Lude Generation

Once again, I am appealing to you all for your thoughts and advise regarding my poor idling issue.

Experiencing high idling around 1300rpm and sometimes bouncing idle between 600-1400rpm.

Upon start up car runs absolutely fine, FITV kicks in nicely until car is warm then it settles and idles great around 700rpm. However, after driving for about 5 minutes when coming to a stop revs will stay up at around 1100-1200rpm before coming back down after about 5 seconds to 700rpm.

If I put my foot down or drive on the motorway, when coming to a stop I find intermittently bouncing idle until I got the accelerated again, this stops the idle but revs are high still at around 1100rpm almost as if it's getting to much air.

I have tried 3 different FITV valves which have all done the same thing, tried 2 different known working idle control valves following a full strip down and clean which hasn't resolved the issue either.

I started to think about when the issue started and I traced it back to 2 weeks after I installed the H22A8 throttle body which has the bigger diameter opening and put a type s induction kit on with pipercross filter.

My engine is an A5, would installing the A8 throttle body cause too much air going into the engine causing these issues?

I haven't bled the coolant system as I didn't think there was a real need to do so, but I'll be honest it's my only other thought apart from putting the standard throttle body back on.

Your thoughts would be appreciated on this!

If you haven’t bled the system you definitely need to do that. Trapped air can easily cause the symptoms you have and switching out anything within the coolant line can easily trap air withing the coolant system.

I did clamp the pipework, but okies that's the job for the weekend!! Cheers nafe!

I agree, sounds to me like it's happening when the engine has warmed up. Out of curiosity if you start it up whilst it's warm does it show the same symptoms sooner?

That wouldn't matter. In theory you're adding a pocket of air for each component you swap in (the air inside the throttle body/IACV/FITV). So every time you swapped a component without bleeding the system through it would have added more air and got worse.

Jackson Bondy wrote:I agree, sounds to me like it's happening when the engine has warmed up. Out of curiosity if you start it up whilst it's warm does it show the same symptoms sooner?

Yeah when it's warm, it won't be long before it starts.

It kicks in as soon as the engine is up to temperature.

NafemanNathan wrote:That wouldn't matter. In theory you're adding a pocket of air for each component you swap in (the air inside the throttle body/IACV/FITV). So every time you swapped a component without bleeding the system through it would have added more air and got worse.

Sounds like it might be time for a complete flush and replace jobby this weekend! It's been a job on the list for a while!

You're supposed to replace the coolant every 2 years anyway, so

I've got an A8 throttle body on an A5 and I've had no problems except I had similar symptoms and it turned out to be a sticking throttle cable. I took the stress out of it, oiled it, worked it and silicon greased it. I also oiled the throttle body spring to prevent friction there. Problem went away. Worth checking. You should definitely bleed it though as well.