Rb20det running on front 3 cylinders (no spark on rear 3)

[thes13project]

Ok, so Ive tried figuring this out with the help of a few friends, but just havent had any luck. Ive searched a wide variety of forums and google to figure this out but Ive gotten no where that way either. So I figured the next step was to make this post.

When I first started the car up, the motor sounded awesome. Idle was perfect, sounded very healthy and the turbo spooled with no issues. A few days later I took it out for a test drive, and thats when i noticed the car felt like it had no balls at all.

We figured this might be a timing issue so we checked timing and it was a tooth off so we fixed that and tried a second test drive. Car acted the exact same way.

We ran a test on the fuel injectors and all are working properly, then we tried the coil packs, and discovered two damaged coilpacks and figured that had to be the issue.

I replaced the two bad coil packs and installed the NGK plugs Carl H recommended. Was ready to test drive again and was hoping for that to be the issue. Car still runs like s***, checked the rear 3 coilpacks, zero spark just like before.

I went ahead and did a quick compression check as well as checked for a broken cam even though I knew I wasnt getting spark to the rear 3 but I did it more for a lets do it so we can say we did to get it out of the way. Compression checked out on all 6, and the cams were fine.

So a few weekends later a friend of mine drove his RB car down to help me figure out what was wrong with my heap. We pulled his entire coil pack assembly out, as well as his coil pack harness, Ignitor, ECU and CAS and installed them onto my car.

We figured once we got the car up and running we could do a process of elimination and find out what was bad on my car and replace it. However even with all of his stuff hooked up, my car runs on the front 3 cylinders with zero spark to the rear 3.

So after being pissed off and emo panda for a few days or weeks, I decided to pull the entire harness back out of the car and go through every single wire to see if something was the issue with it itself. Its the only thing we didnt use from his car.

I found a few sketchy wires, as well as checked all the pins and connectors. I fixed the wires and put the harness back in the car to test it out and see if that was it. Im sure you can already guess it didnt work or I wouldnt be typing this novel out right now...lol.

So this is my situation, hopefully someone could shed some light for me and maybe tell me what to look for or if this has happened to them and what the solution was.

Ive been building this car for 3 years now, and Im so close to having it on the road that this s*** is just pissing me off beyond belief.

I can provide pics and more details if needed. This turd needs to run....haha



Thanks for reading, and for any help and info.

Seth

[Sil240]

Your car makes me happy in weird places..... :-)

Have you tried switching ECU's??Maybe you shorted something.Try swappin ecu's with your buddy, maybe that will work.

When you spin the CAS Key on Engine Off, do you hear the rear Injectors clicking??

[thes13project]

Thanks...lol.

Yeah weve already switched ECUs and the injectors are working

[Carl H]

super clean car, i like it.you have a very odd problem for sure...it should in theroy fire but if you're getting NO spark then im not sure where to go from there as you have seemingly swapped out every part possible.how far down did you tear the harness?bare wires or just unloomed parts?what about the ecu connector, is it damaged or posibly cracked?

[thes13project]

Thanks Carl

There is one issue with the harness itself that Ive failed to mention. The ECU plug was broken and a few wires were not staying seated properly.

Ill show you what I did to fix it, maybe this is my problem???

The 8 pin connector was damaged, I happened to notice that the ka24de has one of these type of plugs on it, so I cut the main plug and sanded it smooth, then repinned the wires into the new plug as you can see below.





One of the wires was completely broken and the connector was destroyed so I used a donor wire from the KA harness to fix it. (the one wrapped with black tape)

Thanks again for the help.

Seth

[Carl H]

i'd place all bets on that plug being junk, the whole plug must be fully seated for it to work properly.i have fixed cars with just a turn of the ecu retaining bolt before, the system's contacts are rather high in the plug and need to be fully seated to work.i'd say source a new plug and carefuly repin the whole thing...if you need a plug i can supply one.

[240daveTX]

i actually bet that is the problem. that whole piece according to the pinouts controls......

you guessed it....

101 Injector #1102 - 110 Injector #5103 Injector #3104 Fuel pump terminal voltage control output105 Injector #2 106 Fuel pump terminal voltage control output107 Injector ground 115 -108 Injector ground 116 Injector ground109 Injector power supply (counter electromotive reflex circuit)112 Injector 6114 Injector 4

try having someone hold that piece in tight while you start the car. i bet all your stuff works right

[240daveTX]

thought having this here would help ya out....

Updated pinout for RB20:

