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More High Idling trouble


Rob

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Idle jumps up when said pipe is removed from tit-end.

 

So a high ide goes even higher when you pull the pipe off? Hmmm. Not what I was hoping for :(.

 

Just out of interest, if you npull the pipe of again and put something that wont get sucked in over the stub pipe, does the idle go back down to normal?

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Have you removed the idle control valve yet...?

 

If you remove this form the car and start it does the car hunt for an idle between 750-2500rpm violently...?

 

Then use a medium sized screw driver butt or similar to half block the hole and see if this then controls the idle, moving it up and down depending on how much or little you cover the hole.

 

Coving the hole completely does what....

On mine it stalled the engine and killed it (effectivily no idle)

 

When not covered as mentioned above it should idle hunt between 750 and 2500, effectively having an idle very very high, so high in fact it hunts.

 

When covered partially the idle should be controllable and with the aid of telling you what rpm the engine is running at, and you should be able to get it to idle correct.

 

This is what my car is doing at the moment and I am hoping that replacing the idle control valve and connecting plug (to prevent bad connection possibilities) should fix it.

 

Hope this helps :)

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  • 2 months later...

Having been inspired by odays dyno run, I stripped down the throttle body and swapped the butterfly springs, from inside the TPS housing. Hasn't made a blind bit of difference, again!!!

 

It's definitely the throttle butterfly being held open, but the spring felt so powerful I can't believe that vac pressure is holding it open. I was playing with the throttle once reassembled and if I revved it, it wouldn't fully shut after. I had to reach in, and manually push the lever shut to get the car to go back to 700rpm.

 

Could the shaft be sticking? It felt okay without the springs on.

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It's a shaft straight through. I've already ruined the cross heads that hold the vane into it, so I'd have to drill then out to remove the shaft. I have a spare throttle body, but I'm reluctant to just change it as if it works it'll leave me me no resolution to the original problem.

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Bugger Rob, I guess I must have missed you at SRR. I would have liked to have had a look to see if we could sort this out.

If you're ever in the Oxford area, give me a shout as I'm pretty sure this is something fairly simple. Just bloody annoying though....

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Swapped the TB and YT pipe with another set. I had no joy trying to set up the TPS on the replacement TB, just couldn't get any deflection on it at all. So I placed it roughly in the middle and tried the "hold down throttle" technique.

Certainly not over-revving now, it dies unless the AC is running. I reckon that must be the TPS setting.

It came off a fully running car, but I had to remove it to check the springs, and to match my original.

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Can't remember if I said already but i've been suffering high idle for a few months. On Friday I thought enough is enough. I unpluged the idle sensor and the plug to the right of that. One of the pins on on the plug to the right had green all over it like a copper reaction. I disconnect the battery, sprayed the plug lightly with WD40 and left it for 5 mins. I came back with a toothbrush and scrubbed it and mopped the residue up. I reconnected the battery 10 mins later but didn't test the car that night. Come Saturday morning it was idling perfectly around 600 instead of 1200. Today I even saw it go down to 500 revs.

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I think that a number of these high idling problems are issues with poor connections to the throttle position sensor.

I've seen a couple now, as well as mine that have had poor connections at the plug. All three that I've seen had the same problems. Intermittent high revving. One was like Dazzi said with a corroded contact. Mine and the other one had female connections on the plug that were loose. Once I'd closed the connections up, the problems were sorted. (Certainly on mine, and I've not heard of any issues with the other two I looked at)

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Certainly not looked at the quality of the connections on the TPS plug> I'll swap my TB back in again tomorrow evening, and check the connectors are crimped up tight.

 

With all of this though, whether its faulty electronic signals from the TPS or the Temp sender or a dodgy ECU, why would the actual throttle butterfly be held open? The spring is massively strong, but can the air being sucked in force the throttle open?

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Nah, the pressure from the airflow would act equally on both sides of the butterfly, neither opening nor closing it.

What I think happens, is that when you lose the TPS connection the idle valve opens a little. This supplies the air required for the RPM increase. Then when you push the throttle against the dashpot it re-makes the connection on the TPS plug so the revs drop.

I spent absolutely ages trying to work out what the hell was going on, as I was thinking the same as you, that it must be something to do with the dashpot.

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Annoyingly, it seems to be running perfectly on the spare TB, with its own TPS and ICV, now that I've fiddled with the TPS a bit.

Mind you that's what happened with Scooter's TB, so I'll give it a few days.

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So, no high idling, the throttle could not be pushed any further shut by the time I got to work...but it felt down on power. I thought it was my imagination, yet I was thrashed off the line onto a roundabout by a new VW Beetle!!!

Even if it had the 1.8T I should've have easily beat it.

 

What exacty does the TPS control, does it affect fuelling?

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  • 3 weeks later...

And two weeks later its still idling perfectly on the replacement TB.

 

So it's either the butterfly somehow, the IAC or the TPS. They are the only things to affect intake that have been replaced.

The butterfly does not hold open a bit on the replacement TB like it did on the original one.

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