Issues With RB20 Swapped S13

Discuss the RB20, RB25 and RB26 series engines.
FawkesThat
Posts: 15
Joined: Wed Oct 15, 2014 10:34 am
Car: RB20 swapped S13

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Hello All, I have lurked for a while know, reading up on different posts, but I have not been able to find the solution so I figured I would start a thread. Back story; I have a 1990 240sx (originally a single cam, automatic car) that I swapped in an RB20 using Zero Point mounts, and an OEM series wiring harness from Wiring Specialties. Car was tuned for 444cc injectors, running a Z32 MAF, and a T04E on 17-18lbs of boost. The RB I bought came with a top mount manifold, the T04E (that needed to be rebuilt), LS2 truck coils, and a Freddy Intake. I got the motor put in with no issues (other than the mounts setting the motor a couple inches back so I needed a custom driveshaft), the wiring harness plugged up, the battery relocated, front mount hooked up on the car, vacuum lines ran, etc. Went to start the car for the first time, fuel pump wasn't priming. No big deal, just put a jumper in the relay to get it going. Started the car up, and the idle was very high. Started to go over my wiriing, and noticed that the MAF was unplugged. I plugged the MAF in, went to restart the car, but the car wouldn't idle. Car would run rough, sputtering around ~600 RPM until it would die, after 5-10 seconds. I have read a ton of posts, trying to fix the issues. So far, I have tried..
-Replacing the MAF (tried two different working MAF's with no difference)
-Tried trouble shooting the TPS, checking resistance and voltage (even tried installing a known working TPS, and setting the TPS voltage to .45-.5)
-I pulled the AAC, cleaned it, and tried reseting/adjusting the idle screw, with no difference
-I have tried unplugging the AAC, does not change anything
-I have checked for vacuum leaks (only leak would be open air breathers I'm running on valve covers, but even plugging these does not change anything)

I am waiting for a consult cable that I ordered to come in, to help me better trouble shoot. I can keep the car running if I feather the throttle, but as soon as I let up, it never "catches" idle, it just bogs and dies. One thing to mention as well, I was testing everything with a GT3071r, instead of the T04E. I had someone holding the idle around ~1000 RPM the other day, while I was checking for vacuum leaks. I noticed that the car started to smoke a little bit, it was buring oil. I turned the car off, pulled the down pipe and intercooler piping, and had a bunch of oil in them. I checked the drain to ensure it was properly draining by pouring some oil into it through a funnel, and there was no problem. I am using a restricted feed, so it led me to believe the seals are bad on the turbo, or that I'm getting horrible blowby, even just at lower RPM. I ended up picking up a rebuild kit for the T04E, so I just pulled the 3071 and through on the rebuild T04E.

With all that said, I believe that the issue may either be a faulty AAC, though I have read multiple places that they do not go bad too often. I think that I read that a KA AAC can be used, but I'll have to double check that, and look for one locally to try and test. The only other thing that I could thing, is that I just need to set my base timing higher, which I believe that I will be able to do once I get the consult cable in. I have installed ECUTalk on my computer, but I'm not sure if that program just provides monitoring/datalogging capabilities, or if I will be able to make any adjustments on it. Any one know if there are better programs, mainly looking for something free to download, but I am not opposed to paying if it is worth it.

Sorry for rambling, I tried to put in all information that I figured was pertinant, in a logical manner. I have to say that I am honestly stumped. This forum has provied a wealth of good information, just wanted to see if you guys and gals had any ideas for me.

Thanks


mixeds14
Posts: 601
Joined: Tue Feb 26, 2008 12:44 pm
Car: 240
Location: nc

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U need to try another ecu. I seen people have that maf problem and the only thing that solve it was another ecu. If u can get ur hands on another one, I would try that and rule that out..

FawkesThat
Posts: 15
Joined: Wed Oct 15, 2014 10:34 am
Car: RB20 swapped S13

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mixeds14 wrote:U need to try another ecu. I seen people have that maf problem and the only thing that solve it was another ecu. If u can get ur hands on another one, I would try that and rule that out..
Thanks for the response. I would definitely try another ecu, but I believe that is going to prove hard to do. I would not only need to find another RB20 ecu, but one that is tuned for a Z32 maf, larger injectors, different turbo, etc. Honestly, if it comes down to it being the ecu that somehow go fried, I will probably switch to a Megasquirt, or some other stand alone.

