Important! : Very rough idle, revs sticking, juddering when driving - only when warm?

4th March 2013, 13:34

Hi guys
My Mk2 Saxo VTR has developed a nasty problem!
Once it gets warm, it rarely revs nicely at idle
I'm talking always over 1k, sometimes revving itself up to 3k!
Sometimes I dip the clutch, the revs don't settle to a nice 850/900, but drop down, before picking back up to around 2/3k

Also when driving and in gear, if I coast (gear selected, clutch pedal not pressed, just rolling), at around 2k it will hold the revs there, rather than naturally dropping! So it can be quite dangerous as it blips itself in revs!

I've cleaned the ICV and MAP sensor.
I've greased the throttle cable
I've done the 'ecu reset' of taking the battery off

But nothing seems to work, everytime it gets warm, the problem arises again!

I've not had chance to have it plugged in - if that'll flag up the issue!

But if anyone has any ideas then please shout up!
It's awkward, annoying and getting dangerous when it blips itself!

Please help!

4th March 2013, 14:15

Look up how to reset the TPS (throttle position sensor) can't remember the sequence off the top of my head.

If that failed i'd be buying a new ICV - they only <£16 - don't think you can clean the map sensor, So if all that failed i'd try a friends map sensor

4th March 2013, 14:23

I have a similar problem as you but also when the clutch is engaged the revs often stick and sometimes rise slightly. i have changed the same bits as you, maybe try the tps next, that's what I'm going to do, also when I plugged mine in nothing flagged up

4th March 2013, 14:40

Quote:

Originally Posted by saxova

Look up how to reset the TPS (throttle position sensor) can't remember the sequence off the top of my head.

If that failed i'd be buying a new ICV - they only <£16 - don't think you can clean the map sensor, So if all that failed i'd try a friends map sensor

I tried a reset for the ICV which you posted about turning the key from position 2, to position 3 for 7 times
That did nothing

Can't find a 'sequence' for TPS reset!

So it sounds like the ICV is just playing up and not holding the revs at a constant?

Quote:

Originally Posted by tomshaw89

I have a similar problem as you but also when the clutch is engaged the revs often stick and sometimes rise slightly. i have changed the same bits as you, maybe try the tps next, that's what I'm going to do, also when I plugged mine in nothing flagged up

Yeah if you press the clutch in, the revs will also stay quite high - awkward in slow moving traffic!
Still doing this!

5th March 2013, 08:24

Having the same problem. It's pisses my off when i'm driving in city traffic. Revs stick at 2k, when I dip the clutch the revs stay at 400-500rpm. Sometimes when I dip the clutch while accelerating an I shift up the revs raise to about 3.5-4k. Changed the icv, new spark plugs and ht leads, new air filter, new fuel filter, ecu reset, greased throttle cable, replaced the vacuum brake hose, but still no solution. Been having this problem about a year now and it gets worse every month.

5th March 2013, 08:26

Quote:

Originally Posted by Realiks

Having the same problem. It's pisses my off when i'm driving in city traffic. Revs stick at 2k, when I dip the clutch the revs stay at 400-500rpm. Sometimes when I dip the clutch while accelerating an I shift up the revs raise to about 3.5-4k. Changed the icv, new spark plugs and ht leads, new air filter, new fuel filter, ecu reset, greased throttle cable, replaced the vacuum brake hose, but still no solution. Been having this problem about a year now and it gets worse every month.

I'm gonna look at changing the coolant temperature sensor - seems to be linked to the heat of the engine!

5th March 2013, 08:59

Keep us updated

, I went to the citroën dealer to check the ecu for faults, but none were found. I have a mk2 saxo 1.1 hdz btw.

5th March 2013, 13:37

Quote:

Originally Posted by Realiks

Keep us updated

, I went to the citroën dealer to check the ecu for faults, but none were found. I have a mk2 saxo 1.1 hdz btw.

Gonna try have the codes read this week some time - see if anything pops up!
Also looking at replacing coolant temperature sensor and ICV for new parts!

29th March 2013, 23:37

So in an update to this:

It happens when the car is warm
When I am at a standstill, the car will pick up revs by itself, gradually increasing to around 2.5k
I am usually stationary with the car in first, clutch pressed in - the revs begin to raise
If I put it into 2nd however, it will idle normally again!
What on earth does that signify?

If it's in neutral, it will also try to rise by itself!
But pushing it back into 2nd will cause it to idle normally again!

What can link engine revs to the gearbox? And only when hot?
Please help, it's starting to really so my head in!

29th March 2013, 23:51

Quote:

Originally Posted by dolby20

I'm gonna look at changing the coolant temperature sensor - seems to be linked to the heat of the engine!

wont be the coolant temp sensor if its doing it when warm, the ecu gets the engine temperature from the coolant sensor on start up then when it reaches op temp it goes into closed loop and changes the fuel mixture using the oxygen sensors. Take it into a garage with diagnostic equipment and get them to read the live data when its running to see whats going on. then it might shed some light on whats wrong

30th March 2013, 23:30

Quote:

Originally Posted by AaronSAXOVTR

wont be the coolant temp sensor if its doing it when warm, the ecu gets the engine temperature from the coolant sensor on start up then when it reaches op temp it goes into closed loop and changes the fuel mixture using the oxygen sensors. Take it into a garage with diagnostic equipment and get them to read the live data when its running to see whats going on. then it might shed some light on whats wrong

Thinking that the diagnostics will be the solution....
I dunno if it's MAP/ICV related - get the feeling it is!

14th April 2013, 06:40

So my car still does this buttttttt
Just went through a real rough patch of using half a tank of fuel to 80 miles
I changed the front lambda sensor + coilpack for brand new FAE and Valeo parts respectively
This seems to have sorted the overfueling issue, had the light turned out and all seems a fine

But now I get a bit of hesitation when pulling away - believe that's from choked up spark plugs from the overfueling?

But if anyone can help with the sticky revs, that'd be great!

My ideas now are coolant temp sensors/coolant system bleed/MAP sensor

14th April 2013, 12:02

Just for good measure clean out the throttle body & put some injector cleaner in the tank.Forte is meant to be good mate.

14th April 2013, 18:20

Had a conversation with a member on here about this today!
Things suggested were MAP sensor change and injector cleaning/replacement - so shall be doing that shortly!

3rd December 2014, 21:35

Did you get the problem sorted pal

3rd December 2014, 21:36

Yep
Was a snapped wire to the MAP sensor
So resoldered it back up and been spot on since

3rd December 2014, 21:44

Will check that ! Have a similar problem, just started a thread to see if I can get any help!

3rd December 2014, 21:45

Try get a diagnostics test if possible - cheap ebay ones will do the trick just for a code if there is one!

3rd December 2014, 21:49

Can't draw any codes up as there isn't a diagnostic port, it's in a race car Only the engine loom is used pal!

3rd December 2014, 21:54

Shit you're gonna struggle
Well try the old unplugging whilst running?
See if that changes anything?
Like start it, unplug the map, see what happens
No change, you know Its doing Nowt!

4th December 2014, 05:45

Yes I'll try that thanks