Rb25det Swap With Rb20det Ecu

[Judasentinel666]

Alrighty mates,

I have been up and down the hill looking for the solution to my gremlins, but to no avail. So I have decided to write my story here and see if someone on here can help me.

I had an RB25DE (N/A) in my R32 Skyline, running with Greddy Emanage and an RB20DET ECU, and RB20DET wiring loom.

Recently, I put in an RB25DET (Series 1). And since then, my car has been running on 4 cylinders. I found this out by removing the coils one at a time, to see which ones were faulty. As it turned out, the revs dropped every time except when I removed no. 2 and no. 5, which makes me think that perhaps there is something wrong with the coils at 2 and 5. I tried testing them for power and they have a spark when I turn the key on. I thought it was the injectors, but couldn't figure that one out, since they seem to be all firing. Somebody said that maybe my coil firing order OR the injection order OR both were out. What is it supposed to be and how do I confirm what order I am running?

Now I am using the RB20DET wiring harness, which was working fine with the RB25DE, but ever since the RB25DET was dropped in, the car is on 4 cylinders and not 6. Cylinder 2 and 5 seem to be not doing anything at all (they are not dead cylinders).....There is a LOT of smell of petrol from the exhaust, which makes me think that perhaps the injectors are all firing, BUT the coil firing order is messed up. I am using an RB25DE/DET ignitor (series 1).

I tried doing the continuity test on the injectors and this is what I found: Injector 4 and 6 seem to be connected, and so do injectors 1 and 3. Nos. 2 and 5 are alone on their own. Is it all supposed to be that way? I cannot for the life of me get it to run on 6 cylinders.

What do you guys think could be the problem(s), and how can I resolve them? Mind you, I have removed the Emanage and now will be trying to run the RB25DET with just the RB20DET ECU and stock RB20DET wiring harness. Realizing that the injectors size is different, I will be getting the ECU chipped soon, but first I want to make sure that the motor is running on all 6 cylinders. I have tried to search on the forum for pertinent info but couldnt find details.

ANY help would be greatly appreciated, mates.

Cheers,

Judas

Edited July 21, 2007 by Judasentinel666

[blind_elk]

What happens if you re-locate coils 2 and 5 (say swap 2 & 3 and 5 & 6)?

It sounds like a faulty ignitor - try and borrow a known working one. Other possibility is someone has slipped a pair of S2 coils in there. Do you still have the original coils from your 25DE? Try using them.

[Judasentinel666]

What happens if you re-locate coils 2 and 5 (say swap 2 & 3 and 5 & 6)?

It sounds like a faulty ignitor - try and borrow a known working one. Other possibility is someone has slipped a pair of S2 coils in there. Do you still have the original coils from your 25DE? Try using them.

When I swapped coil #2 with #1, nothing changed, in that it was still no. 2 that did not result in revs dropping when I would remove it, and same with no. 5 when swapped with another one. Shows that the coils themselves are not faulty. And they are S1 coils that came off my RB25DE.

I checked the ignitor, and the thing is that all coils have power in them when the ignition is on.

I am beginning to think that there is something wrong with the firing order. All coils have power, all injectors are firing, yet there is a lot of smell of gas and cylinders 2 and 5 do not seem to be combusting (producing power). I read somewhere on here that no. 2 and 5 coils are connected. What if their firing sequence is altered/reversed?

I wish someone could help me with HOW to redo the ignition and injector wiring for an RB25DET to run with RB20DET ECU. I think that if I can do that, things will be alright. Thats where I believe I need the real help.

Judas

[blind_elk]

The coils have power to them, then the ignitor is switched by the ECU so the spark is fired. And as far as I can tell (from the workshop manual), the ECU pinouts are the same in the 20 and 25 ECUs. (why aren't you using a 25 ECU?)

Silly question - you have compression in 2 & 5?

[Adriano]

Try making up a short ignition lead, and use that to see if there is spark at those cylinders. Pull the plug out to confirm that it is wet. If there is no spark(which is very likely)then i would say it is probably the igniter. Is it the same igniter you used before on the rb25de?

[drf76]

The coils have power to them, then the ignitor is switched by the ECU so the spark is fired. And as far as I can tell (from the workshop manual), the ECU pinouts are the same in the 20 and 25 ECUs. (why aren't you using a 25 ECU?)

Silly question - you have compression in 2 & 5?

im pretty sure ecu pinouts arent exactly the same, one major thing is that injector 4 and 6 are different, this would cause the injector to fire on the wrong stroke causing it to run on 4 cylinders, u have to swap them around to use a rb25 ecu aswell as other things

I wish someone could help me with HOW to redo the ignition and injector wiring for an RB25DET to run with RB20DET ECU. I think that if I can do that, things will be alright. Thats where I believe I need the real help.

hope this pic helps, its the differences in 20 and 25 wiring that i mentioned

Edited July 21, 2007 by drf76

[Judasentinel666]

im pretty sure ecu pinouts arent exactly the same, one major thing is that injector 4 and 6 are different, this would cause the injector to fire on the wrong stroke causing it to run on 4 cylinders, u have to swap them around to use a rb25 ecu aswell as other things

hope this pic helps, its the differences in 20 and 25 wiring that i mentioned

Thanks, guys for all your replies. The issue is that the wiring loom from my RB20DET was already modified to work with an RB25DE. And since that motor was chucked out and an RB25DET was put in, something got messed up in the motor. Cylinders 4 and 6 are working just fine. And as regards the compression in 2 and 5, even if the cylinders were low on compression, there would still be SOME power in them, and when one would remove the coil on either one of them, the revs would drop. Right now, even if I disconnected coils #2 and 5 together, the engine continues to run unaffected and the revs dont drop.

