High idle speed - sierra 2wd cosworth
 

Hello all

Recently picked up a pretty clean sierra sapphire 2wd, drives very nice - mileage 107,320 from new but I've noticed the idle speed when started is the same even when up to running temp a bit fast in my opinion. It sits at 1100 rpm and does not drop. Is there any thing I can check or clean out ?

Is this the norm or are they meant to drop down below 1000 when at running temp. Car is totally standard not been modified at all

I'm pretty new to the cossie scene - im used to working on a old cvh :bat:

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Thanks
Clark :top:

You could try adjusting the idle screw on the throttlebody. Be aware that the throttle position sensor can cause a high idle if it's not set correctly, although if that's the cause i think the idle is usually higher than what you have.

Idle when at running temperature should be 850-900 RPM.

Turn all electrical equipment off and then with the engine running, disconnect the ISCV connector, this is behind the hose coming from the header tank in your picture.

This shouldn't make any difference in speed, you need to undo the locknut on the T/B, then tighten the screw which will lower the speed, when you get the above figure tighten the locknut.

Reconnect the ISCV, at which point the speed should momentarily increase and then drop again.

You are lucky to find a standard example!

Martin

I'd be checking for any leaks on the inlet side first, adjusting the idle screw manually could just be masking a fault.

This was my thought as I had the same issue on my mk2 fiesta with the 2.0 zetec. It had a leaky throttle body gasket. So may try a bit of brake cleaner around the inlet to see if that pin points the leak.

The car has only one previous owner I'm the second keeper.

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Rare in Mercury Grey too!

That's true and it's worth checking, although I would have thought there would be running issues elsewhere.

Martin

Runs like a dream apart from the idle speed.
Starts first time every time and got plenty of power
Had it serviced at ford last week as it's only done 4000 miles since 2004 ! :content:

It's had a new ford fuel pump & fuel filter last year at a ford dealer on top of a full service.

Cleaned out the iscv with brake cleaner - didn't help it much
Ran lumpy for a minute then back to the high idle.

Gonna put it on the mot gas analyser on Saturday to see of that can pin point if it's a vac leak. It's just strange that when you unplug & reconnect the iscv it don't make any difference to the engine speed

Had this problem before it was the O2/lamba sensor

Won't have a lambda sensor on a 2 wd , will either be sucking air in through the gaskets on the air in take or tps needs setting up , if you disconnect the iscv revs should drop down

Fitted a new idle valve today - and still if u disconnect the valve the revs don't drop. Picked up new gaskets from burton power for inlet , & elbow plus box gasket. Need to try them next.

Squirt some brake cleaner round the inlet whilst engines running you might hear the engine change note , as you squirt over the joints

Great to see such a nice standard example ;-)

Some dealerships used to raise the idle on the early saffs for some reason. Mine was the same for years until we simply adjusted it back (89 standard car).

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More pics of the saph
I've tried the brake cleaner method and it didn't reveal anything
I did get a slight pop noise when I squirted a bit too much over the inlet ??

Lovely looking car mate.

It won't, if the idle has been set to high!

Martin

Was driving it last night & briefly it's idle was 850 rpm then minutes later back to 1100,

Putting it on the emmisions tester today to check the mixture before adjusting anything

Yes that sounds like an air leak.

Martin

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This was a picture of the emmisions test.
They did a test by removing the throttle body hose then with engine running cover the throttle body up and the engine stalled. Which meant there is no air leak.
But I still think the 02 reading was a bit too high.
They didn't adjust co2

I Wouldn't say there is no air leak. It will only need a very small leak to raise the rpm by that amount, probably not enough to allow it to idle on its own. You could always remove the air filter, make a bung for the hole then pressurise the inlet with a foot pump to see if it holds pressure or not.

What's the voltage at the battery when running? I was told the idle speed is kept up at start up until ecu see's 14v.

It's based on temperature and load, the fact is when it's d/c the speed remains the same, therefore air is entering elsewhere.

I agree it still sounds like an air leak, as you said you got a pop when spraying around the inlet, try this again, it may be the chamber is leaking.

Martin

http://i124.photobucket.com/albums/p...pse0ad0d4c.jpg

short vid of the rev counter when u start up from cold.

Just watched your video. Are you revving it or is it doing it by itself ? It should have a constant idle on cold start up of around 1050 to 1100 rpm and then settle back down to around 850 to 900 rpm. As you have already changed the ISCV that must be ok, it seems like an air leak to me not electrical. Hope you get it sorted.

That was the car reving by itself from cold.

I replaced all the inlet manifold gaskets last night - they were all perished so 99% certain that was the problem.
Going to road test it this morning - :top:

Sounds like you have found the problem, tell us how it is idling now.

From cold it still goes up and down a bit but when warm it's idles perfect.
Some times it kangaroo's down the road when in gear.

Think it needs base idle and co2 looked at again now I've replaced the leaky gaskets.

Sounds a lot better but if I was you I would book it in for a rolling road tune up as it probably hasnt been set up for a long time. Well worth the money.

After paying burton power another visit - I was told the iscv can be adjusted if I still have idle issues. So I've adjusted the iscv central nut to match the old iscv - the car now runs near enough spot on.
But like you say book it in for a rolling road setup. I've got a feeling someone just adjusted the base idle to mask the air leak from the inlet gaskets.

Even tried a star tester on it from my ford dealer but it wouldn't connect.

Power Engineering arent that far away from you, they are very good setting up Cosworths on their rolling road.

Refitted original iscv and car starts up spot on from cold now.
Done another gas anayliser test which shows the air leak has gone - inlet gaskets defo the cause.

I'm thinking of giving the engine a "terra clean" before taking it to be setup
Heard it's a lot better than them £5 injector cleaners.