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        General >> Problems >> James Bond Stylee Smokescreen
        
(Message started by: mazzy_j on Mar 20^th, 2006, 9:41am)

Title: James Bond Stylee Smokescreen
Post by mazzy_j on Mar 20^th, 2006, 9:41am

Hi there,

Does anybody know how to tell whether a diesel's EGR valve has failed? I've looked at the EGR pages on the main site but couldn't come to a definate conclusion by them as there were mainly for the petrols versions.

What it looks like:

http://i33.photobucket.com/albums/d94/mazzy_j/turbo3.jpg

The symptoms my car has is excessive black smoke from the exhaust (as in whilst cruising along you can bearly see the car behind :o) -which could suggest the EGR valve is stuck open and the exhaust is dumping straight into the inlet manifold- and no power below 2000rpm (but still the same performance from then upwards).

I disconnected the multiplug to the sensor below and the smoking then stops, also the car is so much nicer to drive which could suggest thart whatever's causing it has been on its way out gradually for a while.

http://i33.photobucket.com/albums/d94/mazzy_j/mapposition.jpg

Thanks,

Matt

Title: Re: James Bond Stylee Smokescreen
Post by sector-9 on Mar 20^th, 2006, 10:52pm

No idea with your problem but the EGR is only supposed to 'do things' when under part throttle so if you floor it does the smoke stop? (kinda silly really because every diesel I've seen smokes when you do that!) You should also be able to pull the vacuum hose off the EGR valve actuator to disable it. The fact that disconnecting the wiring seems to cure it would suggest an electrical rather than mechanical fault - possibly the throttle position sensor???

My only other suggestion would be a choked air-filter, though I'm assuming you've checked this already?

Darren

Title: Re: James Bond Stylee Smokescreen
Post by mazzy_j on Mar 21^st, 2006, 8:30am

Hi Darren,

Yes, i've checked the air filter and is clean which was what i first thought i could be as i was rally driving at the time and some dirt might have made its way into the airbox. Before it didn't smoke that much when you booted it, but now when the revs get up it pours out black smoke :( Revving it whilst stationary it doesn't smoke at all.

Which is the vacume hose that i would need to pull (and then plug) as i might give that a go?

Thanks,

Matt

Title: Re: James Bond Stylee Smokescreen
Post by sector-9 on Mar 21^st, 2006, 11:16pm

Can't tell from the photo what it is you unplugged. At first I assumed it was the EGR system control solenoid but after looking again I wonder if it is a MAP sensor - is your engine the 115 or 125 BHP version? You can tell because the later one has no throttle cable as it is 'drive-by-wire' full electronic control. The older one (like mine) uses a conventional throttle cable and a much simpler engine management system which really only controls cold starts and EGR and doesn't include a MAP or MAF sensor.

Anyhows, if yours is the later one then it could be the Manifold Absolute Pressure sensor which tells the ECU how much pressure (negative or positive) is in the inlet manifold. Typically on a diesel this would increase the fuelling as the turbo builds up manifold pressure. You also wouldn't have a throttle position sensor on the pump itself.

The older system uses a diaphragm actuator (strangely called the "smoke pressure limiter" in the manual) on the pump itself, connected with a hose to the manifold, to achieve the same effect.

In any case, if it IS the EGR valve solenoid you've unplugged then the vacuum hose to disconnect is the one which connects to the EGR valve diaphragm on the top photo (the one you've labelled 'membrane').

Darren

Title: Re: James Bond Stylee Smokescreen
Post by mazzy_j on Mar 22^nd, 2006, 9:38am

Thanks for the info :) Mine is a 1996 115bhp version. I borrowed the picture from the main site as it showed what and where everything is. With the EGR valve solenoid unplugged and revving the engine i can see the EGR valve opening and closing which should rule it out being defective, i then disconnected the vacume hose to it and saw that it now doesn't open. Will give it a run and see what its like.

Thanks,

Matt

Title: Re: James Bond Stylee Smokescreen
Post by mazzy_j on Mar 27^th, 2006, 7:37am

Fixed!! And what a difference disconnecting the EGR valve did ;D On a run from Essex to Leicester this weekend sitting at a steady 65mph my car managed a creditable 45mpg :o 9mpg than it did the 2 weeks before on the very same route doing the very same speed. It also pulls much stronger from 2k rpm onwards than before, and it also doesn't smoke as much which is always a good thing.

Matt

Title: Re: James Bond Stylee Smokescreen
Post by sector-9 on Mar 27^th, 2006, 10:31pm

Glad you got to the bottom of it - mine's still doing about 20mpg (laughable if I wasn't paying for the fuel).

I tried revving the engine but the EGR valve didn't move at all. It isn't jammed as I can move it with my fingers, but it doesn't seem to do anything of it's own. Also the engine note doesn't seem to change that much if I hold it fully open with it idling; there is a small change but not by much!

Darren