And thanks, drf76 for the interesting GIF on the differneces b/w 20 an d 25. I am aware of the differences in the pinouts, but my ECU has already been rewired to run an RB25 (DE, not DET). The issue is not the cylinders 4 & 6. Its 2 and 5. And I need to know if all of my ignition and injection wires are properly sequenced and connected. The circuit diagram does not tell me much except which pinouts feeds what sensor. What I really need is to know HOW to redo these wires (injection and ignition). I want to do it right this time, from scratch. So my query would be:

1. HOW to make an injector loom to be connected to the main wiring loom.

2. Same as above for ignition. I already have the coils and the harnesses with plugs. What I dont know is which pin on thne ignitor goes to what cylinder and how dpo I draw power to the ignitor

3. How can I check if the injectors are ALL firing or not? I tried listening to each one of them by rotating the CAS, and I would hear a tick every half revolution of the CAS shaft. Does it mean that they are all firing or is it possible that the firing order is stuffed?

4. How can I ascertain the firing order for the ignition coils? BTW, how much voltage should each coil have and how does one check that?

For now, this is what I need. I will post my progress when you mates give me suggestions and I will try them all out.

Thanks, mates.

Judas

[drf76]

sorry mate i was aware that you only had problem with cylinders 2 and 5, i just thought ill add that as someone said they have the same pinouts, but i cant understand why swapping just the motor would cause such a problem as you said nothing was changed with the wiring looms between rb25de and rb25det, the only thing i can say is start tracing a wiring diagram from ecu to the ignitor and same for the injectors, like people have said it maybe the ignitor, have you definetly confirmed there is a spark to each cylinder, especially 2&5, if there is have you checked the spark plugs, im not sure what tests u have done so it hard to tell, heres a wiring diagram if it helps and start following the wiring see if everything is connected but i cant see that's a problem as you said it was fine on the 25de.

[Judasentinel666]

sorry mate i was aware that you only had problem with cylinders 2 and 5, i just thought ill add that as someone said they have the same pinouts, but i cant understand why swapping just the motor would cause such a problem as you said nothing was changed with the wiring looms between rb25de and rb25det, the only thing i can say is start tracing a wiring diagram from ecu to the ignitor and same for the injectors, like people have said it maybe the ignitor, have you definetly confirmed there is a spark to each cylinder, especially 2&5, if there is have you checked the spark plugs, im not sure what tests u have done so it hard to tell, heres a wiring diagram if it helps and start following the wiring see if everything is connected but i cant see that's a problem as you said it was fine on the 25de.

Hey......

I have already checked and there is spark on all the plugs and the plugs are also fine. I replaced the plugs in 2 & 5 as well, but no change. If there is spark on all coils, and the injectors are firing, and assuming that the cylinders are all ok (I am pretty confident on that, since the CR was around 180+ on all of them), then the only issue could be a bad ignitor OR the wrong firing order. I cannot think of any other reason. The ignitor is also fine (its the RB25 one, with 7 pins on the wiring loom side and 6 on the coil side). Is that how its supposed to be? And assuming again that the ignitor is also fine, its a weird situation.

That's why I need to know how to check the order of things. Thanks for the wiring diagram too . I have the R33 manual as well as the R32 one. I have tried to compare the two diagrams (20 and 25) and have an idea of the differences, but those differences are already taken care of. The thing that baffles me is that the ECU is showing code 21, which seems to suggest that everything is ok. Now if thats the case, where could be the problem? Hence my desire to know the firing order and wiring issues.

Judas

Edited July 22, 2007 by Judasentinel666

[drf76]

Hey......

I have already checked and there is spark on all the plugs and the plugs are also fine. I replaced the plugs in 2 & 5 as well, but no change. If there is spark on all coils, and the injectors are firing, and assuming that the cylinders are all ok (I am pretty confident on that, since the CR was around 180+ on all of them), then the only issue could be a bad ignitor OR the wrong firing order. I cannot think of any other reason. The ignitor is also fine (its the RB25 one, with 7 pins on the wiring loom side and 6 on the coil side). Is that how its supposed to be? And assuming again that the ignitor is also fine, its a weird situation.

That's why I need to know how to check the order of things. Thanks for the wiring diagram too . I have the R33 manual as well as the R32 one. I have tried to compare the two diagrams (20 and 25) and have an idea of the differences, but those differences are already taken care of. The thing that baffles me is that the ECU is showing code 21, which seems to suggest that everything is ok. Now if thats the case, where could be the problem? Hence my desire to know the firing order and wiring issues.

Judas

hey, im pretty sure that code 21 is ignition ciruit, code 55 is all ok, so it looks like its the igntion side not the injectors

[robots]

I have the same problem but with cyl 5,6. Was working flawlessly until I decided to put battery back to its factory place. Can't make it run properly since. Tried afms, coils, igniter packs and ecus. All wiring is continus. I'm puzzled.