mabru

I'm running RB20DET HKS 264's in my RB25DET with no issues.

I would just like to add a little bit to this massive thread. My 25DET is getting really bad with this 4k rpm miss ............and I run Splitfires, so no solution is permanent. Edit: Fixed it. Car ran great last night then like crap this morning. I ran some errands and it wouldn't start after about one hour of operation. I managed to start it and it wouldn't rev above 2000 rpm, I also noticed the AFR showed that the injectors weren't pulsing above 2000rpm but the AFM voltage was fine. I nursed it home and threw on a spare CAS I had laying around, problem solved No more misfires, pulls to redline, no more sputtering. Finally.

No revs above 2500RPM = bad AFM.

You can't run both an FCD and SAFC, I've tried and failed, then took it to a shop who said it couldn't be done. They both tap the AFM signal wire and I guess it degrades the signal enough that it just screws everything up. As for install, yeah the SAFC is pretty easy, it's just a few wire taps then an intercept on the AFM sig. You can install it yourself but tuning it is another matter entirely, since you run the risk of leaning out and going BOOM.

I can't seem to upload images. I went from the board to the gallery and I had to login again, after I logged in it took away the 'upload images' option.

Memp is correct on their location, as for color mine have a clear-ish plastic covered cap with the wire then the top of the sensors themselves are green with a rubber o-ring. They are little cylindicral jobs, #1 is between cyls 1 and 2, and #2 is between cyls 5 and 6. You can't really see them unless you take the intake manifold off. I was able to unsnap the connectors with everything on the car from the top, I did get scraped up a bit and I don't have HICAS so that makes it a lot easier. I bought the car the way it is, it seems that whoever performed the motor swap didn't hook them up and tried to compensate by adjusting pretty much every other sensor. As soon as I got the car I started putting everything back to FSM spec and my performance went out the door. It's stronger than ever now though The SAFC threw me because it was actually reading knock levels similar to what I was used to on an RB20DET so I didn't think anything of it. The car ran really well off the line (VVT I'm sure) and at low boost but after that the ECU would yank the timing out.

I've been digging at this problem for a while. I have an R32 with RB25DET with most of the usual mods on it. The car never felt as fast as my old 32 with the RB20DET. I noticed a few strange sensor settings when I first bought the thing which led me on a wild goose chase. Making matters more difficult is the fact that the consult port isn't wired up and the ECU has no LED. I never bothered to look at the knock sensors because I installed an SAFC and it was reading knock just fine (or so I thought). I finally looked under the manifold and whoa! the knock sensors have no wires coming out of them. I had to custom make a harness for them and plug them into the ECU since the engine install was a hatchet job, I wish I knew what shop did so I could avoid them in the future. Long story short, I plugged the knock sensors into the harness and it pulls like a mule. I can't believe I didn't look sooner. So if anyone out there has symptoms that sound like mine, do yourself a favor and check out the knock sensors. Sorry for the long post but I'm extremely happy right now -Matt

The differences are enough to screw up cam timing but shouldn't be enough to cause valve/piston interference. I have a friend here that runs a shop and he swears up and down that he's done a few RB25DETs with RB26 cams and they have no issues. I'll give it a go soon. I have a wonderful Japanese comprehensive inspection first though 8(

Tomei's website has all the OEM cam info, http://www.tomei-p.co.jp/_2003web-catalogu...r_engindex.html click on camshaft, then specs on the top of the page. The lobe center angle on RB26 cams are a bit diferent than the LCA on the 20 /25 cams, I'm pretty sure that timing the motor using the standard marks won't work. I think that might explain the low compression and bad idling issues. I tried this swap on my old 20 with standard cam gears and could barely hold an idle and power was nil. At one point we accidentally retarded the exhaust cam 1 tooth and it actually ran a bit better. I'll be trying it on my 25det with adjustable gears shortly and will post results.

