Is it bad to try to start when the ECU grounds are not grounded?

[Darius]

So I had a lapse of reason and forgot to double check my wiring before attempting to start the RB25 for the first time. Didn't fire up, but the relays were clicking and everything. I then realized that I hadn't grounded the ECU. Now after grounding the ECU wires, the starter turns the motor over, there is fuel, but it won't fire up. I also don't have the MAF sensor hooked up either, but I didn't think that was necessary just to get the motor to fire.

I am on my way to check the power transistor and coils if anybody has any other ideas, please let me know.

BTW I followed ehacker01's wiring guide for the RB25DET series 1 into a 1997 S14 (auto to manual at the same time).

[Joe]

So I had a lapse of reason and forgot to double check my wiring before attempting to start the RB25 for the first time. Didn't fire up, but the relays were clicking and everything. I then realized that I hadn't grounded the ECU. Now after grounding the ECU wires, the starter turns the motor over, there is fuel, but it won't fire up. I also don't have the MAF sensor hooked up either, but I didn't think that was necessary just to get the motor to fire.

I am on my way to check the power transistor and coils if anybody has any other ideas, please let me know.

BTW I followed ehacker01's wiring guide for the RB25DET series 1 into a 1997 S14 (auto to manual at the same time).

can you link me that guide? ive never seen it and would like to see how accurate it is.

also, hook your maf up. the ECU is blindly guessing to for how much gas to add. thats bad. it shouldnt hinder startup but it could.

finally, how do you KNOW you are getting injector firing? your plugs wet?

[Darius]

First, here is the link to the guide on racebread.com http://www.racebread.com/Docum...s.rtf

Second, I haven't checked the plugs, but I did check the ECU for codes. Got "21" and checked the ignition system (page EN-319) as it describes. Everything was fine until I made it to part C in checking the continuity between the power transistor plug (pins 2,3,4,5,6,E) and the ECU plug (pins 1,2,3,10,11,12,13,20). I don't have any continuity besides between ECU terminal 3 and power transistor plug terminal 3. Everything else came up negative for continuity. Does this mean that the wires between the power transistor and ECU are fried? Is that even possible?

And lastly, what could have happened because I thought for sure a fuse would blow before $hit really hit the fan and started frying things..

[illdrift]

Sorry to bring up an old post and hijack it. I've read through some of your other posts on problems you were having darius, and im putting the same early series r33 rb25det manual engine into a different car, a 1990 Nissan Laurel (auto RB20e standard). If i still can't get the engine running i'll start a new topic, but i have a question about the racebread guide you posted the link to.

That plug looks like the rb25det plug next to the eccs computer which connects through to the dash?On the table where it says move to ka pin #, are those pin numbers ecu pinouts, or is there a similar diagram of the dash plug for the ka24 which those numbers correspond to. If so, would you be able to give me that diagram please so i can try and adapt it to the dash plug on my car

Cheers

[illdrift]

ok now that im more awake this morning i realise i dont even need that, and engine starts up now

[Darius]

ha glad I could help! I'm going to e-mail Jon Powell my revision to that wiring guide which includes my wiper wiring so it doesn't have to be wired separate from the harness. I e-mailed ehacker01 for some help when my motor wasn't starting but he just sold his S14 w/RB25 so he couldn't look at anything.

[illdrift]

Could i ask you a question about the wiring? This is my first attempt at wiring an engine swap. Currently i have it set up wrong but it starts up. Normally when u do rb20det conversions on cars like mine, theres a plug near the maf with 3 wires, ones a constant 12v, the other is between 1-3v (my batterys old and flat so im not sure on that reading) and then 12v with the key at on, and the 3rd ones something for power steering so duno if its relevant. Now i know ive done this bit wrong but the car will start up anyway:

pin 58 on the computer gets 12v constant (not that i changed anything), and the misc dash wiring is correct i think (regarding start signal, fuel pump relay etc). on the diagram you gave the link to:

wire 4 - red - ignition relay powerwire 12 - black/red - ignition switchwire 24 - white/black - eccs relay power

i currently have 4 and 12 to the wire which is 1-3v normally and 12v when key is at on. wire 24 has constant 12v. so:

Q1 : which wire goes to what. Do wires 4 and 24 need to be 0v normally and 12v with the key at on? (if so then ill have to find another wire to use for the supply)

Q2: which wire does wire 12 have to go to?

i was having problems with my battery not charging with a battery charger and the alternator not charging (think i know how to fix that now if i dont ill ask later). Currently theres .22amps being drawn while the car sits there with the wiring as mentioned above. If i pull out the ignition relay it goes down to .17amps

Q3: does .17 amps sound fine for a car thats sitting there without the keys in etc, or is that too high?

Cheers for any help

Modified by illdrift at 1:48 PM 5/16/2006
Modified by illdrift at 1:56 PM 5/16/2006

[Darius]

First, what car are you putting the RB25DET into? I do not have a pin17 on my M63 plug. Pin 24 is the W/B ECCS relay power (12V constant I believe, someone verify this) that I think you're talking about. Pin 4 is the R IGN relay power (12V constant as well). Pin 12 is the B/R that is the IGN switch that triggers the IGN relay to send power through it. I believe this is 12V "ON".

I don't know how much help this is, but hopefully someone else will chime in.

[illdrift]

Sorry i read the diagram wrong, i meant pin 24 not 17. I have edited the post above. Im putting the s1 rb25det into a C33 Nissan Laurel. Thanks ill give it a try wiring it that way