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[rpont]

Just been out to the shop, about 2.5 miles each way. When I pulled into the car park the engine was running rough and missing, no engine light on dash. Popped in and back out in about 5 mins. Needed slight accelerator to start and running rough and engine light now on.

Reversed out of parking slot but no brake assist. Forward to edge of car park, still no brake assist. Set off towards home planning on long stopping distances but engine light went off and I tried the brakes and they now had full servo assist.

My first thought was stuck egr valve, I've had that before but never lost vacuum to the brake servo. Too dark to have a look tonight so will investigate tomorrow.

It's still the '97 CD 2.5v6 auto. I suppose look for a leak in the inlet track somewhere but I've never lost vacuum for the brake servo in so short a time, well I've never lost vacuum to the brake servo before.

Any ideas of where to look. It's off the road until it's fixed. With a brake problem I'm not risking it when there is likely to be traffic. Could it be a diaphram or some such inside the servo and if so is it replaceable?

[vauxfan2k]

cant read half your post due to the oversized avatar, please fix and we will try and help  

[rpont]

cant read half your post due to the oversized avatar, please fix and we will try and help  

Yes, I've just noticed the pic isn't being resized so I've turned it off.

[Entwood]

First thing to do is paperclip it and report back ..

http://www.omegaowners.com/forum/YaBB.pl?num=1189022687

This will give us all a load of clues hopefully, especially as the engine light is on saying it has a stored fault  

[rpont]

First thing to do is paperclip it and report back ..

http://www.omegaowners.com/forum/YaBB.pl?num=1189022687

This will give us all a load of clues hopefully, especially as the engine light is on saying it has a stored fault  

The engine light went off. I thought that meant it didn't have a stored fault code. I'll paperclip it tomorrow and see what it says, if anything, anyway.

[Marks DTM Calib]

Check the brake servo pipe just after where it exits the plenum....if not fitted correctly it can rub against the aircon pipes creating a hole

[iainb]

From the first 2 line of the problem I suspect your car has gone into limp mode.
When in limp mode the ignition will retard and the fuel will go rich.
This means that there will be little vacum in the plenum hence why the brakes are rubbish.
You need to do a code read and find out why you have gone into limp mode.

[eddie]

As per marks reply.

Sounds like a hole in the vacuum pipe that feeds the servo, loss of vacuum=no servo action and the intake is now sucking in extra air the management system doesnt know about therefore running too lean.

eddie

[rpont]

Thanks Mark/Eddie. I did notice how close the aircon pipes were to the servo pipe when I put the plenum back last time. I thought the non return valve for the servo was inside the servo though, or at least at the servo end of the pipe.

As for engine codes helping, well it's got a vacuum leak so running lean. I'm likely to have codes for either air mass meter and/or oxygen sensor faults at least so I don't really see how codes will help since they are likely to be only symptoms.

[TheBoy]

Thanks Mark/Eddie. I did notice how close the aircon pipes were to the servo pipe when I put the plenum back last time. I thought the non return valve for the servo was inside the servo though, or at least at the servo end of the pipe.

As for engine codes helping, well it's got a vacuum leak so running lean. I'm likely to have codes for either air mass meter and/or oxygen sensor faults at least so I don't really see how codes will help since they are likely to be only symptoms.

sure sign of air or vac leak....

[rpont]

Why did I have to open my big mouth about engine codes  

I've got:
13   O2 Sensor 1 Open Circuit
132   Exhaust Gas Recirculation (EGR) Valve Feedback Incorrect Signal

First thing I did was press the brake pedal and it had held vacuum overnight. Took a couple of presses for it to get hard. The vacuum pipe isn't holed at the aircon connector and I can't find any obvious leaks.

The easiest thing to do is whip the egr valve off and give it a clean and then see what happens.

[Marks DTM Calib]

Block it off with a bit of old coke can

[rpont]

Block it off with a bit of old coke can

Yes I know, end of problems, but it only gives trouble once in a while and it's easy enough to remove two bolts. It last stuck 8 years ago.

It was sticking so I've given it a good clean and it's free again. I think I will block it off when I get an empty drinks can, loosing the brake assistance is a bit drastic to risk.

I no longer have an engine light on and assume the O2 sensor is working at the moment, yes?? I'll check codes in a couple of weeks but do you think I should have the O2 sensor replaced? Number 1 is the drivers side isn't it?