Fast idle after new ex. system. 406Td 2.1

cholin · Post by **cholin** » 17 Mar 2007, 13:21

Just had "box and tailpipe" ,"box and centre pipe", "front pipe reseal" on my P reg, 86000mi. Pug. (A car I am more than satisfied with!). Idle revs have gone up to 1600. Fitter says "Could re-set itself give it a bit and if not bring it back". Fair enough, no problem but I would appreciate any comments or advice.
Cheers

mbunting · Post by **mbunting** » 18 Mar 2007, 09:42

I wonder if there are any sensors which have not been reconnected while the exhaust was being done ?

If you want to reset the ECU, make sure you know your keypad code ( if you have a keypad ), and your radio code, then disconnect the battery, go and have a cuppa, then reconnect the battery - this resets the ecu - you might find it will be a bit "rough" for a short while as the ecu learns what's going on - usual with this is to take the car out for a drive in mixed roads and conditions - including a thrash !

cholin · Post by **cholin** » 18 Mar 2007, 10:04

Many thanks. I will do that and let you know what happens but may be a couple of days.

pugxpert · Post by **pugxpert** » 18 Mar 2007, 21:41

2.1 has fly by wire throttle ,check brake lights are not on whilst driving or flashing on as this will put ecu in default as it thinks throttle sensor has failed

mbunting · Post by **mbunting** » 18 Mar 2007, 22:26

If the throttle sensor had failed, would the revs not actually change at all when the accelerator is pressed

The problem here appears to be that it idles too high, not that it doesn't move at all, unless we're not getting all the story

cholin · Post by **cholin** » 19 Mar 2007, 00:25

Hi, thanks for continued interest, yes you're getting all the story. Car performs perfectly except that the idle revs are high. Hope to try the ECU reset tomorrow if not snowed under. (OAP, brain still works but bones don't like the cold!)

cholin · Post by **cholin** » 19 Mar 2007, 17:44

I retract the previous, I don't think you are getting the whole story. The rev counter is now sticking! I disconnected the battery for an hour, reconnected and went haring round the countryside. With the rev counter sticking at ca. 2000, either that or behaving errantically. I am not sure if the revs have adjusted themselves - I think they have. I did try once to get the instrument cluster out but couldn't release the facia as it was hanging on one of those barbed clips which is out of reach, so I gave up before I cracked something. So thankyou again for your advice etc. but I am going to ignore it until I can get at it in comfort i.e. warmer weather. When I have sorted the rev. counter if it still indicates fast idle I will tap your brains again if I may.

mbunting · Post by **mbunting** » 20 Mar 2007, 12:07

Well, it could be that the sensor has been disturbed as part of the exhaust replacement, this would also affect performance / economy as well because the ECU will detect a fault, and then assume default values.

Either that, or the speedo ecu unit under the glovebox could be dodgy - but this would be very unfortunate given the other smoking gun clearly visible - also if this ecu was faulty, the speedo would also dance.

The third possibility is that you have PCB problems in your speedo ( I have ), but again, given the other smoking gun visible, I think we can discount this.

I would take the car back to the garage NOW and get them to check the sensors - I'm pretty sure one of them is either not back on, or has picked up some dirt during the repairs.

The sooner you do this the better, as it's obviously a direct cause of the repairs - leave it a month and they'll be able to wash thier hands of it.

cholin · Post by **cholin** » 22 Mar 2007, 21:47

Revs have settled down after a few more miles but the rev counter is definitely not performing correctly!