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Popeye775

Idle Blip issue

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Here is an odd one for you guys. Started up my corrado G60 today and it started real funny. Started, idled around 1000 for a split second, then blipped itself to 1500 down to 800, up to 1500, down to 800 and did that a few times - almost like it was cammed - and then started to idle real rich because it was cold last night. Then while driving, every time i came to a stop the idle would come down, blip to 1500 and then come back down. Almost like the throttle got stock or something and continued to do this when i came to stops until it hit operating temp. I’ll add in a link so you guys can see it. In the video when it jumps from 1000-2000 is the car doing it itself. Not me at all. My CO Pot is set a little low - i think 350 OHM - so maybe in this colder weather it needs to be set higher because its compensating too much for fuel? I know my oxygen, or lambda, sensor is only a year old and maybe a couple thousand miles old. I also just tested it a couple of weeks ago and it read just fine, as well as checked the wiring for the lambda when I had done the bottom end swap in the car. As of right now I am not suspecting lambda but am also not ruling it out. The vacuum hose for the ECU is also brand new OEM vacuum hose that is exactly one meter long. This issue didn't come up until it started to get cold again (freezing at night) and the car had not been started for a couple of days. So my only assumption would be the CO Pot needing to be around 400 OHM instead? Any advice would be appreciated

 

Blips from 1000-2000

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Air / vacuum leak

sticky idle valve

Coolant temp sensor

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8 hours ago, Dox said:

Air / vacuum leak

sticky idle valve

Coolant temp sensor

Hi sir, I will search for vacuum leaks but wouldnt it be a consistent issue if it was a vacuum leak? It wouldn't go away once warmed up a bit if it was vacuum correct? My ISV is new but I am going to test it today to be sure it is ok. I got it maybe about 1k miles ago. Same with coolant tempt sensor. These are all things that I will look over to be sure they are good though

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As Dox said check...

Air / vacuum leak

sticky idle valve

Coolant temp sensor.

 

The blue coolant temp sensor can be checked by testing the resistance across the two pins.. it should be between 180 -220 ohms.

The resistance of the CO pot should be around 500 - 600 ohms  across pins 1 and 3 of the CO pot, turn the adjustment screw clockwise to decrease resistance or anti clockwise to increase it.  

 

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As Dox said check...

Air / vacuum leak

sticky idle valve

Coolant temp sensor.

 

The blue coolant temp sensor can be checked by testing the resistance across the two pins.. it should be between 180 -220 ohms.

The resistance of the CO pot should be around 500 - 600 ohms  across pins 1 and 3 of the CO pot, turn the adjustment screw clockwise to decrease resistance or anti clockwise to increase it.  

 


Update on the blip. I resistance checked my ISV, and my CO pot. CO is at 410 ohm - yesterday was at 360 so i adjusted it up about half a turn - and the ISV was within spec as per the Bentley. I checked the Bentley on the blue CTS as well but found a different reading for what the resistance should be than that? The Bentley has a chart for what the cts should be at in correlation to the temperature. So now I’m confused as to what the CTS reading should be?

I went for a drive today and it actually only did it one time in the middle of the drive. The car was already warmed up when it did it. Was coming to a stop and took the car out of gear - at around 2k rpm or so - and that’s when it did it but not one other time during the drive did it do it.


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Ah.. forgot to mention the Blue CTS reading of 180 -220 ohm is when the engine is up to working temp, 220ohm is the upper limit, so if it is 220ohm its best to change it for a new one.

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Think about it, to rev up the engine needs air containing oxygen to burn.

Throttle sticking.

Idle valve sticking

Manifold leak after the throttlebody - vac lines, PCV / hoses, gaskets etc

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Ok sounds good. The CTS is good then. All vac lines are brand new lines - OEM braided vac hose - and all gaskets are brand new and everything torqued to spec when 2L motor was put in. My assumption is going to be idle valve sticking or throttle sticking at this point


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Caught it pretty well on camera. The first blip was the car and the second time me trying to get it to stop. I had turned the car on for about five minutes to check for a coolant leak - fixed it thankfully - and then shut it off for a probably about ten minutes then decided to take it for a drive. First time the car was on it didn’t do it but when i turned it back on to go for a drive it did this after being on for a minute. ISV?


http:// https://youtube.com/shorts/yLywgWbHeec?feature=share


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Update on situation:

Seems like there is a theme. It likes to do it when its colder out and when the AFR is lower than 12 starting. It did it today a few times upon starting until i opened the throttle and gave it a little gas then it balanced out. Seems like ISV is maybe getting stuck?


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