DuoWing

I'd assume it's calibrated for 14:1 ratio? Although that's not a bad idea. I may have to look into that.

That's what I figured. Anyway I'm curious, you're running your car with BCDD plugged off, no EGR, no Air Regulator, etc, right? I think I've now moved it too rich, if I keep the ball valve open during that warm up period the car seems to be really perky and seem to respond quite quickly, but if I run the car during warmup with the ball valve closed then it gets real poppy, stumbling, hesitation, like before. Do you have any issues with after the car's been warmed up, you go somewhere and leave the car for about 10-15 minutes, then when you restart it does it have any problems? It sounded like you had all these problems same as me, but it sounds like after getting the mixture just right it runs just about perfect. Did you set the mixture to 14:1? I may just have to try and find someone who can do an A/F reading or get a wideband, this tuning on the fly sort of works, but still is a pain.

oh, one more thing that I thought. It really stinks having no way to really tell what the mixture is at, but I was curious. If you still check this, do the 2 LEDs on the ECU now blink simultaneously, at least if you do the test?

I have no problem justifying $5000 for an S30. The body being as clean as it was is what helped to justify it. Especially here in Ohio. Although I could probably get one cheaper by buying it from another state and brought up by car carrier. I think what really turned me off was what appeared to be a body that may have been in a wreck. This wouldn't even be that bad, but it occurred to me that should I need a new fender or a door at some point due to the fact that I may find problems in it, a replacement part may not fit or fit like it should. It was said that nothing happened in the 10 years of ownership, but it's always hard to say. Since something like carfax doesn't go back that far you'll never know.

So I'm curious what you guys think about this. I just thought I might get an opinion. I've been looking for a 70-73 240Z to get to work on some then eventually swap my L28ET into. Anyway I found one, it's auto, but it was pretty nice and really clean. Got to see the underside, there's very little rust. So this was a good thing. Paint is old and faded. Car's been re-painted a couple of times, different colors each time. All the weather stripping and ruber seals are old and cracked, to be expected from a car this age and an Arizona car. Interior isn't bad, but it would need some work, aftermarket seats, missing some thing, cracked dash with a cover, headunit that no longer works. Window trim falling apart so it's not sealing very well. Ran good, loud ass grinding in the rear namely around turns or if you got on it hard. It at times almost sounded like when the starter doesn't engage properly or if when you're cranking you hold the key too long for the starter once it's started, but the noise was from the rear. Was leaking a mass amount of oil, which I found was from the valve cover. One of the bolts was missing. My guess is it was probably a stripped out bolt. It was on the front passenger side bolt. Then I noticed the radiator looked really beat up, it looked as if at one point the fan had collided with the radiator, the fan itself didn't look exactly right while spinning, but the car didn't have cooling problems. Anyway on the passenger side fender there was a weird chip in the paint. Like it was just cracked, and kind of humped up, but the hump wasn't bubbled, it was smooth almost as if the fender was kind of bent in at some point. Also the passenger side door took a good slamming to get it to close all the way, much more so than the driver's door. This all got me to thinking that the Z had been in an accident at some point, and the fender was probably warped and just pulled out. Owner said there was no accident, and that the radiator was like that when he got it, but not 100% sure on that. So what do you guys think about the price. I'm probably going to pass unless it comes down, I figure I'll keep looking for an early 70-73 240Z and possibly a 74' 260Z for my L28ET swap.

Alright, I found out that I was beginning to lean the mixture out too much. I went and actually got my car warmed up for once. I closed the ball valve that I use in place of my air regulator, and the car was idling really badly. So I had to start richening the mixture up, basically go back to the beginning, and then I adjusted it a bit more. The idle smoothed out quite a bit, and my car was starting back up with the air regulator passage closed off without needing throttle and not giving me alot of stumble/hesitation like it used to. So I've wasted alot of time by going way too rich then way too lean. When I could have probably gotten real close to having it adjusted right, by just slowly backing off the richness instead of going back to where I started. Anyway this time I really do seem to be about done with getting it set. Next Up: Nistune and Wideband.

Alright maybe someone can give me some advice here. I've really been considering switching over to nistune very soon. I did the Z31 ECU/MAF swap almost half a year ago, the car does run a good bit better, get better gas mileage etc. Anyway I've been debating the JWT tune or going the Nistune route. Nistune seems better since you can tune the ECU yourself whereas the JWT ECU is just pre-programmed. Mainly what I'm wondering would it benefit to have the later 88-89 ECU with Nistune installed or would it really be no different than running my 84 ECU with Nistune installed?

