my vn 5.0 litre is hunting at idle

[lowrida56]

when i leave it idling for more then about 10seconds it starts hunting, sometimes its as much as 650-850rpm but it always varies.

It also stalls if i rev it and then just take my foot off the accelerator, and stalls when i put it into gear if i dont accelerate straight away (this happens mostly when its cold but sometimes when it is hot).

Has anybody got any ideas whats wrong with it?


The car also vibrates a bit when going over 3000rpm is this normal? its not exessive but im not sure if its normal or not.

 

[rattattack1313]

What fuel you using??? BP has a bit of Ethanol in it....my Green-Eyed-Monster hates the stuff......rattles and farts on it , at idle........

 

[jdd]

Vacuum leak or IAC valve needs cleaning, or both.

 

[thorpey]

when you say the car vibrates do you mean from the front, rear or middle? is it moving or still?

With the hunting idle its hard to tell without seeing the car, theres about 5 things i can think of that it could be. how long since its been tuned?

 

[lowrida56]

it hasn't been tuned since it was rebuilt (40,000kms ago) and its vibrating from the front when ur accelerating.

and my last tank wasn't bp

i might try cleaning the iac valve, is it hard to get to?

 

[thorpey]

it hasnt been tuned for 40,000km's!! have you changed the oil?
seriously, when you treat an engine like that it has the right to vibrate.

 

[lowrida56]

its been serviced but not tuned?
what is involved in a tune?

 

[lowrida56]

ok, i fixed the idling problem by replacing the harmonic balancer (which had grooves in it) but now its stalling when in gear worse then ever. When I first put it into gear if i dont put about 1100rpm on it just stalls and when I come to a full stop and idle in gear for more then about 5seconds it stalls.

 

[Mr_Thoughtfull]

hehe idle hunting hey.

with eFI all things are related to each other. it is imperative to set up the throttle stop, and IAC valve correctly. Also as for the idle huntiing/surging, often this can be cauesed by a faulty earth connection on the shared TPS/coolant temp sensor earth point. with a faulty earth the sensors are all over hte place, the car computer thinks its on part load, gives it a squirt of fuel and corrects itself.

 

[lowrida56]

well i fixed it. the trottle bodie looked like the inside of a exhaust pipe.. so i cleaned it out and its good now, but it still hunts a little bit at idle