Help with no spark 89 e30

[darksideracer69]

I'm trying to help a friend out with his no spark issue. So far i've checked the following.

Getting 12v at the coil

ohmed spark plug wires at 6k

replaced the pulse sensor? Thats on the crankshaft, Front of the timing cover. Also made sure that the sensor was 1mm away from the wheel.

Tried a different computer from a known working car.

Looked at cap and rotor and also replaced from a known working car.

Nothing has changed the fact that it has weak spark


Any ideas :crazy:

[jlevie]

Test for spark at the coil output. If good there and weak at the plugs, the distributor, wires and plugs are the suspects. If weak there the coil, DME, and it's power/ground are the suspects.

[E46Twist]

Well no spark and weak spark are two different issues? Is there any spark the plugs? If not then check at the rotor and report back. If it is just weak spark measure from the plugs back to see where your drop happens

"Fast is Sexy"

[darksideracer69]

Checked spark coming from the coil and its weak. By weak i mean that i can barely see any spark in my spark tool. I also tried to test it with and plug, and there isn't enough to make a spark using the plug.

As stated before i already swapped the cap and rotor with my car which is running fine.

Thanks for the help, keep the ideas coming.

[E46Twist]

If your coil is sending weak spark and your battery is charged you need to replace the coil. Make sure the coil is getting the proper amount of juice to it first.

"Fast is Sexy"

[darksideracer69]

sorry i didn't post before, i have also swapped the coil from my working car and there was no change in spark.

what about a voltage drop while cranking? Is there some specific fuse or relay i should check?

[E46Twist]

May i ask where you measured that drop? As far as I know any fuse/sensor problems will cause no spark period or erratic spark. Better let someone else chime in though

"Fast is Sexy"

[darksideracer69]

Drop on voltage at the coil while cranking. Think it dropped to 6-7 volts while cranking and then when back to 11 volts after a couple of revolutions.

Is that normal?

[EatsHondas]

All engine bay grounds clean and tight? Oil pan to chassis and I-forgot-where-it-starts to right shock tower. How old are the wires and plugs? Plugs are practically free, I'd replace them for the hell of it if they haven't been done recently.

No spark or weak
spark observed
during spark test

-Wet or damp distributor cap and/or spark plug wires

-Faulty wires or connectors (primary
circuit).

-Weak or faulty coil

- Defective spark plug wires

- Worn or fouled spark plugs

- Faulty impulse generator (TCI-i
ignition only) .

- Faulty ignition control unit (TCI-i
ignition only)

- Faulty reference or pulse sensor
(Motronic only)

- Faulty Motronic control unit (Motronic
ignition only)

- Incorrect ignition timing (TCI-i ignition
only)

[darksideracer69]

Thanks, im going to check the grounds next. That seems like the only other thing to check.

[ajiiE30]

Thanks, im going to check the grounds next. That seems like the only other thing to check.

I was doing some work on the cooling system and coolant got all over the ground from the oil pan to body and when I went to start the car it wouldn't crank. I cleaned up all the coolant from that area and made sure everything was dry and she cranked right up. Not sure if this will help in your scenario but a possibility, good luck!

[jlevie]

Drop on voltage at the coil while cranking. Think it dropped to 6-7 volts while cranking and then when back to 11 volts after a couple of revolutions.

Is that normal?

No. Voltage at the positive post of the coil should be within a tenth of a volt of system voltage (as measured at the power point in the engine bay) and should track system voltage as the engine is cranked.