Hey all...

I had a local Evo shop install a set of new Cosworth Cams (both intake and exhaust) in my 9 a couple months ago. When I go to start the car ever since the install (and still to this date), the car idles properly until warm. Once the car is warm and has been driven (sometimes even when not driven) it has the weirdest irregular idle I have ever seen:

It sits at normal idle (approximately 750-850 RPM) for about 10 seconds and then jumps and holds at 1000-1100 RPM for anothe 5 seconds. It keeps alternating back and forth, back and forth, back and forth, etc.

Does this sound normal at all? What could be the cause of this and how can it be fixed?

My tuner did not alter the idle from stock because ECUflash cannot control the IX idle (Did someone figure out how yet?). This occurs when no accessories are on too. It is very strange because the BISS screw has not even been touched from my knowledge...

Let me know what you guys think!

Thank you!

 

Yes the proper tables have been found and work. Check the ECUflash forum.

 

Thread giving the correct IX idle tables. There is one more table on the last page, but adjustment of it didn't seem to change much at all.

I don't think increasing your idle speed is going to be the answer. I'd look in to your VVT map and see if any changes were made there.

 

the car must be tune if its not tunned then the idle air controll motor is trying to correct the the cams lobe your tuner will be able to fix the slightly irregular idle

 

Any other insight? Does this sound like normal untuned cam idle?

 

You actual idle speed shouldn't vary so drastically because of the cams. It will have a regular, "tight" idle fluctuation but not the drastic 200 RPM change you are seeing.

 

This is a wild guess.... but maybe one of your cam position sensors is damaged?
Of course it could just be the tune.

 

My idle was really bad after the cam install but after i got it retuned its alot better. The car lopes and you can tell i have cams in. Ill see if i can post a video of my car at idle

 

Im not worried abuot the loping. I just want to know why it has that 200-300 swing and hold in the RPM...

 

My car does the same thing with the cosworths it swings up and down 200-300 rpms. I got a check engine light code was "idle position sensor". I wish it could just stay at 800rpm instead of swinging back to 1100 or so and then back down. When i go back to Al i will ask him about this.

 

i just did a cosworth cam install on a customers car just last sunday. it also had a terrible idle problem right from the get go (idle dipped to 500rpm and then up to 1000 and back and forth). the tables in ecuflash had no effect on the idle, so we fiddled with the BISS and it idled better. then i remembered seeing those extra idle tables in a post so i added them and sure enough, it controlled the idle just fine. i moved the BISS back to were it started, and car idled just fine.


https://www.evolutionm.net/forums/sh...=283300&page=5

post number 66 has the link your looking for

 

Well I'm glad my post about the idle tables has been helpful. I hope those settings work for you.

 

Thanks again guys