cygnusx1

I would NOT make a decision like that without knowing the oil pressure, and the compression. Without knowing those things, you are purely guessing.

Whats the history of the car? Previous owner rewiring? With the pump running, you may be able to isolate the source circuit by pulling fuses/fusible links/connectors one by one.

Aaaanyway. The stock EFI system is a good system. It was leading edge, reliable(most are still working fine). It got you through extreme cold and hot, and it met emissions criteria...even in Cali. It was pretty easy to fix if you had the FSM, and had some basic electrical skills. It drove great, without hiccups and misfires. All in all, I would say even an excellent system. There are DOZENS of options for upgrading/replacing/updating the JECS system. There is no magic bullet. Bottom line, is that in 99% of the cases, I venture to say, the problems are due to age, wear, and corrosion. Not problems due to not having a "good" system in the first place.

By taking control of the timing curves, you can gain performance. However, ALL of the above can also be made WORSE. It all depends on the tuner's and installer's expertise.

1000 hours? Do you speed read?

Forgot about that file. Here it is. It's a webpage that I was able to salvage from bits and pieces of internets history. Yes, modern CAN systems are the coolest things since sliced bread. They make Our JECS system look like a Radioshack electronics kit from 1974. Oh, wait...it basically is. L-Jet Lobotamy.zip

77 and 78 use many different functions. One example is the fuel pump switch built into the AFM. 77 Uses it, 78 does not. I doubt you can simply interchange most of the two harnesses.

Enjoy, my caveman "tuning" guide. Click the link and go to my post #14 http://forums.hybridz.org/index.php/topic/95316-braaps-l6-efi-induction-advice-and-tips/page__view__findpost__p__896858 This is for the L-Jet EFI which is re-badged as JECS for the Datsuns. Some resistors are not used in our cars. OK This report I have is from the stone age of the Internet. I can't get my scanner to work and I don't know who published this information but it was someone with an electronics background for sure. There are photos showing the locations of the resistors but they are not of high quality. I believe that the resistors are all labeled on the board, so ID'ing them may be easily possible by opening up the ECU. Resistors are located on both sides of the main board. The article was written about the generic L-Jetronic system. Here is a summary of what was done: A CD player was used to simulate an ignition signal and a scope was used to read the outputs of the ECU while resistance values were tweaked. 100hz signal = 3000rpm. Resistors and what they do: R103 Low RPM Dwell limit for injector pulse/ smaller R = higher limit on low-rpm dwell. R106 rev-limit smaller R = time of pulse decreases and rev-limit raises R237 & R239 voltage swing compensation during cranking R616 off idle and Post cranking enrichment - works with coolant temp sensor R758 fuel cut-off speed R621 Off idle enrichment max smaller R = more rich R624 Off idle enrichment decay speed smaller R = faster decay R306 timing of post start enrichment larger R = longer enrichment R617 Post Start and Temp enrichment amount smaller R = less enrichment WOT switch (TPS) fixes enrichment to about +9% R345 Injector opening time compensation Injectors open with about 4amps, after 0.5ms current is held at about 2amps by R408 3 Notches in the AFM wheel gives about a 2% change in lambda. This is take from a website that existed in 2/26/1997. I do not have the author's name. http://proffa.cc.tut.fi/~k124775/mods.html Or you can try your luck here: http://web.archive.org/web/19970806040843re_/proffa.cc.tut.fi/~k124775/mods.html http://web.archive.org/web/19970805035446/proffa.cc.tut.fi/~k124775/Injection.html

She turns 40 in 2012...actually in Dec. 2011. I drove the 240Z all day today. Happy 2012! Blessed with Z weather on Jan 1st in NY...priceless.

General chart not mentioning feed rate. http://www.ollivier.nl/html/drillspeedchart.htm Here is some good info: http://store.curiousinventor.com/guides/drill_speed/

This should be true and probably is true with OEM stuff. You never know with the replacement stuff.

I believe there is a metal "tab" that is part of the tank bung, that helps hold the o-ring in place. A non petroleum or synthetic grease is a good idea too. Some greases can dissolve some o-ring materials.

For smallish bits. You want high speed and low feed. You also want coolant, and a steady, steady hand. Dive the bit back out a little, every 5 seconds or so, to help get out the chips. Keep the pressure on the bit perfectly centered. It's also essential that the bit be sharp. If it's not sharp, all you do is make heat.

Winter will do that to us folks that have to deal with it. OTOH, by springtime, you may feel the urge to enjoy the Z again.

I have never come across Webers with opposite starter circuits. It's probably pretty rare. As for the Mikuni's orientation, I can't say for sure. I will research them.

It's still a bargain classic at 13K. IMHO.

This photo is for a Weber setup, to clarify.

Maybe it's just me, but I like that the factory choke lever still has a purpose. I think the Mikunis have an externally adjustable accell pump or float level, which sounds like it might be an ease-of-tuning advantage over the Webers. Functionally, they are pretty much clones for the most part. Weber jets fit Mikuni carbs if I am not mistaking. I am not sure whether it's easier to find a Weber expert, or a Mikuni expert when you need help, but I would imagine that one expert would know how to work on the other anyhow. As far as US suppliers, and books for dummies, Weber wins that one. Mikuni Info: http://www.mikunipower.com/PHH01.htm

I am fabricating billet linkage and a billet choke link for triple sidedrafts right now. The linkage is in the classified section. The choke link is in development, and will be available in a week or so. The starter circuits definitely help the engine fire up and establish a smooth fast idle, even in moderately cold weather.

Here is my first guess and I am almost sure this will work. Unplug the O2 sensor wire and go for a drive. It should fix the drivability issue. If not, simply unplug and replug the ECU and the AFM connectors. Clean them with some contact cleaner if you have some. Here is my thinking. The car drives without reading the O2 sensor until it warms up. When it is warm, it begins reading the sensor, and tries to correct mixtures. If the O2 is reading improperly, you will get stumbling, or poor fuel mileage when the car is warm and under load. I find that typically they will run "better" with the O2 sensor disconnected. They run on a "fixed fuel map" with no o2 sensor, which is richer than when they run in closed loop (O2 sensor mode). You should feel more torque with it unplugged.

It's nice to see what they looked like at the dealership, when they were new.

Here is my BONE stock L28 (1976) with Triple 40 DCOE carbs, headers, and a 12lb steel flywheel. Heel and Toe is pure bliss!

You want it to rev fast (quickly in neutral)? Shorten the stroke, lighten and balance all of the rotating mass, open up the intake and exhaust tracts, use multiple throttle plates, run high compression...did I miss anything?

I got rid of the buggy bumpers on my 76 and then got rear ended. Murphy's law. I still don't regret switching to the 240 style though. Unfortunately, the 77 and 78 has that spot welded apron on the rear end which makes it more difficult if you don't need paint. I came to the conclusion that if I wanted to pamper/campaign/invest in originality it should be a 240Z, not a 280Z. All things equal, the 240 will be more desirable in the long haul. The 280Z will always be a step or two behind the 240's. Off topic sorry.

What Leon said.