Cosworth Mivec 272's Idle problems
 

I had my Cosworth IX 272's installed about 2-3 months ago by turbotrix. We couldnt seem to figure out the idle issue that is occurring, which is a constant surge along with almost stalling and kinda no fuel at idle. I went through 2 tuners so far, Turbotrix and Mellon, and we just cant seem to get it right. Timing is on, the marks are on everything was installed properly.

Mellon has got me to the closest of solving the issue, as we almost had it idling perfectly. But me being stubborn I want some lope in my cams, and when we seem to lower the idle, thats when the issues start to occur.

Anyone have any suggestions or maybe Mellon can chime in...

Thanks,
Dan

how's your vaccum? I'm sure you've done it but if not do a leak test.

every cosworth MIVEC cammed car i have seen idles funny. i've tried many things to get them to idle better, and nothing really helps much. its not your install though.. its just the cams. if you go with GSC s1 cams they idle just fine.

if you want to meet up I'm from Brooklyn ny. I got cosworth cams in my ix also could compare. Send me a pm if you want.

Did a boostleak test, surprisingly it held 25psi with zero leaks and decreased very slowly. So it was holding boost great.Vacuum at idle is around 9-12. Stock turbo IX, full bolt ons, 680cc injectors.

This is such a pain in the ass lol.

Cosworths idle lopey. Is this more than lope?

+1...I have M2's and the idle is rough. Just something you sacrifice to have M2's.

Its a hit or miss with these cams. I had HKS 272's on my DSM and they were really lopey, so Im used to that. But my evo is half and half, itll be lopey when almost stalling, then idles like stock with zero lope at 900rpm with a decent afr. Its a very very inconsistant idle...

my idle sux...i get an SEL every other day...it is what it is...

I think it should be mentioned that I had them idling perfectly by the 2nd ROM I sent and it stayed that way for many revisions as I was working on the WOT tuning but suddenly it lapsed back to it's old self from what Dan is telling me.

my response to Dan yesterday but didn't get a response back yet

Hey Dan,
I have to wonder if the fan is kicking on/off while idling, that'll make the RPM change abruptly and send the stock ECU into a tailspin sometimes as the 02feedback trim tries to update the low fuel trim which moves slowly. About the time the trim catches up, the fan's status changes and you get into that fun loop :) I've noticed this on my own car. For the most part it idles good but sometimes it acts up a little bit. Also keep in mind that when you flash the ecu with a new ROM it had to learn all over again and that can require lots of driving/idling/driving/idling before it settles down and behaves.

Let me know what you witness and FYI I haven't made any changes to that section lately that would return it to it's old self.

I was having same problem.I put an HKS ignition in and IKH24 plugs gapped to .020 an d the problem is gone. I hope this works for you.


S

I also think it would be a good idea if after driving/idling/driving/idling it still misbehaves to go ahead and do a proper boost leak test and check for exhaust leaks around the head/header 02 housing/turbo 02 housing/downpipe

if outside air gets sucked in near the stock 02 sensor it's going to send the wrong information back to the ECU and wreak havoc.

They seem to idle better a little rich, unless that has been tried already.

I have cossies in my IX and had the same issue after install. I was using a Buschur racing intake pipe that does not have a fitting on it that goes back to the valvecover. I read somewhere on here that not having a vacuum line going from the valvecover to the intake could cause idling issues. So I installed a fitting into the Buschur intake and the problem seemed to be fixed. I'm now running a different intake that does have a fitting to connect a vacuum line back to the valvecover, and still don't have any drastic idling issues. What intake is on the OPs car?

I have an ETS intake pipe with the fitting going back to the valve cover.

I have done a boost leak test today and it showed perfect. No leaks whatsoever.

I double checked for exhaust leaks but cant seem to find one.

Now I did recently change to an APS BOV, but I made sure I teflon taped the top screw. I think I may have tightened it down to much, as it likes to buck now on low throttle/rpm shifts. I am going to revert back to my stocker and see how it idles to see if maybe that was the problem.

Mellon,
Sorry I didnt get back to you, but what I do have to say is Mellon is by FAR the best tuner I have had so far. Im not blaming him for not getting my idle right, Because he did get it down idling almost perfectly at 1000rpm with very little surge on his second try. Im beginning to believe it might be the APS BOV. Ill see what happens in the upcomming days.

I apologize Chris, I didnt mean for it to come off like you couldnt do the job. Because you did and you still are! {thumbup}

Mellon Tuning for the mother truckin win!

Dan