Rough Cold/ Intial Start Rb25det Neo

[r324u]

I have been going back and fourth sometime now trying to figure out this cold start issue, It will crank and crank and then it will eventually start and the afrs go from about 9.0 up to 14.7 and will stay running without an issue. Almost immediately after I shut the car down (even when warm) and try to restart same hard start issue is present. I have adjusted cranking tables when changing injectors to which I thought could be my issue but at this point, messed with vq map etc etc but have no positive results. Any insight would be much appreciated


I am running the following:

Rb25det neo ( rb20det ecu)
550cc R35 Injectors
Hpx N1 maf in 2.5" tube

[iyarovoy]

.bin file of your tune would be a nice to have.

[Matt]

VQ map will not solve startup issues. Only those cranking enrich tables are accessed during cranking.

Automatic adjustments (tickbox) when resizing injectors are an approximation only. You will need to adjust each point in the crank table until it starts first time. Also make sure battery voltage is above 12V

[r324u]

Sorry I couldn't post the bin, I was at work and didnt have access to it. But will include it in this post.

So i tried a few things today and seemed to have better luck.

1.Loaded new map from start
2.Changed maf with vq generator
3.changed injectors from 380-550, unticked tim and unticked crank
4.Manuallly adjusted tim to get it started and adusted some crank enrich and she would fire over.


Car Idles fine and runs good, having a hiccup here and there when trying to restart but will play with the crank enrich some more tomorrow.

With above steps i have had better results than letting nistune auto tim and update crank enrich, not sure why that is.


*Also did a boost leak test found a small issue, However is the hpx n1 maf designed to leak if the connector is unplugged? I found that kind of odd that air comes out the top if unplugged, Is that common or is this unit defective.

[r324u]

Spoke to pmas directly, It is designed that way to prevent corrosion. However now that i moved on from that, I decided to do another boost leak test to make sure nothing else was leaking, I found that there was a pin hole in one of the welds directly where the mas sits, Well i think this is positive find, Not happy with the welds from my welder but will deal with that later, I am taking this time to start over and move away from the 2.5" piping go 3.5" as the 2.5" from what ive seen doesnt seem a popular choice and or has not been dyno tested by nistune. I Will start a new map and setup accordingly once everything is good to go thank you for your help.

[Matt]

2.5" has not been done since it runs out of resolution quickly, and involved cutting my existing piping to test. I should probably try a reducer and more dyno time to do a proper map, since a few people use this size

[r324u]

That would be cool, however I think its just not worth it, Sensor barely fits and requires a tad more work and seems to be very touchy from my experience. Could have been that leak as well but looking forward to upgrading to better platform 3" or 3.5".