Idle Sticking At 2-3k Rpm

[pete1986 2]

Can someone point me in the right direction please?

 

My 205 is back up and running following some engine work a mate has done for me. There is just one problem. When i start it it will idle fine, whether its hot or cold. But the next time it idles (after reversing out of a parking space for example) it idles at 2-3k rpm. If i blip the throttle, sometimes it will drop down to just under 1k. But at the next idle it will be back up. Occasionally it will idle ok without having to blip it.

 

The throttle position sensor does click when the throttle is off, so that seems ok according to my limited knowledge. However when its idling fast, pushing the throttle linkage back will drop the revs, even though it doesnt seem to move, maybe fractionally. Could adjusting the TPS slightly be the answer? I have tried some wd40 and spray grease on the linkage and sprayed some wd40 inside the throttle cable (from both ends) but to no avail.

 

Ive tried cleaning out the idle control valve with some carb cleaner, but that didnt really help. I can try another ICV when a friend of mine gets back from holiday, but i seem to remember reading on here that a faulty ICV causes an erratic idle.

 

Another problem (well, not really a problem as such) is that the throttle peddle is firmer than before. Perhaps the two could be related. A kink in the cable maybe? I dont know, im just guessing really.

 

Thanks in advance

[davemar 16]

A sticking cable could be one problem you have. You really need someone else to press the pedal while you watch the throttle spindle move. Another problem, which I had on my MI16, was that the throttle spindle pivot hole was worn, so air was leaking into the side of the throttle, giving similar symptoms to yours. You might be able to hear some air being sucked in there if you use some hose as a stethoscope; or remove it and remove the springs to see if there is any play in it.

[Ryan 99]

If the TPS doesn't switch properly when you close the throttle then the ECU doesn't know to use the idle valve to control the revs. So it sounds like a problem with the TPS - either it needs adjusting, or the contacts are worn and it needs replacing.

[jengis 0]

Before adjusting anything make sure its definately not a sticky or badly adjusted cable.

 

Surely if, like you say, the throttle clicks the switch in the closed position then the TPS won't need adjusting. Clean the butterfly and throttle body again (and then once more to be sure).

 

But I bet its a sticky (or overtightenned) cable. If the pedal feels firmer then the mechanic may have altered it when doing whatever engine work you've just had done.

[jengis 0]

Just re-read your post - if you didn't actually clean inside the throttle body/buterfly itself then this is definitely worth doing.

[taylorspug 7]

Also has a few symptoms of worn throttle body butterflys Pete. I think i mentioned this to Russ the other day. As per the usual ive got a spare if you want to try it!

[Tom Fenton 1,542]

Surely if, like you say, the throttle clicks the switch in the closed position then the TPS won't need adjusting.

 

Not strictly true, I had this problem on my old 405, the TPS was correctly adjusted but the contacts inside were high resistance even when closed, so no adjustment helped. Swapped the TPS for another and all was well.

 

To check if the TPS is the problem unplug it when the car is doing its misbehaving trick. Then with a short length of wire short between the middle terminal and one of the outers, you'll have to guess which. When you get the right pair the idle should drop down to a rock solid 950rpm or so using the idle control valve. If no amount of shorting drops the idle down then either you have a broken wire in the loom back to the ECU, or your problem is something else allowing air to bleed past the throttle butterflies.

[jengis 0]

Not strictly true, I had this problem on my old 405, the TPS was correctly adjusted but the contacts inside were high resistance even when closed, so no adjustment helped. Swapped the TPS for another and all was well.

 

 

like I said - don't adjust it, just eliminate faults.

[pete1986 2]

Ok, ill try cleaning the butterfly tomorrow. A bit of lube on it aswell? What would be best? wd40, multi purpose grease?

 

Then ill try shorting the TPS, if thats not at fault then expect a phone call for that throttle body Dan! Oh, i can drop back ur starter motor as well, and whatever else iv borrowed

 

It seems odd that although the throttle is fully closed, pushing it will drop the revs. Could this be due to a worn spindle causing an air leak, as mentioned above, then once the throttle linkage is pushed, the gap is closed up??

