since the pulley was loose and possibly turned, the last person could have timed the engine wrong causing your bog. re-time the engine and try again. there is also a module on the side of the dizzy that may have been damaged with the batt polarity swap project. its wired from positive as well to coil neg.

 

the car drove perfectly (as far as engine/power) when we go it. i dont think it is a timing problem, unless just changing the crankshaft pulley could mess up the timing.

we were looking at that little module when trying to daignose it... other than the bog, what could be the symptoms of that going bad? we have a good spark, it just bogs hard when under load, and the engine response is slower than it used to be as well.

 

I know how that is, I feel bad about all of the questions I ask and I just hope that the guys here know I appreciate their help a ton haha

Just trying to save myself the money of going to a shop, and learn!

 

ok, still stuck on the same problem. i dont think i burned out that module on the side of the distributor, since it gets power from the ignition coil, and when i did this, the keys werent in the ignition. also, it appears to be in good condition.

we are looking at our AFM, and i dont see anywhere it could be burned out. the reostat looks good, and the connectors are clean. the unit moves smoothly.

i am at a loss. the haynes manual says the timing could be off, but we didnt touch that other than replacing the crankshaft pulley. we didnt open the engine up at all. prior to this, the engine ran well, pulled hard from 3500-6000 rpm, and had fast engine response.

with a multimeter, how would i check to see if the AFM is bad?

 

Check this out:

https://www.zdriver.com/forums/240z-280zxt-s30-s130-tech-tips-275/js-how-rebuild-your-afm-15277/

Perhaps a rebuild will bring that baby back to life? While you're at it take a close look at those AFM connectors if you haven't already and make sure there's no broken wires or bad contacts.

 

so we've done a test, the AFM is fine. the wires seem to be good, and we used contact cleaner to clean it all up. we may have a burnt wire somewhere.

we got it running and driving, took off in 1st trying to merge on the way to a mechanic, and when i went to shift to second, i got silence. the engine shut down. so i put it in 3rd to try a rolling-start with my momentum, but nothing.

the battery is dead. it died while driving it. the alternator checked out fine at napa, but we installed a new one just in case. with a jump pack, it rotates but doesnt even try to ignite.

we checked the distributor to make sure it is rotating while cranking it, and it is. so the following is all the things we have done since the crankshaft pulley fell off.

1.replaced crankshaft pulley, and woodruff key. (thanks trex!)

2.put a belt on the A/C, and attached the connector that allows you to use the recirculating function for the a/c.

3. plugged battery terminals in backward, replaced fusible link with 16ga wire for a couple seconds, heard a click, and a fssshhhhh sound, removed wire.

4. replaced wire with fusible link wire once i found out what a fusible link is.

5. checked all fuses under the dash, none were burnt

6. re-attached battery correctly.

7. replaced burnt out ECU, ignition coil, spark plugs, fuel filter.

8. disconnected AFM, and the engine would start. reconnected afm, engine started, drove but was bogged down when under load. (slower than my wife's prius)

9. got home, turned engine off, and it wouldnt turn back on. we advanced the timing using the distributor advance/retard as shown in the haynes manual. engine wouldnt start.

10. disconnected afm, no start. reconnected, no start. cleaned all contacts, no start. no start. randomly started! used a bottle of seafoam at this point hoping to clean injectors, etc. let it run for 10 minutes, and took it for a drive.

11. RAWR! power is back! yeehaw, right? we decided to take it to a mechanic and have it looked at. accelerator to the floor, pulled out into traffic and the engine shut off.

12. cried. battery is now dead, and will rotate the starter but about once/second. we hooked up a jump pack and it just rotates. however, it hiccups once around the third or fourth rotation. we replaced the alternator, and no change. we moved the contact on the AFM per the article trex posted, no change.

so luckily we werent far from the mechanic, and we just pushed it into the parking lot of the mechanic. tomorrow we will see, i hope.

 

Holy crap good luck.. that sounds like a whole mess of fun.

 

You're flopping about if you don't follow the procedures in the FSM. Go to www.xenons130.com and get the FSM and it will tell you how to check the resistance at the ECU for the AFM.

Regardless when you hooked the battery up backwards expect at least the ECU to be damaged or destroyed and who know's what else. You'll probably need a new ECU.

Replacing the fuseable link with a random wire is a bad idea because the fuseable link works out to be a specific amperage fuse. What current will your wire fail at? That's like putting a penny or a piece of tin foil in place of a fuse

 

He did that one and I remember him talking about it earlier in the thread too.

 

thanks Trex! also, i only had that wire where it was until i found out what a fusible link was. it now has a fusible link in there again.

i am downloading the FSM now, but have been following the haynes manual as much as possible. it keeps pointing at the timing, but the car ran great, and still runs intermittently. i am worried that we will need a new wiring harness.

anyhow, i will look in the FSM once it is downloaded.

