Erratic idle speed 2.5 v6. Please help!

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leon2000_3
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Erratic idle speed 2.5 v6. Please help!

Post by leon2000_3 » Tue Feb 02, 2021 6:44 pm

Hi there, I'm in need of help and advice in regards to my 94 2.5 V6 probe. It's on about 70k. Manual gearbox.

I started the car up on a cold day recently, it usually fires up and idles around 1500rpm until it warms up after some minutes and idles at steady 750rpm. But now its started to behave differently, after a few minutes the revs rise to around 2000rpm, then gradually drops to around 1500 again, and then the revs bounce up and down to a point where it wants to cut out. When I'm driving it feels fine, although I think I noticed the revs drop lower than normal through a gear change. After a drive and back to a stop, it idles much steadier and eventually does go down to about 1000rpm, but still something isn't right with its idle.

The car has been garaged for a while, although it gets started and driven on a short drive every once a week or every couple weeks. Fuel filter, oil + oil filter, and air filter all put in new less than 1000 miles ago, just over a year ago. Was driving perfect until last week!

Has anyone experienced this? Any help or advise on how to solve this would be greatly appreciated!

Thanks in advance!

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Re: Erratic idle speed 2.5 v6. Please help!

Post by Micron » Tue Feb 02, 2021 7:10 pm

Have you checked the water level by removing the cap on the engine on the left?
The water should be filled to the brim.

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Re: Erratic idle speed 2.5 v6. Please help!

Post by Incognito » Tue Feb 02, 2021 7:22 pm

As Trev/Micron says, remove both left and right radiator caps on a cold engine, run until warm, fill the left hand one until the right side spills , caps back on. Should sort the problem . Water on these along with oil level needs to be on maximum. Strange cars ..... :lol:

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

Post by leon2000_3 » Tue Feb 02, 2021 7:28 pm

Micron wrote:
Tue Feb 02, 2021 7:10 pm
Have you checked the water level by removing the cap on the engine on the left?
The water should be filled to the brim.
Thanks for the reply, yes coolant level is filled to just below the full mark.

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Re: Erratic idle speed 2.5 v6. Please help!

Post by Incognito » Tue Feb 02, 2021 7:37 pm

leon2000_3 wrote:
Tue Feb 02, 2021 7:28 pm
Micron wrote:
Tue Feb 02, 2021 7:10 pm
Have you checked the water level by removing the cap on the engine on the left?
The water should be filled to the brim.
Thanks for the reply, yes coolant level is filled to just below the full mark.
As long as you're not just looking at the very far right , plastic water infill , on the passenger inner wing ? The metal cap inlets we mean .

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

Post by leon2000_3 » Tue Feb 02, 2021 7:39 pm

Incognito wrote:
Tue Feb 02, 2021 7:22 pm
As Trev/Micron says, remove both left and right radiator caps on a cold engine, run until warm, fill the left hand one until the right side spills , caps back on. Should sort the problem . Water on these along with oil level needs to be on maximum. Strange cars ..... :lol:
Thanks for the advise I'll give it a go! The oil level is topped up to full.

Just to confirm: remove both the engine coolant cap on passenger side, and the radiator cap driver side whilst engine off and cold. Then fire up engine until warm. Whilst engine running add water to the coolant reservoir until it spills out the radiator cap side, then both caps back on whilst engine still running.

Have I got that right?

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

Post by leon2000_3 » Tue Feb 02, 2021 7:41 pm

Incognito wrote:
Tue Feb 02, 2021 7:37 pm
leon2000_3 wrote:
Tue Feb 02, 2021 7:28 pm
Micron wrote:
Tue Feb 02, 2021 7:10 pm
Have you checked the water level by removing the cap on the engine on the left?
The water should be filled to the brim.
Thanks for the reply, yes coolant level is filled to just below the full mark.
Ah ok got you now, not the plastic reservoir near passenger wing,

The radiator breather cap and the coolant filler cap, metal ones, got it! Thanks!!

As long as you're not just looking at the very far right , plastic water infill , on the passenger inner wing ? The metal cap inlets we mean .

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

Post by leon2000_3 » Tue Feb 02, 2021 7:43 pm

Thanks for the advise guys I'll give that a go this week and hopefully report back with some good news. I hope!

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Re: Erratic idle speed 2.5 v6. Please help!

Post by Incognito » Tue Feb 02, 2021 7:51 pm

leon2000_3 wrote:
Tue Feb 02, 2021 7:39 pm
Incognito wrote:
Tue Feb 02, 2021 7:22 pm
As Trev/Micron says, remove both left and right radiator caps on a cold engine, run until warm, fill the left hand one until the right side spills , caps back on. Should sort the problem . Water on these along with oil level needs to be on maximum. Strange cars ..... :lol:
Thanks for the advise I'll give it a go! The oil level is topped up to full.

Just to confirm: remove both the engine coolant cap on passenger side, and the radiator cap driver side whilst engine off and cold. Then fire up engine until warm. Whilst engine running add water to the coolant reservoir until it spills out the radiator cap side, then both caps back on whilst engine still running.

Have I got that right?
Yes, add water to the drivers side inlet(assuming a uk car), until the (passenger side) black plastic rad reservoir spills.

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Re: Erratic idle speed 2.5 v6. Please help!

Post by mojo98 » Tue Feb 02, 2021 7:56 pm

The drivers side is the filling cap, (next to dipstick) and the pressure cap is the one on the passenger side of the rad,
While the engine is cool remove both the filler cap and the rad cap,
Check the level, if down refill with the correct coolant via the filler and watch the rad exit when coolant comes out of the rad exit (passenger side) then it's full,
You can run the engine and watch the level, make sure the heater control is on hot. If the level goes down refill.
Put rad cap on the passenger side the the flat cap on the filler point, now you can put coolant into the plastic collect bottle on the the passenger side,
Job done

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