Strange idle problem with GTM SC Stage 1
 

I sent an email to my tuner and Sam at GTM, but I wanted to see what the other FI people thought about this idle problem. I have had this problem since the SC kit was installed several months ago. Other than this idle problem, the kit has been fantastic.

Everything pointed to slight exhaust leaks I had with some test pipes. So I put the stock cats back on using all new OEM hardware including inlet/outlet gaskets. Going back to the stock parts fixed the daily SES lights, so I am 100% sure there is no exhaust leak now.

However, I still have an erratic idle. This is video of the problem. It happens at least once a day. What do you guys think might be causing this? You have to watch the entire video, but the car tries to die at about 40 seconds.

EDIT
The problem usually happens after exiting the highway and stopping at a traffic light for example. I was just able to get the video on a restart of the car. It only happens when the car is well warmed up.

Weird. I don't have that problem. What spark plugs are you using?

If I remember correctly, they pulled the OEM plugs to verify they would work OK. I am almost positive they just changed the gap on the original plugs.

I haven't had that problem ...

Dont count on me on this one as i do not know for a fact if spark plugs will adversly affect the idling. Just a suggestion, before when I had the STILLEN sc I was running stock spark plugs also and had major idling issues, wayyyyy worse than what you're experiencing.

GTM did installed some HKS spark plugs on my car when I switched kits. Now I don't have any idling issues at all!

It could also need to have the ECU relearn the idle... I had this problem on my G37 and that took care of it.

Im not sure if that is the same problem you are having... mine would die while coasting... scary when Power steering didnt work anymore!

Mike

Is the AC compressor kicking on?

The erratic idle is independent of the AC. It happens with the AC on or off. It was off during the video.

Thanks for the responses. I am waiting to hear back from Sam and Kenny, but I am leaning towards changing the plugs and trying the ECU learning.

If you watch the video close from start to finish, you see the idle bounce around 50-75 maybe 100 RPM. It feels like a slight knock which I hope are the spark plugs. Then at around 40-43 seconds in the video when it dramatically dips, the car shudders and usually the idle shoots to 750 and stays there. It is really odd but it happens at least once everyday. It is hard to reproduce though. I cannot make it do it.

Bullitt
Mine has never completely died. It comes close and only at idle for 30-40 seconds like at a stop light. It does not happen when rolling luckily.

weiboy718
Do you know the part number for the HKS plugs?

is the car not supposed to drop to 500? my Gtm stage 2 occasionally dips to 500 at a red light and shudder slightly as if its gonna "stall" but always kicks back up. Seb at Specialty z says its normal.

Vapor lock?

I'll get you the part number tonight or better yet you can call Sam directly. Pretty sure he's got all the info you'll need and what you need to do.

These are the spark plugs GTM Motorsports*::*IGNITION SYSTEM*::*HKS M-Series Super Fire Racing Spark Plugs (Heat Range 8)

i know you gotta pay to play but damn!!!! $30 a pop. ouch!

My old M3 would do this too after I got it tuned. Never died, but sometimes felt like it was going to.

watching outcome for future knowledge :)