C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

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cachaciero
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by cachaciero »

Re EGR cleaner et al. The bad condition for the EGR valve is stuck open or partially open so a blanking plate applied at the manifold end would cure this if it were the case it is a cheap and quick way of proving if a stuck EGR valve really is your problem. If it is the problem and you wanted to try sprays etc then disconnect the EGR pipe on the manifold inject vast quantities of EGR cleaner down the open pipe and leave to soak overnight. The fuel additive referred to does nothing more than the additive that FAP system injects into your tank i.e Eolys176 or a similar substance, this just produces carbon that burns at a lower temperature however won't do anything for carbon that exists.

I don't believe that the EGR system looks at air temp only coolant temp. Now when doing my tests I was curious that the boost pressure appeared to be well above the "model" pressure and the mass flow didn't change as much as I expected when reving the engine. Later when I disconnected the two inlet pipes and ran the car without them turbo pressure was as it should be no higher than ambient but the mass flow changed quite markedly with revs as one would expect It was observed that even with coolant up to 85 the hot butterfly did not move i.e stayed at about 5% open as commanded and the cold butterfly stayed at about 95% closed and did not open until the revs approached 3K, the valve position agrees with the command position from the Lexia IF for 95% open (Lexia) you read that as 95% closed. So effectively all the air inlet into the engine is closed off which explains why the turbo pressure is higher than the model is demanding and the mass flow doesn't change very much. Like you I begin to wonder about mapping but I think I do need to look closer at coolant temperature and the calibration of the sensor.

Lexia I had gone from Lexia to Diagbox I don't think the installation went right there seems to be quite a few little oddities. The lexia will draw the traces and save them the only thing is to look at them of line i.e unplugged from the car is impossible as winlex won't run until it has a valid interface connected and F8 doesn't seem to be able to find a printer, maybe another installation plus updates is the way to go.
BenC5HDi
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Re: RE: Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by BenC5HDi »

skycat61 wrote:James, thanks for the suggestion. I can't see how I could get to spray the EGR while the engine is running.
You disconnect the air intake pipe just after the air filter (and MAF) and spray the EGR cleaner spray down it in short bursts as per the instructions.

It's worked on my 2.0 HDi Berlingo ..



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Guest

Re: RE: Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by Guest »

[quote="skycat61"]James, thanks for the suggestion. I can't see how I could get to spray the EGR while the engine is running.[/quote]

You disconnect the air intake pipe just after the air filter (and MAF) and spray the EGR cleaner spray down it in short bursts as per the instructions.

It's worked on my 2.0 HDi Berlingo ..



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BenC5HDi
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Re: RE: Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by BenC5HDi »

skycat61 wrote:James, thanks for the suggestion. I can't see how I could get to spray the EGR while the engine is running.
You disconnect the air intake pipe just after the air filter (and MAF) and spray the EGR cleaner spray down it in short bursts as per the instructions.

It's worked on my 2.0 HDi Berlingo ..



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skycat61
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by skycat61 »

James: what was the EGR cleaner you used?
Hell Razor5543
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by Hell Razor5543 »

I will have to dig it out from the boot of the car, but I will be in there tomorrow, so I will let you know.

EDIT; This is the stuff I used;

http://www.simply-brands.com/additives/egr-cleaner
skycat61
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by skycat61 »

Well, I think we're starting to make a little progress. I fitted an EGR blanking plate and have found a significant improvement in MPG. If you recall we were achieving 24-27MPG on the work run. With the blanking plate in I'm getting 30-35MPG on the same run. Unfortunately it is throwing the "Depolution system fault" message with the engine light on.

So it looked to me like the EGR was open when it shouldn't be so I thought I'd check the vacuum drive to it on a gauge. The EGR is receiving a vacuum of 7 inHg. I checked the inlet heater electrovavle for comparison and it sees 15 inHg.

So what's at fault here? Is it the EGR Valve or the EGR Electrovalve? And what is the operating sense of the EGR? Is it vacuum to close or vacuum to open? Your thoughts are much appreciated.
cachaciero
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by cachaciero »

The mpg you are getting is about what i would expect for the journey you are doing so looks like you are in the right area.

O.K De pollution Fault investigation with the Lexia on the injection ECU should give you some clues as to what is actually causing that fault, certainly blanking the EGR on my car does not cause this. However if when working on the car something has been disconnected and then re-connected while the ignition is on it may well set a fault which will clear after a few start run cycles
The EGR requires a vacuum to open so 7 inhg @ at idle would be about right, (should rise to 15 in @2500 rpm) the inlet throttle valve is the reverse, requires vac to close so as at idle it is closed 15 in hg sounds about right. The difficulty with the EGR valve is determining what it's position really is, it's not exactly the most accessible component.

