hi, my bravo hlx is running pretty rough. when i accelerate it hesitates intermittently, like a smooth kangarooing. sometimes when i pull away too casually it hesitates like i've touched the brakes. if i accelerate really gradually it seems fine and it idles fine. it feels like its getting too much fuel (or maybe too little). its not as bad with a cold engine, which led me to believe the thermostat could need changing, but the temperature gauge sits fine and heaters work fine.
the first time i noticed this it would run well for about 30 seconds and then run bad for a few seconds. now it seems to jump between the two pretty rapidly. the fuel light was on when it first did it. it seemed to go away after i filled up with petrol, but now the problems back after 10 miles. it had new plugs, oil/air/fuel filter a couple of months ago.
thanks, kristian

Sounds very much like your lambda sensor is gone. How's the fuel consumption? bad? That's usually a sign of a lambda problem.
The lambda is ignored when the engine is cold so that also sounds like your symptoms

If you're in the Uk you can buy them on line here
http://www.cats-direct-shop.co.uk/lambda-sensors.php

last week i said that i almost solved mine problem with the car..thats partly true because car now runs great when its warm and when its on normal idle speed of 850 rpm...but ive still got this anoying thing when the damn thing is cold and when it is working on higher idle speed of 1100..so ive got the opposite thing from kpm..when i rev it on idle liitle bit to warm it up the problem is gone which is logical because the car gets warmer faster..when its cold it has flatspots in first,sometimes in second gear...just to remind you,ive changed the head gasket,and the problem before this was bigger..but now is better..so i am now scared that the problem is not coming back..what that might be..somekind temeperature sensor or lambda sensor..it is 1.6 16v elx brava 98..

kpm try checking your coils if its a 1.8 hlx, got a feeling it may be one of them on the blink, its common on the 1.8. you can do an easy test by removing a HT lead from a sparkplug, only remove one at a time, the one that makes no difference to your running leads to the one that has a faulty coil. good luck.

johntra, your car should idle at 1100 when cold, its called a choke, and it should have flat spots in 1st and 2nd when cold too, all cars do. you need to learn to let your car warm up propely, if the car hasnt been run for 5 hours or more i'd always give it at least 5 mins to warm up. dont drive till the temp gauge gets above the min. driving your car cold is like humping her before she's ready, lots of friction, not good for your bits

hi, ok ill try the coil pack thing. can i just remove the plug and leave the coil pack bolted in?

where abouts is the lambda sensor? is it under the manifold cover at the front of the engine?

could my timing be out? my car was in the garage recently to have a crankcase seal replaced (the one behind the crank pulley). they replaced the two belts whilst they were at it. when i got the car back it was great, but oil was still leaking from the seal. so it went back to the garage to be rechecked and when i got it back i noticed the performance problem. they advise me they didnt remove the belts this time, and this garage has always been really fair and honest so i have no reason to doubt them. how can i check if the belt is a couple of teeth out? the markings line up on the left hand cam pulley. i'll check the other cam pulley later. would any other pulleys have markings on them that i could check against the belt? would the crank pulley have a timing mark on it?

its safest to pull the ht lead off the plug leaving it connected to the coil, i've done this loads of times with the car running and i've had a few shocks but it aint that bad, just be wary of the end of the ht lead once its unplugged.

the lambda sensor is on the downpipe before the cat, its the only thing on the exhaust with a wire connected to it, easy to spot.

if a problem starts after a garage has done work, i always blame them, and take a stick to beat them with

can i do this when engine is off or do i need to do this when its running?

interestingly, it didnt do it when i went out this afternoon. it was definitely overfueling but it didnt kangaroo at all. im gonna reset the ecu and see if that sorts it out.

sorry i guess i didnt explain, with the engine running at normal operating temperature you should remove one plug lead, if the engine starts to struggle or the revs drop or it cuts out that is a good sign. if removing one lead makes no difference to the engine's running you have identified a problem.

removing a plug lead should make the engine run worse because one of the plugs can no longer spark. if it makes no difference you can be sure that you have identified which cylinder is not working correctly. for an intermittent fault such as yours the cause may be a faulty plug, lead or coil, and maybe an injector issue beginning to show. since you had new plugs not long ago i'd suspect a faulty lead or coil. fingers crossed you have a worn lead, although a coil from a scrapyard wont cost much.

if you manage to identify a problem you can do further tests to see if it is the lead or coil. by removing the lead from the suspect cylinder and swapping it with the lead from the next cylinder you can retest to see if the problem has moved to the next cylinder. if it has the lead is at fault. if it hasnt you need to try swapping the coil with another to see if that makes the problem switch cylinder. if neither of those swaps causes the problem to change cylinders you have a different problem.

its always a good money saving exercise to make a thorough diagnosis of problems. most people would just go out and buy a new set of leads and later find out they needed a coil instead, or vice versa, i prefer to be sure before i part with any money.

i definitely agree with a thorough diagnosis before spending money! this will sound silly, but what is a lead? i know a car usually has ht leads but on the hlx i just have four coil packs and their wires. will removing the connection to the plug affect the idling, as my car idles fine and revs fine in neutral?

whoops sorry i forgot we were talking about a 1.8 with the spearate coils, hence the confusion over HT leads. you can remove a coil from a sparkplug when the engine is running which will do the same as removing a HT lead on other models. if you pull a coil off when its running it should make the revs drop and the idle will seem rough. this is supposed to happen. if it doesnt then there is something wrong. even with a faulty coil the car may appear to idle fine because the ecu is good at compensating for a fault on only 1 cylinder, but removing a good coil will cause a sudden and noticable change in the revs, removing a faulty one wont becuase the engine has already compensated for that one so it makes no noticable difference when removed. the problem becomes more apparent under hard acceleration, which is harder to compensate for and is also what you are experiencing when you accelerate, hence the faulty coil idea in the first place. good luck mate let me know how it goes

thanks jug for the answer..i always do that too..to let the car to heat a little,about 2 or 3 minutes...and i agree with you on that..i think is normal too to have flat spots when cold,i just needed to hear that from another source,just to feel comfort..thanks..and by the way,what beautifull colour this rosso boreal is..i didnt saw many of these..

i agree rosso boreal is great in fact i'd say its the best colour they made bravos in. some of my friends call it pink but i think they're just jealous

That colour is soooo not pink! Take it from a girl, that is not a gay colour