ecu isolation

[Zfighter76]

I posted this in engine but I guess it should probable go here also. If I'm wrong then please delete whichever one you think it shouldn't be in mOdsssss. Thanks

 

So basically my question is simple, but the answer may be complicated. I want to isolate the ecu for my l28 so that I can rewire everything else in the car freely without possibly making the car not run. I want to basically be able to run my fuel injected engine completely separate from the rest of the car.

 

My problem is is that when I trace the plug in the passengers footwell area on my 280z back to, say, the headlights, and unplug it, the car won't start. Its as if datsun put wires for multipls things into the same plug.

 

I don't mind cutting wires off because I plan to either do a swap with the engine into my truck or completely rewire the z's lights, signals, wipers, etc.

 

Does anyone know what I can unplug, cut, or remover to be able to isolate just the engine and ecu together?

[datsunaholic]

You need to get a wiring diagram. Then, if you don't know how to read and interpret them, you'll need to learn.

 

What you're running into is that the ECU is fed from the chassis harness. The wiring from the ECU to the engine is pretty straightforward but to get power from the alternator/battery it has to combine into the chassis harness.

[Skib]

when you swap it you do run it isolated.

 

its designed as a separate system already.

but you have to wire a few wires to the cars harness for things like 12v, switchable 12v, ground ect.

 

 

 

 

like he said, get diagrams and learn to read them

[datzenmike]

I posted this in engine but I guess it should probable go here also. If I'm wrong then please delete whichever one you think it shouldn't be in mOdsssss. Thanks

 

So basically my question is simple, but the answer may be complicated. I want to isolate the ecu for my l28 so that I can rewire everything else in the car freely without possibly making the car not run. I want to basically be able to run my fuel injected engine completely separate from the rest of the car.

 

My problem is is that when I trace the plug in the passengers footwell area on my 280z back to, say, the headlights, and unplug it, the car won't start. Its as if datsun put wires for multipls things into the same plug.

 

I don't mind cutting wires off because I plan to either do a swap with the engine into my truck or completely rewire the z's lights, signals, wipers, etc.

 

Does anyone know what I can unplug, cut, or remover to be able to isolate just the engine and ecu together?

 

If running leave it alone or you will have a non running car. Nissan designed it to work this way and there were/are tens of thousands of them that run just fine the way it is.

 

If rewiring the lights just leave all the old wiring and go around them.

 

A 280z motor does not in any way fit, nor was it intended to fit a 620. If you try you will have two inoperative vehicles.

[Zfighter76]

Believe me it will get done if I ever start. I've done much measuring, planning, researching, ect. Currently there are two other l28 620s that I know of and one 510 that have had the swap done and work. I will have to recess 7 1'2 inched out of the firewall, move the trans mount or make one (more likely) and the radiator fits in the stock location with just four holes drilled. Using the stock motor mount positions will leave the front of the engine in the stock placement and just force me to cut. the topless620z build used custom engine mounts to avoid cutting the firewall but I'm not scared of cutting the firewall, my car is rusted through everywhere anyways. I will need to have a custom driveshaft made and then just wire up the ecu. The throttle cable will be straight forward and fuel routing is also not a problem. All that is left is coupling the exhaust to the existing and bam. If I left anything out its fairly minor and shouldn't be a worry. I will end up with one non running car but I'm in cali and have a non smog exempt z that I got for free with terrible paint, no interior, no title, and a good engine and trans, I can't register it ever because on record the car was "donated to a school shop class" so its either use parts and scrap it, or just scrap it. I'd much rather use what I can.

 

So now that I've got my rant done, does anyone know if there are color wiring diagrams? I've had trouble finding anything but black and white ones in the past.

[datzenmike]

It can be done but should it be done? The shifter is going to be beside your hip.

 

There are lighter 4 cylinders that make more power and easier to fit. I hate to see a 620 get chopped.

[I'm BLUE]

Just get a clean titled registrable 240z ... shell ... swap in everything ... that way you have smog exempt ... wiring, gauges, fuel tank/pump are priority ... and good to go!

 

You get to keep your carbed truck and a fuel injected smog exempt zcar ... win

 

You don't need a custom driveshaft ... just take yours in to get shortened and balanced ... ham money savings ;)

 

Yup. I like that other l28620 ... but there were two brothers doing it at same time ... with carbs ... your going to be damn close to brake master/boosted if the intake isn't already humping it lol ...

