My car runs for about 2 to 3 sec then cuts off. I have to hold my foot on gas so it doesn't cut off but once the engine starts to warm up it idles perfectly. Any ideas of what the problem is would be much appreciated

 

tune up /bad gas..

and what year is your car and what year is the gsr motor?

 

It's a 96 rs w a 96 jdm gsr

 

what ecu are you running?

 

I have usdm p75, p72 and jdm p72. I want to run the usdm p72 but it makes my car die after 2sec. But on the p75 it runs perfect. So I'm just confused about what is causing it to die w the p72

 

how is the car wired? DIY wiring, rywire kit or what?

 

it sounds like your not wired up properly. You need the matching obd2 vtec computer for the engine. the reason your p75 ecu works, is because it matches the obd2 wiring in your car. It just will not activate vtec. the usdm ecu needs to be the appropriate obd2 for your car otherwise it wont work. Why are you not using the 96'+ jdm p72 ecu?

 

when it struggles to stay running does it misfire ?

 

Na it dosent misfire it starts up fine and I figured the car wiring dosent match up but idk what needs to be switched in the wiring

 

And I'm not running the jdm p72 cuz I won't pass emisons

 

vacuum leak?

 

Is there a check engine light on with either of the ECUs? I'm guessing there is because the JDM GSR won't have the CKF sensor by the crank or the VTEC pressure switch. How do you have VTEC, knock and the IABs wired?

 

I jumped the ckf sensor and vtec pressure switch so those codes wouldn't be thrown and I made a separate wire harness for the vtec, knock and iab. So those 3 go right to the hook ups on the engine then are ran right into the ecu

 

swap ecu's in the parking lot

as others have said you have issues. the usdm p72 works on a jdm gsr if you have the wiring correct and have swapped the cfs, evap and usdm vtec solenoid