Mi16 > Gti Sad

[scumbag 0]

I've got bouncy idle syndrome. Sometimes it will sit dead on at about 950 - 1000, then others it will drop to a near stall, then rev itself up. It will drop about 3 times and then cut out. When started I need to keep my foot on the pedal for a minute or so. There is no autochoke as such. Due to these problems I am guessing my sad thingimajig is up the duff as it works one mo but not the next.

 

If you agree that this is the likely cause, then is an Mi16 SAD compatible with a 1.9 GTi? Many thanks!!!!

[jim21070 2]

So have I to a lesser extent. I THINK I may have finally found my cause.

 

The SAD will ony have an effect when cold. When completely warm it will block all airflow and effectively remove itself from the equation. That is, if it is working correctly.

 

Very carefully check everywhere for air leaks firstly. Give the whole inlet tract and breather pipes, oil pot etc a really good clean out and check for perishing that may admit air. The AFM may be worn and need a re-track.

 

If your idle is still a bit bouncy, check your throttle butterfly shaft. I have had an erratic idle, but not excessively so, for ages and I have found a bit of play in my throttle shaft bearings. This can let air in and a give-away is that the idle screw has to be nearly all the way in to achieve a slow idle. I have just refurbished another and will fit it as soon as I can.

 

I stress this should be your last port of call. Air leaks somewhere else are the most likely cause, folowed by a worn AFM.

 

An Mi16 ICV will not work as a SAD in an 8V. A totally different amimal.

[scumbag 0]

The SAD will ony have an effect when cold. When completely warm it will block all airflow and effectively remove itself from the equation. That is, if it is working correctly.

I think mine may not be working correctly, as even if I have been driving for over 45 minutes etc it will still cut out at lights. The odd thing is that sometimes it will idle perfectly, sometimes it will cut out. Because of the randomness this is what I dont understand. I think before I buy a new SAD I will spray carb cleaner in the throttle body, down that hole on the top which sometimes fills with gunk,and remove idle speed screw and fully clean it!

 

I am guessing that the place i need to check for leaks is between the AFM and the TB? There is a small hole up further between the afm and filter housing!

 

Is this the way to go about it? and is it literally a case of spraying the carb cleaner in the TB and working the throttle and wiping out?

[jim21070 2]

Yes, check for leaks between AFM and inlet manifold. The hole between the AFM and Air Filetr is not a problem at this time.

 

Here is how I would test for leaks: On a cold engine, slip off the rubber bellows between the AFM and TB. Pull off the small hose from the top of the TB that goes to the oil filler cap and block off the hole in the TB.

 

Now grab the hose that goes from the rubber bellows between AFM and TB and the SAD and blow down it with your mouth. Air should blow out of the TB. Place the palm of your hand over the open end of the TB and blow again. You should be able to form a high pressure like this and turn purple. You are blowing down the open SAD and thus pressurising the inlet manifold. You'll certainly know if anywhere is leakings as you'll hear a gentle hiss and you'll not maintain pressure. If you do leak, it just might be that the engine has stopped in such a way that one set of valves are on overlap and you are blowing down the exhaust. Rotate the engine just a bit and try again. I stress that you should be able to really puff your cheeks out and turn purple doing this test.

 

Check the rubber bellows for splits whilst it is off. Check all breather hoses that attch to the oil pot and AFM - TB bellows for leaks/perishing.

 

Reassemble to the extent that you can start the engine. Run up to temperature and then repeat the above by blowing down the SAD pipe with the engine off. The SAD should now be closed and you should not be able to blow past it. Your face should turn purple again.

 

This is a very simple test for leaks and will find most of them in my experience. It's not a bad test of the SAD either.

 

You can use WD40 or similar for leak tracing but in my opinion it's a messy procedure.

 

Another good test is that with the elbow between the AFM and air filter off, you should be able to easily stall the engine by putting a board across the AFM intake to block all air. Don't use your hand as the suck can suck it in and that hurts! If all your bellows are good, this test works from your air filter can intake too...

[scumbag 0]

Ideal many thanks. I will be having a go over next day or so so i will let you know how I get on! cheers jim

[pug_ham 244 3 Cars]

Mi16's don't have a SAD, they have an ICV which won't work on the 8v management.

 

What is your car?

 

Graham.

[scumbag 0]

I have a 1.9 gti 8v. I was looking through ebay and saw someone advertising a SAD that all. I think I now know what is what and am going to try the TB clearing method soon.