View Full Version : Fresh SR20DET swap will not stay running!HELP!

08-25-2012, 04:02 PM
Alright so I have a blacktop S13 SR20DET with the J4 ECU. I just finished the swap by adding my front mount intercooler. I go to start the car and it cranks over and turns on, however id idles very rough and shakes and barely responds to throttle movement, and then shuts off. I have no exhaust, its running from the downpipe, I dont think that should be an issue. Ive gone over all the wiring, and checked for vacuum leaks and I can't find anything. I believe all my wiring is correct otherwise it wouldn't even start and all my headlights and power in the vehicle wouldn't work, right?
Im not sure what i could have missed or what i am doing wrong.
Any help would be appreciated!

08-25-2012, 05:06 PM
check your maf sensor make sure its plugged in

08-25-2012, 05:19 PM
yea maf is plugged in of course. However who knows if it is good?

08-25-2012, 05:25 PM
check the timing?

08-25-2012, 05:26 PM
how can i check the timing if the car wont stay on or idle but for 10 seconds?

08-25-2012, 05:29 PM
Unplug the maf to see if it runs better or worse.

Edit- How old is your fuel pump and filter

08-25-2012, 05:45 PM
filter is brand new. the fuel pump is the stock 240sx pump, however i can still hear it and its squirting plenty of fuel, i think. and when i unplug the MAF it kind of runs better, but still wont idle or stay on. Doesn't respond to any throttle.

08-25-2012, 05:53 PM
its the maf for sure i had the same issue i was idling at 1200 running rough and it took a bit to pick up throttle switched it out ran like a charm

08-25-2012, 10:21 PM
well I thought it was the maf for sure too. I had a maf with part number 69F00 which i found out is for a S14? So i got a maf with part number 52F00 and the car was able to idle by itself and stay on now. However it still idled super super rough and shook super bad. Im able to rev it kind of and actually hear the BOV a little bit. But i am still stumped. I dont know what to check next..

08-25-2012, 11:04 PM
check your tps, and coils. I recently did my sr swap and i get bad throttle response and figured it was my tps. Rough idle could also be caused by the throttle cable being too loose on the tb, could be the gap on the spark plugs, could be bad spark plugs, or bad coils.

I have a feeling my coils are bad, my car idles fine until it warms up them starts missing.

Hope I helped. Keep us updated.

08-25-2012, 11:14 PM
ya im not sure, i dont even have my throttle cable hooked up right now. Compression is 150 straight across. It cranks up just fine with no problems, and idles super rough and cant open the throttle without it wanting to die. The motor sounds like it might have a knock, but im not sure.

08-25-2012, 11:20 PM
If the knock is slight it could be your injectors clicking, and hook the throttle cable up. The cable is supposed to keep the butterfly open a little to keep it at an idle. If you have it disconnected it will keep the tb closed too much and it wont want to idle. So if you can get the cable hooked up and get it to idle but dont have a good throttle response its probably your tps.

BUT first things first! Get the cable hooked up and adjusted.

08-25-2012, 11:45 PM
Make sure the fuel lines aren't switched. VERY common mistake.

08-27-2012, 12:05 AM
PROBLEM FOUND. fixed and runs like a charm. It turns out the company sent me the wrong ECU (J4) and i tried my friend ECU (E5) and it runs perfect. With the J4 ECU it was only firing on clyinder 1.