Hello,
I bought an MS3 with MS3X diy kit from a local ms dealer here in New Zealand about a year ago. I built it following the diyautotune.com instructions for a Nissan RB25DET. I got the car running and everything seemed fine until between 2500-3000rpms under load where there was a slight stumble which couldn't be smoothed out by tuning. The stumble wasn't huge but it was enough to drive me crazy. I tryed many things to correct it such as adding a noise filter to the 12v power and running shielded cable from the cas to the ecu, rerouting away from anything that would cause interference. I eventually found it was the combination of the megasquirt and the standard rb25 CAS. There was no loss of sync on tuner studio and I tryed another cas but that didn't fix it. The only way to fix it was by replacing the trigger disc in the CAS with a more simple disc. I used a 24-1 missing tooth wheel because I was easily able to source one of these. This fixed my problem and the car has never run better
Im posting this subject to warn others because I have seen a few other people having problems like this which could be nissan cas and ms3 related. I haven't had any problems with the megasquirt product other than this. Could this be a code related problem?
There are a number of customers using it with success, I don't know whether they followed the instructions in the manual or used DIYAutoTune's notes instead though.
Yea I tryed changing the injector timing (I found that fix in another post on here) but it didn't help me. It ran really rough at 270.
If that fix works for some installs and not others its a bit of an odd problem. Maybe its just me but I did find another person on here using the sr20det cas (the same as rb but 4 cylinder trigger) and had the same problem. They also fixed it by changing the trigger wheel.
Oh well if anyone else has this problem, the trigger wheel fixed it for me.
It was quite a while ago, about 9 months, when I did it but im pretty sure I used ve analyze live while at 270 and it didnt run well. Should diyautotune.com put something on there page about injector timing for RB25DET? Or is this just a round about way of fixing a problem that occurs on some installs. My understanding , albeit limited and correct me if im wrong, was that injector timing should be 360 degrees or more. If it needs to be less then why?
i'll let james and others address that question because honestly i dont know. all i can tell you is that the injection method worked for me twice on 2 seperate installs. maybe the rb25 decoder needs testing and fixing this glitch.
RB25DET Laurel wrote:Hello,
I bought an MS3 with MS3X diy kit from a local ms dealer here in New Zealand about a year ago. I built it following the diyautotune.com instructions for a Nissan RB25DET. I got the car running and everything seemed fine until between 2500-3000rpms under load where there was a slight stumble which couldn't be smoothed out by tuning. The stumble wasn't huge but it was enough to drive me crazy. I tryed many things to correct it such as adding a noise filter to the 12v power and running shielded cable from the cas to the ecu, rerouting away from anything that would cause interference. I eventually found it was the combination of the megasquirt and the standard rb25 CAS. There was no loss of sync on tuner studio and I tryed another cas but that didn't fix it. The only way to fix it was by replacing the trigger disc in the CAS with a more simple disc. I used a 24-1 missing tooth wheel because I was easily able to source one of these. This fixed my problem and the car has never run better
Im posting this subject to warn others because I have seen a few other people having problems like this which could be nissan cas and ms3 related. I haven't had any problems with the megasquirt product other than this. Could this be a code related problem?
Yes..the Nissan OEM CAS wheels suck. You did the right thing to change it to the 24-1.
On a KA24DE the stock CAS will casue serious kick backs and break starters constanly. The 4 slot wheel just doesnt have enough resolution to get an accurate RPM while cranking.
The MS3 Nissan CAS decoder uses the high-resolution teeth and shouldn't suffer from any kick-back during cranking. Even on MS2, there shouldn't be any reason to be getting kick-back with the right settings.
Yea it uses the 360 slots at low rpm. I only had a problem between 2500-3000rpm and it was only under certain loads while driving. Always at close to 100kpa. If I floored the throttle it usually wasn't very noticeable, neither if I babied it but if I just drove normally then this stumble was very noticeable.
Injector angle should be more than 360, I have the injector timing map for the RB on my tune that is working well in my L28. I can upload it. Change the angle to 390 and see if it helps.
Nissan Skyline R34 RB26DETT ran MS3/MS3X w/ factory Hitachi CAS (sold)
Nissan Silvia S14 RB25DE ITB/NA ran MS3/MS3X w/ factory Mitsubishi CAS (disassembled)
Datsun 240z RB25DE ITB/NA with MS3/MS3X
Now that I am not on my phone, I can show you a screen shot of what I use. Cant remember how I got it, maybe pulled it from a ROM in Rom Editor or Nistune, but here it is. The trick is not to squirt while the valve is open. You have to get the cam specs, this is from the RB26, but it should be fine. You have to figure out when the valve opens, which involve finding lob center and duration. I just change this entire map when I moved it over to my L28, seems to work fine. There are some articles online explaning injector angles but its late. Use this map for injector angle.
Nissan Skyline R34 RB26DETT ran MS3/MS3X w/ factory Hitachi CAS (sold)
Nissan Silvia S14 RB25DE ITB/NA ran MS3/MS3X w/ factory Mitsubishi CAS (disassembled)
Datsun 240z RB25DE ITB/NA with MS3/MS3X
