engine light on?

[s.hammond]

Cleaned idle air valve and throttle body Saturday with little change! but changed the air filter with a Mann one as the old one was clearly in a bad way!! and what a difference drive so much smoother and idle is more stable!

Quick question, the idle valve is it supposed to be spring loaded? i only ask as the one on my 850 was loose you could shake it and valve would rock inside, but my 940 one you have to use a screw drive to open the valve?

Thanks

[Diesel-do-nicely]

The main function of the idle valve is to assist an "anti stall idle strategy" for the engine, e.g more air to increase rpm when cold and the injectors are over fuelling or rpm falling below 600 when sudden demands of alternator current/air conditioner/radiator fan ect.
It basically a solenoid, i dont recall one being "rattley"
In my experience of bosch jetronic engines, the injectors dont last for ever!
Indeed replacing them at every 80 000 miles pays for itself in better mpg in the long run, injector cleaner makes no difference to old worn injectors.
Nor do the HT leads last more than 5 years in most engine bays.
Common sense and a bit of testing , start with the basics,
1 .set the valve clearances, as the seat wears they can eventually be to tight leading to a loss of compression, at idle the gas has longer to escape, therefore it makes more of a difference.
2 . check the HT leads for tracking, loosing spark energy through the insulation, (if you are brave run a wet finger along each lead when its idling & you will know the answer)
3 . clean out the distributor cap and rotor arm, oil contamination or a hairline crack often causes a fluttery idle.
4 . disconnect one injector at a time, then if one makes less of a rpm drop at idle, it is an injector ( a very common problem with Toyotas)
5. next is stuff that costs money in bits, the list is endless so do the free and easy things first. Cheers

[s.hammond]

Originally Posted by Diesel-do-nicely

The main function of the idle valve is to assist an "anti stall idle strategy" for the engine, e.g more air to increase rpm when cold and the injectors are over fuelling or rpm falling below 600 when sudden demands of alternator current/air conditioner/radiator fan ect.
It basically a solenoid, i dont recall one being "rattley"
In my experience of bosch jetronic engines, the injectors dont last for ever!
Indeed replacing them at every 80 000 miles pays for itself in better mpg in the long run, injector cleaner makes no difference to old worn injectors.
Nor do the HT leads last more than 5 years in most engine bays.
Common sense and a bit of testing , start with the basics,
1 .set the valve clearances, as the seat wears they can eventually be to tight leading to a loss of compression, at idle the gas has longer to escape, therefore it makes more of a difference.
2 . check the HT leads for tracking, loosing spark energy through the insulation, (if you are brave run a wet finger along each lead when its idling & you will know the answer)
3 . clean out the distributor cap and rotor arm, oil contamination or a hairline crack often causes a fluttery idle.
4 . disconnect one injector at a time, then if one makes less of a rpm drop at idle, it is an injector ( a very common problem with Toyotas)
5. next is stuff that costs money in bits, the list is endless so do the free and easy things first. Cheers

1. Head rebuild by volvo at the of £1700 two years ago so don't think it's valves.
2. there is a mix of HT leads and will be looking into changing these.
3. as above.
4. I'm not sure as it goes like stink since i changed the air filter and adjusted the throttle cable.

Many thanks

[Diesel-do-nicely]

Ah ha , you just answered the question yourself, any time i did a head re-build i always had the car back after 200miles or so to re do the clearances, and check the timing belt tension.
I always thought it was part of the job that you did this for the customer as a matter of good practice and courtesy.
Use the rule of 5 , when cyllinder 1 has both cam lobes sticking upwards, adjust tappits on cyllinder 4, when its 2 do 3, when its 3 do 2 and when its 4 do 1.
The cam driven rotor is affected by a loose belt.