Generic Ignition Coil - PeachParts Mercedes-Benz Forum

BrierS · #1 08-11-2006, 04:38 AM

I picked up an '86 Volvo 740 (B230F engine) for next to nothing. Though it has several minor problems that I am working my way through, one has me wondering. Ignition coil was bad (secondary resistance test = 0) so I replaced it with a generic/universal I had kicking around. It was known to be good. Question is . . . are the universal coils constructed to operate differently than OEM? Reason for my question is the car starts fine, idles correctly, wide open acceleration is smooth yet mild acceleration results in repeated hesitations. My first thought was fuel related yet the wide open acceleration shows no signs of fuel starvation. Testing the secondary spark delivery w/o load shows no misfire though I haven't tried it with a load. Probably just a matter of working through the good old, fuel, air, spark yet this initially has me perplexed. Has anyone ever seen a coil fail to deliver consistant power under low acceleration? Seems counter intuitive to me since I always thought the greatest demand for voltage was at start/idle.
Thanks
Steve

OMEGAMAN · #2 08-11-2006, 10:48 AM

Generic coils work the same as oem except some coils have higher internal resistance eliminating the need for a resistance wire going to the coil power terminal.
I would look at secondary ignition problems for your missfire at part throttle. If you find Bosch Platinums in there chuck em and get good old plane jane NGK plugs.

BrierS · #3 08-12-2006, 03:20 AM

Quote:

Originally Posted by OMEGAMAN

Generic coils work the same as oem except some coils have higher internal resistance eliminating the need for a resistance wire going to the coil power terminal.
I would look at secondary ignition problems for your missfire at part throttle. If you find Bosch Platinums in there chuck em and get good old plane jane NGK plugs.

Thanks. I had to chuckle when I read the last part. The NGK plugs that were in the car needed replacement so I headed for one of the local parts stores. They had both NGK and the Bosch Platinums. I walked out with the Bosch . . . they seem to work as intended yet I must admit I didn't like the chances of adjusting the gap. As you already knew, the center electrode makes this a precarious task. Oh well. Being a vehicle I am fixing to roll over, they will have to do.

I compared both primary and secondary resistance to the OEM specs and they were both within range. No observed leaking from the wires, so I'll pull the cap and rotor for inspection and cleaning. After that, it will be checking for an accidentally pulled vacuum line. Fuel filter has been another consideration yet wide-open throttle under load pulls very strong. It is just that moderate throttle that demonstrates the missing. ???
Steve

OMEGAMAN · #4 08-12-2006, 05:38 PM

I have seen many cars over the years run really wierd with bosch platinums in there. If you have a drivability problem you cant figure out try getting rid of the platinums it might be the problem.

davestlouis · #5 08-12-2006, 07:40 PM

Not to hijack the thread, but I tried to buy Bosch Super's for a VW Cabriolet today, were told that they don't make them anymove. The genius behind the counter suggested AC/Delco, which I bought only to discover that the tops don't screw off, so they won't work with my OEM plug wires. I went back and bought Autolite, which came with the caps off already and the little metal gaskets that the AC's didn't have. Autozone doesn't stock NGK either, so my choices were limited. They should do IQ testing before they let counter guys make suggestions to customers.