EGR or MAF or both ?

[charentejohn]

Back again with the eternal question.
Car engine warning light on yet again, but was running ok this time only I don't trust it to keep running.
Played around a bit with the following results, do my conclusions seem right ?

I had the MAF connected but EGR bypassed by sealing the hose to the EGR and the relay connection it came from - Car running but light came on after aboout 20 miles.
Took the tape off the relay connection and engine speeded up slightly. Confused as to why as this is only going to a vaccum pump ?
Took the tape off the EGR hose and still running speeded up.
Reconnected the EGR hose to the relay and engine coughing and spluttering.
Disconnected the MAF and still coughing and spluttering.
In all of the above conditions check engine light is on.

So - MAF is ok but EGR is the problem ?
Despite engine light being on should the engine run ok if I blank off the EGR hoses again ? I will change EGR if that's the problem but for the moment I just want to be able to drive the car.
MAF and EGR are linked so if disconnecting MAF means no change to stuttering engine then it is probably ok.

I have spent enough on the car now so don't want to fit an EGR and have no change in the car, not much left to change now anyway.

Currently battery disconnected to wipe memory, will reconnect tomorrow and just blank the hose to the EGR and see what happens. If car is driveable I will have one final diagnostic done befor deciding it's fate.
Hopefully tomorrow with MAF connected and EGR bypassed it will run with no light on ?

[charentejohn]

Well tried again last couple of days. Found a good basic diagnosis here http://troubleshootmyvehicle.com/gm/4.3 ... ve-tests-1" onclick="window.open(this.href);return false; Not for Citroen but the idea is good.

So did disconnect/reconnect of pipe to Egr and had ok/rough running as a result.
I don't have a vacuum gauge but do have a bit of paper, about the size of 4 postage stamps. I disconnected the hose to the Egr and put it against the electic valve outlet and it held there.
From this I assume there is some vacuum ? Perhaps there is always a bit.
From the comments in the above link I assume there should be none at all so perhaps the valve is at fault, hope so as an easy fix.

I have disconnected the electric valve and there is still a vacuum, but now the engine is running ok despite putting the pipe to the Egr back, so confusing as ever.
Any thoughts on simple tests I can do to determine which bit is at fault.

How easy is it to remove the metal air intake blocking my access to the EGR, okay from the engine bay but is it easy to unclip down behind the engine ?
I will try to get a diagnostic done tomorrow afternoon (my Lexia won't work on this car) but an idea of whether this is the solution would be a help.
EGR is about £60 here, electric valve £40 + fitting if I can't do it easily.

[Monkeyfeet]

Well I might not have completely the right end of the stick here but I've messed around with vacuum pipes and egr's on my Cits and Pugs.

As I understand things, the egr requires a vacuum to open it, so removing that vacuum pipe (and blocking the pipe end) should eliminate the egr from the equation. However I've done just that (disconnected the pipe etc) and noticed a bigger difference when I've gone on to blank off the (disconected) egr. So I'm assuming that a partially opened egr caused rough running. Can't remember the 2.0 layout on the 110's but on the later 136's it's £4 and a five min job (really). It would save removing the egr, certainly for the time being.
Vacuum with engine at idle may be normal, not 100% sure on how the ecu uses the egr, sorry.

I always though that if the maf was faulty then disconnecting it would have no further effect?

Hope this helps a little.

[charentejohn]

Some progress, I hope. I haven't looked at this since I put it into the garage as nothing to report so sorry for missing tha above reply. If it persists I may try blanking completely but so far so good.

The garage only charged 20Euros so for here that is about 40 mins work for cash. The Lexia showed poor vaccum pressure so they investigated. Now been ok for about 20 miles and I just checked it would start and run ok when cold and it does. Takes a while to start now, normally nearly instant, in -2C temperatures.
Trying to see what they did I notice a few bits of tape here and there on the inlet pipe to the relay, the long one, and wondered if it was just pinholes in the pipe causing problems. I didn't ask when I picked it up but will next time I visit. That would make sense as they said the pressure was intermittent. I will look round for a new piece.

The slow start in the cold is a new one and I would have thought the EGR would have made little difference to this, but once started for the first time starts instantly from then on. Just the price of having it work ok and summer is coming anyway.