Erratic idle speed 2.5 v6. Please help!

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leon2000_3
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Re: Erratic idle speed 2.5 v6. Please help!

Post by leon2000_3 » Tue Feb 02, 2021 8:13 pm

Thanks for this much appreciated. Will give it a go.

jrh
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Re: Erratic idle speed 2.5 v6. Please help!

Post by jrh » Wed Feb 03, 2021 7:58 am

Most IMPORTANT , get yourself a small tube of Silicone grease.
Use it to smear the surfaces of the filler cap AND the rubber washer in the cap.
Ignore this advice , tear the rubber washer and you have big problems.

cpt black
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Re: Erratic idle speed 2.5 v6. Please help!

Post by cpt black » Wed Feb 03, 2021 11:53 am

Would say its more the IAC Valve sticking and needs a clean (if not low on water)

jrh
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Re: Erratic idle speed 2.5 v6. Please help!

Post by jrh » Wed Feb 03, 2021 7:17 pm

Double check that absolutely every little black pipe is connected up to a fitting , especially round the back of the air filter box.
When you have it all back running as it should , then 'play around' taking one pipe off at a time . You will see what the effect of a 'missing' pipe has on engine running.

Sunfly
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Re: Erratic idle speed 2.5 v6. Please help!

Post by Sunfly » Thu Feb 04, 2021 12:51 pm

If the coolant level doesn't fix it, (lack of coolant going through the throttle body) you might try this.

I had this problem all the time with my 16V, and had to take the throttle body apart for a carbon clean every 2 years (It had done well over 150k before the problem started) but its not the same body on the 24v and works differently. (Cant remember the exact arrangement now. However I did have the erratic tickover problem.

All I did to fix it was to always use 97 octane fuel. Its a cleaner fuel that is supposed to be kinder on the engine and I think we should all be kind to engines, so I always use it. (I wasnt specifically trying to fix that problem at the time but it was the side effect). Plus I add a bit of injector cleaner on its birthday. The result being that that problem and other fuel related gremlins went away all on its own and has never come back. Coincidence, maybe... but I don't think so.

When I got the car it had been badly neglected so all the fluids got changed at least twice. You would be amazed at the number of problems that policy has put right. As an added bonus of 97 octane, I get an extra 0.6miles per gallon and only pay an extra 12p per litre for it. :cry: Worth it in my opinion when its not a daily drive.

jrh
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Re: Erratic idle speed 2.5 v6. Please help!

Post by jrh » Thu Feb 04, 2021 3:16 pm

Absolutely go with that.
So much water dissolved in ethanol used in cheap petrol these days, it's a wonder anything works.

leon2000_3
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Re: Erratic idle speed 2.5 v6. Please help!

Post by leon2000_3 » Thu Feb 04, 2021 9:31 pm

Thanks for the advise everyone, followed the guidelines and pleased to report an improvement. Idle speed has stabilised after topping up coolant with the method explained. Did a clean up of the rad caps as they were a slightly gunky. Also used a little silicone lubricant as the rubber seals seemed slightly perished. Perhaps some new rad caps to improve more?

Idle has stabilised however its now idling at about 1000rpm. So a definite improvement from before, at least its stable and it wasn't revving like nuts! But still slightly higher than it should be.

Next check IAC valve, throttle body clean, air filter and spark plug check, some Wynns fuel additive? What do you guys reckon?

I've read up on some of the other posts in regards to the same problem, seems common! All very useful info.

Any further advise to get it perfect would be greatly appreciated! Seems I've got much further speaking with you guys than I have with local garages and mechanics! So thanks again for all the help! Hard to find a local mechanic who knows what they're doing with this car!

Look forward to hearing, thanks in advance!

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Re: Erratic idle speed 2.5 v6. Please help!

Post by mojo98 » Thu Feb 04, 2021 11:01 pm

If after you have done the rest of the cleaning and it's still runner at 1000 rpm, you may need to set your base idle,
But we will get to that after you have done the rest first 👍
Glad to hear that there is some improvement 👌👌

jrh
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Re: Erratic idle speed 2.5 v6. Please help!

Post by jrh » Fri Feb 05, 2021 8:38 am

Well done , one last little thing to check , though you have probably done it !
Look at the tiny ball-race that runs through the curved slot off the throttle quadrant plate.
Make sure it is turning freely as you get someone to slowly press the accelerator pedal (engine not running ) to the floor.
Really important it turns and not slides through that slot.

leon2000_3
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Re: Erratic idle speed 2.5 v6. Please help!

Post by leon2000_3 » Sun Feb 07, 2021 12:27 pm

jrh wrote:
Fri Feb 05, 2021 8:38 am
Well done , one last little thing to check , though you have probably done it !
Look at the tiny ball-race that runs through the curved slot off the throttle quadrant plate.
Make sure it is turning freely as you get someone to slowly press the accelerator pedal (engine not running ) to the floor.
Really important it turns and not slides through that slot.
Thanks for that ! I'll be working on the car this coming week so will definitely give that a check. Nice one!! :)

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