1 Ign signal (power transistor) Cyl #1 2 Ign signal (power transistor) Cyl #5 3 Ign signal (power transistor) Cyl #3 6 Sub electrical fan relay (engine temp switch)7 Tacometeter speed signal9 AC relay (AC cut signal) 10 Ground (ign signal system)11 Ign signal (power transistor) Cyl #6 12 Ign signal (power transistor) Cyl #213 Ign signal (power transistor) Cyl #416 ECCS relay 19 Power steering oil pressure switch 20 Ground (ignition signal system) 21(RX) Receive (control unit data reception) 22 (TX) Transmit (data sent from control unit) 23 Detonation sensor 1 (cyl 1-3) 24 Detonation sensor 2 (cyl 4-6)25 Wastegate valve control solenoid valve 26 Air flow meter ground 27 Air flow meter intake air quantity signal28 Engine temp sensor 29 Exhaust temp sensor30 Sensor ground32 Monitor and check lamp (red)34 Air flow meter ground 35 Air flow meter inatek air quantity signal 36 Intak air temp sensor 38 Throttle opening output 41 Crank angle sensor (120degree signal) 42 Crank angle sensor (1 degree signal) 43 Ignition switch START signal 44 Neutral switch 45 (IGN) Ignition switch (IGN) 46 AC switch47 (CHK) Check (diagnosis activation) 48 Throttle sensor power supply supply 49 Control unit power supply 50 Ground (control unit) 51 Crank angle sensor (120 degree signal) 52 Crank angle sensor (1 degree signal) 53 Vehicle speed sensor 54 Throttle valve switch (idle connection point) 55 Exhaust gas sensor (rear) 56 Throttle sensor output signal 57 Throttle valve switch power supply 58 Battery power supply 59 Control unit power supply 60 Ground (control unit) 101 Injector #1 102 - 110 Injector #5 103 Injector #3 104 Fuel pump terminal voltage control output105 Injector #2 106 Fuel pump terminal voltage control output107 Injector ground 115 - 108 Injector ground 116 Injector ground 109 Injector power supply (counter electromotive reflex circuit) 112 Injector 6 114 Injector 4

[thes13project]

Thanks Carl and Dave, and yes Carl I would definitely need the plug. I know you do harness work (I followed your write up..lol) and was curious if you would be interested in fixing this and if so how much. I also noticed in your wiring services that you did non needed wire removal which would be a plus for me as well. I know youd obviously charge more since the harness has been tampered with and already wired. I wish I wouldve just done this from jumpstreet and had a running car...lol.

Thanks again fellas

Seth

aim = thes13projectsethpatton @ yahoo dot com if you would like to talk more about the cost of the wiring harness fix or plug.

[Eikon]

If I remember correctly, the coil pack harness is divided into two sections.. part for the front three coils and part for the back three coils.

Did you swap the coil harness over when you traded parts with your buddy?

Coil pack harnesses are notorious with RB's because they run so hot.. over time those wires take a lot of abuse.

Anyhow.. just curious if you tried swapping just the harness?

[thes13project]

Yeah we swapped his coil pack harness onto my car as well.

[thes13project]

Thanks for all the input and suggestions. Boxed my harness up Tuesday night and shipped it to Carl H in NC to give my s*** an extreme makeover and a much needed new ECU plug.



Hopefully this does the trick.

[RustspecS13]

Wow you never said anything about that hacked up harness. I think 95-98 maximas have the same connector but thats just something i read on here. Im not sure if its true or not.

Carl, your just going to build/source a new harness right? That one seems like a gigantic mess.

~Alex

[Largekid]

good luck seth...hopefully carl gets you squared away.

iirc, his harness was all together till he pulled it all apart to test connections and remove the unneeded wires...

[thes13project]

iirc, his harness was all together till he pulled it all apart to test connections and remove the unneeded wires...

You are correct sir, now get that beast of yours going.

[nvrplzd240]

Bump for a buddy of mine. I need to see this car moving under all six cylinders before I ship out!!

[thes13project]

haha Tyler. Ordered my CAS so hopefully this can happen soon.

[RustspecS13]

Yea I have no faith in my spare CAS. Did you find one through the links i sent you?

~Alex

[FAST-DATSUN]

The 3 rear coils have a seperate harness make sure its pluged in....

[USMCgetsome]

you could have easily put a few zip ties on that connector around the ecu and tightened it down for testing procedures.

[FAST-DATSUN]

You can use 300ZX connector to replace you old one.. Connector being broken is going to be a problem if its not your problem already......

[thes13project]

Thanks for the info fellas, but Carl H has the harness now and is repairing it for me. I ended up finding a CAS on ebay but thanks for the heads up

[BrandonSS]

bumpski.. is the harness back yet??? Its been, what.. 3+ weeks.

[thes13project]

I know Carls a busy dude, I sent him an email Monday to touch base with him and see how things are going. Hopefully he can get me fixed up soon cause im more then ready to drive this car before winter gets here...lol

[BrandonSS]

I know Carls a busy dude, I sent him an email Monday to touch base with him and see how things are going. Hopefully he can get me fixed up soon cause im more then ready to drive this car before winter gets here...lol

well he was online and active on the forum.. did you get a reply? Sucks that you might miss the last event now.

[thes13project]

yeah he emailed me today, hoping to have it done by the beginning of next week

[BrandonSS]

yeah he emailed me today, hoping to have it done by the beginning of next week

Its Thursday and you havent heard from him? Even with 2 harnesses before yours I dont see how 4 weeks from a board sponsor/moderator or ANY person(s) providing a wire harness service is marked as acceptable (esp when school is not delaying). I saw your harness first hand.. it was not tangled, no wires crossed, all separated/taped and easily laid out across the floor, just removed the loom to make it easier... and you had me almost talked into contacting him to do my harness for my 240z.... Carl, can you finish this harness?!?! Seth has been dragged through hell with this 2 year build and this is the last thing the car needs to run. He trusted you to repair it in a timely fashion and for a fair price. Its been a MONTH. I know you are good people, so lets get his car to the last event of the year since hes missed every single one this year.
Modified by BrandonSS at 4:08 PM 8/20/2009

[BrandonSS]

bump

[thes13project]

Carl???

[BrandonSS]

Carl???

time for a new thread, Seth.