LegacyZ

So my daughter's car stopped running on her way to school yesterday morning.. she was able to get it restarted and limp to school and I went to take a look and pick it up when i got out of work. It died on me halfway home and had to be towed the rest of the way.

Upon interrogating her, she said it's been hard to start in the mornings and sometimes, she'd be cruising at 35mph and it would slow to about 25-30mph and she would have to give it more gas to get it back up to speed. She said it had been doing that almost a month, but she thought that's just how old cars are...

Here's what I've done so far:

- verified gas is flowing
- checked spark plugs (pics below)
- checked distributor cap
- checked ignition coil
- kinda half assed checked for vacuum leaks

The distributor cap did have a lot of chunky white corrosion on the contacts. after chipping that off, it started a little easier..

I swapped the stock coil for an msd blaster 2 coil and it didn't help or hinder anything.

I ran it with the oil cap off and it ran a tiny bit better, but hardly a noticeable change. (that's my half assed vacuum leak check.. as far as I know, if it's got vacuum leaks, it'll run better without the oil cap in place..)

it's got coolant and oil.

judging by the uniformity of the plugs, I'm not thinking it's a head gasket. none are cleaner or dirtier than the others.

any advice would be appreciated, i don't even know where to begin at this point. I'm scared to bring it to a shop because we're a little low on funds right now, so if i can handle this myself, i'd rather do it that way..

plugs:

1:


2:


3:


4:


5:


6:


Here's a quick clip of it trying to run on the side of the road yesterday:
https://youtu.be/9gFvQrnWWtA

Here it is running a tiny bit better this afternoon:
https://youtu.be/RGKHOPc4jPQ

Still doesn't want to idle, and sounds like not all the cylinders are firing..

I was gonna try to take it around the block, but when i put all the tools away and closed up the garage (I was home alone) and sat in it, it didn't want to start again..

rogerz

you are backwards on the oil cap. if running smooth it will run rougher when you pull the oil cap. if no change you got a vac leak.


if you would really like answers that would help you and avoid flames give the following info when you post: year of car, n/a or turbo engine, stick or slushbox, digital or analog dash. Most of us can tell by the year what model you have ie 85T is a turbo z31. Z cars come in many flavors and they are all different. example 84,85,86 Z31's pretty comparable. there were changes in 87,88,89. in addition 300ZX can refer to two completly different cars the Z31 and the Z32. No mindreaders here

Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion. DON'T USE DIELECTRIC GREASE.

LegacyZ

ahh gotchya, so then I have a vac leak I have to hunt down then.. :/



Sorry, it's a 1980 280ZX, N/A, automatic, analog dash.

The battery is an optima red top, holds a charge well, been meaning to buy the optima recharge station thing though since I have 3 of the batteries, just haven't had the expendable $200..

Connections are all solid on the battery, I glanced over most other but will double check them.

Why not use dielectric grease? I thought that preventing corrosion is exactly what it was designed for?

LegacyZ

I'm a victim of a broken connector..

I did dry compression tests today after work (all cylinders 200-210 psi) and while pulling the plugs I noticed that the CHT connector was ****-eyed.. it's missing the little metal clip that holds it on, like most of these connectors on this car, that broke who knows how long ago..

anyway, after putting the plugs back in, i made sure that was seated and fired it up, and it's running fine now.

Gonna drive it to work tomorrow before giving it back to the kid, but I think that was the problem.

feel like an idiot.. haha

rogerz

you are right about the dielectric grease. unfortunately many people think it is to grease the contacts. it is used after the clean contacts are inserted and applied to the outside to prevent corrosion. I prefer corrosion X spray.

LegacyZ

back again...

replaced the electrical connector on the cht sensor so it locks into place like it should now..

It starts ok, seems to drive alright at speeds, but at very low speeds and while idling, it stumbles bad and tries to die..

I'm broke so I have to wait until payday to order a new cht sensor (figure that's as good a place as any to start searching since almost everything on the car is 30+ years old..)

all the vacuum hoses look good, but without smoke testing it, it's hard to tell..

I drove it to work and didn't have any problem pegging the speedometer on the freeway (85mph speedo, not the 140mph one.. ) but the kid is getting scared to drive it because she drives much safer than i do and like i said above, at slow speeds, it wants to die..

I really want to replace all the injectors just because, but at $90 each, I can't afford that **** right now..

Maybe I'll use some tax money to have someone smoke check the vacuum system, other than that and replacing the CHTS, anyone have any ideas?

LegacyZ

replaced the cht sensor and one of the tiny 90 degree elbow hoses for the coolant return system (connects to a metal pipe under the fuel rail and something on the intake manifold..).

Seems to run fine now, drove it to the store for some coke for my jack daniels... no stumbling, hesitation, or shuddering at all..

I feel like an ******* though... the hose I replaced was a form fit 90 degree bend 3/8's hose.. Can't find it locally and wanted it replaced now.. so what was a 3-4 inch hose with a bend is now like a 10 inch hose with a loop that goes around the fuel rail.. if i tried to make it shorter, it kinked and stopped flow.. that's the type of **** I would look at and swear in my head about the previous owner, but, **** it, i need this thing running so the kid has a car.

Skully

Good you figured it out. Hey if it works it works, sometimes the little 90 degree piece of molded hose is 100$ just because its "oem". If I cant find stuff like this, I use metal bends and then do hose on each end, sure more clamps, but if it doesn't leak, who cares.
If you are still looking for injectors, I have a set of 6 from my 280z that worked wonderful and don't need anymore, also have a fuel rail attached, but I can take them off if you don't want the rail. Let me know, we can figure out a price and shipping.
Cheers