'87 325 w/ '89 m20b25 motor MISFIRE AT IDLE, rough

[noid]

You don't really need a volt meter, if you follow the steps if successful the injector should click (you should hear/feel it).

[mbonanni]

So how do I connect the pins?

[mbonanni]

Download the Bentley manual, someone has a downloadable version on here somewhere.

The Bentley manual also suggests at the 55 pin connector (ecu connector) to

Component or circuit
Fuel injector control (injectors 1 , 3, and 5)


Test terminals
(at 55-point connector
unless otherwise specified)

16 and ground

Test conditions
bridge terminal 36 and 2 with fused jumper wire

Correct test value
fuel injectors (1 , 3, and 5)
click when terminal 16
is touched to ground

Okay, so here is what I just did.

I connected pins 36 and 2 with a jumper wire. Every time I connected these two (2) pins the white five pin relay (on the harness) would click.



Then I tried it like this. I connected pin 16 and ground with no response/clicking.



Then I tried like this. I connected pin 55 and ground with no response/clicking.



And here is what each plug is again

http://84.45.115.78/e30zonewiki/index.php/ECU_Pinouts

Did I do anything wrong?

[noid]

Okay, so here is what I just did.

I connected pins 36 and 2 with a jumper wire. Every time I connected these two (2) pins the white five pin relay (on the harness) would click.



Then I tried it like this. I connected pin 16 and ground with no response/clicking.



Then I tried like this. I connected pin 55 and ground with no response/clicking.



And here is what each plug is again

http://84.45.115.78/e30zonewiki/index.php/ECU_Pinouts

Did I do anything wrong?

You need to have pin 36 and pin 2 bridged at the same time you bridge 16 and ground together, when 16 touches ground you should hear a click of the injectors (1, 3, 5). That is how I understand it.

[mbonanni]

Do I need to crank it to make the injectors click, or should I be able to just have it in the "on" position, then connect those pins?

[noid]

No cranking should be needed.

[mbonanni]

You need to have pin 36 and pin 2 bridged at the same time you bridge 16 and ground together, when 16 touches ground you should hear a click of the injectors (1, 3, 5). That is how I understand it.

I bridged pin 36 and 2 with a fuse. When I touch the pin 36 and 2 I hear the white five pin relay click. I then connected pin 16 and touched it to 2, but the slightest touch creates a spark, and I do not hear a click (I am sitting inside the cabin with the door open)

This is what happens

[mbonanni]

Okay,

I got a noid light. I hooked it up, and each injector wire made the light blink. I am going to recheck spark.

What is my next step? It has to be a fuel related problem in the rail/injectors.

[mbonanni]

Bump.

I am stumped. I will be renting a gauge and checking fuel pressure in the rail tomorrow. Any tips on how too.

Other ideas?

[mbonanni]

Just checked the fuel pressure. It was 45 while cranking, then when I let off it dropped down to 30. Took about 30 seconds. I checked the line that goes into the rail.

Man I am stumped.

[mbonanni]

Okay so the nous light blinked when we were using it earlier.

I just hooked up a seperate set of injectors and rail that I have, to see if it sprays, and I get nothing....

[mbonanni]

Okay guys, so the car starts with little to no effort, BUT I have a problem.

Cylinder 2 and 3 are misfiring at idle. The car shakes and runs rough. I have not taking it on a drive yet because I want eveyrhting fixed beforehand.

What are some things I should check?

I have
-New Cap
-New Rotor
-Refurbished m50 injectors (#17)
-New spark plugs

What should I check?

Thank you

[Quinthirty]

IIRC, this is what the Bentley manual says: Backfire caused by unburnt fuel, incomplete / no spark, stuck valve

1. Check coil
2. Check each spark of plug
3. Check connections of injectors
4. Check impedance of injectors
5. Reset ECU
6. Turn crank and see if a valve gets stuck

Misfiring
1. Check grounds: ECU, main C101
2. AFM flap
3. Distributor cap

I suppose it does not hold an idle either. Is there smoke? If you unplug the spark plugs, are they wet?

I also read that you're running on a 173? I don't think its recommended to run M50 #17 injectors on a stock ECU. You need a chip. I got one when I made the switch, or you'll run rich. I did this swap last week, and had this exact trouble. I ended up replacing the coil because the guy who did the job was too excited and didn't remove the negative terminal before replacing the injectors. Car was perfectly fine before the swap.

[mbonanni]

Thank you, I will check those.

I will have to run the car again and check back on the plugs if they are wet. M50 injectors are okay to use with the stock ecu if they are the 17lbs ones. The 19 lbs ones need a chip. There is definitely a smell while the car is running, but I also do not have the exhaust on after th cat, if that makes a difference.

[Quinthirty]

Here are the values of the injectors from what I gathered from "witchunter"

Stock: 0280150715
cc / min: 152.4 or lbs / hr: 14.5
PSI: 43
Bar: 3

M50: 0280150415
cc/ min: 178.5 or lbs / hr: 17 (likely at 3.5bar as w/ the M50 engine); or 166 cc/ min or 15.8 lbs (likely at 3bar)
PSI: 43
Bar: 3

Nonetheless, if there is more volume of gas coming in, but the ECU is programmed for stock injectors, isn't it likely that there is flooding even at 3bar? If it is flooding, then is it likely that the unburnt fuel is causing the misfire / backfire?