period and peaked at 10.4kPa, but was mainly around 8.0kPa - 9.0kPa. Should the pressure reading have got this high during a regen? For the rest of the journey the pressure readings were mainly between 3.0kPa and 6.0kPa, obviously fluctuating due to driving style, however I did get it up to 9.4kPa, at which time I was doing 80mph on the dual carriageway. Would you mind telling me what you make of this info if you don't mind me asking?

I also had the PID DIS_ASHFULL running at the same time and noticed that as I was driving this reading was going up. It went from 3504.1km up to 3508.0km.Any ideas why this would have increased as I would have been under the impression that it would have gone down. This is presuming the PID is for how full the DPF filter is obviously.

I would be really grateful to hear what you think about this info I've added, and thanks for your help in using Forscan, it really has helped me out a lot.

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Sorry I missed this before!  Will try to answer the latest questions though.

500c ish is the temp you need for regen on these (it's lower on the later coated DPFs), so yes that's what was happening there.

There is only one temperature sensor on these DPFs, 2 on the later ones.  The lowest temperature it can read is 100c so that's normal.

Pressure is an interesting one as no-one seems to know what it should be!  9.4kPa at a constant 80mph does seem a bit high though, in fact 3-6kPa while driving is a bit high as well, should be less than that while cruising, but spike when you accelerate. 

Ash is what's left in the DPF after the soot has been burnt in the regen, there is no way the ash can get out so that's what builds up over time and eventually blocks the DPF.  I never did work out how is that PID is accurate or if it's just working from the mileage (the DPF should be full of ash and changed at 75k miles), how many miles is yours on now?  That PID would suggest the DPF is getting to the end of it's lifespan, as does the pressure to me. 

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15 minutes ago, bigshorty said:

DP DPF reading went up during this period and peaked at 10.4kPa, but was mainly around 8.0kPa - 9.0kPa. Should the pressure reading have got this high during a regen? For the rest of the journey the pressure readings were mainly between 3.0kPa and 6.0kPa, obviously fluctuating due to driving style, however I did get it up to 9.4kPa, at which time I was doing xxmph on the dual carriageway.

Lots of meaty info there! It really can help having some good diagnostics.

Tom has answered most of it, I think. I have to go out now, but will have another look later, & if I think of anything useful I will post it.

Peter.

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Thanks for getting back to me chaps.

With regard to the DPF pressure readings, didn't know if it might be worth having a look at the following link:

http://www.cmaxownersclub.co.uk/forum/technical-36/dpf-error-codes-forscan-elmconfig-46138/

I was reading through this thread and paid particular attention to post # 8. I've checked, and the DV6 engine in my Focus is the same that would have been used in the posters 2008 Mazda 3, and he states that normal pressure readings are up to 30kPa, anything above this signifies a DPF blockage. I'm not sure how accurate this statement is, it would be nice to find some more info about this to check against and I will keep looking.

As for when my DPF was last changed, I really don't know. I bought the car really cheap due to there being not much service history with it, so was a bit of a risk, although the car has done 11.000 trouble free miles until now and 2 passed MOTs since owning, and being honest it is still driving really well almost all of the time. One thing that is confusing me though is if the DPF ash full PID was counting down the miles to when it is supposedly full, why would the reading go up while I was driving along? I did find this next link which might have some relevant info, but I can't make head nor tale of it, and there is a link within that one but takes you to a german site, and I can't speak german.

http://forscan.org/forum/viewtopic.php?f=5&t=20

Any views / ideas would be very welcome.

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6 hours ago, bigshorty said:

the DPF ash full PID was counting down the miles to when it is supposedly full, why would the reading go up while I was driving along?

It looks to me as if the PCM recalculates this value after each regen, based on the DP reduction & some other approximations. The table in the link to Forscan that you gave, suggests this. And it is logical, how else could it do it?

Regarding allowed DPs I would say it should be under 10kPa in normal driving. 30kPa ( 4.4PSI) sounds high to me.

Is the P2458 DTC still coming up? It sounds like the last regen was a success, not too long & a reduction in DP afterwards.

