Finally Got one!!. 1978 280z

[Pharaohabq]

The only reason I wouldn't be thinking you'd want to use the stock is just if there's some issue with your stock wiring. Since your car runs but gets bad mileage, I'd say he's got a good plan wiring it through your existing harness.  That way too, like he said, the MS stays inside out of where it can get wet etc.  The down side is that your original harness is 25 years old so you may have some iffy wires there, crusty old insulation stuff like that. You mess with it, it can go bad.  That can make troubleshooting a bear.  where the MS harness you know is new and wired correctly.  I would buy separate injector plugs off ebay or somewhere rather than cutting your stock harness if you weren't going to use it.

[seattlejester]

I actually didn't have a harness when I wired up my car. The PO never had one, and he wanted to keep his new one for later. I bought a used harness off of craigslist, but it wasn't as advertised, was in worse condition then I thought, (broken plugs, corroded wires) etc. The wires actually cracked when I bent them (and that is a 20 year newer harness), so I ended up making/buying new plugs/pigtails and rewiring the whole engine bay harness.

 

So my options revolve around how you will wire a new harness.

 

The options are either...

 

A: Use the long MS harness and wire it directly to all the sensors, replacing plugs and connections as necessary (as the guy mentions new plugs etc or soldering to really short pigtails, most new plugs will come with short pigtails or crimps and a plug). Essentially your connections will be only at the accessory, i.e. to take off injectors you will have to physically remove the injector plug.

 

B: Buy the short MS harness, make really long pig tails from the sensors and run all that wiring into the cabin and make the connections there. More along the lines of what your mechanic may be suggesting, the old wiring harness is old, that and you won't be using quite a bit of it, won't have to figure out each wire, etc. All the connections will be in the cabin so weather proof in that regard.

 

Both methods require new wiring, it is just a matter of where the connections will end up being. I actually combined both methods. I made some pretty long pig tails and had them meet near my throttle body. That lets you unplug the harness and remove the engine without having to pull everything from inside the cabin. Or pull of plugs from different locations on the engine.

 

 

You can see some connectors right above the throttle body, all the connectors are within a few inches of that area.

 

The way I thought about it was like exhaust. It was cheaper and easier to have the exhaust shop do a full front to back in one piece. I had them make it into a 3 piece system. Came in real handy when I had to add my o2 sensor and I didn't have to drop the whole exhaust.

 

Oh, and please tell your mechanic I meant no disrespect, definitely do what your mechanic is willing to do/familiar with as previously suggested in my post above. He is physically there and will be doing the work, most forum members are not. If he is familiar with reading pinouts and is more comfortable with working with the stock wiring diagram, more power to him. The work is all done (assuming the wiring harness is good), it will just take a bit of time to figure out exactly what wire does what.

 

I think in the end I had to make 12 connections or something if I had to condense it down, maybe 3 hours for mockup and pretesting (soldering longer pigtails to plugs etc), and maybe 3 hours for final assembly. And that is my first time making an engine wiring harness.

Edited February 17, 2014 by seattlejester

[rome03]

Thanks Pharoahabq and Seattle,

 

Ill have to figure out if I want him to wire it for $250 or wire the MS myself and save the money. Im good with following diagrams....is it something I could do, or would someone with experience need to do it?

 

Also, since I'm going to be needing a wideband gauge when I get MS, I was thinking that I could get it now and hook it up and see how rich its running at idle, cruise, and boost. I could also check all my sensors. I read that the coolant temp sensor causes it to run rich. 

 

Is it easy to install the wideband gauge/sensor?

 

does it replace the stock o2 sensor or can I screw it in to another hole in the down pipe? 

[cgsheen]

I think you'll eventually regret keeping the stock harness.  A new EMS deserves a new harness IMO.  I'm super glad I did it that way when I moved to a non-stock ECU.  The old harnesses were never meant to last this long.

 

The wideband sensor will screw into your stock downpipe in place of the O2 sensor - the Innovate stuff usually comes with a weld-on bung and/or they sell the bung for $5.00 so you can mount it elsewhere if need be. 

 

The auto parts store has a new Cylinder Head Temp Sensor for $20 - just a thought...

[seattlejester]

The coolant temp sensor can cause the car to run rich if it is malfunctioning to my understanding. It won't naturally cause the car to run rich once it is warmed up. If you have a multimeter, you can test the coolant sensor with a bowl of hot and cold water to see if it's malfunctioning, but as cgsheen says, it's 20$ and if you are doing a new harness, the weakpoint becomes old sensors/connectors, so that is a cheap investment.

