S15 Sr20det swap, won't idle, runs rough and stalls.

[Reveleven]

I just picked up a 1990 S13 240sx, the shop I bought it from was in the process of doing the swap. They were putting an sr20det (notchback) S15 in it. I bought it missing a lot. The engine bay was pretty bare. I have been ordering and piecing together, I have my IC, intake, MAF, O2sensor, and bov all connected. For the exhaust, all I have is the downpipe on there so I don't know if there isn't enough back pressure, or I have some open vacuum lines. But as far as the vacuum lines, I've plugged what I thought was not important.
I just replaced the ever so fouled spark plugs.
The car will start and hold a strong idle for a few seconds and then start sputtering and start to fall in it's face, when I give it throttle it starts to just pop with no sign of throttle responce and then finally dies. (All within probably 5-10seconds.)
If anyone has any tips, ideas or can show me some vacuum diagrams and electrical diagram's. That would be most dope. Please and thank you. Haha.


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[SilviaSR20DET]

check the maf and tps sensor first then see what happens.

[Reveleven]

Unplugged and checked the MAF sensor. Either way it runs rough and acts almost as a limp mode. Talked with another 240 owner and he said it needs a tune. Do you agree?


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[l adam l]

S15...does it have 6 speed? Sure it's not an s14? What ecu do you have and what maf? Maybe wrong maf...

[Reveleven]

Yes, it has the 6 speed and I bought it from a ago half swapped, the ecu was already wired in... The shop gave me a part number for the MAF. And I ordered one.


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[Dillinja666]

Check your grounds, if it was half swapped they may not be hooked up yet and causing havoc sensor wise.

[Reveleven]

Ground from where to what? Sorry if it's a dumb question.


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[Dillinja666]

There are a few of them, the main one for the sensors is on the intake manifold close to the firewall. There should also be ground going from the engine to the body and obviously from the body to the battery. There is also another one on the back of the cylinder head, one coming from the alternator to the body and one for the coil packs. I think thats it. My Sr20DET is swapped into a 510 so everything is kinda moved around a bit. I'm sure somone will chime in with more specific locations in a bit.

[PedroJG]

Have you checked fuel pressure? My car would start perfectly fine but after a couple minutes of driving the fuel pressure would slowly decrease causing my car to sputter and them eventually die. Won't hurt to check the fuel pump?