ckurtz2

Also for reference, the cam I am running is the Comp Cams 260s. https://zcardepot.com/products/performance-camshaft-comp-racing-cam-240z-260z-280z?variant=19279549825137 Less lift and duration than the one @Reptoid Overlordswas considering and less lift than what you had in the past that didn't like the EFI. Don't know if that matters.

@Jeff G 78 Thank you! So yes, the #1 cylinder didn't experience a change when swapping connector from #1 to #2. Only sometimes would the #1 connector work on the #2 connector. I felt like I was getting close with figuring it out, due to having no voltage at the ECM from pin 15(cylinder 1). However, I then messed around with the dropping resistor connector by pushing it in farther (it didn't seem like it wanted to go farther, but it was barely on). I then started the car again and noticed the noid light I had on the #1 injector connector was flashing. So I reconnected the connector to the injector and magically the #1 cylinder began firing again. However, the car ran even worse than before oddly enough, so I looked if all the cylinders were firing. Low and behold I noticed the #5 cylinder was barely firing or just plain misfiring (it would make the motor drop rpm a lot more before. It also makes noticably less difference than any other cylinder).. I tested this many times to confirm I wasn't loosing my mind. I did this by pulling the plug wire while it was running and would barely noticed a change. I want to mention when the motor was cold it made no difference, and when warm is when I could tell it was firing, just really weakly. So all the cylinders work now, it just bucks like hell and is definitely missing. I pulled the #5 spark plug and it looked wet with fuel after running (probs from pulling spark a few times). So here is a question, have you ever worked on a Z that ran really poorly due to carbon fouled spark plugs? Mine are still kind of fouled, but they are new. They fouled be me toying with the AFM while diagnosing the #1 cylinder issue. Thanks for the info! I definitely need to do a leak down test at some point.

@Captain Obvious Just got some new bullet connectors, some DeoxIT, and other stuff to redo the bullet connectors around the engine bay. All of them look pretty bad:( All the injector connectors are new, tps, water temp sensor to thermostat housing connector, alternator connections, battery wires, etc. The water temp sensor bullet connectors, however look pretty bad. The AFM is a rebuilt unit so the connections are solid, however, I think I will clean up the connector from the harness side. Same with cleaning the dropping resistors. Thanks for the recommendation! @Zed Head Yep the cam was an important part I didn't mention. I figured I'd leave it out though until the end, because I know my current problem is not related to it. Thanks for the contact! I agree that the modifications seemed a little odd, but they all made sense to me except removing the dizzy advance. I agree, I don't want to band aid solution the car. However, if it still has trouble on the top end running lean due to the extra air coming in, then loosening the AFM just a little doesn't seem like a terrible idea to me. By guide, I mean that I am going to essentially play with the EFI until I get it right to the best of my ability and share with the community what was done, if anything. In addition, just an overall review on how good or terrible it runs on stock EFI. HAH!, my tuning shop is Chuck from Sakura in AZ. I don't think any fancy computers or anything will be used, just the ole noggin. This is my first Z that has never quite run right, and they know a lot more about how Zs are supposed to look/run etc, and have a lot more experience in troubleshooting than I do. If I never get it quite perfect, so be it, but I want to get as close as possible. As long as it doesn't hurt the engine and is daily driveable, I can always swap to a different EMS later (with my track record with the EFI system on this car so far, it is seeming O so likely. I don't want to throw in the bag yet though). Man I would love to bring it into a standard "tuning" or automotive shop for work just to see them struggle. However, having worked at crap shop in high-school myself, full of dishonest and terrible techs, I will never let someone I don't trust ever touch the car with a tool.