 

The fast idle is getting progressively higher. Last week it was at 2k, but today is was at 3k at one point, yet for one short journey today it idled perfectly. The car is loud enough normally, but when you're sat at some traffic lights in the town centre with the engine revving its t!ts off, you feel like a right tw@t with everyone looking at you. Iv got into the habbit of bringing the clutch out a bit now, so its not quite as high.

Edited January 5, 2009 by pete1986

[jengis 0]

Ok, ill try cleaning the butterfly tomorrow. A bit of lube on it aswell? What would be best? wd40, multi purpose grease?

 

No, grease is Very bad! (wd40 will help clean it though). I was just thinking a build up of gunk could be causing them to close without a clean surface area to move to. But as its as bad as you just said (3k rpm) I doubt its as simple as that.

 

Go with your TPS volt checks first (but don't adjust it!)

[pete1986 2]

I had a little bit of free time yesterday, so while it was light i had a little play. I shorted out the TPS when it was idling high with a short wire going from the middle terminal of the plug to one of the outside ones. The revs dropped down to a nice smooth idle. I also tried cleaning the butterfly valve and idle control valve with a bit of carb cleaner. Although it still idles high at times, it hasnt been as high as 3k since doing this.

 

So the TPS is fine, and am i also right in saying that this means the ICV is okay as well? Seeing as it is idling using the ICV when doing this.

 

If thats true then surely it must be an inconsistant air leak (seeing as the idle speed varies) possibly from a worn throttle body.

[leon 1.9 0]

If when you shorted the TPS while it was idling high and it dropped down and idled properly, this shows that the TPS switch isn't making (closing the contacts between the two terminals you shorted). Therefore your TPS is the problem.

 

Make sense?

Edited January 7, 2009 by leon 1.9

[pete1986 2]

Aaah, ok i understand. Sorry, im learning.

 

So does that mean i need a replacment one of does it just need adjusting?

 

Thanks for your help.

[jengis 0]

Aaah, ok i understand. Sorry, im learning.

 

So does that mean i need a replacment one of does it just need adjusting?

 

Thanks for your help.

 

Now you have found that the problem is with the tps you can try adjusting it to see if it is just not closing properly. You say you can hear it click closed so it seems that a replacement may be necessary, but you may as well try moving it just in case its not making a propper contact as you've nothing to loose.

[Death_Machine 0]

hi, I got the same problem i got an 1.9 mi on a dizzy and it always running at 2k i thought it would just do that doin the wrong injection for engine so runned too much petrol ect as im on 205 loom ecu and injectors. sometimes it does kick down with a tap on the throttle to one or just under or just above so made me think it does work sometimes but just blamed ecu set up so is this common on the dizzy and can it be fixed i.e the things u have talked about above.

[chocolate_o_brian 0]

Gonna bump this to the top, as I have a problem very similar to the OP.

 

Basically for a while I've had erratic idle. When cold the car splutters etc and when warm the idle can be all over the place

 

This morning was a good example. Sat doing 40mph in 5th approx 2000rpm (1.9 with 1.9 box). Car was warmed up (oil approx 85-90 degrees) and came to some stationary lights. The engine idled at 2000rpm. Blipped the throttle while stationary and it dropped to 1100rpm or so. Then while still stationary in neutral I gently raised the revs to 2000, and they didn't drop Suprise suprise.

 

I'm gonna try giving the throttle cable and throttle body a good clean out and see if this helps. I do need the TPS faffing with as the cars uber jerky around 1200-1500rpm on overrun when approaching junctions etc.

 

Good to see threads like this so new ones don't need to be created for folk to repeat themselves.

[CosKev 16]

Throttle cable could be the problem,had a high idle prob with mine and I'm hoping that I've just found the problem by luck

Had to remove the throttle cable cause I'm re-shelling car and I noticed that part of throttle outer cable is moving with the inner,so I'm hoping this has been sticking