Ruddy shaky idle - tracing it

[Diamond Black Geezer]

So it's been months now, and dribs and drabs of searching lead me to nothing on the shaky idle front. However, the other day we find that after a run, parked waiting for a mate, find the idle is absolutely sewing-machine-style. As a rule it's better when warm.... and possibly gets worse when very hot, after the fans have cut in for a while. This suggests that it's linked to temperature, something expanding etc..

Vac tubes, elbows all fine. Still unsure about the scuttle vac tank, seems to be duff/dickey, (though this shouldn't affect the idle, just power delivery, yes?) Front vac tank works fine. Possibly worse in wet weather, too.

Really getting on my nerves now, because it's not helping economy, and sort of ruins what is an otherwise excellent drive. What the hell is it?

[minifreek]

Could be CTS faulty, thus making the ECU overfuel....?

[Diamond Black Geezer]

CTS? sorry, thats a new one on me, mate?

[Nick W]

CTS? sorry, thats a new one on me, mate?

Coolant Temperature Sensor. That could cause poor economy,  but won't affect the idle.
You're looking at an air leak or ignition fault. Ignition problems are always the place to start misfire diagnosis.

[Diamond Black Geezer]

Thanks minifreek, knowing how long you've spent on the V6s that's a sound bit of advice.

Igniiton should be ok. Plugs not too old, brand new leads, low mileage dis pack.  Appreciate that it could be ignition. Have been thinking about the test the dis pack method actually. Though my spidey-senses tell me it's vac leak related, I won't dismiss it.

Take out a plug, then test with 35-40mm gap if memory serves, then continue unplugging and plugging in each respective 'socket' on the DIS pack with the same lead, yes? What's the 'best' point to hold the spark plug over, is there a convenient earth point?


Hoping it's not the CTS, I've just seen where that little sod is located!

[Doctor Gollum]

Discounted pack

[Diamond Black Geezer]

Sorry, I seem to not be understanding English today!


'Discounted pack' 

[Entwood]

Sorry, I seem to not be understanding English today!


'Discounted pack' 

I think he means "I have discounted the pack as the cause of the problem" ... but I could be wrong !!   

[tigers_gonads]

Give us a shout when your free and i'll plug the laptop in and check both temp sensors are reading about the same and look at other things for you   

[Doctor Gollum]

Discounted pack

Dis pack stupid poxy aurocorrect

[Diamond Black Geezer]

Ahhh, all understood, now! 


Cheers Steve, I'll let you know, though I am under instructions from Bekki you're not to try and reprogram anything, she's concerned about the ECU being wiped by your well-meaning man hands. I have told her men aren't all like me, breaking everything I intend to mend! 

So Mr Smeegle reckons DIS pack?

[Entwood]

Discounted pack

Dis pack stupid poxy aurocorrect

OK  .. I was wrong ..

[tigers_gonads]

Ahhh, all understood, now! 


Cheers Steve, I'll let you know, though I am under instructions from Bekki you're not to try and reprogram anything, she's concerned about the ECU being wiped by your well-meaning man hands. I have told her men aren't all like me, breaking everything I intend to mend! 

So Mr Smeegle reckons DIS pack?

Nah, TuBy filled me full of horror stories about what can happen when you try and reprogram things with "My Naff Code Reader" 
I've had nightmares ever since 

Oh by the way, tell the lovely Becky i'll be around there to shown her my new manual gearstick fitted to my full fat v6   
You can play with the laptop 


While I remember, what type of socket is it on the coil pack ?
Check the MAF plug for a clue because i've a couple of oval DIS packs here if needed

[Diamond Black Geezer]

Oval. Appreciate the offer. Have a brand new one in the box, arrived a few days ago. I got it as a spare in the long, distant future, not expecting any issue with the DIS pack for a long time!

[minifreek]

I think, with the aforementioned bad fuel economy, it'll be the CTS...

Mine had a bad shudder, and hunting at idle, and that turned out to be the CTS....

This was all after changing the dispack, Idle Control Valve and the complete ignition system, including a new set of plugs...

The dispack, if it was starting to break down, would give a misfire and keep misfiring all through the rev-range, not just at idle...

If I'm wrong and it does turn out to be the dispack, then I'll hold my hands up....