My '83 280zxt was running great, but after reading so many positive reviews of the 300zx eccs swap, plus the tuneability of nistune, I figured I'd go ahead and make the swap. I purchased an '89 turbo Eccs, chopper wheel, mas, and the pigtails for the new(er) components.

So it didn't really take long to wire up everything according to the guide on HBZ and Nismopick's tips this site, but the troubleshooting has been killing me. First the fuel pump wouldn't ever turn on. I ran pin 108 to the ground on the FPR, and grounded out the pump to the chassis. Nothing. So then I do the ECCS's job and apply ground to pin 108. Voila, now the pump works. I hate to jumping to conclusions about faulty computers, but that's really the only thing I can think of. So just for temporary testing purposes, I cut that wire and grounded it to the chassis so the pump comes on and stays on with KOEO.

2nd problem was no spark. I'm running pin 3 to the - post on the coil (I know I read it's not necessary, but eh) and pin 34 to the + post on the coil, as per HBZ instructions. Nismo, i Know you say to just run it to a switched 12v source, but the wire still sees 12v so I'm assuming it's good. Anyways, once I verified that everything was wired correctly, I the wires back onto the coil and somehow now I have spark. Ok whatever, don't care at this point.

Now it won't hold an idle because it's being flooded with so much fuel...talking smokescreen rich. I'm not running an AAR, but also wasn't running one with the 280zxt ECCS and it strarted up and idled great (better than with the AAR still attached, actually). So before I start molesting the MAS, what part of this wiring swap can I screw up to make it run pig rich? I double checked the MAS wiring, everything seems good.

I also soldered 3.7 ohm / 10w resistors in for each injector. JWT says to use 6.7 ohm resistors, but jeffp said he used 3ohm resistors and was able to improve his latency and drive the injectors harder. However this was with 750cc injectors, so I doubt I'll benefit anything performance wise from running the lower resistor, but that should still save the injector drivers in the ECCS.

I'm still hoping this swap is worth it, but I'm keeping all my 280zxt electronics just in case.

 

There are several wiring changes between the 84-86 and 87-89 ecu's. If you wired your 89 with the 84-86 instructions, that's probably why you have problems.

Are you running the 3 wire O2 sensor?

 

Well crap. No I'm not currently running an o2 sensor on it, but I shouldn't need it for cold starts. So is there a thread anywhere that just focuses on 87-89 wiring?

 

I'm not sure if there's an official write up for the 87-89 ecu, but our member Duowing is running one, with NisTune I believe. You could message him. Also, just compare the ecu FSM schematics.

You should probably install the correct O2 sensor too... there's no reason to not have it installed (unless you like giving yourself headaches).

 

Of course I plan on running the o2 sensor, I was just trying to see if I could get it to start with this setup. ;-) Yeah when I have time this evening I'll be comparing the schematics between the two...I was just hoping that someone already went through this pain and documented it, haha.

I'm surprised nobody has reported this issue though, even on the HBZ write-up, it states that the wiring applied to '84-89 models, and that there were just minor differences between the two.

 

One main wiring difference is pin 19 controls the air regulator (idle control).

Did you use pin 19 or 16 for the air reg?

 

I didn't mess with that stuff b/c I shaved the manifold, so the only thing I have running to it are vacuum lines, PCV valve, and injectors. But like I mentioned earlier, I was running it this way with the 280zxt electronics without any issues, so I didn't think that'd be a problem.

 

Are you running a 60mm throttle body by cable then?

How do you control idle with no idle controls?

 

Yessir, 60mm t/b But it's been modified to use the factory linkage.

 

Dunno what else to tell you other than when you remove all the idle controls, you will have idle problems.

The only other thing I can think of is either the CHTS or MAF isn't getting / giving the right signal.

 

I don't think this problem is related to the idle air controls. It seems like something is telling it to add more fuel than it should be right now...I literally have to keep my foot in it to keep it running, there is sooooo much fuel being dumped into the engine / black smoke chugging out the exhaust. Maybe I'll see if I can find an '86 ecu and throw it in there to see what happens. Like I mentioned in the first post, it already doesn't send a ground signal to the FPR when it should, so there may be some internal issues with it causing this problem...but I hate jumping to that conclusion.

Btw, for whatever reason I can't unzip your spreadsheet for this swap, is there any way I can access it alone without having to download the complete z31 swap folder?

