A question about my manual tranny
 

Hi everyone, I'm new here. r/datsun from reddit.com sent me here and I thought it would be good to register and see how this community might help me out.

Now, I have a question. I just recently bought a new-to-me 1983 280ZX Turbo 5 speed manual. She's a great car and in pretty good condition overall. She's got high miles (201,000) but runs rather nicely and quite smooth.

Except for at night. Now, I live in Southern California and our weather here is nice 90% of the time. The car runs great during the day but at night, it doesn't seem to be the same car.

First thing I notice is she doesn't shift right. There's no power at ALL on 1 and 2 and when I shift, it shudders like it's not getting enough gas or something. When it gets to 3 and 4 it's fine and runs great. But 1 and 2 are real, how should we say, disappointing? It's also a little concerning since the turbo is boosting but there's no power that you can sense. Add to that the rough ride and it's a combo I don't much care for.

I'm not much of a mechanic but I do have a basic understanding of it. Any possible ideas or experiences you've had that might help me pinpoint the issue? And cost would be appreciated. Knowing how much I need to allocate will help me out a lot.

And by all means, if I omitted a piece of info you need, let me know and I'll do the best I can!:)

Welcome to ZDriver! :006:

When was the last time it had a major tune up?
New spark plugs?
Cap & Rotor?
Oil change?
Fuel treatment?
Sensor connections?
Ecu connections?
etc etc etc. . .

Have you read the spark plugs? Have you bought a Haynes manual / downloaded the FSM from www.xenons130.com/reference ?

I just had the oil changed yesterday, as for a major tune up, I can't really say. The guy kept his records rather haphazardly. It's definitely something I'm planning on doing next month.

I brought the car to precision Z in Canoga Park to have its front shocks replaced and the headlight wiring harness replaced. It ran fine there and back, but that was during the day. The gave the car an inspection and told me the car needed a new water pump. Other than that though they said the car seems to be in pretty good shape overall and that was the only thing that needed immediate attention. Well, that and new tires.

I haven't done any fuel treatment as of yet. I was thinking of doing that tomorrow. Everything else seems to be working as intended. It's really got me stumped. This is also my first manual car so it's possible I'm not driving it like I should. But like I said, it seems to only be at night. During the day I have nary an issue.

I do have a Haynes manual and I'm taking a look at the xenon link you provided.

I'd say start with the basics:
#1: Pull the spark plugs and read the tips (like the back page of the Haynes manual shows). That will tell you how it's running, and if one cylinder is having problems.
#2: Check the CHTS,AFM, & TPS and their connections. Those plugs are notorious for corrosion and literally breaking down over time due to heat. (Our member FricFrac sells a complete harness refresher kit).
#3: Pull the ecu and check the connectors and pins for corrosion. The bottom connector is notorious for loose connections on the ground wires, which can lead to random sensor issues. I chopped it out and soldered in a Z31 ecu connection when I did my Z31T ecu / maf upgrade.
#4: Check timing (super simple and should probably be #1 on the list). The L28ET timing should be 22*-24* BTDC.
#5: Check fuel pressure.

Also, what does your boost gauge read at full throttle when it maxes out?

Just out of idle curiosity have you tried loading up the electrical system durring the day (eg running with the lights on and the blower fan at full blast)? You might have a problem with your charging circuit/battery/battery cables - especially the ground.

I'm just trying to think what would be different from day/night and the S130 is notorious for freaking out when the voltage isn't high enough....

Hmm, that might be something worth looking into. I just got the stereo working in the car (it's an old Sony after market p.o.s. deck) and it only seems to work when the car is moving. Perhaps it doesn't like driving with the headlights on and that could be what's causing it.

Looks like I've got my work cut out for! haha:003:

The boost gauge shows the turbo boosting to the red after 3000 rpm, which I think is where it should be boosting if I'm recalling correctly. I'm still new to the S130 and all its little nuances, so bare with me! =P

Now, I had planned on upgrading the ECU down the line but you said you used a Z31 ECU? Was that stock or was it an upgraded unit?

Also, FricFrac below suggested it might be the car isn't getting enough voltage. Now, I'm thinking about it and it does seem to make sense what he's saying. This only seems to happen at night. During the day I'm not running anything (not even the stereo since it's an old aftermarket deck and sounds terrible.) and it seems to run great. I'm going to go for a quick drive before dark and run the lights and see if I can't reproduce to issue.

Any thoughts on that? It could even be an old battery. I remember on my Z31 it was having starting issues and it turns out the battery was just ancient.

Thanks for the help so far everyone! It's helping me out!:wink:

Most places that sell batterys will do a load test for free or cheap - check the battery. Getting a new battery anyhow is never a bad idea.

Replace the ground side of the battery - I do that automatically whenever I get a new to me S130. I do the positive as well but I build my own cables. I go beyond that and run extra grounds, etc but a new set of battery cables is a good idea. Make sure you have a good ground and the contact point is good as well.

I watch the voltage. I can tell if the battery isn't charging by the volt meter. They aren't all that accurate but I pull mine out and calibrate it myself with a multi meter and a power supply and it's fairly accurate after that (yea it's time to do a DIY reference page like we were talking about before NismoPick :) ) Use a multi meter for now and watch how it responds. Get the RPMs up and you should be close to 14.4V

So, I drove the car today and it's still doing it. I don't have all the tools I need to check the compression and everything so I guess I'll just have to take it back and see if the guys at Precision Z can track it down.

Did you get the battery tested? Don't forget a lot of the mechanics out there don't have the expertise with these cars anymore....

I was going to, but it's really quite a drive to get to the nearest place to do that. I actually just noticed though that the engine is running hot. It's almost up to 270, which is not good. I decided I'll wait until I get paid again to do something about it.

I know the water pump needs to be replaced, but I don't know what kind of bearing that would have on the engine. It also seems like it's misfiring a bit, so the spark plugs would be the most likely culprit there.

That's the problem with buying old cars, you inherit someone elses problems :120: Just gonna have to bunker down and solve these little issues one at a time.

Yes there can be a few problems to work out but the car's are pretty robust. Go through the stuff NismoPick was talking about - the maintainance can be found in www.xenonS130.com in the FSMs. That will take care of the vast majority of your problems and you'll become quite familiar with the car.

You want to avoid overheating as you can easily warp the cylinder heads.... get the stuff fixed that needs fixing before you start driving it or it will cost you $$$$

Thanks man. You guys have been a great help, thanks again. And yeah, I'll be sure to use my spare car for now until I get this stuff squared away. All she needs is a little TLC! :biggrin:

Get the Gm one wire alternator while you are at it. It's nice when the battery gets fully charged!!!

If your voltage regulator is working properly the stock alternator will charge your battery all the way up. The problem would be if the electrical loads you have are more than the alternator can supply not giving the battery a chance to charge up. After market stereos, lights, etc will stress the system - changing to LED markers, etc, HIDs (lower current draw than sealed beams) will reduce the load on the system.

The GM one wire is a good option for an upgrade :)

Which connector is the "bottom" connector? i have too weak of a ground coming from my ecu to make my injectors pulse... this might be the solution to my problem...