Peugeot 406 Idle problems

[larkspeed]

1998 Peugeot 406 Estate 1.8 16v 110hp

Description of problem as best i can:

When we start the car the revs can spike all the way up to 3000 rpm and stay there.

Usually once we start driving the revs will drop back to around 1000 rpm however they do this with a delay, meaning if you pull away and let the car rev to around 3000 and then clutch to shift the revs will hover for about a second, then they will drop to around 2000, then drop to 1500 and finally drop to 900 - 1000, this stepped drop takes about 4 or 5 seconds. (it's this stepping that made me first think of the idle control valve)

Sometimes on start they will drop back down and sit around 1000 rpm before driving but as soon as we start driving it acts as described above.

If we have to do a lot of off on driving, as in going to half a dozen different places with only short stops in between the revs can then go really silly.

If they do this then they will climb to around 3500 rpm and then start to bounce between 2500 and 3500, the only way to stop this once it reaches this point is to pull over and to the 10 second on, 10 second off reset on the system.

After the reset it will go back to acting like described in paragraph 2

There is no stuttering hesitation or loss of power while actually driving the car, the problem only seems to effect idle.

I have replaced both the Idle Control Valve and the Throttle Position Sensor and it has made no difference.

Diagnostics is out because the dealer wants way too much to do a code read on it. (dealers service centers here are stupidly expensive and very unhelpful)

[lozz]

Hi mate,

It might be not much help but thought it might be worth a mention,

I've just got a code reader off. EBay, make is Autel maxiscan
15 quid,

It reads the petrol pugs with no problem might be worth picking one up mate

[larkspeed]

no good pre 2001 pugs have to be read by a lexia3 reader.

A standard OBDII reader will not work. (I have one and already tried it)

[lozz]

Ah rite sorry,
Just re.read

Missed out the part yours is 1998 ... oops

[larkspeed]

Those are all 2001 and newer.

Like I said before 2001 they use a different protocol