 

so the preliminary results are in... and it's weird. please tell me if anyone has ever heard of this:

the fuel injectors are getting a pulse that should tell them to squirt, but it isnt enough to tell them to squirt. its weak. the ecu is telling them to, but not "loud" enough. has anyone ever heard of this happening, and if so, how do we fix it?

 

I personally have never heard of anything like this but I'm pretty new to mechanics

What I would do is clean all of the connections and test for conductivity. Test the injector wiring too.

Edit: Have you pulled the injectors to see if they're alright?

 

no i havent pulled the injectors, but remember, the car was driving fine, and shut off suddenly at around 3000rpm, as i was shifting to second gear. however, it is a good suggestion, and i will probably do that once i get it back from the mechanic. of course, i have no idea what to do to check if they are good.

 

I'd measure the resistance across the terminals, and if you pull them to check them. Check to see if they're clogged or damaged.

 

so the mechanic says my injectors are good. he says he thinks there might be a short somewhere that is frying out the ECU. yep, that means i killed another ECU because i didnt check the wires before installing the new one. however, that doesnt explain how i drove for 20 minutes and when it died, the battery was dead. how hard is it, really to change out EVERY. SINGLE. WIRE. on the car? anyone got a spare wiring/engine harness floating around?

 

Using the FSM, a multimeter, and some patience you or your mechanic should be able to narrow in on any short that could possibly be there. Also if there is a short it doesn't absolutely mean that your ECU is dead. I've created many a short on various boards without long-term problem

I hope this is a mechanic you trust :/ I'd hate for you to get charged for this guy to just throw expensive parts at it until something sticks.

 

I agree Trex, he seems to be into helping out more than charging me, as he hasnt offered to sell me anything yet... he knows i just want diagnostics so i can fix it myself. now if i can convince him to find that short for me... lol. 4 hours of labor so far... 110 bucks. is that expensive? of course, he took 4 hours (or so he says) to find out there was a short.

 

That's a bargin - shop rate here is probably around $110 an hour....

A short in the harness shouldn't be killing your ECU - reversing voltage to it will. A short in the harness will blow your fuse and/or fuseable links.

I suppose if there is a short in the harness you could disconnect the battery and get a power supply you can limit the current to and see if you could find a warm spot on the harness.

What I would do is find out what part of the circuit is shorted - divide and conqour. Disconnect all the fuseable links but one. Find the one that has the short on it. Then pull all the fuses associated with that link and put one at a time until you find the one that is shorted then disconnect everything in that circuit and see if it is still shorted. If everything running off that circuit is disconnected and it's still shorted unplug it from the main harness and see which side it's shorted on then trace out the single wire that has the short on it. If it's not shorted with everything disconnected from that circuit plug in one thing at a time and see what is causing the short when it's hooked up.

It's a wiring harness - you're smarter than it

 

What ever happened with this ZZzzzz?

 

still working on it. i have gone through 3 computers now, all previous owners said they are working, so im thinking that isnt my problem. i just got the new connectors from fricfrac, (which are high quality by the way) and have about half of them installed now.

i read that someone with this same problem had a short in one of their injectors... so i am going to check that out. if nothing else, as i have been replacing these connectors, i have found some mild corrosion (just slight discoloring of the copper) on the original harness, so i am going to use the FSM to do a continuity test on the ground wires, because if it was corrosion on just one of the injectors, it would still fire up... im also going to clean up all of the grounds i can get at and check the 12v ground on various parts of the body to make sure we are getting a good connection.

what blows my mind is that the car ran, and fast! with the chassis ground (the one that comes right off the battery terminal and connects to the chassis) completely disconnected. the other grounds are connected to what basically amounts to chunks of rust on the chassis. so im still trying to work out what the problem could be.

 

it is a short in one of the injectors! injector three, when disconnected, allows the engine to run! i replaced the connector, and still have the same problem. im wondering if it could be the wires, or would it be the actual injector? i have extras that i could use, but what are the odds of an injector frying? how would i check if it is the wires and not the injector?

 

ok problem found. it 100% IS the injector. now i need to remove the fuel rail, and replace it. the fuel rail however, does not want to move.

 

SHE'S ALIVE! all fixed up! Thank you all, Trex, Fricfrac, NismoPick, you all are amazing! with this forums help i found the problem that an ase certified mechanic couldnt figure out. took her for a ride and burned some rubber off in a parking lot.

tomorrow im gonna go put the first real tank of gas in, and if its sunny, drop those tops and take my wife for a drive. woohoo!

 

Good job! Now you can fix anything on your 280ZX