Built RB25DET running badly when Cold

[Malar1898]

Hi all

I recently bought a built R34 GTT. The Car is making around 350kw and uses a Haltech Plugin ECU.

It runs beautifully when warm, but has some troubles starting up when cold and responsing to small throttle inputs. It actually manages to stall if you give it really light throttle and won't turn on again (i guess it drowns in gas) for some time.

If you push the throttle a little more it will response correctly, this also happens during Cold Engine driving and switches as soon as a temp. Threshold is aquired (feels like a different car).

I'm getting in Touch with the Company that mapped the Car and built the Engine, but wanted to be sure its not some mechanical failure of the ICV or something like that.

I tried to show the behavior in this Video:

 

[Ben C34]

That's the tune. Get them to actually tune the cold start properly.

 

How long did they have the car for when they did the tune?

[Malar1898]

I have no clue this was mapped by the previous owner in 2019, i think it can't be more than a day since they only put 2k CHF on the Invoice for mapping, and with how smooth the warm map runs they spent a good amount of time on that

[Murray_Calavera]

Do you have a wideband o2 sensor?

[Malar1898]

Yes, theres a single Wideband fitted and an external MAP Sensor.

The ECU is locked with a password tho, so i can't get into any Data beside logging that the AFR in Cold Idle is 14.2-14.7

[Murray_Calavera]

Ugh, bloody locked ECU's.

Have you asked the tuner for the password? 

Seeing as you have a wideband, you could sort this out yourself very easily once you get access to the ECU.

[Malar1898]

Yes i asked him for the Password today, as i only got to it couple hours ago. Had to sort minor other stuff on the Car first and only own it 2 weeks now.

I work in IT and made an apprenticeship as a car mechanic, so i have a Basic Knowledge about what AFR, Ignition Timing, Cold Enrichment and such is, but actually no idea how i'd tackle that behavior of the car without breaking the Engine.

You're saying i could sort this easily on my own, do you think its running too rich? (Since the Garage is smelling like Gasoline running cold)

[Murray_Calavera]

When you get access to the ECU, post up screen shots of your fuel tables for: 

Base fuel map
Prime pulse time table
Post-start enrich table
Cool temp correction table

This will give us a good starting point. 

Also if you could log all the data for a cold start and upload it here that will be a massive help too. 

You won't break the engine mate, take small steps and you'll be fine. We can help you along the way