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

[mbonanni]

I have a misfire in cylinder 2 and 3 at idle.

Car runs rough and shakes.

I have
-New Cap
-New Rotor
-Spark Plugs
-Refurbished and flow tested m50 injectors (#17)
-Somewhat clean gas (less than one gallon of old fuel I couldn't remove from tank, and about 7 new gallons with fuel system cleaner stuff in it)

Help, what should I check?

[TimKninja]

If you have the harness for the M20B25 there is no need for flywheel sensors. the M20B25 uses the Crankshaft position sensor at the front of the engine for engine speed reference.

Double check your fuel lines, Ive fucked that up EVERY time Ive swapped in an e30 engine.

[mbonanni]

If you have the harness for the M20B25 there is no need for flywheel sensors. the M20B25 uses the Crankshaft position sensor at the front of the engine for engine speed reference.

Double check your fuel lines, Ive fucked that up EVERY time Ive swapped in an e30 engine.

Okay, so ONE of the two plugs comming from the tranny is the flywheels sensor. I do not need that. The other one is a reverse light? But where does it plug in?

I do have the Crankshaft position sensor at the front, yes.

What should I double check about the fuel lines? When I crank it fuel comes out, no doubt about that.

[M44schnell]

just did this yesterday, i had the CPS and the Pulse sensor plugged in backwards (the have the same plug)

[lcoleman]

Okay, so ONE of the two plugs comming from the tranny is the flywheels sensor. I do not need that. The other one is a reverse light? But where does it plug in?

There are two reference sensors. Neither one is needed.

What should I double check about the fuel lines? When I crank it fuel comes out, no doubt about that.

Feed/return can be backwards.

[mbonanni]

just did this yesterday, i had the CPS and the Pulse sensor plugged in backwards (the have the same plug)

I switched both around with no luck. One way i get spark, and the other way I do not. I leave it tjat way, and still no start.

There are two reference sensors. Neither one is needed.

Feed/return can be backwards.

Thanks

Well, when I crank it fuel comes outs like a fountain at the hose that goes into the rail. I feel like the lines are right, but I will still switch them.

I have an extra fuel rail with injectors, I think I might try and hook that up to make sure I'm getting fuel through the injectors.

Keep it comming guys.
Thanks

[noid]

Fuel, spark, and compression is all you need. Have you checked compression in the cylinders and power at the fuel injector connectors? Made sure all the wires are in the correct order on the distributor cap?

[jlevie]

The hose that hose to the rail (not the FPR) is the one that should deliver fuel when cranking. Since the engine has spark and fuel delivery when cranking, the next checks should be to see what the rail pressure is, whether the injectors are firing (using a noid light), whether the cam is correctly timed, and whether the ignition wires are correct. Also make sure that there isn't a major intake leak.

[mbonanni]

Okay thanks. before I could check compression my dad started to take it apart to check all the timing.

Can anyone tell my the wiring configuration for the distributor cap is?

My dad is also asking me what the timing marks are for the first firing cylinder? (sorry if this does not make sense, he is sort of illiterate ;)

Thanks guys. Will double chekc the fuel lines, but I am pretty sure they are correct.

[noid]

The wire numbers are labeled on the distributor right where the plugs plug into the cap. I think it starts with number 2 up top and ends with 5 at the bottom.



If the wires themselves arent numbered then just take a volt meter and check for continuity on both ends of the wire.

As for the timing marks, just make sure they line up at these two points:




Checking the timing is jumping a bit ahead of yourself if you haven't just completed a timing belt job. Check the aforementioned stuff.

Any engine needs three things, fuel, spark and compression, make sure you have all three.

[mbonanni]

I bet the timing is fine, we just redid the TB. So it is fresh.

I will double check the spark wires and the order.

I know that we have spark, and fuel getting to the rail. I do NOT know if there is fuel getting into the cylinders, so I need to check to see if the injectors are firing as well as in correct order.

Then I will check compression, because I will need to borrow one.

Thank you!

[mbonanni]

Guys,

Is using a 173 ecu okay with this setup? From my understanding by using this '87 harness everything is kept motronic 1.1, and the 173 ecu is 1.3?

If this is not the right ecu tell me which one is!

Thank you

[F34R]

The K7 relay to pin 14 on the c101 fixes the starter for the newer jetronic firing of the solenoid retraction. Tells it when to stop firing after it kicks over the starter to turn over the engine.

The 325ic 87 harness is the same since it is using the b25 engine.

[mbonanni]

The car was not an auto, but the '89 motor came from an auto, and the harness is unknown at the moment.

[F34R]

This is the wiring for the starter from swapping a b25 into a b27 spec e30(my sister's). Motronic uses 3 wires for the starter apposed to the jetronics 2. What I did was run a female connector from the c101 to the k7 relay and on the 85 prong I removed it and spliced the new lead into the relay.