Luke: 1989 4ws auto in Yorkshire

[Wayne2014]

Have you changed the iacv? That's the problem. Does it do it with the iacv unplugged?

Ok
Reconnected battery ...
STILL same



Whilst hunting in P...
Got out pulled the IACV plug and it stopped hunting -
But engine rocking back n forth AND engine light came on.


Gave BOTH IACV plug / socket a blast with this..
As also on the THROTTLE BODY plug/socket...
Still no joy



I am just tempted to sell as it is now ....

[RattyMcClelland]

I think its the IACV and the idle needs adjust too.

Take it to a propper mechanic like performance autoworks.

[Wayne2014]

Thanks Ratty

Will see ....

[Wayne2014]

Ok
Spoke to garage and they say "no point in wasting my money, as throttle body / IACV now cleaned" - it just needs the BASE IDLE screw re-set.

He said just google it!
So i will!

Will report back over weekend ...

[Wayne2014]

Excellent steps here ref SURGING / BOUNCY idle
http://www.preludepower.com/forums/show ... p?t=211317

[jjmartin349571]

From memory, didn't you have to adjust the idle screw when you bought the car to prevent it stalling? Maybe it needs adjusting back now everything is cleaned up.

[Wayne2014]

From memory, didn't you have to adjust the idle screw when you bought the car to prevent it stalling? Maybe it needs adjusting back now everything is cleaned up.

Nope!
Car never stalled.

But the yo-yo rev started not long after I bought it.
But only in P and N.

Garage A said thy fixed it.
But then it came back.

Garage B said thy fixed it.
Then it came back.

I thought I give it a GOOD clean (throttle body).
But it got worse - as I split the gasket
Garage C fixed the gasket and clean the IACV but it was back to square 1.

So I assume either there is an underlying problem (now BOTH throttle body n IACV are cleaned) - or the idle screw comes lose EACH time each time it is reset.

If the idle screw fixes the problem - and then it comes back - then I need a new idle screw or throttle body with better idle screw?
Even then at least its fixable

[Vtecmec]

What were the revs at when you unplugged the IACV cable? You say the engine was rocking which suggests it may be too low.

On the 4th gen (yours is probably similar) it should be about 500rpm (from memory).

Unplug the IACV, turn off all the electrics, then set the idle by turning the screw to about 500ish rpm then plug it back in.

[Wayne2014]

What were the revs at when you unplugged the IACV cable? You say the engine was rocking which suggests it may be too low.

On the 4th gen (yours is probably similar) it should be about 500rpm (from memory).

Unplug the IACV, turn off all the electrics, then set the idle by turning the screw to about 500ish rpm then plug it back in.

Cheers Vtec!

That was the plan after looking up on PreludePower - but they suggest 770rpm ...

[Vtecmec]

I would have thought 750-800rpm would be your final idle speed.