406oc.co.uk

Hi all

Yesterday I posted a thread about my (new to me) car not starting, but I fixed that with a new fuse.

Now it is hesitating like crazy while driving. If I put my foot down it clears and accelerates well, when I ease of it may or may not start hesitating again.

The guy I bought it off said it had this problem but the garage had cured it by cleaning out the air inlet below left of the stepper motor. Then he put Redex in the tank, and the problem had gone. Well, the morning after I bought it I filled up with half a tank of fuel, and it drove OK for me for 2 miles. When my wife took it out for a longer 20 mile run, it started hesitating (and then stopped - caused by a blown fuse). With the fuse replaced today, the engine it still running like that although I have also tried adding Redex to the tank to see if the 'clean' fuel was causing the trouble. No real difference, but maybe a bit better. I have tried disconnecting the oxygen sensor as per this thread viewtopic.php?f=1&t=3489 but no change, it still runs poorly.

Any quick ideas?

Cheers all

I'd suggest that the hesitation could well be linked to the fuse blowing. Try changing the plugs and see if you can get a new/used coil pack from somewhere

Thanks for your help mjb. I initially thought about the coil pack, but when I had a coil pack go on my Volvo v40 it was an intermittent firing on 3 cylinders behavior whereas this feels different.

I just went out now, and it's getting worse. Started it from cold and it was hunting like crazy, up then down to close to stall (with a beep from the dash), then back up to 1200-1500 rpm again, then down to close to stall. Once warmed it steadied out. Driving it is still bad around the estate, but the hesitation is always cured by putting my foot down - does this suggest fuel, or sensors, rather than the coil pack?

I really like the car, but I'm getting pretty down about it right now

Thanks again for any help or ideas that you may have!

Cheers

Mass Air Flow sensor?

Idle Control Valve?

I had a bit of hesitation at low revs turned out to be the clutch pedal switch.

I had a bit of hesitation at low revs turned out to be the clutch pedal switch.

Interesting – if I dip the clutch pedal slightly (not enough to ride the clutch) it stopped hesitating. Can't recheck it right now as the idle control valve is sitting here on my desk as I needed the part number to order a new one. The replacement should be here in the morning, so once that's in, I'll know if that's the culprit at least .

Should it not be, how can I test the clutch pedal switch?

My next part to replace was going to the the MAP sensor (I'm assuming that's the 406's MAF).

Cheers, and thanks for your ideas so far.

Hi all

Just a quick progress update. I fitted the new idle control valve (or stepper motor if that's what it's referred to), and 99% of the problem has gone . I did the reset thing of Ignition on/off for 30 seconds x3 and took it for an hours drive. The idle is perfect (I'll try again when it's cold) and the hesitation is almost gone - it stuttered for a second 3 or 4 times during that run, all at about 2000-3500 revs...

Is the next part on the list for replacement the coil pack as previously suggested?

Cheers all.

UPDATE. I've just taken it for another hour long run, and the stuttering has almost vanished (1 short hesitation). Does the ECU relearn that much after the reset procedure (ignition on/off 3 times)?

I've bid on a used coil pack so will replace that in a couple of days too.

Cheers all.

Did you give her an Italian tuneup?

Not quite an Italian tune-up, but a blast down the dual carriageway and back