No spark on cyl 4 and 6 - RB26

[technorb26]

Hi everybody,

just a quick update on my project RB26 S13. My RB25 oil pan is done, and installed. Actually, I did the removal, and installation with the engine in!!! The tricky part was that I had to drop the oil pickup tube in the the pan, then slide the pan sideways, put it in place, and then let it hang on the x-mmeber. Reached in the pan, pulled the oil pickup tube out, and bolted it in, no problem. At first I was a bit scared that the pan will not fit with the engine in, but everything went smooth.

Next big ussue was my harness.

First: I need to verify with the R33 folks out there - is it a gray 3pin or black 2pin plug on the ignition subharness, where it connects to the EFI harness? I believe it is a gray 3pin plug. I have an R32 engine with R33 harness.

Next: the plug on the knock subharness on the R32 does not match the plug on the R33. So, you will need to do some rewiring. Just for a future reference for anybody that is using an R33 harness and R32 engine.

Next: After fixing a bunch of wires on the harness, and testing pretty much everything ( power to ECU, relays, sensor, and continuity on the wires from ECU to sensors), the car cranks but it does not start.

Actually, it started several times, but for like 2 seconds, and then it dies. Actually it takes several turns to start, and then when it starts, it dies almost immediately. It sounds like it is very rich, and the timing is off. I checked the timing belt, and it is fine. I checked the CAS and the injectors, they click. But I have error code 21 on the ECU every time I crank it ( ignition circuit). I tested the continuity on the ign subharness, and everything checks out fine. Same for the ECU-to-PTU wires. When I checked for spark, I saw that cyl 4 and 6 do not fire at all. 1, 2, 3, and 5 fire fine. All coilpacks fire as well, I switched coilpacks with the same plug on the same cylinder to make sure every coilpack works.

So, I guess the only thing left is the PTU? And ECU?

The PTU looks exactly the same as the Z32 PTU , just the plugs are different. The GTR PTU says" DIS6-01B" AND the Z32 SAYS "DIS6-01".

Tomorrow I will do the last test on the PTU, where the voltage at the harness side should be 0.2-0.3 while cranking, and the voltage on the coil side should be 10V while cranking. If cyl 4 and 6 do not check out, I will need a different PTU. If the they do, I do not know what to do. I guess I will need a new stock ECU.

Both connectors on the PTU are very clean, no corrosion.

Several questions:- can I adapt a z32 PTU on the GTR rb26? I guess I can rewire the connectors- can somebody please post a picture of his efi harness, I want to see the ign subharness plug, and the check connector next to it. Wire colors would be very helpful. My harness came back from the wiring service with a black 2pin connector, and the ign subharness on the engine has a gray 3pin connector. I hooked up the white wire to the ign relay, and the black wire to engine ground. I left the third wire loose, that is inj 1 extra wire for timing light hookup. Is that the problem of the engine not starting, maybe? Also, when the engine cranks, I am getting a weird popping in the exhaust,and sometimes the engine stops cranking for a second ( like the timing is completely off). Again, I am getting only error 21, ignition circuit. No error on the CAS. If I clear the error, and turn the ign on, no 21. But if I crank for a second, it gets error 21. - how does the ECU detect the error? Is it supposed to see that 0.2-0.3 volts while cranking, and if it does not throws teh code 21 error?- what happens if I crank the engine with the small black ground wire ( that connects to one of the 8mm bolts on the PTU housing) NOT CONNECTED? I believe that is the ground for the noise suppressor for the main white 12V wire that feeds power to all coils...- where can I get a good used PTU in case I need one ? Ebay does not have anything like that...- can I hook an an AEM C2DI ignition, and get rid of the PTU altogether?

TIA

[FAST-DATSUN]

The Z32 PTU/Ignitor will work, Check fuel line many time the get crossed and fuel can not get to the injectors...code 21 is the CAS the computer is not seeing the correct pulses from it..

[technorb26]

The Z32 PTU/Ignitor will work, Check fuel line many time the get crossed and fuel can not get to the injectors...code 21 is the CAS the computer is not seeing the correct pulses from it..

Hi Mack, thanks for the quick reply!

The fuel lines are fine, all injectors work, that is why the spark plugs got fouled.

I am 99% sure on the PTU, I just hate to have to cut wires again, this harness looks like crap now.


Modified by technorb26 at 1:43 PM 12/28/2004

[technorb26]

Tested the PTU. The only thing that does not check out is that the test between the terminal E on PTU and ground gives 0.2-0.3 volts while cranking, and it is supposed to be 0V.