I did find a long. rather involved but interesting post on DPF regen & cleaning on:

http://forscan.org/forum/viewtopic.php?f=6&t=247

(one of your links lead me to it.)

This suggested cleaning with water could help with an ashed up DPF! (Had to be removed though). (See PS!)

See if the Error DTC re-appears, or what happens on the next regen.

Seems good progress on a tricky problem so far!smile.png

Peter

PS:

Further looking reveals mixed reviews for water washing: A couple of favourable reports that sound honest, but others are warning that the ash could set like concrete if wet! I suspect the setting would take some time, so if the ash is removed before setting, it could be ok. A major ingredient of most ash is calcium carbonate / calcium oxide (depending on the formation temperature). This is the principle ingredient in lime mortar & Portland cement!

So I would only try this as a last ditch attempt to salvage a blocked DPF, where there is nothing to lose. And I would not use pressure jets, just reverse flushing with copious water.

Edited by Tdci-Peter
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12 hours ago, Tdci-Peter said:

Is the P2458 DTC still coming up?

I checked for P2458 after the journey yesterday, when the car did a regen, and the code has not shown up.

I managed to get hold of the chap I bought the car from, and he assures me the DPF filter was changed as near as it could be to the recommended mileage for a change.

I've been checking through the Forscan data that I collected yesterday and noticed that whilst driving constantly at 1600rpm in 5th gear (which is from what I remember around the 50 - 55mph mark) the DP reading was a constant 2.5kPa. Yet at 2350rpm in 5th gear (which I think is about 70 - 75mph) the DP reading was 7.0kPa. It's obvious that the harder I drive the car the more the pressure readings increase, which is what is to be expected. Do you think these readings are still a cause for concern or ok, in some respects, given that they would be quite a bit under the ideal 10kPa reading if I drove steadily? Couple of extra points that I wan't sure might be worth mentioning but could these readings be on the higher side, if in fact they are too high, due to the EGR valve being blanked? I have also had a K&N high flow air filter installed recently and didn't know if this might affect the readings as well? Just looking at all possibilities really.

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I don't know where the 30kPa came from, that really would be high!  Mine was peaking around 12kPa on the knackered DPF iirc.  Don't forget its the pressure difference, not the pressure itself that you're reading.  The pressure difference should be almost nothing on a good DPF while cruising.

I would suspect your DPF isn't genuine as it's been replaced, they seem to be even worse than the genuine ones lol. 

The EGR valve and air filter will have no effect on the pressure differential.

Tbh, in your position I would wait to see if it gets worse.  I could make the DPF codes pop up every time by revving past 3000rpm by the time mine was bad enough to need replacement.

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57 minutes ago, bigshorty said:

1600rpm in 5th gear (which is from what I remember around the 50 - 55mph mark) the DP reading was a constant 2.5kPa. Yet at 2350rpm in 5th gear (which I think is about 70 - 75mph) the DP reading was 7.0kPa

That does not sound unreasonable to me. The pressure drop over the filter is a function of the volumetric air flow through it, and probably not a linear one, it is likely to curve upwards a bit at the higher end. (i could ramble on endlessly about turbulent & laminar & mixed flow, but I am sure few want me to!). The air flow depends on rpm, turbo boost pressure and gas temperature.

As a bit of a wild estimate, lets say at 1600rpm (50mph) Boost pressure is 1.6 bar abs, gas temp 150C.

Then at 2350rpm, lets say 2.2 bar abs, 250C. This bumps the volumetric flow rate up by:

2350/1600 x 2.2/1.6 x (250+273)/(150+273) = 2.5 times, or from 2.5kPa to 6.2kPa or more.

The figures quoted by some of up to 30kPa could be extreme cases of max rpm (4000+), max boost, max temp.

The PCM knows all this, and should be able to judge whether high DP is due to high flow, or blocked DPF, and, hopefully, react accordingly.

EGR blanking: If the pcm uses the MAF as its primary source for flowrate, then the EGR can be ignored, air in (+ fuel, in mass) will equal gas out. If the pcm uses rpm & MAP (turbo boost), and if it thinks the EGR is open, then the exhaust flow (& DPF DP) could be a bit higher than it expects. So a blanked EGR could lead to more frequent re-gens, and a reduced time to ash full state. Trouble is, few people on this planet know exactly what goes on inside the pcm.unsure.png

I do not think the K&N will have adverse affect. If airflow is a little higher, the pcm should see this & compensate.

