Okay guys, got my 300zx ECU/MAF, now have a few questions

[Guest bastaad525]

Just wondering if you guys could let me in on the perks/bugs/pickiness of this setup. I'm not quite ready to put it in yet, still need to find me a '82-83 distributor and z31 chopper wheel, but hopefully this will all come together soon.

 

Well I'm wondering what are any 'quirks' of the Z31 system?

 

For instance... I'm already running more boost than can be supported by the stock fuel injectors, at 13psi, and am using an RRFPR to give me the extra fuel pressure to cover it. Yes, eventually I will switch to 370's but not for now. So, how will the Z31 ECU behave with the RRFPR... any differently than the RRFPR works with the current system (which is quite well actually)?

 

What about the amount of boost I"m running.... will the Z31 ECU be able to properly measure that increased air flow without needing to be reprogrammed? I figure the Z31 ECU is a bit smarter than the '82 I'm running now... maybe it won't be so lenient with me running so much extra boost?

 

What about timing... does the Z31 ecu handle ignition timing any differently? I'm assuming that, since everyone raves about increased throttle response, I know the MAF is probably the big part of that, but does the Z31 ECU run more advance during off boost conditions? Will that present a problem since I"m running more boost?

 

What about various sensors... I've read that not running ALL the sensors will cause the car to go into 'limp mode'... even stuff like O2 (which I'm not running right now) or the speed sensor (which my car does not even have). Though it seems a few people do run their Z31 setups without some various sensors.... are they just always in 'limp mode' and it still drives good or what?

 

What about the O2? Can I use my same (stock 280zxt) Bosch O2 sensor with the Z31 ECU? That has something to do with the year right? I think the ECU I have is an 88 but I have to double check. The 88's were the better ones with the 16 bit resolution right? And I"ll have to run resistors inline with the injectors?

 

Just wondering things like that, any things you guys can think of, quirks or anything I need to be aware of not covered in the sticky topic above (which I've read thru like 5 times).

[SleeperZ]

Z31 will handle more airflow than the ZXT ECU, with less restriction. As far as I can tell, the ignition advance is similar enough. I have no idea how it will behave with the RRFPR, I've never used one. I pulled a used O2 sensor off a Z31, but you can use the 1 wire version as long as you either use an n/a Z31 ECU or a '84 -'86 turbo Z31 ECU. Later turbo ECUs used a different O2 sensor, and will NOT read a 1 wire properly. The speed sensors were never used except in the cruise control, and unless the sensor is critical it will not go into a limp mode.

 

The knock sensor is one that can be a problem. Even if you have a Z31 knock sensor, I think the solid cam followers are too noisy for it to work properly, and the ECU will give a code. If you just connect one of the wires, the knock sensor will not operate, but it will not throw a code either. I made sure to connect all the extra wiring to the ignition coil, as it threw a code for not being able to read the ignition pulse.

[AnTmanS130T]

Keep in mind .. I am sure someday you will want bigger than the 260cc injectors that the z31 ecu runs on ..(even though you have a rrfpr) so I would suggest that you find an 88-89 turbo computer because those are the only reprogrammable ones. The timing is going to be a little different at idle but the actual timing under boost is set pretty safe and the ecu def runs wayy rich under boost.. it will get as low as 10.8 even on stock cars. It is a lot more effecient ecu than the 280. The z31 afm is going to max out around 300 hp .. so you might want to look into a 93 cobra afm or a z32 afm which the ecu would have to be modified to run. The detonation sensor will no longer work on your car but that is not a big deal. I am just breaking some things down for you. I run the 89 turbo computer on my car with the 93 cobra afm and have no problems with it. My friend reprograms and tunes ecu's so it's pretty easy to do whatever I want.

[Guest bastaad525]

sweet thanks for this info guys. I'm almost positive it's an 88 turbo ECU.

 

About the MAF maxing out at 300hp that's fine as I'm still and for the forseeable future, stuck with the stock T3... never intended to run more than 14-15psi anyways. I WILL upgrade to 370cc's at SOME point... someone offered me a set for cheap and I meant to pick them up but delayed and delayed... was just too much going on at the time... so I missed out. So now I'm just waiting for another opportunity to present itself. About the stock setup getting into the 10:1's... sounds just like the 280zxt ECU Man they like it rich don't they?