So, I agree with you both that I think the mixture is off at certain RPMs, especially high RPM. However, the bucking at idle is completely new. I want to mention that my Z has the 260s cam, and I knew it was going to need a lot of tuning to get the original EFI to work right (adjusting the AFM flapper, timing, etc etc). Many people advised against it, but I believe with such a small cam most of it can be tuned out. However, I still think that something electrically or mechanically is amiss in my car, because cylinder number 5 now seems to have almost no change to idle or engine when at a little higher rpm. In addition, it is just running in general a lot worse than it used to before I started having these weird problems. Here is a what gave me faith with the stock EFI and the 260s cam. https://www.zcar.com/threads/biggest-cam-for-stock-efi.292280/ "I ran the Deltacams 260 cam with stock efi and it ran great. I ran the cam for a few years then sold the car since I had to many z's. Yes, 110.00 plus shipping. Don't forget the thicker lashpads to make up for the regrind. 0.160" thickness from courtesy nissan for another 36.00. this cam does require some tuning to the stock efi. Run more ignition timing, loosen up the afm flapper a few teeth, adjust the tps to the off idle position. You can run stock ignition timing if you move the vacuum advance to a manifold vacuum source. This will add vacuum advance at idle, so it will make the engine idle with 30 degrees of timing (10 initial + 20 vacuum advance). the cam has a very slight lope at idle. pulls hard to 6000 rpm. a nice improvement in my car. A 260 cam should idle in the 16 to 17inhg range. Lower than expected vacuum is a sign of low ignition timing and improper air/fuel ratio. A Z efi computer doesn't measure vacuum like a modern efi system, The only thing in a Z efi system that measures vacuum is the fuel pressure regulator" That being said, my vacuum is currently at around 15hg at 950rpm. So I either have a really bad AFR, vacuum leak, weird electrical issue, or it's that semi dead cylinder, or likely all of the above causing bad AFR. Thanks for mentioning the water temp sensor tweak, it is a great gadget. I made one many moons ago, and tried it to see if it would fix anything at high or low rpm following that comment. Didn't do much except bog the motor down with fuel, so I don't think the problem lies there. I am going to be taking it to a shop this weekend where they can actually measure my AFR, smoke test it, do real electrical work etc using all the big boy tools I don't have. As well as tune the EFI for the cam. I will update this forum once they find the issue(s), so to keep everyone informed. I would also like to mention if I get it running right with the 260s cam I will make a separate thread as a guide on how to tune the EFI for it, so members can use it as info in the future, knowing that putting a cam in the stock EFI is a highly debated topic. Thank you everyone for the help thus far! I genuinely would have zero headway when working on the Z without help from this forum:)

Wow, thank you everyone for the replies! All this information is great. I did not disconnect the other injectors when doing the voltage test, so I will make sure to correct that mistake, super helpful. I also am beginning to think there is some sort of intermittent break in the harness like CO and everyone else mentioned. Here is why. The connection at the dropping resistors seemed kind of loose. Such that it wasn't pushed in all the way (was at a slight angle), however, when I tried to push it in all the way it looked like it physically couldn't reach, seemed like too much tension was being put on the wires. I kinda just pushed it in further, but now it seems really hard to take out. Anyways, at the time I didn't think too much of it. One of my friends was over and had never seen the car start, so I said why not I'll start it and see if for whatever reason #1 noid light starts working again. And so I did this and waboom it was working. I connected it back to the car and boom idle change. I was astonished, to be honest, and now #1 works. So I checked for voltage down at the ECM again and there it was, #1 was reading voltage on pin 15. I would also like to mention I test drove the car immediately after #1 was firing again, and it was bucking much more than before. Noticing the motor seemed like it was running just as rough as before if not rougher, I pulled plug wires and now it looks like #5 isn't firing properly. I notice an ever so slight rpm change (before it was a lot more apparent). Ok, weird. I checked voltage back at the ECM for #5 and it was reading fine. I then checked with a noid light on #5 and it seemed to be flashing ok. If the only thing I touched was the dropping resistor connector, I would think that the two issues are related. However both connector ends seem fine, it is just hard to get the two to mate. The leads on my multimeter are too small to reach places, so I need to get longer ones before I am able to properly go through the harness:( Not really sure what any of this means yet, as even though the dropping resistor connector isn't pushed in all the way, it is 100% making contact with the male and female inputs. Does anyone have a photo of the connection of the two? I can't tell if mine should go further together or not.

Update: So I checked voltage at the pin on the injector connector. It gets the proper voltage. I also checked it at the pin on the dropping resistor. Gets good voltage. So it's my understanding that the fuel injector plug gets 12v constantly correct? And that the injector fires by the ECM alternating the ground to the injector plug, thus firing the solenoid in the injector. So, in theory, if my connector is getting 12v than the reason for it not working is that the ECM is either malfunctioning and not pulsing the ground, or the ground in the harness is bad. But then that begs the question, if my injector connector is getting 12v, why would it not be reading 12v at the ECM? 1975 280z #1 Injector Circuit.pdf

Thanks guys. Time to start poking and probing. Is it me or does all the recommendations like EF-42 seem like it is for the wrong cylinder according to the FSM. It looks like EF-52 is the one I should start following? Also I am admittingly a 100% noob at reading electrical diagrams and wiring. Do I just check for continuity between each section of the harness as per the diagram on the positive side. And then the negative side. And if those check out then do I start testing relays and resistors to see if those units themselves failed?