 

If you know how to do a good crimp, have a good pair of strippers, and familiar with amperage and wire gauge, know how to use a multimeter etc, I don't see why you couldn't do it. I do recall you saying this is your only car though. And if something goes wrong it may take a while to diagnose. Now if you aren't familiar with the electronics, it only takes an accidental ground or touching a power wire to the wrong thing to cook the board on an ECU.

 

It seems like whatever shop your working with is actually quite generous if they are offering to wire in a new harness for 250$. If you are confident in your skills, want to be very intimate with the car, then wire it up your self. If you trust the shop you are working with, and don't plan on looking at the wiring harness ever again, then have them take care of it.

 

Getting a bit philosophical here, but basically money shouldn't be the reason why you do something yourself. It should be a bonus/reward for doing so, the real reason should be a pursuit of knowledge or the reassurance that each step was accomplished to the best it could be. Now a days people tend to overcharge for really menial tasks (firestone tried to charge me 125$ for an upper radiator hose replacement, took me 5 minutes at home with a 10$ hose and a flathead screw driver...), but when someone is offering a service at a fair price, the deciding factor should be knowledge. The desire to learn, or the knowledge that it was done as well as it could be.

[rome03]

 

Getting a bit philosophical here, but basically money shouldn't be the reason why you do something yourself. It should be a bonus/reward for doing so, the real reason should be a pursuit of knowledge or the reassurance that each step was accomplished to the best it could be. Now a days people tend to overcharge for really menial tasks (firestone tried to charge me 125$ for an upper radiator hose replacement, took me 5 minutes at home with a 10$ hose and a flathead screw driver...), but when someone is offering a service at a fair price, the deciding factor should be knowledge. The desire to learn, or the knowledge that it was done as well as it could be.

I agree with you 100%. I want to do it so I can learn about it and stop having to pay or rely on someone to do it. Plus, I think its awesome knowing you took on a task that you knew little about and took the time to  research and accomplish it successfully. Only problem is that it is my daily driver so I would hate to have it sitting there for weeks if something went wrong. 

 

Also, the shop isn't wiring a new harness for 250, he's charging 250 to connect the stock harness the the MS ECU plugs. 

 

Seattle just want to make sure I understand this correctly.....

 

 

A: Use the long MS harness and wire it directly to all the sensors, replacing plugs and connections as necessary (as the guy mentions new plugs etc or soldering to really short pigtails, most new plugs will come with short pigtails or crimps and a plug). Essentially your connections will be only at the accessory, i.e. to take off injectors you will have to physically remove the injector plug.

 

If bought the MS harness from DIYauto and wanted to use that harness and wire it to all the sensors and injectors, you're saying i could cut the oem harness and solder it to MS harness at the sensor or I could replace the plugs and not have to cut the stock harness at all right? 

 

cgsheen,

I would like to have a new harness as well since I could clean up the engine bay a bit. I read something about getting noise into the wiring system and having a shielded harness but I don't understand that concept..... How does it work? Would I run into problems if I used the harness for MS that they sell at DIYauto?

Edited February 20, 2014 by rome03

[seattlejester]

Ah, I see, well it still isn't a bad deal. I think the local shop charges 200 to wire megasquirt if you bring the stock harness, and 450 for tucked/custom harness using all new bits.

 

If this is your first big electrical wiring job, I would at the bare minimum have someone who is familiar with electricals or better yet megasquirt handy. If you haven't done a lot of soldering or crimping in the past, I would suggest getting some tools and a variety of wires and practicing. I am all for DIY, but I don't want to suggest you into failure. Keep in mind on top of electrical wiring, you will need a drill, zip ties, rubber insulated clamps, etc to make your routing work out nicely. Making good crimp connections and good soldered connections aren't difficult, but it does take a bit of practice and the right tools. I guess I am just covering my ass over here, lol.

 

If you can find new plugs they will either come with pig tails or crimps. So to answer your question, if you want to go for option A, yes if you bought all new connectors, you would not have to cut the stock harness at all. Granted I am almost positive you will end up cutting something off of it if you plan on using the stock components as some plugs are proprietary/unavailable/or the item itself doesn't use a plug. 

 

Now just to put things in perspective, there is nothing wrong with using the factory 280zx turbo harness, what the garage suggests isn't bad or anything per se, especially when the harness that runs your car is even older than the harness you are replacing. I guess it depends on which side of the "if it ain't broke, don't fix it" argument you are on.