Well apparently, it was just a coincidence as the issue came back today.

It's hard to say if it could cause that low of a reading, but it could definitely cause a really low reading, as if it's stuck all the way open fuel would be going right through the rail rather quick. There woudln't be much there allowing it to build pressure. I agree with what roger.svoboda said. While you're running the car and watching the pressure gauge, pinch off the return line and see if you're pressure suddenly jumps. If it does I'd definitely go with crapped out pressure regulator. If not, then quite possibly fuel pump. I don't know what kind of issues you have with it running rich, but you're issues would probably lie within the Fuel Pressure Regulator, the Water Temp Sensor, and the AFM. I see you're running a 77' 280Z, so the EFI system on that is really basic. If the water temp sensor hasn't been replaced, I'd say it's a good bet it needs to be as these all at some point seem to go bad, whether it's the WTS on the 280Z or the CHTS on the 280ZX. Also you could always crack open the AFM and adjust it.

This is weird, because something very similar happened to me very recently. It could be a coincidence in the way that it went away. I have an 83' 280ZXT, but I'm running the ECU/MAF combination from an 84' Z31T, which would be wired up very similarly to your 87. Anyway for a while my idiot lights would all start lighting up, after a while it stopped. Then a month or two later it seemed like the issue came back with a vengeance. Anyway I would start the car and it would idle real low and my idiot lights would be off, the second I revved it, turned the headlights on or basically did anything the dash would light up with all the idiot lights coming on. I thought it was my charging system, but it didn't seem to have any problems running everything and my car would still continue to start up fine. I was clued in by a fellow Z driver that in the 280ZXT harness there was a crimp connector that Nissan had put in which had a tendency to go bad and cause grounding issues. I had driving issues where when I'd shake the wiring harness it would run better. Anyway I cut out the crimp, stripped the wires down, and made a newer, better connection for these grounds. After that my idiot lights stopped coming on. They haven't come on sense, it's been a few days now, but still. It could just be a weird coincidence though. Also before I fixed the connection I was driving the car around in the daytime with everything off to see if it was a charging issue or something and it was doing the same thing, idiot lights were off while idling, but once I got above 1000 or so RPM they all came on, then would go off while idling. This crimp if it exists on the Z31 Harness would be I'm guessing on your top ECU plug, as the way the Z31 ECU sits in my 280ZX is basically upside down, or the plug closest to the little hole on the side to see the red/green leds. There were two black wires coming out of my ECU that ran into a electrical taped part, then split out into 3 wires. Again this may just be a coincidence, but it seems weird that our problems are very similar and mine stopped right after I fixed this.

One other thing I forgot to ask was about your tuning by wideband. Did you just run the car at idle and adjust the MAF until you got the right mixture ratio? One thing I'm wondering is, how much would you say a half turn of that mixture adjustment screw on the MAF cause your mixture ratio to change? If I could get an idea, that might at least help me get closer to getting it right. Anyway my car seems to be running really good. I keep adjusting the mixture screw about a quarter turn after every drive, and it seems like it keeps improving. Although I think I've noticed the lean surging issue that's known with the earlier ECUs. When I'm driving along just for a few moments, mainly at slow speeds or small amounts of throttle, the car feels like it does surge a bit. I don't know if you've encountered this or not, but I don't really have much if any hesitation. If there is during cold then it's very little. I went ahead and ordered a heated 3-wire universal O2 sensor that would fit an 84' 300ZX Turbo. So I'll throw that in and that should make the warm-up period even better as I'll get into closed loop much quicker.

My fuel pump does exactly the same thing, where it keeps running when the key is turned on. I know I was told that I need to cut the ground wire for my fuel pump and directly ground it to the chassis, and disconnect my fuel pump modulator. I'll have to do that and see if that solves my problem of my fuel pump continuously running. Well I finally went ahead and fixed my ground wiring, and that seems to have cleared up some things. So far I keep turning that screw counter clockwise or lean about 1/4th a turn after every drive, to see if it makes a difference upon the next cold start. Glad to hear that you have finally come to the end. From what I can tell is I'm right about there. I really had pretty much no stumble on my drive home tonight, but now I'm definitely thinking about getting a wideband O2 sensor. Just for future tuning, diagnosing issues, etc. Do you run the wideband O2 sensor in place of the normal O2? Or do you have a separate spot for your wideband? I don't know much about a wideband, but if I could just run a it in place of my existing O2 and make the ECU work with it then I think I'll definitely have to get one.