 

well I was talking to Alex at Vildini the other day and it seems the setup should work fine with the RRFPR as it is... well if it is an '88 it's good to know I can get it reprogramed. Though of course, lord knows I'll never get around to THAT, either.

[Cody 82 ZXT]

The z31 afm is going to max out around 300 hp ...

 

 

I don't think that is true. No dought it would be more restrictive then the Cobra MAF but, not to the point of limiting a car to 300HP. Didn't SleeperZ but, more than that down to the ground?

[AnTmanS130T]

Supposively 300 hp is where it will max out around, meaning it reaches the max voltage of 5.2 volts and it will not exceed that. I don't know if the car will continue to make power or not but if you are going for over 300 you would want to look into a z32 or cobra one. Sure you are thinking well if it works why change it, well it probably isn't reading anything above the max flow so it has no compensation on anything, sure you are making more power but it wont do anything different from 300rwhp - to lets say the 350rwhp you did. That's not good at all especially if you want to tune and be safe. The only other thing besides the ecu that will help with fuel even if you are maxing out the afm is the fpr which the turbo ones or aftermarket usually run on a 1:1 ratio meaning for every lb of boost it will throw an extra lb of fuel.

[SleeperZ]

I don't think that is true. No dought it would be more restrictive then the Cobra MAF but, not to the point of limiting a car to 300HP. Didn't SleeperZ but, more than that down to the ground?

Yes, I put more down, but my MAF is modified. I transplanted the wire element into a 3-1/2" intake pipe, this, combined with the 370cc injectors tricks the ECU and runs the engine at a lower load point.

[AnTmanS130T]

You see Cody? There are many ways of doing things, I was just suggesting a wise plan if he is going for more than 300hp.

[Guest bastaad525]

that's cool guys really I probalby won't ever exceed 300hp anyways, well my goal has always been 250hp to the wheels at about 14-15psi of boost. I'm already pretty close... Honestly, the main reason I was interested in the Z31 setup is because of all I've heard on how it improves driveability with the spring door AFM gone, and I guess it gets better gas mileage too... 'little' things like that. It's no secret the stock L28ET is kind of a dog off boost so anything to help that will be sweet.

[Cody 82 ZXT]

You see Cody? There are many ways of doing things, I was just suggesting a wise plan if he is going for more than 300hp.

 

 

I agree there are many way to get the job done and I also agree that the lager cobra maf would be a good choice if the funds and the goal involved where there to make the cash outlay worth it. In my ride with the 84 computer and the retune by JWT I'm right about 300whp. No dought the Cobra MAF would help free up a few ponies at the top of the scale.

 

The only reason I made my first statment is because here on this site it is recommended that we stay away from statments that are not 100% true.

[Guest bastaad525]

Sweeet so I got a great deal on a dizzy, now I just need the oil pump shaft and the Z31 chopper wheel and I am in business!! Man... I know it will still be a little while, but I can't wait to get this upgrade up and running.

 

I'll swap in the dizzy first... I've always suspected that my CAS wasn't functioning 100% properly anyways... so that's cool at least I can run the car on the new dizzy for a while with the stock ecu before I take it to Vildini for the wiring.

[Sean73]

Don't forget you need resistors for the 88T ECU, as well as a titania oxygen sensor, and the appropriate O2 bung adapter.

 

If you don't want to fuss with this stuff initially, you can get a 84-86T ECU that doesn't need resistors and uses a regular O2 sensor.

[Guest bastaad525]

yeah I knew about that... still not sure exactly what year it is, but I'll find out soon enough. The resistors aren't much of a problem but I'm more against getting that O2 bung and new O2 sensor...

 

maybe this is stupid of me but I'm considering just running it w/o the O2 for a while... I mean heck, I've been running my stock ECU w/o the O2 for two years now

[violacleff]

Its an '88

[Guest bastaad525]

well there you have it

 

Actually, I'll ask Alex at Vildini about getting a new bung welded on, and maybe they can get a good price on the sensor. If it doesn't add TOO much money onto the cost of the wiring I will have them do that as well while it's there.

 

other good news is that my friend/parts guy has an '82-83 oil pump shaft for me and the Z31 chopper wheel, and will let them go cheap, so I'm in business. The dizzy should be here within the week. I'm hoping to get it installed in the next one or two weeks, and then I'll get the Z31 stuff installed in another month or so. Or maybe a little longer... I still have a $400 ticket to pay