 

Edit: Regarding shielding. Basically there is interference everywhere. If you run a magnet or a rotating metal object next to a wire carrying current you can actually get it fluctuate a bit. Depending on your grounds and grounding locations there can be some noise in the chassis (signal noise). So shielding a wire is a way to isolate the wire from ambient noise that can be transmitted through the wire shielding. In computer talk you shield to prevent cross talk between electrical wires. They accomplish this either by using shielding or alternatively some companies use ferrules to absorb the noise. You can shield a wire by insulating it. The insulation is usually metallic in nature and physically shields the insulated wire from ambient signals. It is a good idea to shield wiring if you can, it will produce a cleaner signal, but it isn't always practical nor cost effective to do so. The most commonly shielded wire in the automotive world is the crank/cam position signal wire. This wire has to regularly send pulses sometimes at high speeds to the ECU. A fluctuation in voltage in the CPS wire can cause the ECU to think that the timing event has occurred later or earlier which can cause the timing of the spark or fuel injection to be sped up or slowed down. Thus it is critical to shield this wire at the minimum. Thankfully this is already taken care of. The megasquirt harness comes with a shielded wire pair for the CPS. You can also buy a shielding sleeve to wrap around or slide over any exposed bits of that wire when you make the connection.

Edited February 20, 2014 by seattlejester

[rome03]

Thanks for clearing that up Seattle.

 

In the mean time, before I go and spend money on megasquirt, I bought the Innovate mtxl wideband sensor/gauge since I knew I was going to need it regardless. I disconnected the old O2 sensor and replaced it with the wideband sensor (which isn't connected to ecu), so I'm running without an O2 sensor.

 

Here are the initial AFR readings. This is when I was getting 15 mpg on the freeway at a steady 80 mph. It gets really rich at 80. I was also getting headaches from all the fumes when i would drive out of town since i was doing about 80 the whole way on my trips.

 

Cruising with no load

80 mph = 11.2

70 mph = 13.3

60 mph = 12.6

Almost anything under 55 at cruise with no load 13.5

 

Under boost

pretty much all gears would go from 10.5 at WOT and lean out as revs increase.

 

 

Then I started playing with the AFM and monitoring the AFR readings. Here is what its at now. Ive been looking for the stock settings online and the FSM but I can't find them. Im going off of what I've seen in other posts. I don't know what the limit for running lean under boost is or how lean it should be at cruise.

 

 

Cruising with no load

80 mph = 13.3

70 mph = 15

60 mph = 14

Almost anything under 55 at cruise with no load is 15.5

 

Under boost at WOT

all gears would go from 10.5 at WOT and lean out to about 12 as I hit the redline.

 

 

So the fuel mixture didn't change much at WOT but I did get it to lean out for cruising. The idle was really lean at about 19.5 but would idle ok. I adjusted the idle air screw a bit to bring it down to 18 and it idles well.

Edited February 28, 2014 by rome03

[rome03]

I forgot to add that I was looking at the tps sensor and it has three pins in it but the plug from the harness only had 2 metal connectors and two wires going into the plug. According to the FSM this connection has two readings, "idle" and "full throttle", and the metal connector for one of those is missing in the plug. 

[seattlejester]

I'll get a little sciencey for a bit. Please don't be offended if you know all this, just trying to be clear.

 

14.7 is the stoichiometric AFR ratio. That also happens to coincide with 1 atmosphere aka 1bar aka 101kpa. What that means is for every 1 unit of fuel you are running 14.7 units of air. Depending on the motor the definition of where you are lean versus rich can very, but traditionally the point of reference is 14.7 AFR. Run much leaner than that and you risk pining, run much richer and you risk bogging down the engine/being really inefficient.

 

Warning, this is what I have seen, I don't tune for a living so all this is just observational. Definitely some room for someone else to chime in here.

 

For turbo cars the ratio that people tend to shoot for under load is ~12 from what the local tuner sets at his shop. Keeps the mixture somewhat cooler and adds a bit of a buffer for random unforeseen events. So hitting 12 at WOT is actually pretty decent. On most tuned cars that I have seen, it tends to go opposite though, starting at maybe 12.5 and richening up to 11-11.5 near redline. I imagine your power curve would show it being quite peaky towards redline. 

 

For cruising you can run quite a bit leaner, you are not using the throttle very much or very much horsepower your cruising seems ok, the question is how it responds when you give it throttle. 18 seems to be on the higher side of things for an idle though. 

 

For the fumes, definitely check the intake/exhaust gasket and the nuts/washers holding the manifolds to the head. Unless everything is perfectly level with respect to each other you are going to have some pretty extensive air/exhaust leaks. There are also a number of threads for tips to lower the exhaust fumes, my favorite is the turn down muffler, that let me drive around without a respirator on.

 

Also spending 30$ on a carbon monoxide detector is not a bad idea. 

 

Without a tunable ECU, you are kind of at the mercy of the pre loaded map. At least is shows that you aren't running terribly rich everywhere.

