Jennys280Z

I'm also wondering if these AFM resistance values in the EFI Bible ever changed from year to year of 280Z?

Yes I suppose it's possible my AFM is toast and it's possible I've already wasted money on a 2nd bad one. If I'm going to prowl junkyards I'll take my multimeter with me and give myself an extra guarantee. Looking at my ECU test results and my recent results with the AFM in hand, my AFM tested identically the same whether from the ECU or directly. Both my ECU and AFM had exceedingly clean connectors. The ECU's pins were (are) immaculate. I certainly hope that the AFM's not what the problem is because they are very expensive rebuilt parts.

Congrats argniest! Now come do mine! I'm going to order some more from Kano Labs soon, too. My FI screws are going to take a bath in that stuff before I even start trying *giggles*

Pins AFM 1 AFM 2 (in Ohms) 6-8 226 226 8-9 126 126 7-8 199 200 6-7 73 75

But I got the exact same values on two AFMs. When you said your numbers were the exact same as mine, that told me that my AFM was fine. Particularly because here's a third AFM, again with the exact same values. Maybe that is wrong. Maybe these AFMs go bad and then all arrive at the exact same numbers (126 and 226) ? Did you do anything else to your car at the same time you had the AFM off which might account for the difference? For some of the measurements, my backup AFM was reading higher in ohms until I cleaned it. After cleaning it, it is now within 1 ohm of my original. I could put that AFM on the car and see if there's any improvement The EFI Bible lists "continuity" for some of the expected results. For instance pins 7-8 is listed as "continuity" yet I get exactly 200 ohms on two independently owned AFMs. So if 200 ohms is considered "continuity" then I'm guessing 126 is close enough to 100. Or, if 200 ohms is NOT continuity, then what? All bad AFMs go bad the exact same way? Ok fine but why isn't that in the Bible? If anyone with a '75 or '76 280 wants to drop their ECU and test their working AFMs, or have already done so and can produce their results, that would be cool. If they get the same results, that will be the 4th AFM with the same values. I think that'll prove conclusively that my test results are really flying colors. The two tests are with an ohmmeter testing pins 6 to 8, and 8 to 9. Maybe I should be following the Bible militantly and expecting to get exactly 100 and 180 ohms or else it's gone bad? And now for the biggest question, if the AFM is possibly responsible for this, does the AFM generally go bad all of a sudden?

Stant (NAPA) had two flavors that fit my '76, a 180 and a 195. I chose the 180 OE 'stat. When it's cold outside, my temp gauge stays just under the halfway point on the gauge while driving around.

I've lowered my idle speed at the screw a few times as I've done work to my car we've talked about on this thread. So my idle is kinda rough but I'm idling right now at 770-830. It was 1100 and pouring dark smoke with the TPS jumped to full enrichment. Remember I idled my car several times in the cold with a bad thermostat to boot. I wonder what havoc that could have caused that may have resulted in my running problem? I'll follow your advice in your 2nd paragraph Cozye thank you.

My mixture probably isn't ideal right now, but I bet that's true for the majority of us (but not you ). A few things I can't get around are how it began running badly in the space of one or two drives. I probably made the mistake of starting it and just idling it in the cold a few times during its downfall. Based on road tests the problem is independent of mixture. It feels like a miss. I'm not experienced enough to use the right adjectives with the word "miss" so I don't know if its regular, irregular, random or what. Would a mixture problem come out of the blue? I was blaming the AFM for a time there, but that passed all the electrical and mechanical tests with flying colors. Whatever it is, it's hit the performance of this car to where it's only 75% what it should be, mixture held constant. Anyway, focusing just on vacuum for a moment, my car may be getting between a quarter and a half inch less vacuum now than it was before moving the AFM wheel three teeth CCW. Maybe I should have left it alone. My distributor is becoming toasty toast. It's grimy and gross inside all dirty and sticky looking. No vac advance when my car is likely "tuned" to run full-time vac advance. Just saying... Do you think a new dist will have more static advance than this one or do I need to adjust something underneath the dist? I hope you won't stop coming here when you start working on your other car. And yup I'm waiting for a warm day over 50F to go for a fun drive.

