speed racer

iTrader: (10)

Yea, inline fuses help alot and prevent short circuits b/c the fuse will blow and the circuit will no longer be closed. Just make sure the fuse is the same amp power as in the fuse box.

JClaw

iTrader: (17)

I used the same fuse for the fuel pump since it was still good. Just to make sure.

So I went Broaner's way and pugged the fuel pump direct circuit. I used a fuse housing that came with my B&M line lock I bought about a month ago. I wired it to a switch for the moment.

The fuel pump works fine (regular humming) and I unplugged the fuel line right before the fuel rail - it's pumping fuel all right.

Now the problem seems to be that the ECU gets power but it's not sending any power to the entire engine wiring harness. None of the sensors are getting power.

The ECU isn't fried. Just 2 days ago we put it in my bro's maxima. It started and ran 100% normal. The same way it runs with his 96 auto ECU daily.

What could cause the ECU to not send any power to the engine wiring harness?

nismology

iTrader: (8)

The ECCS relay, or lack thereof.

speed racer

iTrader: (10)

Check all possible grounds that would inhibit power to the ECU.

nismology

iTrader: (8)

Generic answer that might be plausible otherwise, but not in this case. He said that the ECU is getting power. The ignition switch sends a 12V signal to the ECU. The ECU then sends a 12V signal to the ECCS relay which is what powers up the main board of the ECU, and sends power to the injectors, coils, all sensors, etc.

JClaw

iTrader: (17)

Edit: Found it.

JClaw

iTrader: (17)

I wired the ground ECU like this:
http://forums.maxima.org/showthread.php?t=429049



It's a turd gen but it's most likely the same with a 4th gen.

Still no spark. I might go ground for ground i.e. check all the ones coming out of the ECU and ground each of them to the chassis even though they are all internally connected. Nissan did include six (or so) wires individually after all...

Where is the ECCS relay? And what's it look like? I'm looking at a 95 maxima FSM right now and there seems to be several grounds going into the ECU for the ECCS.

Broaner

iTrader: (10)

I gave power to all the pins that the FSM said were ECCS 12v. As for ground I used no other grounds besides the ones already on the harness.

JClaw

iTrader: (17)

I pulled a coil and it's definately not getting power. In fact the ECU is not sending any kind of power anywhere in the entire engine wiring harness.

Pins 67, 72 (ECM power supply) and 80 (ECM back up supply) are wired to the positive and go on when the key is on "ON" and "START". All 8 grounds are grounded directly and to the engine block (Pins 10, 19, 25, 32, 43, 108, 116, 124).

I'm looking at the 95 ECU spreadsheet (.pdf file) and other than grounds I don't see 12v ECCS sources, what pins are you referring to?

There is pin 4 (ECCS relay self-shutoff) but it says it should only get power when the ignition key is on "OFF".

eng92

iTrader: (3)

Jclaw, I told you yesterday that the power to the coils is not sent from the ecu. The ecu only sends a pulse every other crank revolution which you will not pick up with a voltmeter. There is a problem in your harness if there is not 12V to all the red wires (terminal 1) to your coils when the ignition is on.
This has nothing to do with the wiring to the ecu.


Pin 4 provides a ground to the coil on the ECCS relay when the ecu gets power on pin 24 through the ignition switch. This pulls the relay in and supplies power to pins 67 & 72. Pin 4 does not get power. You measure 12V on it relative to ground when the ignition is off because it is not providing a ground.
You have everything wired direct, so there is no need to be concerned about it.

You need to start by sorting out your harness issues to get power and ground to your coils.

JClaw

iTrader: (17)

You're right. I'm fed up with this. Stuck with a modified 99 auto harness. Tons of plugs and wires that seem to go nowhere.

I'm pulling the harness and ripping it apart. I'll cut out every single wire that's not necessary and trim it down to its bare essensials just like you did with your 2k2 harness. There's no reason to have that much spagetti under the hood. And I'll be absolutely 100% sure every single wire goes where it should go.

3 pounds off the front end

Fred Allen Burge

Taking the engine harness apart is the best thing to do, by far. It will take you a while but is well worth the work for the cleanness.

Have you seen this wiring diagram?
http://www.jimwolftechnology.com/wol...ORENGSWAPS.PDF

was very helpful to me when I was making my harness modifications.