IMO the best sounding BOV are the Greddy Type S' venting to atmo. I can't stand that NFSU chirp the SSQV makes. I have an Apexi Twin Chamber and it makes the big 'Whooosh' sound but I'm not that fond of it.

If your pedal is self adjusting, was this a manual conversion car? If so, did you fasten the upper bolt that holds the top of the clutch pedal bracket under the dash. I've had first hand experience with one that wasn't bolted in. Through usage, the pedal bracket was bending slowly but surely until there was no more room to disengage the clutch. We kept having to adjust the rod to keep up but finally got the bolt put in (after bending the bracket back into shape that is)

Haven't taken any yet, it's really hard to tell from visual inspection. It looks a little different than the one I put in. The edges were a bit rounded off. I suppose the entire unit could be bad. I'm just happy the thing is back to normal. I can take a pic when I get home after work, I'm not sure how well pics will turn out though.

Update: I think I've nailed it. CAS nub was worn on the edges causing the timing to shift quite a bit. For the first couple minutes after starting the car it ran like a demon, then the ecu would pull the timing out and ran like garbage. Replaced the CAS and the idle changed, egt's changed, and fuel curve is out of whack now but the car still feels stronger. I need to retune. I'm pretty damned happy

Sounds kind of like a knock sensor going bad or maybe the plug is loose on one. Only because of the retardation, not sure if they trigger the engine light or not.

Yes, you need the engine to ecu harness. You COULD go splicing and soldering but that's worse than just running the other harness.

I'm not trying to threadjack but I have a timing issue that is drving me nuts. If all timing marks are dead on, what whould cause a light to read high advance off the number 1 plug (measured with a high tension lead)? The CAS is centered and three different timing lights have been used to check against one another but they all come up with approx 29-30 btdc. It's reading in the 30 degree range at idle and the car feels like it's lost a bit of power at WOT but feels ok at part throttle. I'm pretty sure I'm not screwing anything up with the timing measurement and this is the first time I've ever heard of this on an RB.

Outstanding post, nice pics

ECU an harness, they are different.

I have not, and I suspect that yes a bad knock sensor could cause this. My TPS seems fine, I've swapped the CAS so I'm pretty sure it's not to blame, I've checked almost every sensor and they all check fine. The only ones I've neglected to look at are the knock sensors, that would explain my loss of power, I'm not sure why the engine would think it's so far advanced when it isn't though.

I was speaking of the electrical connection socket, OEM ones are usually color coded. Doesn't matter though, it's the only 2 prong sensor on the water inlet there.

I have a similar problem. Everything on my RB25 is set up correctly and the car runs ok but makes me nervous. The cams/crank line up perfectly and the CAS is centered which in the past has always been around 15btdc. My motor claims it's sitting at around 28 degrees or so at idle and doesn't ping at all. It feels like it needs a little more advance but I don't want to do it with it reading as high as it already is. I've tried various timing lights and one of them was a snap-on, all of them read the same. The idle rpm is right, the tps is unplugged during the check, the engine is at normal temps, all marks line up, and I see 0 knock on the SAFC. I'm stumped, I can't find anything wrong with the engine or any of the sensors but that timing number has me concerned. My other RB never did this so this is a first for me. I'm glad someone else has a similar issue, I'd love to see the fix for this edit: Oh, all my timing checks have been on a high tension lead off the number 1 plug and not that stupid timing loop (which is 14 degrees off on my engine)

On a 25 it should be red or blue, it's the same general location as the RB20. The little TWO prong sensor on the radiator inlet on the manifold. The one prong sensor is the temp guage sender.

Right PowerFC's won't pull timing like the stock ECU. So all the sensors are good for with the PowerFC is the numerical reading which is what it sounds like he wants.

The fins on the water pump impeller could be gone, they more or less corrode and rot right off. I didn't believe it until I saw pictures.

25's and 20's share bolt patterns for inlet and exhaust, the 26 is different. You would need adapter plates or cut and weld to fit.