Stevemd24 Posted December 20, 2013 Share Posted December 20, 2013 I have a Rb20DET. It Runs as if its in limp mode,(super rich runs bad at 3500 rps or higher) but it throws NO Codes at the ecu, ITs has a Nistune, Type-2, when i got the car it ran fine, but on a random start it started acting funny, so as far as i know its nothing I physically did to the car... with a oscilloscope it showed a signal on the signal wire, pin number 27 The wiring harness looked like crap so i replaced the harness from a custom one from wiring specialties, but anyway that didnt fix the problem, and who ever built the car used like a 1980 power pack from a firebird or something so i replaced it with a new RB power pack To make sure its not the MAF i put in a good stock MAF (had a z32) Still didn't fix the problem, I went on to replace the ECU and had the Nistune re-flashed just in case it had currpted data Now while the car is running it runs the same with the MAF plugged in or not, So I am pretty positive the problem lies between THE MAF or the Ecu, does anyone have any suggestions? I personally was thinking I could maybe find someone with an RB20det and plugging in my ecu/nitune board into there car and see if the problem shows up in that car... here is a vidieo link https://www.youtube.com/watch?v=x0y1wGy2Zaw Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted December 21, 2013 Share Posted December 21, 2013 (edited) That's how that ecu family runs without a working prom chip in it. It could be anything from a badly soldered socket to a nistune board that is non-functional. To prevent issues in that case, I usually pull the prom chip undamaged from the ecu or burn another one from an image someone has posted online and plug it in instead of the nistune board. Seems the commonality is the nistune unit. Can you communicate with it in the nistune software? Edited December 21, 2013 by HowlerMonkey Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted December 21, 2013 Author Share Posted December 21, 2013 I can commuicate with the software. yes Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted December 25, 2013 Share Posted December 25, 2013 Can you communicate with the ecu? Can you see rpms when running or throttle position when key on and engine off? If you can, try sucking the tune from the nistune unit and save it as if you are going to burn it to a prom. Then compare it to a stock rb20 tune you can find on the internet. If you get errors when trying to do this, then it could be that he nistune unit has issues. If can insert a stock prom in the socket and the car still runs as described above, then it is a sensor or actuator affecting the ecu and putting it into crisis. I would check the easy stuff first and move on to the more complicated stuff if you get no solution. Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted December 25, 2013 Author Share Posted December 25, 2013 I had to reorder the cable i seem to of misplaced mine, but i will be getting back to you guys with i get it o and merry xmas Quote Link to comment Share on other sites More sharing options...
ihiryu Posted December 31, 2013 Share Posted December 31, 2013 Hmm, I have a chipped ecu from Carl H, so this may or may not apply to you. My car had a loose connection with the TPS. One minute the connection would be fine and dandy and the car would run great. Then the TPS would go out (while on the road) and the AFR's would go rich then lean, then back to rich. I ended up removing the plug for the TPS and hardwired it in, and that seemed to fixed my problem. Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted January 1, 2014 Author Share Posted January 1, 2014 this is what happened My car was fine as i drove to Safeway, when i get back in after shopping, it ran poorly, I took it to auto mechanic that said he could fix it he had my car for 6 months, and then sold it to another guy.. the new guy said he could fix it, He said the wiring harness was bad and its probably whats wrong with it, so i bought a new harness from wiring specialties (it looks great) it cleaned up my car and i am impressed with the results but it did nothing to fix my car, He said i should change the power pack cuz it was crap, and while i am at it my auto gauges, so i did, I got a new power pack and i bought some sexy ass gauges from speed hut, still didn't fix the problem My mechanic then said he had to be my ECU since my Maf Is showing a signal on the scope going to the Ecu, but the signal gets "lost" in the computer and it shows not having one... I bought a new ecu I had the nistune professional soldered onto it. It still didnt fix the problem, at this point my Mechanic gave up and just gave me back my car, I sent my ECU with nistune attached to it, to auto Vaughn performance he saids the the board looked good but he is going to reflash it just in case there is currpted data, and my soldered looks solid. He did it for free so i was happy with the service, got the Ecu back but my car is still not working, SO everything from the maf wires ecu have all been replaced, there is not much left i can do, i am at my wits in, i need someone that can look at my car and fix it, I live between san fran and Sacramento, and i cant find a decent Mechanic that can help me out, Id be happy if i could find someone with a rb20det engine to send my ecu to, so they can plug it into there car and at least eliminate or norrow down the problem to my car. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 5, 2014 Share Posted January 5, 2014 (edited) . Edited January 5, 2014 by NewZed Quote Link to comment Share on other sites More sharing options...
ihiryu Posted January 7, 2014 Share Posted January 7, 2014 You say the car runs poorly, can you be a little more specific? Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted January 8, 2014 Author Share Posted January 8, 2014 Not really sure how i can go in more detail, It runs in limp mode, Means the ecu uses a safe default map to make the car run but not run well... It chokes, back fires, the mixture is incorrect. anything over 3000 rpm and it shutters and almost dies Quote Link to comment Share on other sites More sharing options...
ihiryu Posted January 9, 2014 Share Posted January 9, 2014 And removing doesn't change anything? Usually when you disconnect the MAF she won't rev beyong 2500. Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted January 10, 2014 Author Share Posted January 10, 2014 Unplugging the MAF does nothing, I have changed the MAF THE ecu and the wires running between them... Quote Link to comment Share on other sites More sharing options...
ihiryu Posted January 11, 2014 Share Posted January 11, 2014 My vote is on a bad ECU then. You tried a different ECU yet? Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted January 12, 2014 Author Share Posted January 12, 2014 My vote is on a bad ECU then. You tried a different ECU yet? yes i have bought a new ecu, it doesnt fix the problem i tried a new maf i have tried a new wiring harness Quote Link to comment Share on other sites More sharing options...
ihiryu Posted January 16, 2014 Share Posted January 16, 2014 (edited) Check timing yet?? Mechanical and electrical timing. Edited January 16, 2014 by ihiryu Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted January 20, 2014 Author Share Posted January 20, 2014 not sure why the timing would be off, it was fine before, like i said it happened in mid trip, there is a signal going from the maf to the cpu (pin 27) but for some reason the cpu isnt reading it, but i have replaced the cpu, lol i really think its the nistune itself, best way to check it is to just plug it into another car takes less then 5mins, but i need to find someone with a Rb20det engine with a nistune chip Quote Link to comment Share on other sites More sharing options...
ihiryu Posted January 24, 2014 Share Posted January 24, 2014 But you said you've plugged in a stock ECU and nothing right? Quote Link to comment Share on other sites More sharing options...
Stevemd24 Posted January 25, 2014 Author Share Posted January 25, 2014 no i said i replaced the ecu i guess i could buy a stock one and see what happens Quote Link to comment Share on other sites More sharing options...
ihiryu Posted February 8, 2014 Share Posted February 8, 2014 I hAve a few stockers but am out of the country until the 15th Quote Link to comment Share on other sites More sharing options...
ihiryu Posted February 8, 2014 Share Posted February 8, 2014 Oh have you checked the physical plugs on the maf and ecu connectors?? Quote Link to comment Share on other sites More sharing options...
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