Fred

JClaw

iTrader: (17)

The harness is out. The most annoying moment of my day came when my bloody hand was stuck on something sharp somewhere between the motor and the firewall getting eaten alive by musquitos while my extremely irritating neighboors were engaged in an intense shouting match. Fun for the whole family.

Hopefully the next time I put the harness in, my neighboors will be greeted to the enjoyable chant of an open headers VQ35.

At 6 AM.

Broaner

iTrader: (10)

I definitely disagree about pulling the harness apart. I got it running and then paired it down making sure that I hadn't cut a required wire.

Eng is correct about the powering. There needs to be a seperate power supply to the ignition. I ran that on a seperate circuit. I ran one circuit for the ECU and my aftermarket gauges. Second circuit is for Ignition. As I said before, the two thick solid red wires on the two plugs that would originally connect back the body harness in the engine bay need to recieve power. I don't recall which plugs those are labeled as in the FSM. In OEM location they are reward of the Drivers headlight on the vertical sheetmetal wall in front of the strut tower.

Its been so long I was wrong about the ECCS relay issue. I think the main purpose of the power when the key is off is to maintain trouble codes. For me thats actually a good thing since I have no way to check or clear the codes. The codes will automatically clear after a some hours. Actually I just realized that could be what my issue is. When the ECU has no codes the car runs great. But after an hour or so of driving the exhaust note suddenly changes. Sounds like it drops a cylinder or two. Power goes into the basement.

This makes me want to ask another question. It kinda applies to all of us with OEM ECU/harnesses in swap cars. Is there any way I can hook a scanner directly up to the ECU? The OBD-II plug is actually in the body harness under the dash so I have no way to check anything anymore. Thats been one of my main reasons for contemplating a standalone.

JClaw

iTrader: (17)

Well either way the harness is out. Doesn't anyone have a 1995 5-speed harness for sale? The one in my bro's car seems sooooo simple compared to my '99 auto harness.

Junkyards are quick to say "no" whenever I mention a maxima, imagine a 5-speed. Plus they like to smash plugs, carelessly cut wires and generally f... the harness up (Where did I buy my current harness? That's right, a junkyard!).

I already had the 124 pins' descriptions but didn't have the other diagram. Very helpful indeed. Broaner and Eng92 are right about the 2nd source of power directly to the ignition.

Broaner

iTrader: (10)

That is a great diagram. I forgot about that one. There are also some others too that are very paired down, online somewhere. There are several iterations of VQ powered sand rails out there.

JClaw

iTrader: (17)

VQ is a great lightweight, compact powerplant. The 3.5 easily produces more than 1 HP per pound of engine weight in N/A form.

As if my financial situation couldn't get any worse, I just told my boss to shove it today. I really need to stop doing that

JClaw

iTrader: (17)

Update: I cleaned up the harness somewhat and put it back in. I looked at the engine bay of my bro's max and plugged the two red wires that Broaner was talking about along with the rest of the harness that went along with it to the positive.

Now my coils and injectors are getting power. The moment I cranked it I noticed the starter was weak so I put the battery on charge for 4 hours. I'll continue tomorrow.

Broaner

iTrader: (10)

Definitely get a full charge on there. Seems like the Z starter has a huge draw when it first starts cranking. All my gauges shut off at the first crank. Could be due to my super old motor which is probably all outta whack in the critical smooth turning areas.

JClaw

iTrader: (17)

About the crank sensor; since I have the 2k2 sensor hooked up, I don't need to dremel anything. I used that sensor on the 3.5 all last year. I thought I would have to drop the tranny. I'm happy I don't have to.

I just sealed the oil pan and cured some leaks in the cooling system. My new rear brakes are coming in today. Looks like she might roll this week end!

MorpheusZero

iTrader: (10)

Jesus Jclaw, post some pictures... I don't care if it looks like a cat's butthole, I still want to see it.

JClaw

iTrader: (17)

Scanner = dead

because the engine bay looks great with those headers.

JClaw

iTrader: (17)

The injectors have power, the coils have power, the ECU has power, the f'cking fuel pump has power, the starter has power, all the grounds are grounded correctly, all the positives going from the engine wiring harness to the positive ARE wired to the positive, the cam sensor is plugged correctly, the crank sensor is hooked up fine and gets positive and ground... hell I even stuck the TB plate and the TPS open a little when I crank. Same sh*t different day. It cranks but won't start. I just want to drive something that does 0-60 in less than 11 seconds before the winter. This is draining me. I need to bang my head in a car door or something.

speed racer

iTrader: (10)

How bout fuel pressure. Keep trying. You should get it started soon.