Thank you sweetie I'm glad you're here. I'll follow all of that good advice! I wish I had a dyno that would be so nice...or at least a boyfriend who worked at a place that had one The symptom I'm having here (the major one) I don't think is mixture related. Because on driving the car leaner, the way it is now, and both rich and super rich, the "problem" existed across all of these mixture conditions. I've learned so much here in the past months...so cool! And oh yeah how is your new car??

cozye that's great advice about the vacuum. But then...putting vacuum aside, does my motor merely idling so much faster indicate that I was too lean? All we did with the TPS was enrichen the mix. It seems I contributed enormously to improving my idle but doing nothing for actual driving performance, huh? I think I mentioned the valves in the long post about the history of the car. Maybe I'm wrong. But yup if I can trust the repair invoice it was done at at 125,000+ miles. So then I'll do the compression test first. Also I did just what you did, cozye. I got my tune up parts at MSA and my clutch stuff at RockAuto.

I wanted to acknowledge what Zed said, that the projection of the tip is a function of the heat rating of the plug. The pictures show the difference between a heat rating of 5 (old plugs) and a 7 (new plugs). I agree it doesn't advance the timing of the spark per se, but the longer nose would combust a bit "ahead" of the air/fuel, not in time but in displacement. And another thought I'm having is that if you're right about just driving it, then maybe I'd be better off with my old hotter plugs back in.

Yup it was a 4th gear-only deal. My car is set up like a California car for whatever reason. Theoretically I should be full-time vacuum advanced but I'm unfortunately full-time vacuum retarded. :ogre: On the first sunny day after I throw my tuneup parts on, I'll drive it like that. Howeverrrrrrrr.....I have my taillight assemblies removed and disassembled at the moment so actually I'm also waiting on getting things like taillights and license plates on the car. The "chrome" around the taillights was coming off and looking bad so I took everything off the back of the car. I found two petrified hornets nests behind the rear panels between the taillights that were anywhere from 15-35 years old. And probably took a couple pounds of dirt off my car in the process of cleaning everything.

Cozye, it's big news that I'm not running lean....then why the 17in of vacuum and 1100RPM idle at full enrichment? I guess this invokes Zed Head's larger point, which is, I was obsessing over a vacuum gauge

Wow excellent advice Zed Head. I will watch out for the induction which is the clamp-on kind (I had it clamped on the #1 wire about six inches from the plug. It was kinda touching my fuel gauge installed near there. I'm focused on vacuum because I like the feedback I get from what I've done to the car so far. A barometer of sorts, but I see what you mean, I am excessively focused on it. Also it was the way the car ran (which is my true focus!) which brought me to the vacuum gauge. Oh yeah, and I'm timed right at 12deg where I'll leave it at. Rotor and Cap will be on the way tomorrow.

Noooooo...Valves were done 16,000 miles ago according to my repairs paperwork. Someone already told me to take it out on the highway. A 10-mile jog at 60mph and stretch its legs for the first time since ummm...Bill Clinton was President So this makes three of you saying that. Hey oh yeah, RockAuto has a thing I can buy where I pay $108 plus $5.00 handling fee and I take my dist off and send it to them and A1 Cardone will rebuild it for me. Another option to consider. I've also considered just buying a used one on Ebay for $20-30 and practicing taking it apart, cleaning/rebuilding it. I haven't ran vacuum advance on this car since maybe ever. So I'm just comparing how it ran without it before (at all throttles) to how it's running now. It's capable of running awesome without it so it keeps me motivated knowing its potential. But driving it is on the agenda....hey something really fun. xxx Thanks for helping me