 

If you follow through ... offset the engine/crank centerline ...to passengers side ... people do all the time.

 

Throttle cable may not be as straight forward .... idk what you have in mind .... i used a lokar (lokar.com) ... expensive but a good cable.

 

You will have to end up re-plumbing clutch ... and throwout arm will have to be possibly clearances ( sheetmetal) ... so your shin or foot might or will rub it.

 

Actually all the minor details turn into ... medium or bigger details as the swap progresses .... i too thought swapping motors was just the big stufff ... i was wrong ... its all the little stuff lol :lol:

 

Not against it ... but depending on how much you can get another 240-260z shell with clean title <---- cheaper route with what you have on hand.... hands down... do run and drive

 

But if you truly want a badass little 620 ... go for it ... just have a dedicated apace :cool: ( yes i am a fan of a the l28 620 southern build)

[Zfighter76]

The main problem is my grandma doesn't like me having two cars let alone three, clutch and brake line relocation is no problem, just a few bent lines. And I really wish I could afford a new 4 cylinder, but high school budgeting sucks haha. If anyone wants to trade a torn apart 280z with bad paint, interior, and 25k original miles (no joke) for a ka or something, I'd do it, I would make it dual sidedraft setup though.

 

About the offset engine setup, my truck is actually going to be a prerunner style truck so I don't think jumping or trying to stay stable over rough grounds would be a good idea with the weight biased towards one side haha.

 

Also does anyone know if I will have to modify my driveshaft if converting an l16 4 speed to a 280 z four speed? Mine went out today :( or basically went out.

Thanks

[datsunaholic]

I don't think having all the weight biased towards the front would make a very good prerunner either. An l28 is nearly 50% heavier than the L20B. Not unless you're trying to turn it into a lawn dart on the first jump.

[datzenmike]

The L16 4 speed is 26" long so the drive shaft is the longest in all the 620s. The L18 and L20Bs all use a 31.5" transmission so the driveshaft on them is about 5 1/2" shorter. You are planning an L28 swap by moving the motor back 2 cylinder widths (8-9 inches you said?) plus the 31 1/2" 4 speed.... so yeah you will need a major shortened driveshaft by well over a foot.

[I'm BLUE]

The main problem is my grandma doesn't like me having two cars let alone three, clutch and brake line relocation is no problem, just a few bent lines. And I really wish I could afford a new 4 cylinder, but high school budgeting sucks haha. If anyone wants to trade a torn apart 280z with bad paint, interior, and 25k original miles (no joke) for a ka or something, I'd do it, I would make it dual sidedraft setup though.

 

About the offset engine setup, my truck is actually going to be a prerunner style truck so I don't think jumping or trying to stay stable over rough grounds would be a good idea with the weight biased towards one side haha.

 

Also does anyone know if I will have to modify my driveshaft if converting an l16 4 speed to a 280 z four speed? Mine went out today :( or basically went out.

Thanks

 

Driveshaft question ^^^ ... when both are side by side ...count splines on inside yokes, ,, measure length ... eye to eye on u-joints located on tube, ,, measure slip yoke length .... measure rear bolt pattern flange size .... measure protruding center flange cup .... <--- all can be done with a measuring tape and more accurately a machinists square ;) .

 

I see ... i entirely respect that ... use what you have, nothing wrong with that, and its what i am doing in my build as well ... ;)

 

I should have clarified myself on the offset ... i set my crank-centerline ... 1" offset to passengers side ... its pretty close to factory specs .. yet ... not lol ... i weigh about 190lbs , putting battery in back, lower to ground, etc ... so it works for me haha. But def not for everyone ;)

 

Driveline shortening is no big deal ,, trust me ... the shop will take care of it.its really a matter of cost and EXACTLY what you need done. If you personally can replace your u-joints, and set your pinion ... they should shorten and balance it for around $100 ( good deal) ... of course 280z drivelines have swedged u-joints ... so driveline shop will have to cut them out and replace them with clip style u-joints. If you can snag a replaceable u-joint driveline from 620 ( replaceable !? )or 240z ... that will mate up ... you will be in good shape.

 

You may have to change your pinion angle or not ... one diy way is to buy shims... that sticsprings/over leaf springs ... summit.com or jegs... sometimes people guess with whim sizes and it costs them $$$$.

