Car Hesitates On Pulling Away

[Guest rob W]

Hi Im new here hope some one can help.

Ive a 99 2.3 zetec and some times when pulling away mainly when its cold the car hesitates and jerks away untill the revs hit around 2000 rpm then it runs well.

Ive changed the plugs ( the only thing i could think of) but its still the same.

It does not happen all the time and also not only when its cold.

Anyone got any ideas had this problem.

cheers Rob

[johnb80]

Lambda / O2 sensor in the exhaust getting lazy, I think in this system it's output is ignored for 60 seconds by which time it should have reached operating temp and be giving meaningful readings.

 

Regards - John

[Guest MATT]

my diesel corsa runs like crap when its cold (on a cold day) once it has warmed up, its great.

 

MATT

[seatkid]

Sounds like ignition leads to me.....

[johnb80]

Never listen to ignition leads, they can give you real ear ache. I would have thought ignition leads would give problems when load on the engine is increased, the fact that this is mostly when cold and pulling away below 2000 rpm and the age of the vehicle would point me towards mixture and thus the oxygen sensor.

 

Of course you can expect miniscule fuel consumption if you get the same brand of leads as delboyt so it may be worth a try first <_<

[HJT]

Of course you can expect miniscule fuel consumption if you get the same brand of leads as delboyt so it may be worth a try first :o

Meeoow :o :lol:

[P2k]

I also had the same problem, it was down to a lead not making a good connection to the plug. I just pulled the spring a bit, in the lead. This sorted it

[seatkid]

90% of rough running/ misfire problems with petrol engines are ignition related.

Cold -> damp -> leads tracking due to insulation being aged/perished.

Faulty Lambda doesnt usually cause rough running just emission problems, and wouldnt that be across the rev range anyway?

[johnb80]

90% of rough running/ misfire problems with petrol engines are ignition related.

Cold -> damp -> leads tracking due to insulation being aged/perished.

Faulty Lambda doesnt usually cause rough running just emission problems, and wouldnt that be across the rev range anyway?

NO

When cold the lambda is ignored for about 60 seconds and the engine runs on a fuel map in open loop, IF the lambda was slow at warming up or slow switching this could result in a weak mixture and thus hesitation. When the engine warms up the switching usually gets faster and fuel trims smaller and hence my suggestion.

If it were plug leads I would agree with you if it coincided with damp mornings BUT the current weather we've had (until the last two days) has been anything but damp.

Just my humble view, easier to replace ignition leads and plugs first I suppose.

 

Regards - JB