I was trying to edit my previous posts, but it looks like I can't? Anyway one thing I came across is, the other day I went out and drove the car around, got it warmed up, then followed the instructions for getting the lights on the ECU to blink simultaneously. Anyway, I finally got them to blink which took a bunch of turning it to the right, which the FSM indicates is adjusting it to be rich? Anyway now my car was running worse, popping, more hesitation, etc. I put it back and now it's better again, so now I'm going to just lean it out maybe a quarter turn at a time to see if I get better results. Oh and I wonder if my alternator which seems to be going bad would have anything to do with running issues?

I wonder how much of a role the ignition plays in this setup. I know that people say using something such as a mallory or MSD ignition and coil alone is definitely an improvement over the stock 280ZX ignition, I also know that people say the Z31 ignition was much better. I need to get my mallory and balster coil in there and see what kind of a difference that makes.

No unfortunately the stock turbo throttle bodies didn't have an idle adjustment screw, it can be adjusted, but you have to loosen the nut and tighten the screw for the throttle stop. I've upped my idle some and got around to drilling out that plug on the MAF so I could get at the mixture adjustment screw. So now I gotta go drive around, warm the car up, check my idle speed and see if I can get the lights to match up in how they blink and what not. Although just from that information about the 84-85 ECUs having a lean surging during warm-up it sounds like we're never going to completely get rid of the issue. So it sounds like if you're encountering just a spot of stumbling or hesitation it sounds like you've got it fairly sorted.

Glad to hear you're making progress, I still need to adjust my mixture ratio. I'll have to go drill out that plug. I almost think my issues are coming from running too rich. I encountered a few problems when restarting the other day. When the car was fully warmed up and I stopped for gas on my trip back home, the car started up fine. I had the ball valve that I put inplace of my air regulator completely open. I closed it off some to bring the idle down as I hadn't yet adjusted my idle at my throttle body. The next time I went to start it would turn over then die, unless I gave it some throttle. It reminded me of my 76 280Z when trying to start from cold with the way the air regulator is faulty and stays closed. So I'm thinking I'm running a bit too rich.

It's a rather long process. Have you made any progress with your issues? At times I sorta wished I had waited and made sure my ZXT was running with no problems before I converted over the 300ZX ECU/MAF, but ahh well. It seems like the biggest issue with these issues is primarily linked to old connections. Also before I swapped to the Z31 Setup my Z would have problems generally with restarting which I found out was linked to my VCM being hooked up incorrectly, which would be the equivalent of the BCDD on the N/As. After the swap it's no longer really controlled properly so I unhooked it, plugged off the EGR, removed the AAC, the VCV, etc. This all dropped my idle and made the car run a bit better. I came to the conclusion about the ECU wiring due to an issue that would happen once in a while. On two separate occasions my car upon startup would start acting real goofy, the idle was real unstable, but it would idle. Upon any throttle the car would start popping through the intake and nearly die. If I'd continue to give throttle the car would just stall. When warmed up it would run a little better, but my A/F gauge was not registering as if the car wasn't getting fuel correctly or if the O2 was dead. After looking at a bunch of things trying to make adjustments to correct it. I figured I'd shake the wires coming out of the ECU. I've heard of a lot of problems related to the ECU wiring. Upon shaking the wiring instantly the idle smoothed out, sounded better, my A/F gauge started bouncing around like normal and it seemed like I had no problem. Every so often I mess with the wiring and it seems like ever since then my initial throttle hesitation has been alot less. It sounds like there's a known lean hesitation during warm-up with the ECU, but now I just get maybe like a quick spot of hesitation before the car goes. Where before it would pop and sputter and barely move and then after a moment it would go fine. I'm not sure on the N/As but the Turbos on one the ECU plugs has a spot for the main ECU ground wires. It's two ECU ground wires that goes into a little open metal connector then spreads out into 3 other ground wires. It doesn't seem like a very good design and I wouldn't be surprised if everything improved upon making sure all the wires are just connected or twisted right together rather than relying on them touching through this metal piece.

Although I haven't actually respliced the one major section of grounds for the ECU, I did pull it apart and mess with it. It does seem like ever since then my stumbling hesitation has really calm down alot. Before it use to really pop through the intake and have some bad hesitation, where now it's only a slight hesitation before it goes. So I need to redo that, but I'd almost think that getting the mixture to match up right should correct the rest of the issues. Although for me since here in Ohio temperatures get a good bit colder it would probably be beneficial to put in the heated O2 sensor.

I think he means that you wouldn't have the differentiated warm-up and then operating temps. You would have to adjust for the two settings. I think you'd just be better off opening up the AFM marking the default starting spot and little by little adjusting the spring tension to make it run more lean.