 

Another way is to.... grind off spring perch pads, ,, set magnetic base angle finder on pinion flange ... record degree ...set magnetic angle finder on tail-shaft ... adjust ... adjust check ... final check ...and re-weld perches at desired degree ( may or may not, obviously a little more involved haha)... this is cheaper, and more labor intensive, but accurate first time if patient. ... but i am not sure if you will be 4-linking or what for a pre-runner eventually haha.

 

Fuel tank measure up to see if fit ... but i am sure if pre-runner ... you will be mounting the 280z tank in the bed or close haha.

 

I assume battery in back! ? ... if non-sealed ... build a box for it :)

 

 

 

Yeah 7.5"set back may or may not be enough ... just co-laborating ;) ... prepare to go 10" give or take ... if it were me i would go back as far as possibly allowed lol ... 12" or so! ? Idk ... :D :blink:

 

Just another thought ... 25k ... wow! !!! Put it together ... put prices on things you dont need... reasonable ... sell it for what you need ... grab a ka setup ... put dual su's on ... bam and go!... people are always looking for quarters, rockers, fenders, occasionally clips ... etc ... interior stuff is always coin $$$ ... almost ollz

[Zfighter76]

I'm saying if I stick with the 4 cyl and put the 280z 4 speed in would I be able to use an l18-l20 620 driveshaft? Or still cutting it.

 

The engine l28, if using stock mount positions would put weight towards the center of the car, not in front of the front wheels. So I don't know hoe bad it would lawn dart, but normallyweight over the back actually makes you lawn dart believe it or not. Go figure, but bottoming out of the rear suspension is what causes the bucking action. If the rear doesn't bottom and rebound while still on the ground then the car normally will fly fairly level. Physics states that gravity acts upon all objects of same aerodynamic resistance regardless of weight equally. Only once an object reaches its terminal velocity does the speed at which it falls become slowed down. Drop a 1 inch diameter sphere of aluminum and a 1 inch diameter sphere of lead from the top of the empire state building at the same time, and they will hit the ground at the same time. Its a trip huh? Or do it from a standing height and it'll still work out the same. Now that the physics lesson is over haha :P

 

And dtp? What does your post mean, I don't quite get it

[I'm BLUE]

There done :lol:

 

Post pictures of driveshaft(s) ... parts ... etc ....

 

Start selling what you do not need ... spring time ... people will be looking for parts :)

 

Try to put up feeler ad to sell whole shell ... if title ... individual parts lists as well ...

 

Keeps pocket money for you!l either way!

 

My project 240z ... have a 350sbc + 4-spd + Ford 8.8" (4.10 and 2.73 ratios axles) ...at this time i am in process of mocking up 4-link , and in the process of converting ford driveshaft to Chevy trans ... ( all probably made by Dana and spicer ... looks 1310 spicer series u-joints crossover haha ;) ) ... engine and trans in... exhaust in ... driveline shortened ... converted to hydraulic clutch

 

So i have an idea what you will be going through haha ;) :)

[I'm BLUE]

I'm saying if I stick with the 4 cyl and put the 280z 4 speed in would I be able to use an l18-l20 620 driveshaft? Or still cutting it.

 

The engine l28, if using stock mount positions would put weight towards the center of the car, not in front of the front wheels. So I don't know hoe bad it would lawn dart, but normallyweight over the back actually makes you lawn dart believe it or not. Go figure, but bottoming out of the rear suspension is what causes the bucking action. If the rear doesn't bottom and rebound while still on the ground then the car normally will fly fairly level. Physics states that gravity acts upon all objects of same aerodynamic resistance regardless of weight equally. Only once an object reaches its terminal velocity does the speed at which it falls become slowed down. Drop a 1 inch diameter sphere of aluminum and a 1 inch diameter sphere of lead from the top of the empire state building at the same time, and they will hit the ground at the same time. Its a trip huh? Or do it from a standing height and it'll still work out the same. Now that the physics lesson is over haha :P

 

And dtp? What does your post mean, I don't quite get it

 

What portion? I mean no offense, but this could be possibly over your head ... if you cant measure a driveshaft ... suspension articulation and setting a motor back is not for you ... if you can .. great ...don't give textbook "googled physics lessons" :rolleyes:

... thats all i will say about that... if you're a 100% serious about a pre-runner .. than yeah l28 is a bad route ... then go KA ... couple members on here have them

 

I was trying to help the budget portion.... save money ... otherwords highschool budget wont work

 

Driveshaft shit is easy ... you will be shortening/balancing it ... you measure to see if you can use... and no you will cause more problems by trying to shorten yourself. .. trust me...

