Niku-Sama

i guess when buying a lower milage car you wind up doing the work when the milage racks up.

lately i have been DDing my 79 and lately the problems are racking up.

aside from the interior being a mess and the dash crapping out and the front valence got nailed by **** in the road (its pretty crappy lookin under there now) i am having other problems. i'll list em off with the most prevelant problem.

no real major mods, i have a MSD Blaster coil and a 90 amp maxima alternator. put in a new battery about 2 months ago and i also replaced the battery cables with something a bit better guage.

first off vapor lock. its been happening often and been increasingly more difficult to start the car after i have been driving. i've run air through the return lines and they are not clogged at all i cant figure it out beyond that and possibly needing to replace the fuel "maze" with a simple in and out rail

seccondly the car has always done this but has been getting worse, theres a front to back pulse when cruising, very ****ing annoying, no ammount of adjustment and anchoring has stopped it, its just been getting worse. nots not like a out of balence pulse its just front to back, i dont notice it while accelerating and i never notice it affecting RPM or how the engine performs.
at higher speeds i dont notice it as much but theres still something there.

third, missing at higher cruising speeds, might be related to above. at random there will be a huge miss, like all cylinders drop. i tried a different distributer and still have this problem. mabe its not spark?

fourth, something needs to be done about the rear calipers. they let the back pads drag constantly and they make noise constantly. i've replaced the hardware and it still does it. these calipers are ****. i checked them recently and they've rubbed about half way through and theres less than 10k mi on them. is there any direct swap from somethin that has a real caliper instead of a piston on one side and a bar that goes across the middle of the pad on the other side?

fifth, happend only once but it sounded kinda bad, i pushed the clutch pedal in and i herd a werid metal grinding noise, almost like the starter running while the car is already started but it wasnt that loud. hasnt done it since that one time but is that a sign of impending doom?

NismoPick

#1: Vapor lock is not a common problem on the L28E, and even less likely to occur at ambient temps below 80-90*F. I can't imagine it's that hot right now in Oregon... How do you KNOW it's vapor lock?

#2: Check your injector flow, spark plug gap, all sensor / ecu connections for corrosion & broken wiring. Check your TPS to make sure it's turning on / off / full throttle at the appropriate times. Check your AFM carbon track. Have you ever adjusted the AFM spring?

#3: Same as above.

#4: Indeed the 79-81 rear calipers suck. I don't know of any solution other than swapping arms with an 82-83 and get the advantage of better calipers / rotors... and the option of 240sx calipers?

#5: Throw out bearing? I dunno unless I hear the noise...

BlueKitsune

You can swap out the entire trailing arm!? I learn something new everyday about these Z cars! *now goes to rip off the trailing arms off his junk 83... Tomorrow*

NismoPick

Yep. Or just drop the entire rear end & plug it in to the other car. That would be more simple, but somewhat awkward because it would be so heavy.

BlueKitsune

Holy ****.... I might just do that. I was getting sick of the little 2x2" pad for a brake. You have to swap the ebrake cable too tho huh?

NismoPick

I think so, but it's virtually mix & match / plug & play with all the parts.

BlueKitsune

Sweet! Ok I'll do that sense I want better brakes and my car is out for the count atm!

/thread derailment lol

Niku-Sama

i'm positive its vapor lock, if i stert it and let it stumble for a while a bit after i take off it smooths out.
also if i park it and pop the hood and come back out afterwards it either doesent stumble at all or if it does its very little

if i can find rear trailing arms then that would be awsome but i cant unfortunantly, theres gotta be something out there

BlueKitsune

Do you still have your injector cooler fan? If you have it, make sure it still works. If not you might wanna find one by the sounds of it

rogerz

Next time you have a hard start try pushing the accelerator to the floor and leaving it there while you crank. May have leaky injector and actually getting too much fuel in the manifold. Once it is started and running doesn't matter much except might run a little rich.

Niku-Sama

injector fan didnt do any thing when it ran durring the summer, i also dont think that it'll help any more than it used to now because this is kind of a sudden thing

are you thinkin that its pushing the fuel past an injector when it heats up with the car off?

once its started it rsome times wont stay started so yes it does matter alot

Niku-Sama

any one else?

i have a feeling a clutch is going to be soon happening, i'm getting a werid belt like squeak but it sounds closer to me than the front of the engine, all the belts are less than a year old, arent glazed over and arent cracked. pretty rubbery still, they are tight as well.

so the list is:

injectors
suspension bushings (all)
shocks
struts
clutch
flywheel resurface (more like replace i bet)
slave(possibly)
rear calipers
diff mount
fuel rail...thing (aka MAZE)
waterpump (atleast check, Factory OEM pump)
exhaust (soon)

thats just the running list, the body list isnt too bad, interior list is growing. damn dash pads.

theres got to be something thats direct swapable for 79 for calipers. wasnt there something about 2nd gen maximas (85-88) or something else?

i guess some of the things on that list would cost me the same to get something a bit better, like a lightened fly wheel or exhaust headers or a grab tastic clutch that isnt 30 years old (thats just a guess)

RodMoyes

The vapor lock issue you speak of IS common on these cars. it's been mentioned here a gazillion times but with a lot of different descriptions. I wrestled with that problem for quite a while on my car until I finally replaced the Fuel Pressure Regulator and it went away entirely.

Niku-Sama

hmm i have already replaced the regulator.

we had a gas theif, and they tried getting gas out of my car but didnt get any, either way i noticed all day while i was driving the car (which it was a warmer than usual day) that it wouldnt do it nearly as bad. at the end of the day i realized the cap wasnt screwed on all the way so i did and the problem came back the next day.

no now i am stumped

autophile

Mine doesn't vapor lock, but does seem to be running on 4 or 5 cyl.

Also backfires once in a while.

The plan is to replace some vacuum lines and put fresh seals on all injectors since this has helped the problem in the past.

Thanks to advice on this thread, I'll also replace the TPS and adjust the AFM spring. Again.

Also thanks to this thread, I'll be swapping the entire rear suspension from my 82 parts car to my 79 DD. They're both coupes, and I'm hoping this will cure my brake light on the dash and help improve the overall performance of the car.

Duck Ryder

Probably not related but might give you something to think about...

My motorcycles gas tank imploded once. What happened was that the pressure difference release valve failed so the fuel pump kept sucking fuel, as the fuel was removed a vacuum was created inside the tank causing it to imploded. The mechanic at the dealership explained that I should have experienced power loss and possible hesitations. Unfortunately for my story, the bike ran just fine. Imagine my shock as I looked down at my disfigured gas tank when out in the middle of some windy logging roads

Anyways, my suggestion for the vapor lock theory is to get a pressure gauge on your fuel lines and see how quickly you lose pressure. Pressure changes the boiling point of fuel so I am guessing that if your fuel pressure drops to 0 psig within 30 mins then you probably have good conditions for vapor lock. And since your gas cap is creating some sort of effect, I am going to hazard a guess and say that your fuel pump is not preforming very well (not keeping pressure up) and that it is failing to prevent back flow after it is turned off.

VenomousZX

+1.5 for the injector cooling fan, I have mine set to turn on automatic after the car is shut off these things run for 15 minutes on their own & then shut off,


120amp alternator, MSD 6-AL and a few other tweaks here & there but with 78,203 original miles as of this posting I feel your pain on stuff racking up this car sat for 20 years before I got it, lot-rot hardcore I had to replace all of the steering brake & suspension bits... added up quick