Just seen Tom's answer, and I agree, I think he is saying similar things to me, but in a more straightforward way!

But if those DTCs stay off, and the DPF regenerates at reasonable intervals, then all seems fine. Lets hope it stays that way for a while!smile.png

 

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Thanks for the reply Tom

So its sounds like a new DPF is on the cards, and sooner rather than later I suspect. From what I've read its not just a case a fitting a new one either, some programming of ECU is needed when a new DPF is fitted, is this correct? Any cheaper options available, like being to program myself?

Bit of an update for you here, I took the blanking plate off, started car up and the EML came on giving the following DTCs, P2141 - Exhaust gas recirculation throttle control circuit low, P0488 -  EGR position control performance/range fault and P0487 - EGR system throttle position control circuit malfunction. I'm guessing that the EGR valve has given up, does this sound likely? If it is, is the EGR a straight swap, or does it need programming? Before I took blanking plate off I went for quite a long journey and P2458 didn't show up again, no signs of another regen as yet but it was only 120km since last one.

Any advice / help anyone can give would be greatly appreciated.

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46 minutes ago, bigshorty said:

DPF is fitted, is this correct? Any cheaper options available, like being to program myself?

I have seen information on the Forcsan website that that system can reset the DPF learned parameters, and that seems to be all that is needed. The pcm then relearns the new dpf.

The EGR errors sound like electrical faults (circuit malfunction, out of range etc). It looks like when it was blanked, it was not even trying to open the valve, but unblanked it is trying & failing. But it could just be the change has upset it, try resetting the codes & re-trying a few times.

I am a bit surprised that you had no error codes with the plate in, most people say you get errors on this engine if it is blanked, unless the pcm is re-programmed. Hopefully Tom will confirm whether this is true or not.

But it is still good that the DPF error has not returned. And it has not needed to do another regen too soon, so the DPF may be good for quite a few more miles yet.

 

 

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Cheers for the reply Peter

Good news concerning the programming of the DPF, just in case I do need to replace it at some point in the near future. But as the code hasn't come back and hasn't done a regen too soon after the last I'm sort of hoping it won't need doing for a while, I'll keep an eye on it for now though, just in case.

I did find it odd myself that the codes didn't show up whilst EGR was blanked, but I've also heard that some have not experienced DTCs with a blanked EGR so I guess I may have been one of the lucky one's. I did blank the EGR as a safety measure because I had a fault code relating to the EGR pop up sometime ago, and thought it wise to blank it until I got it sorted, if the EGR had in fact started to malfunction.

I've attached an image of the Forscan results I collected the other day, it just so happens that I had collected info for the PIDs for EGR valve position (pink line) and EGR throttle valve (purple line), I have also increased the time line to show more elapsed time per screen (if that makes any sense). What do you think of these readings? I'm presuming they should be more variable and not just a series of regular peaks.

Just out of interest, do you know what sorts of issues I should be looking for relating to possible EGR related problems? Anything specific I should investigate? I guess I should be checking the wiring, connectors, etc

Forscan1.jpg

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2 hours ago, bigshorty said:

What do you think of these readings?

I have to be completely honest here, and I am very impressed with the amount of data taken, but am struggling to understand it all!

The time axis says "Time, ms". But the way the Regen km is clocking up, you would have to be doing several times the speed of sound to move several km in 200ms! So I assume the time axis is in seconds, ie <2030 sec to >2600 sec, or several minutes.

It is only a few hours since I first saw that a DV6 engine has a Throttle valve, (EGR Throttle), I guess this is what most people call the anti-shudder valve.

As to why they are pulsing, two explanations come to mind:

1) Forscan is monitoring the power signal to the valve. This is pulse width modulated, probably about 1kHz or so.  If you sample a pulsing signal at a rate less than its pulse rate, you get what is called aliasing, or a beat frequency, and you can see a much slower image of the original signal. And this could be what is visible in the graph.