I would suggest first thing to do is to identify why with the EGR blanked you are getting a warning as I don't think you should get one just because the EGR is blanked. However I may be wrong because there were changes to the ECU software on the 2.2 at facelift time and I have no real knowledge of what that involved but some of the changes were related to the FAP regen cylce conditions due to a change form DPX42 to Eolys176 fluid. (Mines DPX yours will be Eolys)

With the vac control line from the EV to the EGR disconnected the EGR should be closed (blank the port on the EV from which the pipe has been disconnected), with the EGR blanking plate removed you should get the same mpg as with the plate fitted if the valve is closing properly. or back to square one if it's stuck.
skycat61
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by skycat61 »

Hmm. I think I might have confused the situation. When I say the the EGR was getting 7 inHg of vacuum this was not under idle conditions but driving the actuators via the lexia in test mode having first built up a vacuum by running the engine. I found it odd that under actuator test the EGR electrovalve delivered just 7 inHg whereas the inlet heater electrovalve delivered 15 inHg. But a week vacuum would not open the EGR valve so logically (to me!) this would seem to say we have a stuck open EGR valve given that the EGR valve is vacuum to open.

The "depolution system fault" only appeared after 15 miles or so after fitting the blanking plate, but since then it now appears a few seconds after starting the engine. I will try to get the fault codes for this...

Many thanks for your input Cachaciero
cachaciero
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by cachaciero »

7 in Hg is not a weak vac thats 23.6Kpa ambient pressure is approx101.3 Kpa so anything less than that is a vacuum and the smaller the number the greater the "suck" I am assuming that your gauge reads absolute pressure. i.e open to atmosphere the gauge reads 32 in Hg more or less.

Now if using the Lexia to drive the EGR valve open the EV will apply max "suck" which is what you appear to have. The problem is that you can apply whatever vac you like to the EGR valve BUT there is nothing to show that the valve position actually corresponds to the vac you are applying.

All you can deduce is this;- Lexia select EGR valve open vac=7in Hg abs Lexia select EGR valve close vac=32 in Hg abs ergo EV good or, if, when Lexia select EGR valve close vac=7 in Hg abs ergo no change EV bad.

I miss read your previous post the heater inlet valve is also vacuum to open, so 15 inHg will open it don't know by how much though!
skycat61
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by skycat61 »

Oh dear! I've made a complete sow's ear of communicating the vacuum measurements. My gauge shows gauge pressure not absolute pressure. It reads ZERO for no applied vacuum (atmospheric pressure), so the figure 7 inHg is actually about 23 inHg absolute, which I thought to be quite poor. I apologise for the confusion caused.
skycat61
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by skycat61 »

The lexia had the following new injection faults stored:-

P0400 Permanent Fault. Exhaust Gas Recycling Circuit. Amount of air measured in the circuit inconsistent

P0400 Permanent Fault. Exhaust Gas Recycling Circuit. Amount of air measured in the circuit lower than setting

I suppose this is only to be expected with the blanking plate in place.
cachaciero
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by cachaciero »

Re Vac readings yes 23 in hg abs is not good out of the EV for vac on i.e EGR valve open but it may be enough to open the valve does it change between open and shut and by how much.

The fault code is interesting the only way that I can see it can measure air in the system is via the mass flow sensor which you have changed and it's lower than the engine model dictates so what does that look like in terms of flow and what is the history of the replacement Mass Flow Sensor, Air Leaks in the ducting down stream?. My view is that it was good for 15 miles and then something changed!!!
unclenewy
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by unclenewy »

Hello everyone,

Firstly I would like to say hello to this website and forum, I have been searching furiously over the past couple of weeks for answers to a few problems I have had with my 52 plate C5 2.2 hdi and have found most solutions in this forum and another Citroen site (which I have also joined).

I have just read virtually every post in this thread as the title is the exact problem I have with mine, plus it's the most recent thread I've found and I think I may be closing in on the answer but I should firstly list the jobs I have done, as to eliminate a lot of suggestions I know you helpful guys have already offered previously.

OK

Full service after purchase.
Started to notice no power at all, narrowed down to blocked DPF as car had been showing 'low additive' signal soon after buying it, and whilst adding 1L of PAT fluid bought online (£33!!) I discovered EOLYS tank was empty, so more fluid needed, brilliant!!
Anyway, removed complete exhaust from CAT backwards, split DPF from CAT and cleaned with a soak and jet wash (may be coming back to this for more 'work' later). Drove car without exhaust and, although it sounded like I used to before I stopped smoking, it definitely had better pick up but only after about 2000 rpm. Also, strangely, no warning lights even though I had disconnected 2 sensors.
Refit everything back on car, took it for a low gear high revs run hoping it may give itself a clean out. Car ran well, 70mph in 4th at 3000rpm on cruise for 30 mile round trip, and a boot in 5th up to 90mph at the end no problem. Happy with my work.

