Rich's BB4

Rich · Post by **Rich** » Tue Jun 12, 2012 8:30 pm

Oh well, the problem isn't fixed. The cold start problem is sorted, but the car is still bouncing between 1000-2000rpm every time I lower the revs after it's up to temp (i.e. at lights, junctions & roundabouts). At one point the idle was stuck at 2000rpm so I could just put it in gear & the car would drive itself.

It's really annoying cos it makes me look like I'm revving my engine at traffic lights... even had someone in an Impreza WRX STI think I wanted to race & sped off on the green light.

Post by **4thgenphil** » Tue Jun 12, 2012 8:35 pm

checked your vacuum lines/hoses for splits?

Post by **NafemanNathan** » Tue Jun 12, 2012 8:48 pm

I've not read this all the way through bud, but it's not simply the throttle cable sticking is it?

Once it's up to temp, pop the bonnet and just try fiddling (without adjusting) the throttle cable/throttle body. Pull it slightly to accelerate, and then manually return the cable/TB to what should be it's resting position. If this appears to sort the issue, then one of these, or possibly even your pedal could be at fault. I had a simular issue with a past lude.

Rich · Post by **Rich** » Tue Jun 12, 2012 9:16 pm

Cheers for the suggestions Guys. I'll check these things tomorrow.

BMCC · Post by **BMCC** » Wed Jun 13, 2012 8:16 am

I'd look to see if the FITV (Fast Idle Thermo Valve) and the IACV are working right. Get the car up to temp and make sure the car has the bouncy idle. Take the intake off so you can get access to the throttle body. If you look inside the TB you will see two small holes. The lower one is for the FITV valve and the upper is for the IACV. Put your finger over the lower hole to block the FITV if the Idle settles down then the FITV is playing up. They can be cleaned out but never done this. Also make sure the coolant is full and no air as this will cause the FITV problems. If this doesn't work then put your finger over the upper hole in the TB. The idle should go to base ~ 500rpm. If not then your IACV is playing up.

Post by **NafemanNathan** » Wed Jun 13, 2012 8:40 am

BMCC wrote:I'd look to see if the FITV (Fast Idle Thermo Valve) and the IACV are working right. Get the car up to temp and make sure the car has the bouncy idle. Take the intake off so you can get access to the throttle body. If you look inside the TB you will see two small holes. The lower one is for the FITV valve and the upper is for the IACV. Put your finger over the lower hole to block the FITV if the Idle settles down then the FITV is playing up. They can be cleaned out but never done this. Also make sure the coolant is full and no air as this will cause the FITV problems. If this doesn't work then put your finger over the upper hole in the TB. The idle should go to base ~ 500rpm. If not then your IACV is playing up.

Definitely this ^^^ if you haven't already tried this. (Sorry, I didn't have time to read through the whole thread yesterday)

Post by **Merlin** » Wed Jun 13, 2012 8:59 am

A vid of what to do:

[youtube]wwm0-tlsNHk[/youtube]

BMCC · Post by **BMCC** » Wed Jun 13, 2012 10:31 am

A quick edit to my post, if you put your finger over the upper hole then it will stall as no air is getting into the engine! If you pull the IACV electrical connector then it should go to base idle 500rpm as no air should be getting in from the IACV. Only air getting in should be from the base idle screw (Found on top of the TB). Air enters the upper hole splits to the IACV and the base idle (you turn the screw to adjust the amount of air getting past it).

You can see from Merlins vid that there was no effect on the idle when the bottom hole was blocked but the car was going to stall when the top hole was blocked. I believe the dodgy idle on Merlins car was a faulty alternator signal since a new alternator cured the problem. The ECU picks up signals when the alternator/power steering/brakes/air con etc are on and opens up the IACV so that Idle quality isn't affected by the extra strain on the engine these cause.

The FITV is usually the cause of a bouncing idle as far as I can tell though so it is a good place to start. Chapter 11 of the 4th and 5th gen manaul goes into how to test the idle control system.

Rich · Post by **Rich** » Wed Jun 13, 2012 11:34 am

Again, thank you all for your help. I will look at this later today and hopefully get it sorted once and for all. Cheers!

Rich · Post by **Rich** » Wed Jun 13, 2012 2:53 pm

Just had a look at the car again:

I got the car up to temp, parked up and removed the intake. The idle was bouncing between 1000-1500rpm.

Here's a video:

When I blocked the bottom hole there was no change - so am I right in thinking the FITV is OK?

When I blocked the top hole it went to a steady 1000 rpm instead of stalling... It also did the same when I removed the IACV connector. So it may be the IACV? But the base idle appears to be high. Could someone have perhaps fiddled with the idle adjusting screw?

Strangely enough, when I pushed the throttle cable the wrong way (not in the video) the idle also settled, but at around 1250 rpm this time; still way high, but could it be that someone has adjusted the throttle and the idle adjusting screw?

I checked the hoses and they all seem OK, only did a quick check though. I still need to bleed the radiator too to ensure there is no air in the coolant but I want to leave that 'til last as it is a bit daunting.

Lude Generation

Rich's BB4

Re: Rich's BB4 - "Tulip"

Re: Rich's BB4 - "Tulip"

Re: Rich's BB4 - "Tulip"

Re: Rich's BB4 - "Tulip"