MorpheusZero

iTrader: (10)

Argh... yeah, check fuel pressure, all connections... maybe something's toast? Hang in there man, it's tough as crap but like he said you'll get it started soon, and you'll have a huge grin on your face when you do.

scrhale

This sounds stupid, but throw it down a hill and pull the clutch. I read a thread somewhere that someone did this and ever since then they never had a problem. Doing this will determine if it truely is a starting problem or a problem that inhibits the car completely.

Broaner

iTrader: (10)

Dude, call me. I'll be glad to talk details with you over the phone.

eng92

iTrader: (3)

Your coils have power, but are your plugs firing when the engine is cranking?

krismax

iTrader: (15)

my max did all of what you say had spark fuel power to everything grounded . BUT the same grounds i used on the IM for my 3.0 where the prob tilley lead some stereo wire to diff points of the car for grounds and the car started this took a couple weeks to fugure out he was about to tear the engine down thinking a tooth was off somewhere.

JClaw

iTrader: (17)

I highly doubt that is a problem. The same engine/plugs fired right up in the middle of the winter after 5 months of not starting it.

Fred Allen Burge

Do you have the front crank sensor hooked up?

Fred

JClaw

iTrader: (17)

Mean the one on the pulley? Broaner said his started without it. But yeah I made a bracket for it but need to relocate it closer. I'm also doing the TPS/throttle cable bracket so I can play with the gas while I try to start. I don't have much faith in either of those but I have to do them sooner or later.

Like I said I've got the flywheel crank sensor in its position and hooked up. The wire colors are different but still simple. On the 1995 crank sensor there's Red, Black and White. Red=Positive. Black=Ground. White=Pulse to the computer or whatever.

On the 2002 Crank sensor (which fits right in no modifications BTW), there's Red, Black and Green so it's pretty easy to figure out that green has the same function as white on the '95 sensor. That's how it's hooked up. I didn't touch anything regarding the timing chain Cam Sensor. It's plugged in 100% stock.

Those three sensors together seem to be the important ones when it comes to starting the car. It will even run without a MAF since it doesn't use it below 2500.

Fred Allen Burge

I fought with mine for weeks until I finally got off of my lazy butt and made a bracket for the front sensor, it started up on the first crank then, I was a happy man! Make sure the sensor tip is very close to the teeth and aligned properly.

Fred

JClaw

iTrader: (17)

With the Z oil pan it's somewhat tricky to align it properly. My setup looks pretty gettho. Can you post a picture of what your bracket looks like?

Fred Allen Burge

Mine was extra ghetto but I'll look for a pic.

Fred

JClaw

iTrader: (17)

Finished making both brackets, one for the pulley crank sensor and one for the throttle cable & TPS. Now the sound it makes while cranking is somewhat different it seems. More normal. Maybe it's just me. I dunno. But it still won't start.

As for fuel pressure I used the stock 240's fuel pressure regulator (Stock Fuel Pressure on a S13 is 43.5 psi, which is fine for me). I'll throw on my bro's stock 95 maxima FPR (which we know works good) but I doubt it's gonna change anything.

Fred Allen Burge

Pull one of those suckers and ground it to the chassis while cranking just to verify that they are firing. Test all 6 actually.

Fred

JClaw

iTrader: (17)

Looks like I read your mind because that's the last thing I did before reading your post. It's not firing. I know the coils and spark plugs are good and their getting 12V and ground alright - the problem has to be that the ECU's not sending the pulse it's supposed to. I'm redoing the isolated grounds at the ECU like Broaner said.

Is there a way to measure if it's sending the pulse it should when I try to start it?

Fred Allen Burge

My final advice would be to check with a multimeter that you have continuity between terminal 3 of each coil pack plug and it's corresponding ECU pin (ECU pins 1,2,3,7,8 or 9) to make sure the wire harness isn't broken or damaged where you can't see it.

Fred

JClaw

iTrader: (17)

Tomorrow I'm gonna go looking for a 95 5-speed harness. We're gonna swap out the one in my brother's car (which we know works 100% fine) and replace it with another identical one. If both work fine and tested, we're putting one of the two in my car and starting from there.

At this point it could be a million things. It's the best thing to do IMO.