Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Subaru WRX wont stay running once hot

General Tuning Discussion

Forum Posts



Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads


So here is the platform and background info:

2012 WRX, Cobb Accessport, Speed density (no MAF at all), E85 fuel.

The car when cold starts on first crank and will run without needing to feather the throttle at all. Even once warm, as long as you dont rev the engine, it will stay idling. Once you shut the car off and try to restart, I need to put the throttle to 100% and it will after several seconds run but quickly dies within about 3-4 seconds. If i let the car cool off, it starts normal again.

What am I missing here? Can someone point me in a direction of what tables / compensations I should be looking at? Thanks!

Sounds like the intake manifold is heat soaking the intake temperature sensor and throwing off the SD calculations.

Hello Kaipyroami,

I thought the same thing at first. I actually just logged IAT on the car while recording the issue. temps were only a couple degrees above ambient. Here is a link to a youtube video of the car exhibiting the issue:


The first time it stalls in the video I just revved it once or twice. the 2nd start i kept revving the engine to keep it running long enough to see the gauges on. the AFR seems to stay in range to where I think fuel is not issue, but i could be wrong. Also, I have every DTC code disabled to avoid any logic issues with MAF being removed, no cats, no TGVs, ect.

Thanks everyone for your help as always!

Anyone have any thoughts on where to look next?

so perhaps your IAT isn't really measuring the temperature of teh air in the manifold, and by opening your throttle 100%, you are able to get the cooler air into the manifold, so that the fueling is correct.

The stock car doesn't have that issue because the MAF handles that case.

Where is the IAT sensor located on your build?

Not a RPM limit is it? I spend a few hrs fault finding a similar issue, to find the RPM limit in a specific temp was missing a zero..... and killing the engine.

If you are still using the IAT in the stock MAF sensor your IAT won't show you what is really happening. Did you relocate the IAT to right before the throttle body or is it in the intake maniford?

@kellygnsd, Kaipyroami, and David Ferguson

Sorry for the delay in a reply. The IAT was relocated post intercooler, about 12in approx before the throttle body.

See attached photo for idea.

Attached Files
  • Screenshot_20180805-223741_Video-Player.jpg
  • Attachments may only be downloaded by paid Gold members. Read more about becoming a Gold member here.


Good question, I went and checked to verify. Here is a screenshot of the coolant vs idle RPM tables. All 4 idle tables are exactly the same. The car has Brian Crower 280 cams so they are a bit higher than stock.

Attached Files

For anyone with access to Accesstuner, I have uploaded the tune so you can look over the file if its helpful.



Also wanted to add that I did a compression test today on the motor, here are the results:

Cylinder 1 - 120

Cylinder 2 - 120

Cylinder 3 - 135

Cylinder 4 - 130


So I was able to get the car to idle when hot by making a change to the target throttle open table (both TGV open and closed). (see attached photo).

I have always left these tables set to 0 at requested torque = 0 and on a stock car that works fine. I am thinking with large cams this is just not possible.

Please correct me if I am wrong though, This could just be a hacky fix for an incorrect tune elsewhere.

Attached Files

Have you modified your hot restart/warm up enrichment tables for e85?

yeah ur idle tables are out if it will rev while u keep plusing the throttle. does ron98 table idle ok?

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?