Honda Civic 1997 unstable RPM fuel average and ECU [Solved]

[Hassan1991]

you need multimeter mainly to start wiring diagnosis.
check continuity of IAC wire.
have you checked the injectors and Fpr?

[hasankhurshid29]

check

His ecu has 2 plugs which is different than normal obd2a/b or obd1 ecu. Also the ecu pinout is not available online.

[hasankhurshid29]

you need multimeter mainly to start wiring diagnosis. check continuity of IAC wire.have you checked the injectors and Fpr?

Just done a little research. His ecu has 2 plugs. It means he has SFI system (Simplified Fuel injection). And here is the pinouts for SFI type ecu: https://dodo-upgrades.nl/index.php/pinout-sfi/

Please correct me if I am wrong @hassan1991

[Hassan1991]

yes you are right
he can also double check the pinouts by tracing the wires.

[kashif91ahmed]

As per @hasankhurshid29 advice i have tested the continuity of IAC wire but found the output at pin 7 and 8 while

https://dodo-upgrades.nl/index.php/pinout-sfi/

shows that it should be pin 6 and 7, well now my plan is to check every sensor pin-out on my ECU connector.

[kashif91ahmed]

Well today, i have checked the injectors pinout from ECU connector to injectors grip and found that both ECU connector pin 1 and pin 2 connect with all 4 injectors which is wrong if my ECU is SFI standard.

How can i get the right pinout diagram for my ECU, now i feel not good about my car how can i fix this wiring part. I don't want to go to car electrician or any mechanic now until and unless fix this issue.

Today morning i was trying to prepare pinout diagram for my ECU connector also can anyone guide me that should i need to prepare this pinout diagram of my ECU now ?

I am really motivate to fix this wiring issue myself, but need some guidance from Pak-Wheel community that what are the next steps for me to fix these abnormal issues.

My ECU model : 37820-PEJ-901
Engine: D15B (NON-VTEC)
Headcode: P2A-8 (99)

[hasankhurshid29]

@Hassan1991
@shabbir.1
@rajaahmed96
@Xulfiqar
@nfssaad

[Hassan1991]

have you checked the voltages? that would be ignition +12 volts.

[hasankhurshid29]

have you checked the voltages? that would be ignition +12 volts.

I think he was checking continuity/resistance between ecu plug pins and the injectors' grips

[kashif91ahmed]

No I didn't, check the voltage at this stage, right now my efforts is to trace all the sensor wiring.

[Hassan1991]

Then only check the feedback pins of sensors.
If you look at the voltages pins you will get confuse.
For example only trace centre wire of TPS.

[shabbir.1]

Please, share clear pictures of the following:

1. engine and it's head code
2. distributor and it's connector(s)
3. map sensor and it's connector
4. Throtlle body, throttle plate pulley and cables attched to this pulley, stop bolt and base idle set screw??
5. IACV and it's connector
6. ECT sensor and its conenctor
7. O2 sensor if available
8. Injectors and color code of the wires attached to the injectors
9. All vacuum connection pipes like brake booster, PCV , fpr etc.
10. Connectors attached to the strut towers on each side
11. Engine bay fuse box (withlid removed)
12. Gear box and it's code
13. Solenoids attached over to gear box casing and attached conenctors

Have you noticed any severed wires in the ecu harness and also joints in those wires.

[hasankhurshid29]

Then only check the feedback pins of sensors.If you look at the voltages pins you will get confuse. For example only trace centre wire of TPS.

How can ecu plug pins showing continuity on all 4 injectors plugs? I think it's against basic working of the engine as all injectors cannot fire at same time

[Hassan1991]

It would be +12v wire of ecu. As injectors get ignition +12v direct. So any positive power wire will show continuity.
Honda ecu's have 2 +12v power wires and 2 ground wires going into the ecu.

[kashif91ahmed]

Bro I can not get you this point, can you explain in easy technical term.

Sorry I just involved with car since few week ago.

[kashif91ahmed]

Well I could not find and joint from connector side, yeah I will share you all details tomorrow. I.A

[hasankhurshid29]

But how can pin 1 and pin 2 of ecu plug A both are providing 12V to all injectors?

[Hassan1991]

@kashif91ahmed
Pin1 and pin2 would be coming from ignition switch.
When you turn on the ignition +12volt will appear across them. Those same wires are going in injectors and all other accessories which need 12 volts from ignition.
Matlab pin 1 or pin 2 ignition switch sy +12volts provide kr rahien ecu ko voe same wiring injectors ko bhi volts dy rahien.
And all positive wires are connected to each other in wiring and so does the ground wires. You can confirm by checking the voltages after turning on the ignition. note you have to connect negative probe of multimeter with ground.
Ecu will turn on the injector by providing negative pwm signal in the other wire. Which you have to trace.
So what you checked is constant 12v wire which will be all connected together.
But atleast now you got the main positive power wires of ecu.

[hasankhurshid29]

Check this pinout.

[hasankhurshid29]

Maybe he has tested pin 12 and pin 13 on the opposite side. Those ones are the ignition power you are talking about