Engine dropping revs - Loss of power

[guvna]

Hello from newbie here.

My scenario is this........

I have a standard factory VTS.
About 6 months ago, at complete random intervals, whilst driving at any speed, my engine would sieze and both the rev counter and speedo would drop to just above zero. If I dropped the clutch, and put my foot down on the accelerator, I could just about keep it alive, but there would be little response in power. The revs would go up and down quickly normally to about 2000 for a few seconds, then the whole thing would kick back into life again, and I would carry on. Strange thing is, my foot will be on the floor, but it sounds like it's trying to rev. When this happens, it's almost as if the brakes are jammed on because it throws you forward at great force. Not so bad at higher speeds, it coughs, a bit of a jolt, then ok again, but at the low end, it's enough to really jerk you and sometimes will cut the engine all together.

It happened for about a fortnight, and as I was low on cash, I just beared with it. But then it seemed to cure itself........for a few months.

Except, it's back.
And it's happening on a more regular basis now. Nearly every time I take her out on a run.
I'm not driving it abnormally. No mods have been done.
I've had it looked at by a local mechanic, who has only changed the fuel filter, cam belt, and fan belt. Has also had a computer plugged into it, but it doesn't show anything while it's idling. Seems ok. Only when it's on a run does it play up.
Not being the greatest of minds on the workings of a car, could anyone possibly shed some light as to what might be causing this?
I'm left to believe that it's something that's not mechanical, as when she's being good, you wouldn't think there's anything wrong.

Many thanks.

[123-samsung123]

This sound like a fuel problem or iacv, i would be checking the fuel pressure and claening out the throtte housing, first if that doesnt cure it start looking at the throttle poistion sensor, or the coolant temp sensor!!

[aran2k2]

weird that is cures itself then back again, hmmmm when its jerking does the engine managment light come on?? if so itll be either fuel or ignition problem. so look at bits 123-samsung sed. i had similar problem with my old vts changing the thps and the map sensors cured my cars irattic jerking and loss of power.

[123-samsung123]

Could be a coil pack breaking down too

[adzer]

if one of them was the fault it wouldn't cause the car to stop dead in its tracks??? it would just coast wouldn't it?

[guvna]

Thanks for the replies. Much appreciated.
I've got it going into a garage on tuesday, as I don't know where any of these things are, and wouldn't want to start to be honest, but at least I can relay this information over to the mechanic who can check them out for me instead of looking at it for five minutes then telling me there's nothing wrong.

aran2k2, only once did the engine management light come on. Very strange, it coughed, tugged, carried on whilst doing 50, and the light stayed on. When I finished the run, turned her off, then turned the ignition back on again, the light stayed permanent, however, the following morning, the light was gone.

adzer, I'm not sure. it certainly feels as if the whole engine locks up when it does it. Imagine all the internals just stopping dead in their tracks while doing whatever speed. Thank christ the seatbelts work ok, because it really pulls on you.

I hope this can be sorted easily, because even though loads of people tell me I drive a chavmobile and to ditch it and get something else, I don't want to because it's just a seriously fun car to drive.

Thanks guys.

[guvna]

Just to bumb this a bit and to give an update to those that have helped out............
Have had it in citroen garage who said that the diag machine showed that the coil-pack had broken, and wanted £305 for the pleasure of changing one out.
Naturally, I've gone to an independant dealer who sourced a new one for a considerably cheaper price and fitted it.
However, it coughed and spluttered the following day BADLY, to the tune of not even being able to keep the car started enough to pull over properly.
Ended up being towed back.
Decided to take her out on a little run the following day, and for some miracle of god, she was good as gold. Coughed once, but hardly any jerk. Since then, have done 50 odd miles, and not even a whisper out of her.
Took her into citroen this morning, and they say that the diag machine is showing nothing wrong with the car. All sensors check out ok.
Have been advised that it could "possibly" be the fuel pump acting up, but this wouldn't necessarily show up on the diag machine if it was running ok at the time.
I got told that if it played up again, to switch her off, and turn the ignition back on to listen out for the pump starting up or not to narrow it down.
And that's basically how it's been left. No-one seems to know what's causing the problem.
I did suggest what the previous posters in this thread had suggested, but citroen have told me that their computer says they're ok.
Might try giving it some red-x in with a full tank of fuel, just to clean the pipes and see how that goes.

