News:

The ORG - No shonky business!

Main Menu

Ignition Coil, help wanted

Started by revilla, 17 March 2019, 06:28 PM

revilla

Hello there.

Any advice is welcome.

3 months ago my car wouldn't start. After some testing, changed the ignition coil and bingo, problem solved.  Same exact situation repeated today. Engine begins to loose power, hesitation to accelerate and stops.  Impossible to re-start. Swapped ignition coils with my other 280 and all back to normal.  The last ignition coil installed in December was new, Bosch branded.  Either it was defective, either something else is damaging the coils.  I repeated the swap 3 times with the same results (failure to start "follows" the coil).  Any ideas to find the root cause?  Or would you advice I simple buy another coil and assume the previous one was just defective?

Thanks all

Peter

Have you checked or replaced the ballast resistors ?

djenka018

Voltages should be like this when ignition is on and engine is not running (for TSZ/inductive pickup ignition):

A -[==]- * -[==]- B -()()()()- C -[TSZ]- GND

A= 12V
B=4V-5V
C=0.5V-1V
TSZ enclosure should be 0 Ohm to the car chassis and batt neg.
B and C nodes are on the coil

-[==]- ballast resistors
-()()()()- Coil (bobbin)
-[TSZ]- electronic ignition
Vitamin C for SL... the SLC

revilla

Thank you both for your replies.

Ballast resistors checked (only physically, measures later today).  In fact I just noticed one of the 2 (the one closer/towards the wheel) has the ceramic cover broken but the resistance is still in one piece.  The metal part seems corroded.  However the car starts like a charm with the good coil.  Which lead me to think the ballast resistors are doing its job.

Would that broken ceramic in the resistor cause the damage of the coil with time?  Previous coil lasted years, but the last one lasted only 3 months.  I need to replace it anyway.  Any idea of the PN's associated?

I'll measure tonight when at home.

Thanks for your help.


revilla

OK so to wrap up this thread, I found the issue was a bad coil/distributor cable.  It had very high resistance.  I'm guessing because of the bad lead, the coil was overworking, getting hot and lasting only a few months.  Not sure about that though.  All I know is that after changing the cable the car starts good with its usual stable idle. I found the 0,4 and 0,6 resistors not too expensive and changed them anyway.  I'm glad it wasn't the ignition module.  Thanks to those who helped me diagnose.