Really frustrated now. Feel like giving up. I won't give up but I'm feeling like it. Vacuum is no better than it was....about 15in, if that. Cold idle is the same as ever. It was almost 50 here this afternoon and I had the opp. to drive the car but I"m just too bummed out. I tightened the AFM boots a few twists of the screwdriver. I pulled the vacuum hose off my Fuel Pressure Regulator. It was dry. Even more convincing, it didn't smell like fuel. Put the hose back on. Another possible culprit eliminated. I called Motorsport Auto this morning and talked to a customer service rep who told me that their caps and rotors are a Japanese import called Nippon (sp?) RockAuto has very good prices on Beck Arnley stuff so I'm going to place an order with them for the dist. parts including all my clutch hydraulics. I verified that my distributor static advance was indeed turned ALL the way over. So 14 (if that) degrees of advance is all that I can get from this distributor. Why is that? Why do others get 17-18 degrees and will my new distributor have this problem? And I also noticed this. I loosened the bolt on the distributor and turned it back to what I hoped would be about 10 degrees advance. I left the bolt loose on the distributor, walked around the car and checked the timing light and it was sitting on about 10 degrees BTDC. BUT my spark in cylinder #1 became intermittent. (I have observed spark to completely fail in cylinder #1 before cleaning contacts; since then I've replaced plug wires and now, plugs) So the lesson here is either 1) Never leave your distributor loose when checking timing; or 2) Something else is going on here and I wanted to tell the pros here about it. xx I was going to throw in a fuel pressure regulator and ignition coil because I'm really getting frustrated and ready to start throwing parts at it. I'll do some DD later on how to test my iggie coil. I just went through all of the repair history of the original owner of my car. He even included quote sheets and the bill of sale when he bought it new in 1976. This was/is my first car when I first got my driver's license. It had about 84,000 miles on it when I got it. 141,000 miles now. I noticed he replaced the master cylinder in 1988. It was still working in 2000 (going bad but hanging on), but failed during the storage period. It was stored for about 9 years from 2000-2008. It was no longer driven in 2000 and garaged for two reasons. One it developed the classic leak under the firewall to the floorpan every time it rained. And two one of the little "heater" hoses on the top of the engine spaghetti developed a leak and started spraying antifreeze up in the air. I knew nothing about cars at the time and was scared. Didn't want to lose the car and couldn't afford to fix it at the time, so into the garage it went. In 2008 I dropped the tank, had it cleaned, blew out my fuel lines with an air compressor, changed the fuel filter and a few suspect looking pieces of fuel hose in front of the fuel pump and before the fuel rail. Because I couldn't loosen the brake fittings on a slave cylinder I had it towed to a mechanic. I was really upset when I saw one of their mechanics put a vice grip to it and with the flick of his wrist loosen one of the fittings. Something I couldn't do at all. The mechanic at the time told me I did a great job on the fuel system reconditioning based on how well it started up. So I replaced the master cylinder and both slave cylinders in 2009 however the booster was already about to fail. I had good tight brakes for a couple of weeks (a week) when the new hydraulic parts were too much for the old booster to handle. Coincidentally my car went from running great to running like hell after this "whooshing" leak in the booster became obvious. JUST a coincidence, right? Another observation, when I drove the car around (after adjusting my AFM and brand new spark plugs) with the timing set back to 10degBTDC, I got some small backfires out the tailpipe when I was driving around. I don't think my car's problem is fuel/air mixture related because it still "gargled" like this on the street even with TPS at full enrichment belching out thick grey smoke (though the idle and manifold vacuum were higher). The pick-up of the car was no better then than it is now either. It would seem that the ignition coil on this car is 35 years old. As well as the alternator. But that's something I can't even replace myself because an unknown mechanic in years past broke a bolt in half that secures the alternator to the front bracket and the tip of the bolt is still inside of the hole. I would need someone to tap it out or dye it out or whatever the right word is...I have zero experience with an electric drill and would need to apprentice with someone before doing that myself. In some cases it's best I know my own limits and humble myself. I'm not suggesting that I'm considering replacing the alternator too...just sharing the unfortunate fact that I couldn't replace it even if I wanted to. The distributor cap I have on the car right now is a Nissan brand. Can't get those anymore. I hope the Beck Arnley parts are okay. 12 month warranty same as Bosch but I'm more concerned about materials and air gap precision. Going to adjust my valves soon but I don't think that has anything to do with my problem either for a couple of reasons. 1)They were adjusted 16,000 miles ago according to my repair records (and yes I know I should do it anyway)...and 2) I don't think that a valve mal-adjustment is something that happens all at once. Something...whatever it is...that is wrong with my car happened to it between drives - almost overnight. In the photos of my spark plugs, you guys can see the extra-long projected tip of these "V-Power" plugs, vs the projected tips of the regular projected NGKs. The shape of the tip has a carved-V shape on it so it doesn't look flat and shouldn't be confused with thinking that there is worn metal on the center electrodes. The pictures are for all six cylinders, in numerical order from #1-6. I took two photos of cylinder #6 for some reason, hence the 7th unintended photo. And a theoretical question...I wonder how much advance these projected tips deliver. That is, what is the mathematical translation between length of the tip and degrees of advance. Driving around at 10degBTDC with these new plugs was driving it around more retarded than before, hence perhaps, the tailpipe backfiring that I never got with the old plugs.