That being said, if anyone is in Texas with an ecu that wouldn't mind me trying, please let me know!

5M0K3
Posts: 7
Joined: Wed Apr 05, 2017 10:51 am
Car: 96 240sx RB20DET

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+1 for tune. Seems like your tune is f****** up.

FawkesThat
Posts: 15
Joined: Wed Oct 15, 2014 10:34 am
Car: RB20 swapped S13

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5M0K3 wrote:+1 for tune. Seems like your tune is f****** up.
Whelp, lets hope not! *crosses fingers*

I get in the consult cable today, counting by the hours at work until I can rush home to hook it up. I wired in the consult plug the other day, hoping that I dont have any issues with connecting on my computers end.

FawkesThat
Posts: 15
Joined: Wed Oct 15, 2014 10:34 am
Car: RB20 swapped S13

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Well, finally got my consult cable in. I downloaded ECUTalk, free verison of Conzult, and two other programs (Nissan DataScan and Scan Tech I believe), but could only get ECUTalk and Conzult to work. I checked out each program, and tried to check the readings on most of the senors, verifying them off info in the FSM / different forum posts. My TPS was reading around ~.38V through each program, so I adjusted it up to ~.44V, at closed throttle. At wide open throttle, its reading 4.10V. One of my Z32 MAF's was reading around ~.57V, but my girfriend said that it was bouncing around a little when I would attempt to crank it, or even just in the key on. I swapped it with a different MAF, voltage at key on is .5V. Looking at the "duty cycle" of the AAC valve, during cranking it would shoot up to around 80%, I'm not sure what this should be at. My timing said that it was at 16*. Temp. Sensor was giving a reading of around 84* F, which is ambient temperature. I'm sure there are other's I am missing, but I cannot thing of any right now.

I pulled codes again for the heck of it, the other day it had said no faults. This time however, I pulled Code 21, Ignition Signal. I did a quick google, saw plugs could be a problem, swapped them out, cleared codes, tried to start car, nothing. Pulled codes again, still Code 21. I checked all the connections on my LS2 coils, everything felt good, checked the coil plug on back of motor, igniter plug, spark plug wires, etc. Cleared codes, Code 21, wont start.

For the heck of it, I unplugged the MAF again, and car fires right up immediately, Idle jumps really high. I turn it off, plug the MAF back in, car wont start. I'm super baffled, I can't even get the car to idle right now while giving it gas, it seems like it is missing ( which doesnt make sense, when I pull the MAF it doesn't sound like it is misfiring at all ).

Any help would be appreciated, I haven't seen much on the forums about what Code 21 could be. I checked the FSM, not a whole lot of info in there as well. I'm starting to think that the ECU may be the problem as well, but I'm really hoping that isn't it.

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LSDrift
Posts: 199
Joined: Wed Apr 19, 2006 4:54 am
Car: 1990 RS13 RB25

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Just throwing this out there...and there's a fair chance I'm way off...but have you checked any of the wiring between your MAF and the ECU? I realize you have an awesome harness from wiring specialties (as do I for my S13/RB25) but that could be the culprit since it'll idle w/o MAF. My coil pack harness from wiring specialties had a wire backwards on one of the coils when I got it and it took me forever to figure out why I was running on 5 cylinders. Just a thought...I'm with everyone else though regarding the ECU/tune otherwise. That or there's a vacuum leak you haven't found.

FawkesThat
Posts: 15
Joined: Wed Oct 15, 2014 10:34 am
Car: RB20 swapped S13

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*UPDATE*
I have been out of town for the last couple months, so haven't really had a chance to go through the car. I ended up checking pretty much every sensor based on the FSM, replacing this and that, but had no luck. I finally bought the bullet and purchased a EMU from ECU Masters. I ended up getting a REALLY good deal on the standalone, wideband, IAT, and EBCS. They were a little backordered when I placed my order, which I was fine with, and they ended up sending out an upgraded Canbus unit so I didn't have to wait any longer :dblthumb: Awesome customer service, much appreciated! I downloaded an RB25 basemap, and made a bunch of tweaks changing the displacement, injectors, coils, e.t.c. I hooked everything up, loaded my basemap, and the car started right up. I had a steady idle, perfect throttle response. Now to go get it tuned!

I just wanted to post on here for anyone having the same or similar problems, as well as to thank you all for the posts and advice.


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