Ok guys, time to get some electrical wizards on this thread. So, I started out by renting some noid lights from O'reilly. Here is what I discovered. When the engine was cranking over I saw the noid light on #1 flash a few times then quit once the engine started (cold start). So, I disconnected and reconnected it a few times and it wouldn't light up. I did this a few times and once the motor heated up a little then it started working (flashing). Ok interesting... I put the connector back on #1 and noticed seemingly no idle change. Put noid light on #2 and it worked (flashed) fine, trying this on every cylinder up to #6 (My poor motor lol, did this while the engine was running). So I turned off the car reconnected the noid light to #1 and started the car. Once again no noid light flashes. Put it on #2 and started flashing normally. I also observed that the noid light would get brighter at higher rpm on other cylinders if that means anything ( I am assuming the light just appears brighter because it is flashing more consistently). So here are my points of confusion. First, why would it seem that the injector connector works only part of the time? In addition, once it was working wouldn't that make the #1 cylinder come back to life once I connected it. Something very odd is definitely happening here... I DID THIS AFTER WRITING THE ABOVE^^ Ok so next I went to the wiring harness check recommended by @Barefootdan. Testing each pin for the injectors at the ECM with the ignition on for proper voltage. Every pin tested perfect except #15 which is injector #1. To be honest I am lost inside the FSM on what to check next. Any help would be appreciated!

@Reptoid Overlords You are 100% correct that the plug was carbon fouled to a rich mixture. When I originally noticed the motor was running rough, it was behaving exactly like the motor did when it was running super lean across all cylinders. So I probably did exactly what you shouldn't do, but I richened the idle mixture screw on the AFM to see if it made a positive difference. It didn't, just choked out the motor. I since corrected the AFM back to normal and the plugs all look good again besides #1. However, right after running the motor super rich is where I decided to get smart and see if every cylinder was firing. That was when I made the discovery that #1 wasn't. Super easy to tell with the carbon fouled plug, and then other from #1.

Ok thanks guys! I think after reading these recommendations I will do as follows: Test with a circuit tester to see if the light flashes at #1 connector. Check the proper pins on the ECM. Then check for vacuum leak. Then swap #1 and #2 injectors to see if the problem follows the injector. Yes, I sure wish I had some color tunes. After that I think I'm out of ideas and tools:( @Zed Head the resistance at the injector is good at 2.7ohm if I remember correct. Matched the others. In addition the solenoid fires. Tested with a 9v batt. I don't have a fuel pressure gauge unfortunately. Thank you everyone for the help!

Now, I was super intrigued by your post as it would make sense. However, I remember playing with the idle enrichment screw on the AFM to see what was happening if the motor was lean or not. Lets just say I fouled some plugs whoops. But here was cylinder 1 compared to #2, Which I think pretty accurately confirms no boom🔥 is happening in #1:(

I will make sure to do this and will update you this Sunday when I am able to work on the car again. Thanks!

No. It had like a small drip of some sort of fluid on it. However, sometimes it would come out completely dry. Here is a photo I took in the beginning of the process yesterday.

Man, I was praying it was the distributor cap or rotor yesterday when I did all the testing. However, I checked this by removing the spark plug wire from the distributor cap and hovering it right over the #1 terminal. I could see the spark arcing for each revolution of the rotor. So I think that, in addition to all the other tests, rules out the cap and rotor. Yes, so I got a remanufactured unit from AUS injection down here in Tempe, AZ https://www.ausinjector.com/mp-21024/ . The connector was already new where I just assembled on a new connector earlier in the year. However, this time I snipped the wires a tad further down the harness and wired on a new connector that was preassembled with the wire leads coming out.. There is no way it is shorting out at just the connector... I think I really am just so confused. Because the #1 injector connector works on the #2 injector half the time. Sometimes the test works, sometimes it doesn't. The new and old connector seemed to make no difference. Always did the same thing. In addition the #2 injector connector never seems to work on the #1 injector. Affect idle that is. I can't tell if I have two problems, or one.

