Rough cold start idle
 

First, a small background...
2014 BRZ, original motor ran perfectly fine with EcuTek tune.
Swapped out for a FBM built 2013 FRS motor and put on FBM turbo kit. Still original ECU, but with new EcuTek turbo tune. The below run was my first driving log and was only the 3rd time the motor was fired up, all times had the rough idle.


Now the problem...
When I first start the car, it idles so rough that it dies after a couple seconds. Have to keep starting and it dies multiple times before it warms up enough to bypass the cold start function(w/e its called). Once that 20 seconds or so has passed, it will idle perfectly fine. I did get a code, P050A which refers to the cold start and could point to many different potential issues.
Now, I also had my tuner review my last log and the "VVT on" didn't kick in until about 12-13 minutes into a 20 minutes log. Near the end I coasted, idling down a large hill which comes to a flat area then to a stop sign. When I came to the flat after the hill, I put into 3rd gear for a bit then pressed in clutch to coast to the stop sign. Somewhere between pressing in the clutch and stopping, the car died. Fired it back up at the stop sign and drove the 1/8mile away home and parked it. Been sitting since. During this log, I was driving very easy, never over 4k rpm. Prior to this log, I had the idle issue as well.
I am not getting a P0016/17/18 code to point to any specific bank or A/B, so I'm kind of lost as to where to begin.
I've removed all the OCV solenoids and pressed on the valve on the gear and all move smoothly. The OCV solenoids all test 7 - 7.1ohm and the pin moves freely. Some pins make a slightly different noise, such as oil pressing through a small hole and others don't. That's about the only difference.
Any advice on where to go from here?

YIKES, that is waaay over my pay grade!

Allow me to ring up ol @steve99 for you -:thumbsup:


humfrz

Car starts on port injection only then it runs on port injection only for first minute or two.


Then it runs whats in the pi\di ratio tables


Im guessing that you have bigger port injectors. If these are scaled badly or injectpr latency is set up badly car will often idle rough for first couple of minutes till di injection stsrt being used as a lot of tuners run 100% di injection in po\di tables. But this wont fix the period between startup and when di kicks in.


As for the vvt if the car wont idle properly after a tune reflash for about a minute with no throttle input then ecu eont eeont enable vvt. At some point car needs to idle with zero throttle before vvt will engage.


Could also be a bunch of other issues


Check your DI compiter is bolted up to engine will all three bolts, if hthat box has no earth weird stuff happens


also check for vaccum leaks especially hoses on underside of manifold , if your boosted did you clamp them as if not they will blow off with boost

@steve99

I double checked all hoses were clamped under the intake manifold. They are.

I removed the DI computer, cleaned up all points of contact by grinding the paint off of every spot. Resembled with my original DI computer.
Still the same result.

I also plugged in via Techstream. I played with all 4 vvt angles while idling and all function. None seem slow to respond or anything.

Where to go from here?

Oh, while idling, after the rough patch when it smooths out, if I give a steady light throttle to say...2k rpm, the idle will sit and fluctuate and want to die. It actually did die once. Just noticed this after I tested the vvt's.

As Steve said, it's probably poor port injector tuning. The latencies are likely wrong, and it gets covered up when the direct injection comes in. See if there are any canned latency tables somewhere on the internet for your specific injectors

they are Grams 1000cc.
I called Grams and had then email me their latest tables. I then sent them to HRI.
I think I will have HRI re map to stock injectors and swap to stock injectors to see if that solves the problem.
Unless anyone else has an idea???

@steve99 @DarkPira7e

Tried swapping to oem injectors with oem injector scaling, still no luck. Just as bad as before.
Any new ideas? I'm stumped.

When you swapped back, did you reset the rest of the fueling that was mapped for the larger injectors? I'm also wondering what your MAF scaling looks like for that RPM range if everything else is fine. Did you ever adjust your cold start and happen to adjust the MAF scaling table for cold start? It uses coolant temperature as a measurement for adjusting this scaling, until 20f the scaling is quite a bit different from factory. If you had accidentally copied the cold start values to the entire table, maybe that could account for this?

@DarkPira7e

I'm not the one doing the tuning, James Martin (HRI) is. I can reference this post to him and see if he can answer those questions for us. I would assume he did do everything needed, but it doesn't hurt to ask.

If he's tuning your car, I'd recommend working 1 on 1 with him about the issues with the tune. I have no doubt that this is something he can fix, he's definitely far better at this than I am.

I'm more or less trying to get ideas because I do believe in his abilities and if he says the tune is good that there is something else. It's the something else that he is unable to see via the Ecutek logs that I need the input on.

So injectors, at least I'm my opinion, have been ruled out as a cause.
Given all 4 vvts test via techstream to perform and are not slow to react, I believe the vvts are fully functional. I ruled out the vvts as a cause.
The ECU is not engaging th vvts though. As steve said above, it is most likely due to the rough idle.
DI computer is grounded well.
No visible or audible vacuum leaks.

So figuring out why it has a horrible cold start idle is what I need to do, and if the tune is good.... What else could it be?

Is there something I missed when swapping a 2013 FRS manual engine into my 2014 BRZ manual? Any changes that were made between the model years or makes that could be a cause?

I see that you have catch cans, have you always had them since adding a turbo to the car? I'm wondering if the MAF has oil buildup on it. Have you taken it out to check / clean?

I added the catch cans shortly after purchasing the car last year. I've not had a single drop in them since i put them in. When I switched engines from the stock 2014 to the built 2013, I changed them to vta.
The built engine had this poor idle since the first start after I swapped it in. The turbo was installed at the same time as the built engine.

Small update.
Primary o2 has been swapped.
Cam sensors have all been swapped.
Issue remains.