 

Hum... that file stopped working (probably from a site crash years ago). I did a few updates since that orig version was from 2006 and attached it here:

 

Still can't open it. I was able to open it at home with my laptop (but no printer), but not at work. No biggie, I'll just e-mail the file to myself.

As an update, I found something interesting:

According to the schematic on the '88 300zx, there is no wire going to terminal A of the MAS. Pin 30 on the ECCS actually goes to an exhaust gas temp sensor (but says CAL only...and i have no clue if my ECCS is cali edition or not). I'm going to unplug it and then run continuity tests on everything else to make sure they're where they should be. That's really the only thing I noticed between the wiring (that I modified for the swap) between the '85 and '88 ECCS.

 

Idles great with the MAS unplugged, but no change with terminal A disconnected.

 

Alright so I ran a continuity test between MAS pins and ECCS pins according to '88 FSM schematics, everything checks out good. However the MAS failed the voltage test:

According to FSM, Key On Engine Off the MAS should read 1.6 +/- .5 v. Mine is reading 3.75. Then when the engine running super rich and me having to feather the throttle just so it will keep an idle, the voltage increased from 4.45v to 5v - specifications are 2-3v at idle and 2-4v "racing the engine" in idle. Plus I removed the MAS and measured the resistance on each terminal...it is way out of specification, other than the D-E pin resistance. So guess I'll try to find another one from a junkyard and go from there. I don't feel like spending over $200 on a new one for my 'budget' ECCS upgrade.

 

Alright so it's not a MAF. I just picked another one up this weekend from a local junkyard, all resistance tests passed, and the car still the does the same thing...blows black smoke rings at idle.

I did notice one thing: the filament for the MAF glows as soon as I plug in the MAF. I'm assuming this is only supposed to happened when the MAF goes into regeneration / self-cleaning mode. Time to check my wiring again?

I've already verified that it goes where I *think* it's supposed to go, but maybe I've been reading everything wrong?

 

Not running an o2 sensor will also make your car run stupid rich. Your computer isn't getting any feedback from the sensor so it goes into an open loop which just dumps as much fuel in as possible (as if you were at WOT). At idle it's not really burning all that fuel and will produce a strong unburnt fuel smell and can make a little black smoke too. When I first got my car up and running again I had no sensor and it was running extremely rich as well. Now it sounds like you may have other problems if it's running so rich that it has a hard time idling, but I'd at least try hooking up a sensor and see if it helps at all.

 

Check the chopper wheel in your dizzy to make sure it's installed right. I once installed it incorrectly and had a huge amount of raw fuel coming out of the exhaust. Other than that, do you have any vacuum leaks? The Z31 setup is much more sensitive to any leaks than the stock 280zxt afm is.

 

No, I fixed all vacuum leaks using a smoke machine when I still had the 280zxt electronics. I installed the chopper wheel via pictures found on here and hybridz. I can double-check it, but I'm pretty confident it was installed correctly. Plus the fact that I can unplug the MAF and it idles perfect tells me it's probably installed correctly.

Does it not sound odd that as soon as I plug in the MAF, the filament inside immediately begins glowing orange, as if it's in the burn cycle? I just verified all MAF wiring (for the 10th time) and everything matches up as per hybridz write-up. I'm going to remove the self-cleaning wire from the ECCS and see if that changes anything.

I also found a local guy that's pretty familiar with z31 stuff, I'm going to pick up an '85 z31T ECCS from him today or tomorrow. He said he tested it to be in proper working condition. Kinda bummed b/c I was wanting to use the 16 bit resolution of my '89...but we'll see what happens I guess.

 

OMG....FINALLY. FINALLY. FINALLY!!!! FOUND THE GREMLIN

So I traced back the wire that controls the MAF regeneration to the ECCS...turns out I added the new wire for it onto ECCS pin 13 instead of 12. I'm assuming pin 13 just sent a constant 12v source to the MAF and kept it in regen mode the whole time. Just started it up but haven't test driven it. Gotta push the rx7 out of the way and will report back

 

Drove pretty well with the exception of it dieing on me after I'd let off the gas on heavy acceleration, and it running pretty rich. But I don't have the o2 sensor installed so I'll get that taken care of tomorrow (hopefully) and be done with this swap.