C5 Mk.1 2.2 hdi EGR blanking

[Millerboy79]

Hello peeps,
In an effort to stop my car surging and holding back under acceleration I unplugged the vacuum pipe from my EGR valve and plugged the end. Instantly the holding back had gone and it went quite well again! However, as you would expect it figured out I'd done something and dropped into LHM. I've now reconnected the vacuum but I've blanked off the EGR at the inlet. Will this do any harm and will it figure out I've blanked it off? I'm aware I need to find out why the EGR kept opening and flooding the inlet, hence the surging and holding back, but I've checked the EGR and the spring is good, and I've also cleaned it out. Does anyone know which particular sensors tell the EGR when to open? Do those same sensors tell it when to operate the swirl valve? I know it's supposed to be confusing as it's a Citroen but a slim chance of it running right would be nice!!!!

Cheers Todd

[cachaciero]

There's a variety of inputs to the EGR mapping, MAF, Turbo Pressure, Temperature, FAP regen. Vacuum wise the vac source is separate from the Swirl Valve Turbo control vac in that the latter is fed from the same source via a restrictor and has it's own vacuum resevoir to isolate it from the brake servo. You really need to eliminate problems in the vacuum supply to the EGR.
Interesting that it put's the engine into LIMP mode, doing it the way you have done it i.e by removing the vac source on the valve and plugging the pipe the ECU has no direct way of knowing the valve is not there. Further I can't see that failure of the EGR valve on it's own would be likely to cause an engine damaging situation which is the only reason for going into LIMP mode.
I suspect that you may have another fault which operation of the EGR valve is masking. Blanking the EGR line on the manifold should be o.k I've done it on mine but my guess is that when you do you will still have your surging, which would tend to point to something vacuum related, I wonder if you have a vacuum leak in the system somewhere.
You need a Lexia session to find out exactly what the ECU believes is wrong

cachaciero

[Millerboy79]

Cheers Cachaciero,

I've checked the vacuum and they are all intact, and on my brief test drive last night it didn't surge and it pulled away quite willingly when it was cold, which it normally grumbles at. So I am highly confused, when it was holding back it was as though the EGR was opening and staying open for too long and screwing the mixture up somehow, as if it was blowing the boost out so to speak? I am looking into buying a lexia in order to plug the lump of sh*t in!!

Todd

[Millerboy79]

On my way to work this morning it ran lovely with the egr blanked, and then dropped into limp mode. Stopped it and restarted it and all was well again, did it again on way home. While it was working the surging had gone, it pulled cleanly and revved smoothly. Interestingly, or not, with the egr valve blanked the cruise control will work, with the egr open it will not hold a set speed on cruise. Also after changing the coolant sensor the swirl valves, despite having no splits in the pipes and a working solenoid, still do not operate.

[cachaciero]

On my way to work this morning it ran lovely with the egr blanked, and then dropped into limp mode. Stopped it and restarted it and all was well again, did it again on way home. While it was working the surging had gone, it pulled cleanly and revved smoothly. Interestingly, or not, with the egr valve blanked the cruise control will work, with the egr open it will not hold a set speed on cruise. Also after changing the coolant sensor the swirl valves, despite having no splits in the pipes and a working solenoid, still do not operate.

Do I understand that the swirl valve has not been working for a while? Swirl valve failure / vacuum loss is often due to holes in the actual swirl valve actuator diaphragm as much splits in the pipe, loss of vac here will cause the turbo to overpressurise and this WILL cause limp mode. You need to measure the vacuum in the swirl valve line should be about 200mBars abs with engine at idle. The only reason the swirl valve will not work is U/S electro valve, not that common or loss of vac.

cac haciero

[Millerboy79]

It's a brand new actuator from Citroen, if I bridge the vacuum pipes, i.e bypass the solenoid, the actuator works as you would expect, put the solenoid back into the equation and it doesn't operate, and it is a working solenoid. I have had all the pipes out and checked/replaced as applicable. The actuator prior to replacement never worked, which was down to a faulty diaphragm, hence the reason for replacement. However it still does not operate as it should at 2500rpm.
Hateful car.

[cachaciero]

Yep! you really need a Lexia, with that you can make the ECU operate the swirl valve. As far as I know the swirl valve uses rpm as it's main control, now RPM is kind of integral to the operation of the ECU so it has to be present which leaves non operation of the swirl valve a bit of a mystery

cachaciero

[Millerboy79]

Lol! The whole car is a bit of a mystery! And it's running out of chances! Lexia or different car it is then!

[Millerboy79]

And today, on the way to work and back it's been fine! If a little thirsty!