Wouldn't it be easier to put a 90* elbow in there, screw the PCV valve into that and just get some extended hose and run it right into the normal spot on the block?

Also I don't know how much this helps, but did you rewire your injectors? Or I should say switch the wiring for the #2 and #5 injectors? From what I've read and what the FSM states. The 300ZX uses a batch fire system below 3000 RPM, not full throttle, etc. Where it will fire the injectors in two sets injectors 1-2-3 then 4-5-6. Once it gets up to higher throttle it fires all 6 simultaneously so this isn't an issue then, but at idle, lower throttle etc, it's firing to match up with the firing order of the VG30 which is 1-2-3-4-5-6, but on the 280ZX the firing order is 1-5-3-6-2-4, but the Z31 ECU is firing 1-2-3 then 4-5-6, so you're having the #2 and #5 injector firing out of order. I switched this on my car, I want to say it made a slight difference, but I'm not sure. This may be more noticeable if my idle mixture were properly adjusted. As for putting a resistor on the FTS wire, that's not a bad idea. At least that way it wouldn't throw a code, I don't know if this would cause an issue with the ECU or not.

It seems to me like part of my issues was related to the ECU's main ground wires. After I played around with them, I've noticed that the problem is very minimal. It's not right at start-up, and it doesn't happen once the O2 sensor comes on. It will also have the issue after I go into the store or something, come back out and start the car. I think it has to do with that known lean surging problem during warm-up that the earlier ECUs have. I've noticed at least for me on days about 50+ degrees, my O2 sensor will come on quite quick pretty much eliminating this problem. Now the period of sitting and restarting still exists, but again happens for a much shorter amount of time. The only conclusion/difference I can come up with is: I'm running a non-heated O2 sensor, even the early 84-85 Z31 Turbos ran a 3-wire O2. Also for me, I've followed the FSM and checked my idle mixture ratio: http://xenonz31.com/AFMCalibration.html it's off and needs adjustment. One thing this page leaves out is that in the FSM they have you also check your mixture basically all the way up to 2000 RPM. So this alone may make a difference. On this page: http://www.redz31.com/pages/fuel.html at the bottom of that page he mentions about the lean surging, and says this can be remedied by switching to FTS I assume means Fuel Temp Sensor signal. Although I don't know how you'd accomplish this. You and I appear to be running primarily stock setups, rather than running larger injectors, an aftermarket ignition/coil, etc. So that alone may help to balance out or someway make up that extra difference. I also think that by going to the later ECU or a JWT tune may eliminate this issue. I added some stuff to your Z31 swap thread over on Zdriver, I don't know if you saw that or not. I'm not sure what the VSS is, but as for the Fuel Temp Sensor I don't have that connected. My ECU will throw out the error code for the FTS and the Knock Sensor, but I'm not getting any other codes. When fully warmed up my car will sit at right about half on my temp gauge. It's the stock gauge, so I'm not really sure what that temp is. Like I said, I almost think the biggest things to do would for the 3-Wire O2, and make sure your mixture ratio is correct.

Well a few things I've found is that my mixture is off. I've followed the 84' 300ZX FSM and checked my idle mixture, which basically has you calibrating it up to about 2000 RPM. Anyway that needs adjustment. My fuel filter is fine, I remember once thinking it was that, I pulled it and checked it to find that it was not clogged at all. Although I did put a new one in with no different results. From what I can tell the stumbling almost seems to be related to the ECU not having a good ground.

It sounds to me, that anyone running 18psi on a stock engine, with no fuel management upgrades, intercooler, injector upgrades, just goes to show that this person is a bit of an idiot. I've found so many threads amongst these sites about stock boost that you can run, and it sounds like without any sort of upgrades with the stock system about the most you can run is 11-12 psi, before the system can't even keep up and even at those boost levels it's still risky with no upgrades.

Ok I couldn't figure out a good part of this forum to post this question. Anyway I have a running Z31 ECU/MAF swap and everything on my 83' 280ZXT. Anyway I was reading the page on the differences with the Z31 ECUs here: http://www.redz31.com/pages/fuel.html Anyway at the bottom he mentions that the earlier ECUs have a lean surge problem during engine warm-up, and this can be corrected by switching to FTS vs. CHTS signal during start-up. Now my question is does anyone have a solution for this? Is there a way to effectively correct this? Primarily the problem presents itself more in the extra cold weather where it takes longer to warm up. In warm weather it's pretty much un-noticeable, although I'm looking for a solution.