not sure if its a ecu problem but maybe someone can help

[ursin]

ok so having a starting issue with my rb25. running z32 ecu with nistune. i've got a rough tune on it and right now it idles and drives at cruise perfect. still a little rich under boost but its working at the moment. the problem im having is starting the car. during cold and warm starts it takes FOREVER to get this car fired up. i finally get it started every now and then and i can go drive it, as soon as im done i shut it off and if i try to fire it back up literally 2 seconds later it takes about 3-4 different tries of turning the key to get it to fire up. if i let it sit for a while and cool down its even harder to get it fired up. the one thing i noticed is that if i throw my battery charger on it it helps and it fires up a lot easier. i tried playing with cold and warm start enrichment tables but they didn;t do anything. im figureing its got to be a wiring problem. bad grounds perhaps? just wondering if anyone had a similar issue and could chime in. thanks!

[Matt]

Whats the injection time consult reports during cranking?

What injectors are you running?

Post your tune here also please

[PL]

Make sure your ECU is getting the Start signal. They should get 12V from the IGN key while cranking. If they don't get this they'll give the symptoms you describe.

Check in NIStune if the Start lamp goes red while cranking.

PL

[ursin]

ecu is getting start signal. running detschworks 740cc injectors. im going to do some street tuning with a buddy tomorrow so i'll check into the injection time tomorrow. i added some grounds today which i knew i was lacking on, seemed to be a little better. still not the greatest though

[PL]

Large injectors will always make everything more critical. The problems I've had (albeit with SR20's) with 740's have usually been from overfuelling while cranking. If engine didn't start first time then it would flood. Had to adjust cranking tables to help.

PL

[ursin]

yea i have a feeling thats what it is, what map, table exaclty should i be looking at? like i said its at both starts, with engine cold, and even when its at normal operating temp.

[PL]

I'm not sure which table it is for RB25 - and I don't have NIStune in front of me right now. Some of these table locations are still being worked out, so I'll leave this one for Matt. He drives an RB25 powered car too, so may know exactly which one.

I had to do some bench testing to work out exactly what table was needed for SR20's and in the end I found that the cranking pulsewidth was not reported via Consult anyway. This isn't very helpful but unfortunately that's how it was coded in the factory so we're stuck with it.

PL

[Bernardd]

adjust first time injection by the same amount you adjusted the k value for the new injectors. that should give you stock like starting.

[PL]

Matt has actually added this functionality in NIStune now, so when you do an injector re-size it automatically adjusts cranking tables. For engines where cranking tables are known anyway...

This was a recent addition.

PL

[Matt]

For Z32:
First time enrich is when it is cranking
After start enrich gets used once it starts and tapers off

Other later ECUs (SR20 etc) have various 'cranking' tables different names. Need to make these all common names when I get around to it

[ursin]

awsesome matt thanks i'll give it a try tomorrow. i'll post up the tune as well since it has been fine dialed in tonight. just on the street and we got it running 1 bar. rb25det stock with gt35r. pulls pretty friggen hard very happy with the setup so far. haven;t messed with timing at all yet since im going to do that when i get it on a dyno.

[Matt]

Yeah I still need to adjust cranking tables on my R34 after putting this change to the code. It takes a while to start. End up working on everyone elses cars before my own!