Pak_37

Thanks in advance to anyone offering advice.

We're traveling in South Dakota right now near mount Rushmore. No places for parts or service.

Car has been running great until this morning. Did 175mile spirited drive yesterday with no issues. Parked the car overnight and when I started it this morning it was very rough idle, backfiring, stalling.

The coils, plugs and dist.caps have all been changed recently.

Have tried running it with the o2 sensor disconnected. No change
Tried running it with the mass airflow sensor disconnected. No change

Disconnected the primary ignition coil at the coil and it idles much better. We're about 900 miles from home. Would like opinions on whether we can drive the car home on only one coil?

Crystal Cranks

Don't think you will do much harm running on one coil, I would check the following,

1. Take the distributor caps off and check all is well inside (check the belt has not slipped)

2. As you have just had work done double check all wires are going to the right plugs.

You say it idles better just on the secondary, how does it idle on JUST the primary?
Maybe try the secondary coil on the primary cap to see if that can give more info to solve this.

Hope you solve it, it's not nice having a sick car when you are away.

Shamus964

+1

Maybe interference through the HV lead to, or plug wires from, the primary? