Wade Nelson

No. No. No. No. No.

What's your repair theology --- do it all at once, or one step at a time. For instance, when I replaced my injectors, I did it one step at a time. Two weeks before I replaced all my high pressure fuel injection hoses. Next was replacing the injectors themselves, and the connectors. Today I got around to replacing the fuel filter. My theory is/was, if I do things ONE STEP at a time, and something goes wrong, I immediately know what to look at -- because I only changed ONE THING at a time. If I do it ALL AT ONCE, and things screw up, I don't know if it was the hoses, the filter, or the new injectors. Now, if my fuel filter was holy, and feeding crud into my NEW injectors, that could be a very bad approach. (Perhaps replacing IT first, then the hoses, would have been the better order in which to do things). What's your repair doctrine? Do it all at once, do it RIGHT? Or slow and easy, one step at a time?

Go to the junkyard and buy a used flywheel. Pay $20 to have it turned and get back on the road. Or buy a resurfaced one. Be SURE you clean the oil off the flywheel after it's turned using a can of brake cleaner before re-installing in the car. The machine shops leave 'em oiled because otherwise they begin to rust within a few hours, and customers HATE seeing rust after paying $20 they expect to see shiny metal. Lighter flywheels are great if you want to rev quickly to higher rpm's. For good solid take-offs, far more common in a daily driver, the stock (heavier) flywheel gives best launch performance. While I might re-use a clutch with good meat still left on it, I'd STILL replace the throw-out bearing JUST BECAUSE...if it failed a year down the road, you'd be kicking yourself for having not done so when you already had it apart..

Why would you order a replacement $60 Fuel pressure regulator (+ shipping) instead of "Teeing" a gauge into the fuel line, sucking on the vacuum line on the FPR and seeing whether you NEED a new one first? Do you prefer hanging parts to doing diagnostic work??? Checking your fuel pressure could ALSO help you identify a leaking check valve back at the pump or other issues.

You posted a little while ago that you were planning to replace your injectors, no? Replace the cold start valve (injector) while you're at it and your cold start problems should go away. There's no point checking fuel pressure with a handful of 30 year old drippy injectors. You already know they're leaking. And I'm going to arse--U & ME you've already read all the threads about re-habbing your Auxiliary Air Regulator, AAR...which ALSO needs to be working properly for a smooth warm-up.

http://www.classiczcars.com/forums/thread46090.html

I bought the same injectors off Ebay. Car runs better than ever. Be sure you read this thread on injector replacement before you start: http://www.classiczcars.com/forums/thread47184.html

Thank you so much for sourcing these.

I'll give ya $10 for the Tupperware.

*Facepalm*

Good battery, good starter, but it either clicks, or does nothing when you turn the key. This time of year when it starts getting colder is when most batteries and starters fail. The engine oil is thicker, it takes more torque to crank, the battery puts out less amperage when it's colder, blah, blah blah. If you've already tested your battery (or replaced it), and ditto for the starter, but it still does NOT crank, here's your diagnosis path. It's a how-to for voltage-dropping your starter circuits ---- and cheating, to save time. Before you voltage drop ANYTHING you need to take both your battery terminals completely OFF the battery. I have seen them look PRISTINE but they were ever-so-slightly loose and there was a THIN layer of white lead oxide between the terminal and the post causing all SORTS of problems, like not charging, failure to crank, etc. Go buy a $5 battery post brush at Autozone/Checker whatever and clean your posts, and re-assemble, and if you're a pro, spray it with red battery terminal corrosion protector available from NAPA and elsewhere. If they are the bolt-on, "repair" type cable ends instead of the "factory, crimped on" terminals you need to unbolt them and inspect where they smash the copper wire, and perhaps refresh (or replace) that if its full of corrosion. If that doesn't solve your problem, it's time to voltage drop some circuits. One on the big heavy red/positive cable going to the starter, the ground connection, and the other on the smaller wire coming from the ignition switch to the solenoid. . (But read this WHOLE article before you get out your meter and start voltage dropping) Take your meter, set it on volts, and attach the black lead to battery minus (B-) using an alligator clip or whatever. First, take the red lead, and touch it to B+. See what the voltage is. Should be around 12.6 if the battery is fully charged. This step confirms you have your METER on the right setting, unbroken leads, etc. If your battery reads less than 12.3 YOU HAVE A PROBLEM. 12.6 is a fully charged battery, 12.4 is 50% charged, 12.2 or less and you probably have a failed cell in the battery. MEMORIZE: You CANNOT diagnose electrical problems unless you have a KNOWN GOOD battery in the vehicle. Without disconnecting anything, touch the red lead to where the main positive cable attaches to the starter/ solenoid. Before you crank the motor, it should read 12.6 also. Make sure you're in neutral, brake set, and have someone attempt to crank the motor. With a good battery, and the starter actually cranking, the voltage should not drop below 9V. Below that, and either your battery terminal is corroded, the cable is damaged, or the lug bolted to the solenoid not tight, corroded whatever. Next, you need to voltage drop the OTHER leg of the circuit -- the negative side. The negative (black) battery cable should be bolted somewhere directly to the block. Start by visually inspecting, removing, cleaning, and retightening that, and looking for damage to the cable. Make sure someone didn't paint the engine block and bolt the ground right on top of non-conductive paint! Now take your meter, put the red lead on B+, touch the other lead to the CASE of the starter --- any metal part should do, and crank. Again, it shouldn't drop below 9V WHILE actually cranking, spinning. Next is to voltage drop the actual starting circuit, the lead coming from your ignition switch. If you disconnect it and have someone turn the switch, it should show 12.6 volts also. But as I taught in the article, SO WHAT! It's easy to show 12.6 volts when there is no current flowing, no load on the circuit. It's like static electricity --- millions of volts, but no amps! Meter doesn't care! So leave the starter switch input connected, and either probe it , or stab the wire with a t-pin, you must establish a connection WITH IT STILL connecting the switch and the solenoid. Again, have someone crank it while you watch the voltage. If it's below 9 volts or thereabouts, you may have damage to that wire, or whatever is FEEDING 12V to your ignition switch. There's actually a much SIMPLER way to determine if the crank signal is the problem --- just run a jumper wire from B+ directly to the starter switch input on the solenoid. If THAT causes it to crank, but turning the keyswitch does NOT, then you know the problem is in the keyswitch circuit. Again, that is so much faster, I'd do that BEFORE I spent time voltage dropping anything. So now that I've taught you how to voltage drop circuits, I'll teach you how to cheat and skip actually doing it 95% of the time. Connect a pair of jumper cables from the battery terminals directly to the starter, but only ONE AT A TIME. (not one AFTER another, only ONE pair connected at any one time) Hook up a black cable from B- to somewhere metal on the starter, turn the switch, and see if it cranks. If it does, then your ground terminal / battery cable has a problem. Unhook that, and hook up a red jumper cable from B+ to the post where the fat red cable normally attaches to the solenoid. Turn the switch, and see if it cranks. If it does, then your positive cable / lug has a problem If NEITHER of these "fix" the problem you have a failed starter, seized motor, bad battery, whatever. If it does fix it, use voltage dropping to determine WHERE you have a problem preventing adequate current from reaching your starter.

Yes. Vacuum is vacuum. How the car fuels itself doesn't affect MANIFOLD vacuum, only the pumping action (or inaction) of the motor. And, as another thread points out so clearly, if you live at 9000', you're going to show a lot less vacuum than the guys @ sea level. 1" per thousand feet, appx.

The 280ZX's sold in places like Denver had a special "altitude compensator" that tied into the ECM to lean that sucker out when it sensed it was above 5000'. I don't know if the 280Z's did or not. It was a little barometric switch that connected to two leads on the ECM. It's shown on the wiring diagram. Apparently it was mounted up under the dash. You might do some research, find out if your model COULD have been equipped with this doo-dad, and if so, figure out whether shorting those two wires together, inserting a resistor, whatever, could be used to simulate that switch tripping and saying "Yes, I'm at high altitude, and need to lean things out" With an oscilloscope attached to one of the injectors, you could simply watch and see if the injection pulse gets shortened when those leads are connected, etc. with the motor held at a fixed rpm. I would probably start by shorting them through a 10K resistor, then 5k, 1k, 500, etc until I saw some effect. Or else FIND a car so equipped, pull the compensator out and measure it with a DVOM to see how to "fake it."

Here's a great tutorial; take you 2 minutes or less to view the whole thing. http://www.secondchancegarage.com/public/186.cfm Vaccum readings will give you a very good indication of the mechanical condition of an engine, the rings, valves, etc. You can attach a vacuum gauge and have a reading in 30 seconds or less. These days reading a vacuum gauge has become a lost art, which is a shame, because doing it FIRST can save you a lot of time chasing in the wrong direction. It's fast, and easy, and with tutorials like this you no longer even have to memorize all the different possible reading scenarios.

Borrow someone else's vacuum gauge and see if yours and his match readings. Then spend 10 minutes on this website, learning how to read it, and decide which of these 12 scenarios match what you're seeing. http://www.secondchancegarage.com/public/186.cfm

Here's another tip for anyone replacing injectors: A week afterwards go around and re-tighten all your fuel line clamps. I was simply amazed at how loose mine felt after the rubber compressed for a week.

http://www.lucubration.com/pdf-tile-printer This website will allow you to print a FULL SIZED version of Xenon's 280ZX schematics. (.pdf) http://www.xenons130.com/reference.html It annoints them with an ugly watermark, but ....it's free. I printed the schematic out, full sized, tiled across 22 sheets of 8 1/2 x 11 paper, and I intend to mount them on a sheet of plywood, and put clear plastic over so I can use dry erase markers to trace various circuits. If each "X" is a regular size sheet of paper, it looks like this: XXXXXXXXXXX XXXXXXXXXXX My old tired eyes simply cannot handle tiny schematics anymore. There are other ways to tile-print large PDF's, but none I've found as simple, fast, or cheap as this.

Here it is stated yet another way, to help any of you still trying to "get" it. Voltage dropping a circuit tests its ability to supply FULL battery (or alternator) voltage, (or very nearly so) while UNDER actual load. Simply measuring voltage, or using a test light, only indicates that voltage is present, or that continuity exists, but it gives no indication of how WELL the wires/switches/connectors are able to handle the needed amount of electrical current. In older cars, with "tired" wiring, connectors, switches, etc, the ability to located corroded contacts, connectors, grounds, etc. is key to repairing them. And you do that with voltage drop testing.

We once mounted a neighbor kid to our front bumper like that. He was white as a ghost when we unstrapped him, didn't talk for two days. Didn't seem to do much for high speed stability either.

Honestly, Omar, if you don't know how to find an IGNITION feed wire you can tap into to run the relay, you need to find someone who does to help you. On the back of the IGNITION switch itself there are is an input for the battery and outputs for ACCESSORY and IGNITION and CRANK, but you probably don't want to cut into those wires, but instead find something under the hood or the dash, like the feed to the coil or something else that ONLY gets powered up when IGNITION is on. And it has to be a circuit that you're not going to screw up by tapping into it.

Excellent addition. Pictures tell a story the way words NEVER can. Thanks.

Whoever wired it up hooked it to an ACC circuit instead of an IGN circuit. My guess? they did that on purpose to try and reduce vapor locking problems. On a hot day, they climb in the car, switch it to ACC for 5 seconds to prime the fuel rail, and THEN crank the engine. You could certainly switch it back in about 5 minutes, just re-wire the relay to an IGN circuit instead! But how often do you sit in the car listening to the radio on ACC, or whatever? Unless you have a leaking injector, you shouldn't flood the engine. Or go a step further, and add a momentary switch so you CAN prime the fuel rail when you climb in, but connect the circuit to an IGN feed. I've actually thought about doing that to MY car to see if I can reduce the hot-restart problem these cars have.

I'm gonna put that one in the "Nightmares I hope I never buy into" category. 300cc injectors? .

Spook = front air dam?

Every Tom **** and Harry knows how to use a voltmeter (DVOM) to measure voltage. Yet there are even a lot of auto MECHANICS (techs) today who don't fully understand the concept of voltage drop. Take 20 minutes to read and understand this, ask me any questions you need to completely "get" it and you will be light-years ahead of 99% of people diagnosing auto electric problems. Voltage DROP has to do with a circuit's ability to supply adequate voltage/current UNDER LOAD. It's more a "quality of power" type issue than "just voltage." Imagine you have a fully charged battery, 12.6 volts or so, when you put your meter across the battery terminals themselves. Imagine you now go and stick your voltmeter leads on your headlight terminals, with the headlight itself unplugged, and you measure 12.6 volts. Everything's great, the wiring's fine, right? Wrong. Turn the headlights ON, pull 4-6 amps, and you may only measure 12.2 volts. You've got a voltage DROP of .4 volts. That's the simplest part. Identifying a loss. The question is, "Where did that .4 volts go?" Every length of wire, every connector, every light bulb socket adds SOME resistance to a circuit. Its when they add TOO MUCH that you get a voltage drop. Remeber V=IR? voltage equals current times resistance. So the MORE CURRENT a circuit uses, the MORE voltage drop will be created by an undesired resistance! NO circuit is more affected by voltage DROP than your 60A or so starter circuit. But more on that later! 30 year old corroded connectors, wire gauges that were too thin to begin with, worn or corroded contacts on switches and relays, corroded bulb sockets, paint underneath body grounds, corroded battery terminals, all that resistance adds up, and STEALS some of the voltage you INTENDED the bulb to receive. How much voltage drop is acceptable? It depends on the circuit! For a computer, like the ECM, you want .05 volt drop OR LESS! For headlights and taillights, .3V might be acceptable, .2V desirable For things like temperature sensors, etc. === .1V! For your car stereo? Well, how loud do you want it? So back to our headlamp example. We've "lost" .4 volts. How do we "find" it? First, we have to determine which "leg" of the circuit lost the voltage --- the power side, or the ground side. (or a little on both!) In other words, WHICH side has an undesired resistance that we need to correct! This is where you need six foot leads for your DVOM. You put the black lead on your battery minus (B-) terminal, and the read lead on the power wire RIGHT AT THE HEADLIGHT, with the headlight on. Let's say you read 12.55 volts. Dang, that's pretty good! you've only got a .5 drop on the POWER side of the circuit. Now reverse the leads. Red on B+. Black on the negative side of the headlamp circuit. You've only got 12.25 volts. You've got a .35 volt drop! Somewhere between that headlamp connector and the B- terminal there is UNDESIRED resistance. You've most likely got a bad body ground. Usually the headlights share a ground wire, going to a screw against the body somewhere. And instead of shiny metal underneath that screw, and a star washer, all too often there's paint, ESPECIALLY if the car has ever been repainted! Body shops are the absolute WORST about cleaning off paint beneath body grounds! So you fix the ground, and all of a sudden your headlights are white instead of yellow. You're getting 12.5 instead of 12.2, and THAT ALONE will make them 40% brighter. (Actually, at night, with the alternator running, it'll be 13.8 or so at the battery terminal, and only 13.4 or whatever @ the headlights themselves BEFORE you fix the bad ground.) I just PICKED a bad ground for an example. It could have been too-thin wire going to the headlights, corroded headlamp connectors, a worn out headlight switch, bright/dim switch, headlight relay, any of those could have been STEALING your voltage. (And sometimes you can't fix all of them, so you simply wire in a relay and use the old circuit simply to turn the brand new relay on!) Now, let's go to example #2, which happened today, and is why I'm writing this. Neighbor asks to borrow a 10mm socket, to replace the starter in his sistah's Honda Civic. I lend him the socket then get back to playing online poker. An hour later I motorcycle past where he's working on it, stop and ask how he's doing. The starter clicks, but doesn't crank. Fairly new battery, terminals don't look bad, and he has pulled the starter out of the car. Lying beside the car, I show him how to test the starter with a pair of jumper cables and an alligator clip test lead. Hook the black cable to B-, clamp it to the flange on the starter. Hook the red cable to B+, then touch it directly to the motor lead. The starter motor spins. So the motor itself is good. What about the solenoid. Hook the red cable to the place it normally connects on the solenoid, and use the test lead to jump into the starter switch input on the solenoid. The solenoid slams, the motor spins. By all tests, there's nothing wrong with this starter. Put the starter back in the car, turn the key, and all it does is click. It doesn't spin. So is his keyswitch bad? Putting a test light on the keyswitch output (where it plugs into the solenoid, it lights up. Now that's not a GOOD test, but it'll do, for now. We really SHOULD voltage drop the keyswitch, too! Next I do a VOLTAGE DROP test on the main power lead, the one that goes from B+ right to the starter. (Black lead on B-, red lead right on the solenoid where power comes in from the battery) I have him crank it. Five volts. He's only getting FIVE VOLTS to the starter, UNDER LOAD. If I had just put a voltmeter right on there, without the starter connected, I would have seen a full 12.6 volts. Why? Because, without a load, there is virtually NO CURRENT FLOWING Remember, V=IR? If current is near zero, the VOLTAGE DROP will be also. He's got one of those bolt-on battery terminals, and when I open it up, sure enough, it's full of white and green oxide. Looked fine from the outside. But that oxide adds a LOT of resistance to the circuit. Let's calculate how much, ok? Let's assume a Honda has a 60A starter. He has a voltage drop of 12.6 minus 5.0 volts, or 7.6 volts. V/I = R, so 7.6V / 60A = .126 ohms That's all, .126 ohms worth of corrosion-created resistance is enough to keep this car from cranking. I cut off the ends of the cables, wire brush the terminal, re-assemble it, and it's good to go. (I shortened this story for the blog's sake, he had ACTUALLY already gone and gotten a new starter, and it did the same exact thing the OLD one did.... and this was AFTER Autozone had already told him there was nothign wrong with the OLD starter!) so what are the key points here. A voltage drop is created whenever current passes through an UNDESIRED resistance. The greater the current, the greater the voltage drop through the same resistance. A bad ground, or dirty battery terminal offering as little as .1 ohm of resistance can make your headlights dim or even prevent your car from starting. You can only measure voltage DROP when the headlight is on, motor is cranking, whatever is pulling a LOAD. A voltage drop can exist on the positive side, OR the ground side of a circuit, or BOTH. Voltage drops are primarily created by corroded things, connectors, contacts, switches, terminals, and paint beneath body grounds instead of shiny metal. by measuring voltage DROPS, rather than just VOLTAGE, you can quickly identify WHERE the problem is --- a corroded old connector, a bad ground, dirty battery terminals, etc. If you've read this far, congratulations. You will never go to the parts store and by a starter you don't need. Your headlights will always shine a little brighter. And you will quickly become the person everyone ELSE turns to when they can't figure out why some particular circuit doesn't work, "Even though it's got 12.6 volts! and lights up a test light!"