Idle increase once warm

[340R]

Hi there as i have posted before i have put an F7P in my volvo 340 and am over the moon with the way these engines perform.
Quick question, when i first start the car from cold and the 5th injector is working the car idles perfect, but as soon as this stops it hunts ever so slightly.
Then if you take the car for a blast it revs at around 2k then when you come back to standstill. Took the car to a renault dealer and the bloke seemed helpful enough. He suggested changing the air temp sensor first?
I thought this sounded like lambda, although teh lambda is only a month old, althouth not a genuine. The lambda did look different to the OE one!!
Any help much appreciated!!
Cheers Adam

 

[Chris H]

did you fit the road speed sensor cable with the engine? if not thats the 2krpm idle after a drive.

When its hunting what exactly does it do. drops low chugs then revs high then fine for a bit then does it again?

 

[340R]

It doesnt have a speed sensor on it, as i figured looking at the wiring diagram not all cars had them. Also surely if it doesnt have a sensor it doesnt know the car has been for a drive?
Yeh thats what its doing with the hunting yeh. AFAIK there are no air leaks. Could the TPS cause hunting at all?
Cheers Adam

 

[340R]

Another question where is the road speed sensor?
Cheers Adam

 

[Chet T16]

Speedo end of the speedo cable

 

[Chris H]

it may not know its been for a drive but its been loaded etc which alters the fueling which causes this issue.

The tps can cause huinting, but only if its unplugged in my experience.

Is the lambda good? Try a jump lead onto the exhaust and see if that helps.

 

[340R]

Any chance of any pics of the sensor, or anyone know if it can be bypassed?
I do have an earlier R19 ECU from a 92 car that i can try. I was told not all cars have them fitted?
Cheers Adam

 

[stan]

Take the clocks out, on the speedo cable u will see 3 electirc wires going into the plastic body. splice into one of the black ones, and earth to the metal work.

whereabouts in swansea are u?

 

[Chris H]

All 16V's came with the road speed sensor.

Theres 3 wires like craig says but in his haste he jumped to the assumption that it was a renault.

Anyway its at the speedo end, earth, positive and pulse which goes to the ecu..

 

[340R]

So if i could get hold of a sensor and left it connected it would assume the car is at standstill? If this is the case would it affect any of the mid range fuelling etc?
Cheers Adam

Oh i'm in Penllergaer mate.