High Idle, Knock & throttle position question

[powderedweeman]

On Friday, i took the car for a spirited drive (200), on Saturday when i first turned the car on it idled high at 2000rpm, even after engaging first gear the revs didnt drop. I turned the car off and back on again same happened again. I then left it for 30 mins and it was fine, drove home no issues. About 5hrs later i went to put the car in the garage exactly the same idled at 2000rpm, this time i left it. After 2 mins idle dropped to just under 1000rpm.

I got the laptop out to see if there were any fault codes logged, none that i can see. This has lead me onto a couple of other questions. The knock sensor on cylinder 4 seemd to reporting very high numbers to the other 3 - now i dont know much about knock figures but im interested in people opinions. Also at full throttle the accelerator pedal only registers at 89% at full i would expect this to be nearer 100%.

Can anyone shed any light on my queries please?

 

[powderedweeman]

anybody any ideas, on anything?

 

[shakey_hand_man]

Throttle Control okay? is it closing fully?

Is the idle speed controlled, or does it keep revving up and down around 2k?

No Inlet Manifold air leaks??

Water Temp Sensor signal okay??

Are there any pending codes??

Also I can only remember one knock sensor on the F4R engine??

-Andy

 

[ryan197]

have you tried cleaning the throttle body out, they are prone to getting oily.

 

[powderedweeman]

Thanks for all the responses, i couldnt see anything saying pending codes. I too thought there was only knock sensor. Cylinders 1-3 were showing knock figures in the 80's cylinder 4 was like 400's. No idea how it was calculating them.

What do you clean the TB with, carb cleaner or just a wipe out? Wouldnt want to damage any electronics.

p.s i believe its a standard tb not a 64mm one but i wasnt the first owner.

Cheers

 

[ryan197]

i always use the wynns carb/injection cleaner, come with a straw like wd40, blast it and wipe down.

 

[shakey_hand_man]

Thanks for all the responses, i couldnt see anything saying pending codes. I too thought there was only knock sensor. Cylinders 1-3 were showing knock figures in the 80's cylinder 4 was like 400's.
Cheers

Have a look at the plugs, look for any pitting, electrode damage etc, try comparing them see if number4 looks different.. note cylinder 4 is timing belt end, because its French

-Andy

 

[tspringbett]

The exact thing is happening to me, was there any out come to this?

 

[The ANT]

Mine often does that when it's cold but after a minute or so It behaves normally.

 

[chris1888-197]

My money would be on a dirty tb! This happened to me with my 172! Cleaned the tb of oil and was fine afterwards.

 

[tspringbett]

Yup, just took the tb off and it was pretty dirty, given it a good clean with wd40 and all seems fine now!