A little help with idle (video inside)

J

japakos

Member +
Hey mates, I need some help. All of a sudden the car started doing this thing.
If I turn on the a/c it seems to cure itself . Sometimes it might get worse. When I start the car it drives fine but it sounds like a 3 cyl but doesn't go like one if I make any sense lol. When it gets worse, vacuum goes aroun -0.1 and jerks and then comes back. a/f is 14.5-15.2 . When it does that it goes lean like 16+ and then returns to normal. It drivers perfectly though, 1bar @ td04. It just jerks on idle and when it does, idle goes from 500 to 900 rpm. It's like hunting.
Any help?

without a/c


with a/c


With a/c on car is idling at 1000rpm steady, no jerks no nothing but it jerks if you floor it and try to take off.
 
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C

ChrisD

Member +
You are losing vacuum somewhere... 0.4 is low... you should be around 0.7 normally and when on ac it should increase a litle bit.

What's your idle rpm?
 
C

ChrisD

Member +
Check for leaks. Use a flammable spray like carb cleaner and spray around the engine bay and look for rpm changes...
 
J

japakos

Member +
Did that and found nothing. I even pressurized the intake and used my boost leak tester and nothing no leaks. It is getting worse when the car warms up and after a long drive. If you turn on the ac then idle goes to 600 and vacuum to -0.2 and jerks. Without the ac and after a good drive -0.4 vacuum 750rpm and engine shakes
 
R

Rev

Member +
Just a small test , unplug the air intake sensor...does it shake now?
Also after this test check the oil level.
Finally check the usual electrics as lower idle like this can indicate a drop in voltage.

After that it is fuel system but would check electrics first as in hot weather injectors can use more voltage to hold closed when less fuel is needed for the less dense hot air.
 
J

japakos

Member +
unplugged every sensor I could think of but still does it. hmm.. I actually think that it might be the injectors as you said. See, when it's cold it sounds like a boxer engine but as soon as it warms up it goes away but this stupid up and down idle is very annoying.
 
J

japakos

Member +
I just saw something. When on deceleration , vacuum reads -0.7 bar. On idle goes -0.4 and roughly -0.5. Any help here? Exhaust doesn't pop or anything and car drives fine. I have only idle issues
 
R

Rev

Member +
There are a lot of possibilities. I thought taking out the air sensor plug would show up leaning but it didnt.
I am thinking check spark plugs after reading this typical vaccum gauge guide http://www.atlanticz.ca/zclub/techtips/vacuum/

Scooby sounds usually come with water on the plug or a cable shorting so worth a try.
 
J

japakos

Member +
plugs changed, leads changed, king lead changed. Injectors supersonic cleaned, new injector kit installed. Still the same shit
 
R

Rev

Member +
Going back to your first comments the main questions are why is the idle so low.....only 500 rpm ? and why you get low rev leaning ?
 
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J

japakos

Member +
It's not low. Idle stays around 800 but when it starts jerking it's rough and sometimes it goes 500 and then back to 800. Problem is that when I start the car cold it sound like 3cyl, then clears a little bit but you can still hear it when warm. It idles and doesn't die when warm but it's rough and after some time it develops the thing I posted on video. :( I'm lost I don't know what else to check. Any ideas?
 
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