 

a bit less " right" and a bit more "open minded" ... goes a very long ways ... you're obviously young

 

Happy to help whenever you are ready for it ;)

[Zfighter76]

Dtp, I didn't think you meant harm, I honestly didn't understande your post when you said at first, and it appears as if you altered your post so, I don't even know what you said now haha, and yeah Its a textbook physics thing but if anything I was just helping datsunholic understand how it wouldn't be such a lawndart haha. I assumed you meant move the whole engine towards passenger side, yeah my z20 has a slight bit of skewness to the angle of it, driveshaft actually points slightly towards the driver (whoever made those motor mountd dunn goofed.

Yeah I'm young but I like to believe that I'm not as naïve as most people my age, I understand the difficulties of a swap and the problems that you know you'll run into and the ones you don't even thing could happen ever. I should in reality start posting things for sale, but again my grandma hates an old car in the backyard, let alone a shell and tons of parts after I sell some of it haha. I still don't quite understande why you say that a six wouldn't be a good prerunner engine, I'm actually considering doing the 280z driveshaft (one piece) and shortening that, ir would be a helluvuh lot simpler (possibly reliable and cheaper too). In my mind the torque of the six would be awesome in the sand and on dirt trails. And yeah the firewall probably should be back a bit further than 7 1/2 but I was mainly just referring to my measurements on the engine length as compared to the stock l16. Of course there would have to be some room. I appreciate any shared knowlege believe me.

[Zfighter76]

Oh yeah just btw, it wasn't google lol ;P I've just had to convince people so many times that didn't understand how something heavier could fall at the same speed, even teachers, plus I think its interesting, but enoug of that :P

[I'm BLUE]

I did not alter ... moving forward.

 

*Yup you can use your 280z driveshaft ... if it fits :)

problem is the u-joints will "swedged" in ( from factory a machine presses them in and expands them out ... )

<--- it simply means a u-joints will have to be cut out or drilled out by driveshaft shop= more money ...

i would guesstimate $200 to have replaceable u-joints installed , shortened and balanced ...

^^^ make sure rear flange bolts up, center protruding cup is matchedcon pinion and slip yoke ... done ;)

 

*This is only in reality $60-70 more than if you replaced u-joints yourself ... so its actually a good deal at those prices ...

 

*Take what you think it will cost for this project x2 or even x3 ... seriously :( ... :lol: ( rule of thumb)

 

*Awww i see ... circumstances on for sale stuff ... :)

 

*L28 would be an good "budget" choice, but def gotta be farther back than 7.5" ... i would "assume"... set the thing back as far as you can stand working with reasonably ;)

 

*pinion angles are not a huge deal ...

you can shim the rear axle to change pinion....

or grind perches off ... and re-weld at desired angle back onto rear to reset pinion ( i prefer)

 

What's your skill level of welding sheet metal? ( i recommend clamps, vise grips, copper spoons, body hammers, ball Pepin hammers, wood blocks, weldable primer, and other helpful items)

 

Take some pics and post them up :D

[I'm BLUE]

Oh yeah just btw, it wasn't google lol ;P I've just had to convince people so many times that didn't understand how something heavier could fall at the same speed, even teachers, plus I think its interesting, but enoug of that :P

 

Now that you said that ... i remember that from 6th grade ... we conducted "tests" :lol:

[Zfighter76]

Cool thanks for the help, I'm really considering doing a rivited sheet metal bulge in the firewall so I don't have to weld and still have somewhat easy access to the rear of the engine just in case. Also I'm wanting to do a floor mount pedal setup which could make the brake cylinder issue non existant, now the problem becomes my legs being too long and being uncomfy, which leads me to raising the seat to extend my legs. I'm only 5'9" or so so the ceiling shouldn't be such a problem. Also I wanna move the steering wheel toward the fireall a bit.

Cost always exceeds expectations, you're completely correct, many a time have I started a project with "more than enough money" and not finished until 3 paychecks later