rb20det rebuilt and running needing some help...

Discuss the RB20, RB25 and RB26 series engines.
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cmoody2006
Posts: 2061
Joined: Wed Jan 31, 2007 7:13 pm
Car: 1993 Nissan 240sx vert

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This is what I am working with...

Started out in this car...
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tore it down and took it all to a machine shop.

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used cometic street pro gasket set and arp head bolts


did rhd swap and rewired everything to the other side of the car
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got the motor put in
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Got it running and idles fine without ic piping hooked up here's a video
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Running the buick coil pack setup but it had a ground wire that wasn't getting a good connection so thats what the red wire is in the video. My current issue is that it will crank all day long and won't start unless you give it a little help with some starting fluid on a cold start. Fuel pump kick's on when you turn the key on (Walbro 255 brand new) it has 40lbs of pressure at the fuel rail. I have another rb parts motor that I pulled the cas off of and if you plug it in with the key on you can hear all 6 injectors pulse/prime and you can hear the spark plug's fire. If you plug the cas plug back into the cas on the motor it fires right up b/c the fuel has primed into the intake runners. It run's good but everytime I go to start it I have to either prime the system like that or take the IC piping off and spray starting fluid to get it to initially fire up. I have been trying to figure out this issue for days now and I know there are smarter ppl out there than me so any advice is greatly appreciated.

More background info... I have rb20 stock maf and stock injectors and stock ecu. I have a v-band down pipe with no 02 bung in it. My stock 02 sensor plug is not hooked up. Was doing some reading and saw something about that could be my issue? but I was going to run my aem wideband o2 So I didn't care about the stock one. But since I don't have an 02 bung I can't hook it up yet.....


Yellow4g63
Posts: 3718
Joined: Mon Jan 20, 2003 6:07 pm
Car: 95 Nissan RB20 240SX RB20
91 Nissan NX2000 VE power
95 Nissan 240SX Stock
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Maybe the power for the coils and injectors aren't getting constant uninterrupted power when the car is cranking? I know when I hooked mine up wrong I had a hard time with the car starting. Also check to see if you wired the cold start source to the ecu. This will let it know the car is on and trying to start.

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cmoody2006
Posts: 2061
Joined: Wed Jan 31, 2007 7:13 pm
Car: 1993 Nissan 240sx vert

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Yellow4g63 wrote:Maybe the power for the coils and injectors aren't getting constant uninterrupted power when the car is cranking? I know when I hooked mine up wrong I had a hard time with the car starting. Also check to see if you wired the cold start source to the ecu. This will let it know the car is on and trying to start.
What specifically did you hook up wrong? And can you elaborate on the cold start source to the ecu? That sounds more like my issue here.....

Yellow4g63
Posts: 3718
Joined: Mon Jan 20, 2003 6:07 pm
Car: 95 Nissan RB20 240SX RB20
91 Nissan NX2000 VE power
95 Nissan 240SX Stock
Contact:

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I think it's pin 43 on the RB20 ecu plug.
this link has the info on which wire in the dash plug. start-signal-wire-t228994.html

I don't have a S13 anymore I switched over to a S14 so I really don't remember. It's on the forum just search for it.

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cmoody2006
Posts: 2061
Joined: Wed Jan 31, 2007 7:13 pm
Car: 1993 Nissan 240sx vert

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Okay so here's an update.... checked wire 43 on the ecu someone had cut that wire and soldered it back together but was corroded. So I cut out the corroded part and hardwired it to the orange wire on the brown plug (f1 in the fsm). Still having the same issue. cranks all day but won't start without ether. So I decided to check the codes yet again. Got code 12 which is for the maf. Someone has extened the maf wiring at one point on this harness and one of the wires got left out along the way.....


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cmoody2006
Posts: 2061
Joined: Wed Jan 31, 2007 7:13 pm
Car: 1993 Nissan 240sx vert

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wire 43 - orange wire on brown plug


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