Next day found it's REALLY sluggish from standing until about 2500rpm then decent pickup, so next job......blanked egr at inlet, no noticeable difference but no harm either.

Onto MAF sensor, unclipped it. All this did was flag up ESP/ASR fault and restrict revs to 4000. Had to reset BSI to get rid of lights after refitting.
After reading about possible wet air filter and dirty MAF I checked these. Filter brand new (to be expected after service) and dry as a bone. MAF clean as a whistle but sprayed with carb cleaner anyway. Also, whilst air box was off I drilled hole in the very bottom of it to drain any possible moisture. This also gave me good access to the throttle cable just under the fuse box so I tightened that whilst I was at it, pedal is now almost as high as it will go and doesn't quite reach bump stop.
One thing I hadn't considered was intercooler, and whilst I had all this stuff off the car it was pretty clear mine was clocked up with oil.......so........ebay. 2nd hand intercooler, easy swap, check the top pipe for pressure, seems strong (blew my hand off easily).........next!

When I was under the car removing the intercooler pipes......all intact and no splits or holes by the way........I noticed a pipe coming from deep inside the nearside wing up to the air filter box, which was what can only be described as a foam pipe inside a black plastic bag. Well the plastic bag had holes and tears in it with noticeable air blowing onto my hands and face. I made a makeshift new bag and gaffer taped it around the pipe to stop the air loss.........I figured this was just the start of the air intake rather than a pressured pipe because of its design. Also I didn't fancy having to take the wing off to get to the other end of it.


SO........a recap.

DPF cleaned.
MAF sensor checked
MAF cleaned
Air filter dry
Throttle cable adjusted
EGR blanked
Intercooler replaced
Air intake filtered pipe fixed

Next discovery was the swirl valve actuator is supposed to kick in at around 2100rpm......exactly the point at which my car finds some power. So, lets have a look at this then..........All working as it should, I got the missus to slowly rev to 2500 and watched it move forward easily. Now I'm flummoxed, the description of how the swirl valve works is too much of a coincidence as to how my car picks up, suggesting it's faulty, but I can see it moving fine.

So after all this war and peace novel.......Sorry people but didn't want to keep coming back with question after question..........My question is.

Is it possible for the actual butterfly valve that the actuator arm should open, to be stuck open, even though I can see the arm and pivot moving properly?
cachaciero
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Re: C5 2.2 HDi 136 Facelift - poor MPG and no bottom end grunt

Post by cachaciero »

I believe the answer to the question is no as regards being stuck but I am not sure that it is not possible to assemble it 180 degrees out so that closed becomes open. But then the crank arm would be up rather than down. You could disconnect the rod from the crank on the swirl valve and lock it (tie wrap?) in one position and try it then lock it in the other position and try it. There is no doubt that if the swirl valves are stuck open it does make it a bit sluggish low down but if my memory serves me that disappears after about 1500rpm. There are other things that happen around the rpm point you mention, EGR valve closes and Air throttle valve opens up fully round about this point.
You really need a Lexia on it to see what's happening it would be particularly interesting to see what it would tell you about boost pressure and mass flow. The "foam pipe inside a black plastic bag" puzzles me I have no recollection of anything like that in that area but it's a few years since I last had the front of mine apart. Why would you have air blowing out of a supposed air inlet?. As I recall the complete air inlet filter box can be removed from the top without having to take the front off but I can't remember what the inlet to the box looked like :-(
If you send me an e-mail address that will accept large attachments I will send you the info that I have given skycat61 it may help you understand how it's all supposed to work :-)
It does seem to me that the problem may be turbo related, i.e stuck in low boost as a quick check you could try disconnecting the vacuum control line from the Turbo EV to the turbo (blank the output from the EV so you don't loose vacuum to the rest of the system) Now with the turbo vacuum control open to ambient pressure the turbo should be in max boost mode. Go for a test drive ,at some point if the turbo is working correctly you will likely go into overboost and limp mode but it should be enough for you to see if there is an improvement. Don't do this too much it is my belief that overboosting too often and too much can blow the intercooler :-(..
Another quick check is to disconnect both vac control lines to the butterfly valves on the front of the inlet (blank the pipes) this will ensure that the cold inlet is fully open and that the hot air inlet is fully closed and then see how it goes. Note from personal experience it is very easy to cross the vac control to these two valves when re-assembling this area, the lower butterfly (hot air) connects to the EV adjacent to the side of the inlet box.