Strange Return To Idle

[dobboy 231 2 Cars]

When I rev my engine up say 3k to 5k etc, and let the gas off, the engine returns to about 900rpm, but then it goes to 1.5k for half a second or so, before dropping back to idle.

 

I renewed all gaskets and everything is torqued up. Also cleaned all sensors etc.

 

Any idea what sensor I should be looking at first? Or any other idea etc?

 

TIA

[2052NV 24]

I have a similar issue but dont think its worth chasing all my stuff is brand new also. Mine just drops from what ever revs and stops at about 1500 for a second then settles to a perfect 900-1000rpm idle

[dobboy 231 2 Cars]

My friend's does exactly like yours, although I think he said his sometimes hangs between gear changes too.

[welshpug 1,657]

idle valve.

[Ryan 99]

Check the throttle position switch is working correctly too. The ECU won't try to control the idle speed unless the idle switch is closed.

[welshpug 1,657]

Check the throttle position switch is working correctly too. The ECU won't try to control the idle speed unless the idle switch is closed.

 

 

what switch?!

[jackherer 543]

I get the impression some people are talking about XU9J4 engines while others are talking about XU10J4RS engines...?

[dobboy 231 2 Cars]

I'm talking J4RS

 

 

If I rigged up my odb socket, is this the type of thing/fault a reader would pick up?

[welshpug 1,657]

no, you'd need a proprietary Peugeot diagnostic software, they aren't OBD2

[dobboy 231 2 Cars]

I have a similar issue but dont think its worth chasing all my stuff is brand new also. Mine just drops from what ever revs and stops at about 1500 for a second then settles to a perfect 900-1000rpm idle

 

I was having a go last night on a small bit in front of my garage, doing emergecy stops/trying my breaks. I noticed it was doing this at times too.

 

I found this, (pdf page 41/43)

https://www.google.co.uk/url?q=http://www.306gti6.com/downloads/index.php%3Fid%3D20&sa=U&ei=evpQU9fWFMXOOYXSgKgD&ved=0CCUQFjAB&usg=AFQjCNGFSs-AuJb85V4LXXRaNBSIJmxqgQ

 

Running on?

 

 

I have another full set of sensors for the throttle (not that i know if they are any better or not but i can test the resistances where required and see how they compare with

 

http://www.306gti6.com/forum/showthread.php?id=80340&page=1

 

Will probably change all them one at a time starting with the IAC (as per WP) and see if it fixes it, when i've got time.

[dobboy 231 2 Cars]

Took the IAC off my spare throttle, cleaned the soot off it, put the multimeter on as per the link above, 50ohms on both accounts. I put this being under the data sheet due to calibration of my meter.

 

I fitted it, and it was similar, but the revs only were going up to 1300.... But I didn't think the engine was running so sweet, I thought it was a wee bit lumpy ticking over although the rev counter never showed anything.

 

I measured my original one, 54ohm on both accounts, dismantled it and gave it a good clean, then re fitted it.

 

I think the clean may have helped, no hanging at all, but still this bounce up on the revs.

[dobboy 231 2 Cars]

"

Often blamed on the temperature sensor or the idle speed control valve, the engine idle speed may drop and rise periodically, or the engine may 'race' - ie. hold high revs when it should be stable. Both can be caused by lambda failure.

The ECU will be confused by inaccurate information supplied by the sensor - as a result it will not be able to set the fuelling accurately. Some ECU's may cycle the engine speed up and down in an attempt to clear a problem.

We see a lot of unnecessarily replaced idle control valves and throttle bodies - if idle is fluctuating, the valve is only acting upon information supplied by the ECU, which may be inaccurate due to sensor failure. If the idle speed is changing, then the ECU is at least capable of controlling the idle speed, and the valve is obviously operating okay.

EGR valves can be erroneously blamed for these problems - they are essentially mechanical devices with an electrical connection to modify their behaviour under certain conditions - they normally require a clean and can be operated manually to check their operation"

 

http://www.lambdasensor.com/main/peugeot.htm