Hey guys, back again to solve another mystery on my 1977 280z California spec coupe. So in short my number 1 cylinder doesn't fire (I have no idea how long it has been like this). Or if it does it is extremely weak. Anyways, the reason I know this is that when I pull the spark plug wire the engine idle does not change noticeably. Also the idle is slightly rough and will surge if I have it anywhere lower than 1000rpm, as well as the car doesn't like full throttle under load. I have also disconnected the fuel injector and that made no change at idle. Disconnected any other cylinder causes the idle to drop very noticeably. So, here are the tests I have run thus far. First I checked for spark in a number of ways. I pulled the #1 plug and had it zap the valve cover by cranking the engine over. worked fine, spark looked strong. I swapped plug wires just for the heck of it between #1 and #2. No change. Dead cylinder did not follow the wire I swapped spark plugs from cylinder #1 to #2 and vice versa. The dead cylinder did not follow the plug. Always dead on cylinder #1. Next checked compression Even between #1 and #2 at 150psi. Didn't bother with the rest. Pulled valve cover and turned over motor. Valves opening and closing as should. The wipe pattern on the rockers looked very good. Next I went to the fuel injector. Which is where I get confused. I listened for injector noise with a screwdriver. I swear I heard a 'tick tick tick' like all the others. However, I still heard that noise when disconnected. Possibly the sound from another injector is carrying through the fuel rail. Tested injector for ohms. It passed matching all other injectors. Next I checked the connector. It was fudged up, but I would get 12v with ignition on. Measured with a multimeter with 1 pin in the injector connector and the other pin in the injector connector and going to a ground on the intake manifold. Thus is is getting current. Just to be safe I rewired a new connector on. Tested perfect. Removed #1 fuel injector Tested with 12v batt very briefly to see if the solenoid would actuate. It did. it also was not clogged and would spray fuel. Checked fuel rail for fuel coming out of #1 injector rail port. Worked perfect with starter signal disconnected and fuel pump on. So no clogs there. Gas looked crystal clear. Replaced #1 fuel injector At this point might as well try. It did not help. Disconnected both #1 and #2 injectors while car was running. RPM dropped Swapped #2 injector plug to #1 injector. No change in rpm. Swapped #1 injector plug to #2 injector. It improved rpm. however I did this test many times, and sometimes the rpm would not climb. It is not consistant. So, what the heck is going on here. Is it possible that the ECM is for whatever reason not alternating the ground for cylinder #1? Or is it possible that the #1 injector is firing but angled somehow and completely missing the spark plug. I would like to emphasize that during this process I would check plug #1 consistently and I never noticed it really appear wet. As well as it appearance never changed in general. All the other cylinders have more carbon on them as they are running a bit rich right now. Any suggestions are welcomed, thank you!

Thanks guys. Sounds like some jb weld and patience with a file is the way to go. As well as a bigger clip once finished.

Hey Guys, Ran into an interesting problem on the Z. Went to install the original driver's side lock on the car (Found it inside the car when I bought it, never was in the door). Anyways, I got it clipped in and noticed that the lock didn't have enough throw to actuate the lock. I looked at forums and it was because the lock had too much slop due to the clip having too much slop on the lock shaft. The solution was to go to just a thicker clip to pick up the slop. Before I did that though, I noticed with the clip out, that the actual seat for the clip had been partially chipped off. Here is what I mean Do you guys have any experience with this happening and a method to fix it? Or am I out of luck and need a new lock. If needing a new lock is the case is there a lock I can get that can be keyed to fit my original car key. Having multiple keys for a car would annoy me immensely. Thank you!!

Glad you found some help within the thread. When you get it all figured out please do share the results (if it worked and what sized grommet/washer you used)!

These two replies sum up everything I hoped would have been answered. Thank you both very much!

Hey guys, Wondering if anyone else has run into the same issue as me. Can't see any evidence of someone else with this issue, thus why I am posting. On my 1977 280z the inner door latch has some sort of rubber piece on the eyelet coupling between the latch and the springed rod. Do you know where I can get a replacement, or recommendations for a substitute, or if I should ignore it. It seems to keep the rod from rubbing on the metal it threads through. Redoing the mechanical parts inside the door, so figured I would address this while I am in here. Thanks! Here what I am talking about on the door. This is the other door that still has a small bit of the tattered rubber left. Pretty nasty looking

View Advert 1975-1978 280z Original Clock My original clock has been wasting away for 30 years falling apart inside of a cracked dash. Not referbishable, rusty, fogged, etc. Looking for anyone who has a clock that is original to a 1977 280z. It doesn't need to work, just needs to be a super solid core so I can send it off to be restored/rebuilt to functional condition. Thanks! Advertiser ckurtz2 Date 02/20/2022 Price Category Parts Wanted Year 1977 Model 280z

Hey! Hop on this and see what ratio this diff is and if it's the CLSD. If you don't I am sure other members will! https://portland.craigslist.org/wsc/pts/d/gaston-1983-nissan-datsun-280-zx-turbo/7435972177.html *** Edit Never mind:( Wrong year don't think its the CLSD. Bummer

Scour craigslist and other sources for 280zx part outs in your area, or check junkyards. That is where I got mine after a few months of hunting

I might have a cam. However, it has some scoring on the cam lobes. Let me know

I can't say what set up you will like, but here is what I am running on a 77 280z and I love it. 81 280ZX NA close ratio 5speed (love the overdrive) Fidanza light-weight flywheel ACT stage 1 clutch kit (great brand, used them on many cars, smooth engagement) 88 Turbo 300zx 3.7 R200 CLSD (rare but if u find one get it). Also all the R200s are direct swaps as long as you get all the parts required for a 280z to 240z conversion. Personally I would recommend the R200, because they are more robust than the subie LSDs, and more robust then the 240z R160 diff.