Electronics hack job.

So, I saw on inspection the horrors of the wiring/ connectors and sensor repairs done with this car.
To properly diagnose this car, it first needs to be right as I don't trust the data coming from the computer.

Below are pics of 2 questionable items.
The car is running rough, like 5 cylinders rough. I thought I had found the coil at fault, however upon doing a coil swap with another cylinder, I didn't get much of a result that was obvious.

I did an hours worth of data from ECU Talk, not much obvious with a result except maybe the temp sensor needs to be changed, (didn't read higher than 62deg)

 

Yeah, that's a portion of the poor wiring.
Every connector has broken tabs, all the coil connectors are simply pressed on as the tabs are broken.

I removed consecutive plugs connected to the coils, I thought I had found ... cylinder 6? To be at fault as the rpm never changed when it was connected or not.
I then swapped 2 coils, and found it ran really no differently, but hmm.

I have downloaded the conzult software and have a usb cable, so will give that a try.

The laptop with conzult I cannot find the car 12v charger for as the laptop has no battery.

 

ECUtalk reported no fault codes.
Conzult I cannot get to run, keeps reporting 'winerrors' ...

 

Get a mechanics stethoscope, or a long screwdriver, and listen for the individual fuel injectors to click at idle. You'll soon know if one is not working.

As rob said, in a 4 stroke engine, it's the holy trinity of fuel, air (compression) and spark. If you have an issue with one of these, you're going to have a bad time.

 

Sounds good, will try that out.

Didn't think it was a factor of an injector not firing as the car smells like it's running rich on idle, good strong smell of fuel.

So, always took it as being no spark for a cylinder.

Have found another piece of sotware which works with my usb nissan plug (dr300) so will try that tomorrow morning and see what it reports back.


Meanwhile, I think i'm also probably better off replacing those 2 pieces connected to the engine. (One being Mitsu, the other being.... who knows)

 

Fair enough, so they wouldn't be causing a drama if the wrong type of device?

 

Not a hack job, we call that S2 ptu loom patch an upgrade.You can check the CaS and PTU pins for oxidation and then Carefully use some dielectric grease the pins. Sounds like you will be replacing some broken connectors. Get onto that group buy if the testers and plugs are still available

http://www.aus300zx.com/forum/showthread.php?t=331682

 

Ahh, cheers for the clarity.
I thought they had simply used random parts, especially given the CAS has the Mitsu logo on it.


Might do that QLDZXR.

 

CAS with a Mitsubishi logo gets a few comments.
Nissan used a CAS manufactured by Mitsubishi Electronics.
The reason for the "large" bulky wiring is probably someone used crimp connectors to join the "pigtail" wires from the series 2 PTU to the main wiring harness.
The crimp connectors might be fault on cylinder 6.
As the others have said, narrow it down to the component by a compression test - rules out mechanical.
Then use a spare coilpack and sparkplug to see if No. 6 coil is firing.

With the 20+ year old connectors the rule is Clean,.. clean,.. and clean again.

 

Going by the impression that you like to have clean reliable cars and intend to make the Z a keeper you might be interested in just going straight to a new engine loom, many people use and recommend wiring specialties. You end up with a bit of extra loom in the cabin because they come from america but once installed you'll forget its there. Your loom is probably workable with cleaned connectors but the option is there if you'd prefer.

http://www.wiringspecialties.com/wsprvgtofaze.html

 

Cheers all for the responses.
I am not sure which way to go, I have moved all the connectors back and fastened them all as best I can with broken tabs, to their original brackets, instead of zip tied any bloody where the previous owner found a spot.

Tossing up on buying new connectors from the group buy or what. Honestly have little free time as is.

As soon as I arrived home I whipped out the tools and did a comp test.
Below are the results.

I also did the screwdriver to the injector test and found the injector on cyl 6 was pulsing at twice the rate to the other injectors.
Oddly however, that cylinder is not getting extra fuel.
There is definitely a strong scent of fuel coming from the plenums, perhaps perished injector seals???
The car was reportedly stored for 14 years, and as was quite a lot of the hoses and radiator were replaced.

Might be a factor of doing a proper tear down of this engine...

I also noticed there was quite a bit of oil in the passenger side plenum, though again, the spark plugs did not seem any different from the drivers bank to the passenger...

 

Those figures aren't real good.
An N.A. engine should be 186psi on the high side, with a minimum of 142psi.
Three of your cylinders are reading under the specified minimum.

 

Hmm, yeah, one thing I neglected to do was pour a small amount of oil in to the cylinder to see if rings or valves.

 

In my experience the VG has pretty good oil rings so even if its getting blow by it wont necessarily burn much oil. Mine doesn't use any oil around town although it does tend to disappear at the track I still need to see if that is just because it pools up around the PCVs on all the right handers at wakefield.

 

A miss can be caused by injectors also.

I and many other forum members continually need to remind owners of fuel injected engines that a malfunctioning injector will also cause the engine to miss.

Check the injector connectors on the harness and injector side as these do cause issues.

MichaelZ

 

And your fuel smell is probably an under-plenum fuel hose that has perished. Do a plenum pull asap.