Technical High revs at start up

[chrisb7777]

I have replaced the air temp sensor, coolant sensor, cleaned out the pipes for the pcv system and gone around the entire intake with care cleaner whilst running to no avail

I am positive this isn't an air leak, it's just too controlled like the ecu is putting it there. It very much reacts to what the outside temp is.

For example, 0c outside will make it go beyond 3k and 10c outside get to around 2.8k in the summer its barely noticeable

I'm really stuck now

 

[Pep0]

Hi

So it is cold and it is idling at 1200rpm, how long does it idle at 1200rpm before dropping to 850-900rpm, or does it not drop to a warm idle?

The ECU is controlling the idle speed on the basis of how cold it thinks the temperature of the engine sensor is. If the idle is not hunting but reducing slowly, measure the temperature sensor resistance, cold and warm.

Noel

 

[fingers99]

It needs that pipe to be attatched and air tight.

1200 could be accounted for by by engine air temp or air temp sensor (but you've changed the air temp sensor with the TB).

3000 has to be too much air. Did you do all the throttle checks I suggested?

 

[chrisb7777]

Hi

So it is cold and it is idling at 1200rpm, how long does it idle at 1200rpm before dropping to 850-900rpm, or does it not drop to a warm idle?

The ECU is controlling the idle speed on the basis of how cold it thinks the temperature of the engine sensor is. If the idle is not hunting but reducing slowly, measure the temperature sensor resistance, cold and warm.

Noel

It idles around 1200 for around a minute before slow dropping to 850,take about 5 mins overall. Idles really smooth at all times

I have had the car plugged into my laptop and the water temp sensor reads the same as the guage

 

[chrisb7777]

It needs that pipe to be attatched and air tight.

1200 could be accounted for by by engine air temp or air temp sensor (but you've changed the air temp sensor with the TB).

3000 has to be too much air. Did you do all the throttle checks I suggested?

It is too much air but i think the ecu is opening the iac to get it that high. It smoothly drops to normal cold idle over 5 seconds not suddenly

Yes throttle cable moves freely and linkage moves and springs back no problem, always rests on the stop no matter what

 

[Pep0]

Hi

I'll try my auto tomorrow from cold but I think mine does that as well.

Noel

 

[NeilCinq]

Have you tried another idle air controller??

 

[stephensdg]

Re: High revs at start up (Occasionally)

I'm not sure if I am right to quote the previous thread (below)?!?

My problem is that occasionally when I start the engine, it's like the throttle cable is stuck and the engine revs escalate. Generally, I just turn it off, and re-start and the car starts normally. Probably happens about once a week.

I don't suppose anyone has experienced this too?

Hi guys

I have mentioned this before but its getting worse now as the cold weather has come upon us and I have just fitted a new engine so i don't want to damage it!

On a completely cold start the car will rev up to and sometime beyond 3k for about 5 seconds before settling down to its normal 1200 rpm cold idle. Surly this isnt normal? Its certainly unnecessary!

Im stuck on what to do, i almost feel like holding the clutch on in gear until it settles to keep the revs down.

The car idles perfect at all other times even when cold. I cant remember if it has always done this but it has been at least a year and gets worse in the winter months. In the summer it will only go up to 2-2.5k

Any help will be much appreciated

Chris

 

[fingers99]

Re: High revs at start up (Occasionally)

Best guess, sticky Idle Air Control.