Newbe need engine help :-( jerking spluttering under fueling

[dunkers1797]

mk2 saxo vtr 1.6 8v latter engine in it on a 2001 plate

Right to the point....
on a 1/4 throttle the car jerks bad in every gear but not under 2000rpm...
it is on a serton part of the throttle and nowhere els.
If you use full throttle it is ok until i change gear at about 5500rpm then hesitates (not enough fuel) and goes again.
Car is not as fast as it was and as i said it jerks like no fuel/spark about 1/4 throttle but not after or before.

I have changed... temp sencer on top of engine, throttle sencer, lambda sencer, as always been running one as decated. cleaned up idle controle valve and thats working and idles fine. changed plugs and coil pack.

I checked new plugs and the tips are white hot. Car drives fine unless you hit that spot on the throttal but is at its worse between 2000 and 3000rpm and after that its not as bad.

Any ideas as really thinking of just taking it to scrap yard now.

Also was pluged in and only fault was missing cleared it took it out and re pluged it and no faults were found.

Really need help now. fuel pump primes fine and when cold and choke is on it drives perfect through hole rev range and through all the throttle. so 100% sure it is fuel.

[dunkers1797]

oh and car does not cut out ever. I am confused.com :(

[davidharvey]

sounds like fuel starvation? Maybe a choked breather on tank, faulty pump or blockage in fuel filter?

[K567]

CHOKE...... it doesnt have a choke.....

i think its coil pack, my wifes car did it all the time turned out to be a wire that had worn and when the car was hot it would arc... easy way to test, when engine is running under bonnet at the back sits the coil pack theres a plug with wires, run your hand along it and see if you get a shock, or feel the ignition pulse if you do im right

[dunkers1797]

i can hear pum and seems fine as have taken the black tops off to check while driving. checked all pipes and they seem fine and clear. i dont under stand why it jerks just on one small part of the throttle. makes me look like a learner lol.

[jasonmayall]

CHOKE...... it doesnt have a choke.....

i think its coil pack, my wifes car did it all the time turned out to be a wire that had worn and when the car was hot it would arc... easy way to test, when engine is running under bonnet at the back sits the coil pack theres a plug with wires, run your hand along it and see if you get a shock, or feel the ignition pulse if you do im right

He never said its the choke.

And my god DO NOT feel for shocks, this is an absolutely idiotic way of testing for electrical faults.

Buy a multimeter before you kill yourself.

[dunkers1797]

CHOKE...... it doesnt have a choke.....

i think its coil pack, my wifes car did it all the time turned out to be a wire that had worn and when the car was hot it would arc... easy way to test, when engine is running under bonnet at the back sits the coil pack theres a plug with wires, run your hand along it and see if you get a shock, or feel the ignition pulse if you do im right

i have done that and no luck. also has new coil pack on and new plugs.

[dunkers1797]

when engine is cold it drives fine for a min or 2. it is defo not enough fuel as plugs are white hot

[K567]

He never said its the choke.


Read his last sentence, he does...

and 12v wont kill you, might sting a little tho lol...

besides im not talking about rubbing the coil pack im talking about the wiring to the coil pack if its wearing out youll feel the slightest of pulses, this tends to get worse as the car warms up

[K567]

a little more on plugs are white hot?.....

if your saying too hot, id say its running lean, which is either EGO control ( lambda sensor are both still plugged in and working ph2 has 2, one that was on top of the exhaust manifold/cat the other down stream after cat )

and also back to fuel system likely pump

[jasonmayall]

Read his last sentence, he does...

and 12v wont kill you, might sting a little tho lol...

besides im not talking about rubbing the coil pack im talking about the wiring to the coil pack if its wearing out youll feel the slightest of pulses, this tends to get worse as the car warms up

my mistake lol - I thought you were referring to the post above your first post. I'll go and sit back in the corner now :)

[dunkers1797]

a little more on plugs are white hot?.....

if your saying too hot, id say its running lean, which is either EGO control ( lambda sensor are both still plugged in and working ph2 has 2, one that was on top of the exhaust manifold/cat the other down stream after cat )

and also back to fuel system likely pump

i have green pluged lambda plugged in and not the blue. was like it when i got car and ran fine for months and months. I have changed lambda incase it was that but no luck. And i can hear the fuel pump when driving so not sure if it could be that?

It jerks badly on just a serton part of the throttle. this is why i am so lost as i have changed a lot of things to try and fix it.

[K567]

Have you still got back seats in? If yes and you can hear the pump its obviously labouring
Take it out and check the pump and filter.

[dunkers1797]

Right i have taken the covers off under the seats to hear the pump and runs ok while driving etc. I have checked plugs again and all 4 have white tips so still not enough fuel. run out of ideas now :-( just need this fixed.

so still jerks at 1/4 throttle and before that its fine but its just that one spot. then if u floor it it goes ok but at 4k it misses once and carrys on. Does it in every gear.

parts changed...

throttle controle
Temp sencer on top of engine.
coil pack.
plugs.
cleand idle sencer but never has a problem idleing.

maybe give up and scrap it??

[dunkers1797]

Oh and still runs fine when cold while the auto choke is on i guess.