RPM goes down after long runs

[Hungry_Minder]

Hi guys,

My CK2 (EFI,1998, 190k odo, tiptronic, gear oil level seems to be fine) has a strange issue for last 2/3 weeks.According to given rpm of ck2 is about 700 (has mentioned that under the hood) and it perfectly running with and without ac.

I have noticed that after running it for few kms rpm goes down to 600 and seems like engine going to die and vibrating.I have done a tuneup but no luck.After a tune up it was ok for about 2 weeks and now I have this issue again.

this is happenning mostly when I put the gear to D (idling) or R.Parking and N runs smoothly.

seems me when engine is heating it cannot keep the rpm and acting weired.Sometime it automatically comes to correct rpm and stop vibration.

Any ideas and any recommended place get fixed this issue? 

Thanks

 

 

Edited July 16, 2016 by Hungry_Minder

[Hungry_Minder]

This problem solved.There is a small door near to ideal valve control and they said it was hard to open and close.They simply cleaned the door and everything is perfect now.

[Davy]

Sounds like a sticky Idle Control Valve. What was done as part of the tune-up?

[Hungry_Minder]

I am not 100% sure what they did.But I saw they cleaned valves, throttle body and other parts.I am rather happy about the tune up as it was perfect and now car has much better perfomance.Only issue is this.Is this a expensive part and time consuming

[Davy]

If they did a proper throttle body clean-up, they would have cleaned the ICV as well. When you start your car in the morning/when cold, does the RPM go above normal and then slowly come down as the engine reaches operating temperature?

[Hungry_Minder]

2 hours ago, Davy said:

If they did a proper throttle body clean-up, they would have cleaned the ICV as well. When you start your car in the morning/when cold, does the RPM go above normal and then slowly come down as the engine reaches operating temperature?

morning/when cold, does the RPM go above normal and then slowly come down as the engine reaches operating temperature? - Yes it works as you described.

[Rumesh88]

Check if any of the vacuum piping disconnected/left hanging loose - particularly the one goes to the charcoal canister - after the tune up. Also while the engine running in idle and with RPM dropped as described above, open the fuel lid and see if there is excess vacuum (subjective of course) and the engine RPM changes. Some wild guesses but you can check these at no cost and risk.

[PerfMad]

Looks like a problem with idle controlling valve.. could it be due to blockage of fuel pump or filter as well? i had same sort of engine knock specially when engine was hot.. after tuneup it was ok for about 2 days then issue came up again.. later replace the fuel pump inside the tank and issue vanished ...

[Hungry_Minder]

I have replaced the petrol filter.when they do the tune up.I think I need to get checked and replace the idle controlling valve.

Edited July 18, 2016 by Hungry_Minder

[Iced-T]

hi... just a suggestion. have u tried switching off the Air con and seeing if there is a difference? 

[Davy]

On 7/26/2016 at 3:48 PM, Hungry_Minder said:

This problem solved.There is a small door near to ideal valve control and they said it was hard to open and close.They simply cleaned the door and everything is perfect now.

Glad you got the problem solved.

The "door" is the idle control valve. This is why I said initially that it is probably a sticky idle control valve. This means whoever did the initial throttle body cleanup on your car hasn't done a proper job.