no fast idle when cold

[johntom]

Hi
my 1980 sc doesn't have a fast idle when cold, it starts at about 950 rpm and then drops to around 850 within a few seconds.

Today I removed the AAR, for inspection. When cold there is a small crescent shaped hole visable, it has 33 ohms across it's pins and the plug has 12v. When the car has been run, the hole appears to be totally closed.

I also joined the AAR in/out pipes together (as though the AAR was fully open without any restriction) and started the car from cold, the tick over started at 1100rpm then climbed straight away to 1800 rpm?

Should the AAR hole be nearly or fully open when cold, or is the crescent shaped hole right, if so why doesn't the car have a fast idle ?
many thanks

[pete3799]

Spray some penetrating oil in it.
Sounds like it's not opening fully.

[boyt911sc]

Originally Posted by johntom

Hi
my 1980 sc doesn't have a fast idle when cold, it starts at about 950 rpm and then drops to around 850 within a few seconds.

Today I removed the AAR, for inspection. When cold there is a small crescent shaped hole visable, it has 33 ohms across it's pins and the plug has 12v. When the car has been run, the hole appears to be totally closed.

I also joined the AAR in/out pipes together (as though the AAR was fully open without any restriction) and started the car from cold, the tick over started at 1100rpm then climbed straight away to 1800 rpm?

Should the AAR hole be nearly or fully open when cold, or is the crescent shaped hole right, if so why doesn't the car have a fast idle ?
many thanks

johntom,

The AAR when cold is usually around 1/4 to 1/3 OPEN. Spray some lubricant (oil) to the sliding valve and move the valve back and forth. Dirt sometimes prevent the valve from moving. Test the AAR while it is out with 12-volt and measure the amount of time it fully closes. It would range from 3 to 5 mins. depending which model you have. Keep us posted.

Tony

[johntom]

Hi
when cold the crescent shaped hole is about 1/4 to 1/3 of the full hole and the slider will move fully open under spring tension with a small screwdriver. The hole is definitely closed when the car is warm, i will check how long it takes to close.

Should it open more than 1/4 to a 1/3 when cold ?

If 1/4 to 1/3 is right when closed, what else would effect the cold rpm?

[Ron.G]

I would like to know this also. My idle does not rise when cold and I have replaced the air box and have no vacuum leaks. all pressures are within spec with the WUR and the car runs great otherwise.

[magnumpi]

Strange, I have the same model and year of car, 1980 euro, and the same problem. Cold start, no fast idle. I'm going to also try bench cleaning/testing the AAR to see if it helps.

[GothingNC]

Sorry to hijack the thread.

I noticed that my 82 SC only has a fast idle to 1,100 RPM when cold only if it's below 50 degrees outside.

Above that, the idle is on the low side until it warms up.

[mike635]

>I noticed that my 82 SC only has a fast idle to 1,100 RPM when cold only if it's below 50 degrees outside.

Same thing on my '81, only get the fast idle when it's cool outside

[Benny771]

So, did you find your issue?

It drives me nuts when there is no end result posted....

[john walker's workshop]

what is your warm idle speed now? what is your warm CO reading now? i like to set the warm idle at 1000. if the cold CO is too rich, the cold idle will be low and possibly chuggy/surging for a short time. if your warm idle is say, 750, you can't expect more than about 200 extra rpm cold.

[johntom]

Hi
after 12 months of ownership I have made a major breakthrough in solving the performance issues that were present when I bought the car ie poor performance, lack of acceleration. etc.

When taking the car for it's annual Mot test, the hydrocarbons were 3700 (the pass limit was 1200!). After removing the plugs, 4 were light brown, 2 were like new (after 500 miles!) so unburnt fuel was going through cylinders 4 and 5 (i had previously tried the plugs against the block and seen a spark?, tested fuel pressures and looked for air leaks etc). I have just replaced the HT Leads and the car is so much smoother and responsive, when the car was taken back for its Mot test the hydrocarbons had dropped to 100 !!! The car now drives much better and is a pleasure to drive.

The cold start tickover still isn't right, it does surge a little for the first few seconds (won't rev without bogging down) however within a few seconds things improve. Warm tickover is steady, around 950rpm. I turned the tickover down to 1.87 % during the Mot (spec 1.5-2.5%) but afterwards I have increased it by 1/8th of a turn clockwise to richen it as advised by some (around 3% now). There still isn't a definite high tickover when cold though ?

I still wonder if the AAR crescent shaped hole should be more open when cold ?