[cgsheen]

I forgot to add that I was looking at the tps sensor and it has three pins in it but the plug from the harness only had 2 metal connectors and two wires going into the plug. According to the FSM this connection has two readings, "idle" and "full throttle", and the metal connector for one of those is missing in the plug. 

 

Then you're looking at the "EFI" section of the FSM and not the "ECCS" section regarding the TPS.  The turbo TPS is a 2-wire, single switch.  It only "looks for" ON or OFF idle condition.  The turbo ECU does not use the WOT switch (even if it's present).  That's why only 2 wires in the stock turbo harness.

[rome03]

Yea I realize that there is only so much I can do without a tunable ecu, I'm just trying to get it a little better and document gas mileage, hoping I can hold off on MS. 

 

I do realize the AFR ratios can change from vehicle to vehicle, I just wanted to get a base number for AFR under boost and cruising so I don't detonate. About the idle, I know its really lean but if I get the idle AFR closer to 14.7 or say even 16, then Im extremely rich at boost and cruise which really hurts my mpg. I decided getting the AFR closer to where i want it at WOT and cruise to increase mpg is better for my wallet. I can adjust the idle screw a bit which makes it a bit richer but increases idle rpm.

 

Crazy story, 2 weeks ago my girlfriend and I did a 2.5 hour trip to see our family and when we got there she passed out from the fumes. We drove with the windows down the whole way and had to stop 3 times to get out of the car. We were being poisoned by the carbon monoxide. My hatch and taillights are sealed pretty good though. Before the swap I never had any problems with being dizzy or headaches, given I did have a catalytic converter. Now I'm running 3" straight from the down pipe and I think not having the CAT is the biggest problem. Its what converts the carbon monoxide to carbon dioxide.....So this brings me to my next question, should I get a high flow cat? would it really restrict performance? I will be buying a carbon monoxide detector.

 

cgsheen,

Thanks for clearing that up........thought it was broken

[seattlejester]

Yea, I have had major problems and still have a bit of problems with the fumes. I usually take a nap after anything close to a long drive because I feel light headed afterwords.

 

Carbon monoxide will get you pretty sick, dizzy, light headed etc. A high flow cat should pick up some of the gas, but....if you are generating a lot of carbon monoxide you can clog up the cat pretty quick. If fumes are getting into the car, the CO2 is just as bad. It can displace air in the cabin and can literally knock you out if you are not careful. I would definitely check the hatch gasket (dollar bill trick here) as well as the taillight gaskets and around the fuel vent lines. I would imagine dry rot would be quite common out there. Also a place that is often overlooked is behind the black panels on the side. A place that is also missed is the firewall. Making sure to seal unused holes will keep the smell of gas and oil (which can be mistaken for exhaust fumes) from wafting into the cabin. Checking fuel vent lines is also a good idea.

 

Definitely check on the intake and exhaust manifolds and make sure there are no loose nuts and the gasket isn't pinched somewhere. 

 

If the fumes get real bad and you are positive everything is as good as it can be, it may be time to forgo style and add a 6 inch tip that extends past the rear of the car and has a turn down to try and get the fumes out of the rear vortex.

 

If gf/health is important to you, maybe time to consider a cheap run around and move this car into the project car category?

[NewZed]

It is possible to seal the leaks in the back of the car so that no fumes can enter.  Just to give you hope.  A large leak that often gets missed is the vinyl covered trim board on the bottom inside of the hatch.  Seal the edges of that piece all the way around (stick-on weather strip from Home Depot works) and any fumes that enter the hatch framework, through the drain holes or the latch mechanism area, will not be able to enter the car.  After that the only other seal is around the perimeter of the hatch, the factory weatherstripping.  You can usually eye-ball the seal area and see if it's making contact, along with using the dollar bill trick.

[Edward]

Idk if its just me but i love the smell of gas , oil , and exhaust haha. Thats to first thing i loved about my first z lol

[rome03]

Just a Little update.

 

I got the MS2 installed and had the car tuned. Everything is stock except I added an intercooler I pulled from a SAAB. The injectors maxed out at 10lbs. It did 211hp and 240tq. 

 

Next step will be getting larger injectors and probably the KA throttle body. I'm really happy with the numbers. It feels really strong when it pulls. 

[cgsheen]

Awesome.

[rome03]

cgsheen,

 

I might need new tires soon if I keep driving like I am now haha.

[rome03]

Well the happiness was short lived. The left ujoint snapped and the half shaft where the ujoint is inserted twisted. They were new and were supposed to be the strong ones. Anyone swap their halts shafts for aftermarket?

Edited April 20, 2014 by rome03

[rome03]

Driver side broken u joint and a shot of the charge pipes.