[guvna]

ok, redex didn't help, broke down again the other day. Just couldn't keep the revs steady. bouncing up and down. replaced a fuel pump relay switch, and still playing up.
have noticed however that only sometimes when i turn the ignition on, do i hear the fuel pump prime. maybe i'm just hearing things or not, but seems to prime more often than not when cold. but have been testing over the last 15 minutes, and basically, only sometimes do i hear it prime. am leaving it 30 secs between turning the key to make sure the fuel goes back through the feed back to the tank.

Can anyone shed any light?

Could it be the fuel pump acting up? Do they go like this? sometimes work sometimes not.

Cheers

[guvna]

Just to bump this quickly.
Got a vid here of what it's doing if it's any help to anyone.

http://uk.youtube.com/watch?v=lZ8aANSW-W8

[GroomGTI]

Mine is doing exactly the same, cuts out when slowing down through the gears and coming to junctions engine jerks sometimes when just driving steady at low revs. Going to try a new idle air control valve if not then i have no idea.

[onzakieron]

I'd recommend unplugging this and cleaning any oil from the plug/socket with a tissue, caused huge problems like you describe on mine and I was VERY suprised how simple the little thing was to cause sooo much trouble.

[guvna]

ok, a little more info, had it taken to a garage yesterday, and they cleaned, poked and tried loads of things including cleaning the map sensor and idle control sensor.
however, when applying a meter to the fuel pump, they noticed that it was getting intermittent power when i turned the ignition and flickering away when playing up.
so have been told it's either some bad wiring somewhere, or the ecu is playing up. the latter being the last thing i wanted to hear as i'd already replaced the fuel pump relay yesterday morning.
so tomorrow i'm gonna speak to a place down here that can test ecus out of the car, and see what they can come up with, because if it's fecked, i'm off to ebay for another one rather than citroen direct.
i REALLY hope it's a dodgy wire somewhere.

[guvna]

Ok, have had the fuel pump replaced, and still the problem exists.
I've read about having the throttle body cleaned. Would this be a cause of this fault?
I'm tearing my hair out here as my wallet is sooooooo stretched and I'm fast running out of ideas as no mechanic wants to touch it with a bargepole. INCLUDING shitroen.
Somebody save me from defecting to another car.

[saxosxi]

sound simliar to what my car was like mate, but mine was just the plugs in the wrong order also try resetting your ecu

[fossie]

I had a similar thing with mine with the rev counter fluctating..............mine had an alternator problem and also the connections to the fuel pump

[guvna]

sound simliar to what my car was like mate, but mine was just the plugs in the wrong order also try resetting your ecu

Not sure if it's the plugs, because I've just had them changed for new ngk's and a new coil pack fitted.
Is there still a way for them to be wrong still?

[guvna]

I had a similar thing with mine with the rev counter fluctating..............mine had an alternator problem and also the connections to the fuel pump

Yeh, I've not changed the alternator yet. Although I've been assured that this is fine.
I've no idea of the layout of the connections to the fuel pump. Ideally I'd like to trace them back, but have no idea what I'm looking at.

[saxosxi]

firing order is 1432 so on the coil pack top left is 1 top right is 4 bottom left is 3 and bottom right is 2,

[guvna]

one thing i noticed today while it was playing up, is that it doesn't seem to affect it in reverse. Strange, but wether it's just coincidental or not i'm not sure, but wierd none the less.

[guvna]

Fast running out of ideas here.
Have just had the unit back from ecu testing who have said that there's no fault found over 48 hours of testing.
I'm absoultely stuck now as to what to do next.

Would injectors have anything to do with this problem?

[fossie]

Has the timing been checked fella

[guvna]

Hmm, not being the brightest spark when it comes to engines, I'm not sure.
I know that about 2 months ago, the cam belt and drive belts were changed for new.
Does that cover it?
Could the alternator cause this?