2) Forscan is monitoring the position status returned from the valve, and the valves are both pulsing on about every 35 seconds. This could be a result of the faults that are giving rise to the EGR DTCs.

Since the graphs are labelled EGR_TV,% and EGRVP,%, I am inclined to believe no.2. And that looks wrong, the valve positions may ramp around quite a bit (my EGR does, when not blanked), but not like that.

Perhaps do a re-run with the valve blanked again. If the engine works ok blanked, and the DPF Ashfull PID does not improve with the blanking removed, then keep it blanked, I would say!

The alternative looks like repairing or replacing the EGR. If most of your mileage is urban, then there is some merit in having a working EGR to reduce NOx. But in a rural environment, I would say the net benefit of an EGR is minimal, or negative. But then that is just my opinion, others may differ!

Re EGR problems, yes check connectors, perhaps remove the valve (if not too difficult), clean it, try to check if it moves freely. I would stick a variable power supply on & see if it moves, but most people don't have the luxury(?) of such things.

Contact cleaner on connectors rarely provides a permanent cure, but may at least help to identify a problem area if the unit starts working after.

The DPF is much more important than the EGR, particulates are nastier, and are an MoT test, and it sends the car into limp mode, so the main thing is to keep that bit working! EGR actually tends to increase particulates, it is there to reduce NOx. Also EGR must be shut (and probably with no EGR related DTCs) for DPF regen to occur.

Peter.

 

 

 

 

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8 hours ago, Tdci-Peter said:

It is only a few hours since I first saw that a DV6 engine has a Throttle valve, (EGR Throttle), I guess this is what most people call the anti-shudder valve.

As to why they are pulsing, two explanations come to mind:

1) Forscan is monitoring the power signal to the valve. This is pulse width modulated, probably about 1kHz or so.  If you sample a pulsing signal at a rate less than its pulse rate, you get what is called aliasing, or a beat frequency, and you can see a much slower image of the original signal. And this could be what is visible in the graph.

2) Forscan is monitoring the position status returned from the valve, and the valves are both pulsing on about every 35 seconds. This could be a result of the faults that are giving rise to the EGR DTCs.

Thanks for all the info Peter, some good comments there, even if I don't quite fully understand all of it.

In regard to your explanations of pulsing readings, are you relating these to the EGR valve, the EGR throttle valve (anti shudder valve) or both? I've heard some people end up cleaning out the throttle body assembly as these are prone to getting very grubby and can cause problems. Could this be a cause for the DTCs and something worthwhile doing?

8 hours ago, Tdci-Peter said:

Perhaps do a re-run with the valve blanked again. If the engine works ok blanked, and the DPF Ashfull PID does not improve with the blanking removed, then keep it blanked, I would say!

The Forscan results I attached to my last post were with the EGR blanked. I took the blanking plate off, started the engine and up popped DTCs P2141, P0487 and P0488. Why the DTCs didn't pop up while EGR was blanked is a total mystery to me, I'm presuming with the Forscan results I took these codes should have popped up.

With regard to checking / cleaning the EGR, I thought it wise when I decided to blank the EGR valve to take it off and have a look and give it a clean. From what I observed everything seemed to move freely within the EGR, and to be honest wasn't that clogged up with soot but I did clean it up anyway. If I do go down the route of fitting a new EGR valve, is it a straight swap or will the new one have to be programmed, and if so, can this be done using Forscan?

I will fit the blanking plate back on again to help preserve the DPF, I just need to get these codes sorted so that they don't affect the DPF regen process.

Sorry to keep bugging you about this Peter, but you are helping me a great deal to make sense of how these processes work and what I should be looking for, I do appreciate your help.

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Hmm, I think you may need to reset the EGR parameters now (can be done in FORScan) as it may have 'learned' the blanking plate, I didn't expect that though I must admit!  It also shouldn't be opening every few seconds as it appears to be on your live diags, unless I'm reading the PID wrong?

If you need to reset the DPF, EGR or DPF fluid, all can be done in Forscan.

Also, just to pick up on something Peter said above, EGR needs to be open, not closed for regen to occur, that's one of the ways it gets cylinder temps hot enough without melting anything lol.

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