Evan Purple240zt Posted September 27, 2008 Share Posted September 27, 2008 This is for my RB25det powered S14. I finally hit the track again last night. Somewhat frustrating evening but good, because I am working bugs out. One of them being that I blow off more pipes than a cheap prostitute. I need to totally redo the I/C setup and bead roll everything. My first and fastest clean pass of the night was 13.15, not too bad since I am a horrible driver and couldn't get outta the hole to save my life. My real question here is about my 2nd to 3rd. The car was absolutely hauling through 1st and 2nd. Downright violent accelleration. When I would shift into 3rd and drop the hammer it would bog like there was NO power then all of the sudden take off. I mean, literally 1 second of bog. I tried pulling some fuel out of the acceleration map at 5k and above thinking I was overfueling when shifting and going rich. Garrett said he didn't see black smoke or anything. I never got a clean run in after I made that change. I was also having major problems with my launch, this car just makes NO torque down low. I couldn't light up those ET street radials out of the hole to save my life. Maybe I was being too gentile on the go pedal. My act clutch leaves no room for slipping. Its on or off. Suggestions or thoughts? Evan Quote Link to comment Share on other sites More sharing options...
Racinjitter Posted September 27, 2008 Share Posted September 27, 2008 Is your engine a s1? If so I would suspect the igniter. They seem to get hot and just shut down for a second. Mine did that a few times before insulated it with rubber feet. It has not messed up since then. You also may want to check out the ground wire that comes off of the coil harness and bolts to the valley in the head. Corrosion between the head and the connector is pretty common and will cause things like this. As for getting out of the hole... Clutches are cheaper than drivetrain hard parts. I have ben experimenting with different laubch rpm's with my car. So far launching a 3500 yeild me a 2.10 60' time. I also feather my clutch though. I completely agree, rb's dont make torque. I am going to the track again tomorrow. I have to get a 1.9 60' and a 12 second run before the season is over. Quote Link to comment Share on other sites More sharing options...
Canadianz Posted September 28, 2008 Share Posted September 28, 2008 Racinjitter, Our RB does the exact same thing, Im not sure either what causes it. What all have you done to you RB ? I was reading on skylinesaustralia that if you max out the AFM the computer drops the timing and fuel. Im running just the stock ECU and injectors at 10psi and its really rich by my wideband but when it drops like you say it does go lean so im wondering if it is the AFM issue. On a side note if I get into it a little slower it never seems to happen its just if I floor it. Im running the series 2 RB25 and it doesn't have an external ignitor. Any how this is a very interesting thread I hope we figure it out Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted September 28, 2008 Share Posted September 28, 2008 I can't express detail from an RB25 ECU, but if you max out the MAF and it doesn't hit fuel cut, then you will basically peg the signal. The higher beyond this you go, the leaner the car gets. I am sure it ramps timing way down when it gets in that range for protection. Sounds like time for some upgrades. Quote Link to comment Share on other sites More sharing options...
Racinjitter Posted September 28, 2008 Share Posted September 28, 2008 Racinjitter, Our RB does the exact same thing, Im not sure either what causes it. What all have you done to you RB ? I was reading on skylinesaustralia that if you max out the AFM the computer drops the timing and fuel. Im running just the stock ECU and injectors at 10psi and its really rich by my wideband but when it drops like you say it does go lean so im wondering if it is the AFM issue. On a side note if I get into it a little slower it never seems to happen its just if I floor it. Im running the series 2 RB25 and it doesn't have an external ignitor. Any how this is a very interesting thread I hope we figure it out I will try to duplicate the issue when I am running the wolf ecu. That way all of the data can be recorded. I am pretty sure it was the igniter though. I am pretty sure the MAF doesn't max out with the stock turbo. IIRC they can meter enough air for 350whp and the stock turbo will max out between 300-325 whp. My rb25det is completely stock including the turbo. The only things aftermarket are the FMIC and exhaust. Also The most boost I ran is 14.5 psi. When the issue first occurred I was running stock boost and had just washed the car. However after a few weeks of not driving it, I went for a long drive (very spirited) ~100 miles and a few miles away from home it would cut out sporadically. I then suspected the ingiter and isolated it from the coil cover with rubber feet. The issue has not returned. When I replaced the spark plugs down in Branson Z fest, I noticed that the coil harness ground eye lit contact area on the head was very corroded. I cleaned it then. When I changed the spark plugs I changed brands also. I went from NGK to ac delco spark plugs. My engine did not like NGK's for some odd reason. When I bought the engine it had HKS spark plugs, but I never started the car with them. I know who I can contact to fully diagnose this issue though... Motohiro Matsumura will know what to do. E-mail is sent. (I wish I could speak japanese) His english is hard to understand sometimes. Quote Link to comment Share on other sites More sharing options...
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