Throttle body vacuum

JayJay · Post by **JayJay** » Tue Feb 07, 2012 6:43 pm

Right, I'm just trying to work out why my idle sits higher than it should.

My cold idle is in fact 1500rpm, then it drops down to 1000rpm.

Am I right in saying that in the throttle body, the hole at the bottom goes to the FITV, and the hole on the left hand side almost at the top goes to the IACV?

Both holes are sucking in air. At warm, the FITV shouldn't be bringing in any and should be completely closed, it IS sucking a bit so I think it's faulty. The IACV is sucking in quite a bit. Blocking either hole doesn't make a difference, neither does unplugging the IACV!

The only thing I can think of is the idle screw? It seems I'll need to replace the FITV anyway, unsure of the IACV though.

Cheers,
Jay

Post by **Vtecmec** » Tue Feb 07, 2012 6:47 pm

If you have a look inside the FITV there is a little white threaded plastic piece, if you wind it in a few turns then it should stop the FITV leaking.

Though unplugging the IACV should lower the revs a little, if it's not then it could possibly be faulty.

BMCC · Post by **BMCC** » Tue Feb 07, 2012 8:17 pm

The air for Idle goes through the upper port then splits to the plenum via the throttle screw and then on to the Idle air control valve. If you blocked both ports the car would stall. If you block the lower port FITV and then pull the plug on the IACV then I would have thought the rpms would drop unless of course the Idle screw is so far off the IACV was never running in the first place? Try pulling the IACV and then blocking the lower port and see what this does.

judderod · Post by **judderod** » Wed Feb 08, 2012 5:03 pm

Try setting the idle speed properly before replacing anything. Get the car nice and warm (fan comes on), turn the engine off, and unplug the IACV.

Start the engine (it might need a tiny bit of throttle to get it going).

Adjust the idle screw on top of the TB until your idle is at about 550RPM. All electricals should be switched off while doing this.

Turn the engine off, plug the IACV back in, and reset the ECU (if you can be bothered). Otherwise just start it up and give it 5 minutes to re-adjust. Should now idle at about 700RPM.

JayJay · Post by **JayJay** » Thu Feb 09, 2012 9:20 am

Cheers judderod

I'll give that a shot!

judderod · Post by **judderod** » Fri Feb 10, 2012 11:06 am

Oops forgot to say after you've unplugged the IACV, short the service connector as well.

JayJay · Post by **JayJay** » Fri Feb 10, 2012 11:08 am

Will do

When resetting the ECU, is there any difference between disconnecting the battery or following the proper reset procedure (assuming there is one?)

judderod · Post by **judderod** » Sun Feb 12, 2012 11:48 pm

Naah just disconnect the battery and push the brake pedal (just in case there's any power left in the system). Wait about a minute to be sure. Then reconnect. Should do the job.

There's something in the manual about disconnecting the clock radio fuse but I'm sure I tried that years ago and it didn't reset jack.

Post by **NafemanNathan** » Mon Feb 13, 2012 8:36 am

Just one thing though... 1000rpm at warm idle isn't that unheard of as sometimes it's purely down to an in-accurate reading of the counter. Are you sure it's not just the clocks?

JayJay · Post by **JayJay** » Mon Feb 13, 2012 9:35 am

I've actually changed the clocks since and no difference, and it was previously reading correctly. It's not a major problem for me really as the idle is just a few hundered rpm higher it's not bouncing or anything.

Lude Generation

Throttle body vacuum

Throttle body vacuum

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