rb20det cutting out

[zrated]

Hi all,

Having a little drama with an RB20, 444cc injectors and z32 afm.

It seems to run ok on stock boost however even at approximately 12psi it cuts out at approximately 4000-4500rpm. I've move the tp limit up to 255 just to make sure it's not hitting that limit but it's still cutting out.

I've just completed a log on the dyno and i'm not too sure if the tps may be the problem? I held my foot down after it cut out while doing the log and the car bucks a little, revs up and cuts again but it looks as if the TPS is still at .44v when i'm flat footing? I'm not the best at reading these logs.

I've also noticed that the speed sensor isn't working properly and doesn't show up in the logs.

Can someone please check it over and give me some ideas?

Thanks

[zrated]

anyone? this is driving me a little insane

[Matt]

Sorry could only look at this tonight, looking at all the params in your log to work it out, and then what is in the Z32 address file

My money is on the missing speed sender. There is a 'Rev Limit Parked' param. This is used when the ECU thinks that you are reving the crap out of the engine when the car is stationary, so does an earlier cut

Currently that is 4400rpm. So without fixing the sender, try increasing that and should fix this cut problem

[zrated]

Disregard the whole 'Z32' titles as I'm not sure why I named the file name that.

Bit more info:

The car is an S13 (used to be CA18) with an RB20DET (R32) engine. The wiring is definitely up to shit; whoever installed the engine should be shot IMO.

It has some weird aftermarket speed sensor in the gearbox, the speed sensor was wired to the cluster however it wasn't carried through to the ECU so I've wired that up and it does record a speed. There is a problem with the sensor however, both the speedo and the ecu will show the correct speed and then cut out completely (reading zero) around the 90km/ph mark. You can see that in the new log too.

I changed the 'Safety Rev Limit' to 7500 but it still cuts out at around 4500rpm. The other thing which is strange is that on approximately 6-9 psi of boost the car will rev up and wont cut out however if I move the boost up to around the 12psi mark it will cut. It reminds me of the TP Load Limit but even if I change it to 255 it still does the same thing.

Any ideas?

[Matt]

looks like might be a TP safety limit also, related to speed. Does the neutral switch work properly (neutral light inside nistune?)

8E60 : F6 14 07 ldab VEHCILE_SPEED
8E63 : 5D tstb ; check if zero
8E64 : 26 39 bne L8E9F ; skip if not equal zero
8E66 : F6 FF E9 ldab XFFE9 ; REV_LIMIT_SAFETY
8E69 : 8D 2C bsr L8E97
8E6B : 24 32 bcc L8E9F
8E6D : B6 14 13 ldaa X1413 TP_2
8E70 : B1 FE EA cmpa XFEEA ; TP_LIMIT_SAFETY
8E73 : 25 2A bcs L8E9F
8E75 : 72 80 50 oim #$80X0050
8E78 : 96 50 ldaa X0050

added this to the attached address file. put the file in your c:\program files\nistune\address folder and increase from 64 to 255 and see if it makes a difference.

AF_LIMIT2,&H7EEA,1,1,1,1,TP safety limit

[PL]

RB20's most definitely need a speed input. Same as many other Nissan engines - notably SR20DE's. All these engines will run fine until held wide open at high load for a certain time. I can't remember the time for RB20's but S13 SR20DE will cut hard after about 6 seconds at WOT.

I had a local RB20 owner who actually used this to gauge the improvement in his driving! He figured that as he was hitting the cut more often that he was holding the throttle wide open for longer on the track. Fair enough. I fitted an oscillator board to the ECU to fake out the speed sensor and now he can hold it open for as long as he likes.

PL

[zrated]

added this to the attached address file. put the file in your c:\program files\nistune\address folder and increase from 64 to 255 and see if it makes a difference.

AF_LIMIT2,&H7EEA,1,1,1,1,TP safety limit

I added that into the address file and increase the limit to 255 however it's still cutting, this time at 5500rpm so it's a little higher but still not right. I believe the neutral switch is not working either.

It would be best to fix the speed sensor and neutral switch then go from there. Agreed?

I've swapped out a number of different things to try and narrow down this issue but nothing seems to work.

These include:

• Fuel Pump
• AFM (Upgraded from RB20 to Z32)
• Ignition Module
• Rechecked Ignition Timing
• Recalibrated TPS

Is there anything else that I could look at swapping out? The timing in the log seems fine so I doubt it would be CAS. Also, the car cuts power completely and doesn't missfire/stumble so I would assume that coilpacks would not be the issue either.

Edit: I'll also add that I took the car off the dyno, turned the boost down low and took it for a drive around the block. At wide open throttle on low boost in 2nd gear, it's also cutting out and the speedo is still reading 65-70km. Would it still be the speed sensor?

[PL]

Neutral switch doesn't usually matter. Many engine conversions just leave this open. So the ECU thinks you're always in gear. As long as the input for the neutral switch isn't shorted to GND - which would mean that the ECU thinks the car is always in neutral.

Are you sure the speed signal is getting to the ECU? It may be getting to the speedo but not the ECU maybe? A NIStune log would tell.

The way they cut doesn't seem to be at an exact RPM. It's just a matter of having high load, high RPM and then holding throttle wide open for a certain time. I bench test ECU's/wiring looms all the time for this...

PL

[zrated]

Are you sure the speed signal is getting to the ECU? It may be getting to the speedo but not the ECU maybe? A NIStune log would tell.

The speed signal wasn't getting through at the start because it wasn't wired into the ECU. I've since wired it into the ECU and it does work but the signal cuts out at 106km. See the pic below.

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One thing I've also just noticed, see the image above.... TPS idle is on and the TPS is reading 4.3v.... wtf?

Edit: I don't know why TPS idle was showing up in the pic above. I've rechecked the log and it isn't idle at that voltage.

I've also attached the current log and bin for anyone to look over.

[PL]

RB20 uses a separate switch for TPS Closed, so maybe that's not functioning correctly?

PL