Yes here's a company in the UK that sells buttery leather boots for cheap. I got a pair (shift and handbrake) for Christmas but haven't put them on my car yet. http://cgi.ebay.com/ebaymotors/DATSUN-240Z-260Z-280Z-LEATHER-SHIFT-BOOT-E-BRAKE-NEW-_W0QQcmdZViewItemQQhashZitem3a565819a1QQitemZ250556717473QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories 102,000 transactions; 100% satisfaction is pretty awesome for a leather boots vendor.

Might be a good idea to address your fuel tank soon too. If the car was stored for as long as it was...I'd have a healthy dose of concern for the inside walls of your fuel tank, in addition to the other matters at hand you are addressing.

This website is like a clinic! The best site on the internet for owners of old Z cars who aren't trying to blow their engines up with mods! *giggles*

But when a car smells gassy it smells good hehe

Well our consensus was that I was running too lean, a little bit. My car was running too rich with the TPS jumped to full enrichment. But my idle speed was 1100RPM! (up from 800RPM) I wasn't impressed by the performance while driving it like that though and the grey smoke was bad. But you're suggesting that the ideal mixture results in maximum idle speed. So I could have seen 1200RPM with a slightly leaner mix than the full enrichment jumper? In any case I don't want to doctor the idle up too much when driving performance is more important. My AFM is at the stock setting now. Maybe 0.5 teeth CCW. I have an idle speed readout with my digital timing light so I'll move the AFM flap with my finger again and study the results carefully. I just put new plugs in today. About 1/2 - 2/3 of a turn past finger-tight with a wrench is all the spark plugs take to tighten. I haven't run the motor yet though. It's cold till Sunday but good driving weather then. I was going to retard the static advance back to 10 or 11 with the engine off but it is so sensitive to just a little bit of rotation it's best if I just wait till the motor is running and do it with the light. :bulb:

Early 280Zs were the first models not to have a suggested replacement schedule for their brake boosters. The 240Z especially, had a booster replacement schedule that was crazy short, at least per my '70-'79 Z shop manual. So if you can buy the 280Z coupe booster, by all means!

I remember reading about that distributor problem on another thread Cozye, and I wonder if the cheaper dist. cap you bought was a defective fit? Or in other words, not "compatible" enough? I wouldn't blame yourself for that, it might not be as much your fault for installing wrong as you think. It makes me want to stay clear of some of the cheap/obscure brands and spend a few dollars more for the best. A 90-day warranty is out of the question and 12-month warranty isn't good either. My rotor is 15 years old. In part, it's reading stuff like what happened to cozye's distributor cap that makes me scared. Sometimes I'm surprised my car even starts at all after I work on it. But I've had good fortune with everything so far thanks to y'all. I want one specifically designed to precisely duplicate the OE cap and rotor. Should I buy a Nissan brand cap/rotor ideally? I wonder if Nissan dealers carry these parts? I would think not, due to the many aftermarket choices. Nissan Beck Arnley Bosch Standard Daiichi YEC And the MSA brand? Wish I knew what brand they are! That kinda puts me off with their website btw, that they don't communicate to people what brands of stuff they're selling. Like with NAPA. Stop telling me it's a NAPA brand thermostat and tell me the truth (that it's a Stant).

Wow that makes me feel better already. :classic: I think the 3-tooth AFM adjustment has made a difference and set my mixture right. I should be ~0.5 teeth rich right now. I can say for sure that it's running better now than it was with full enrichment on the TPS. Anyhoo on my last test drive, it smelled a bit like gasoline when I drove it but I like that smell. And no grey/black smoke when idling like w/ the TPS jumping. Some obervations here: At full enrichment my car was idling at 1100RPM and I was getting over 16inHg. With the 3-tooth AFM adjustment I am getting 900RPM which is up from 800RPM before. I wonder if the higher idle (1100RPM) suggests that I need to be that rich? I need to see what my vacuum is at this point anyway (I was hoping for 16in!) so I'm making some little hoses for my T-connector at the FPR like cozye said.

The cap and rotor sold at MSA is the cheapest of all. $10 for both cap and rotor, and that's higher quality? Do you remember what brand you tried first, cozye? My rubber boot on my throttle linkage at the firewall is falling apart. Is this boot just to keep dirt from getting behind the firewall?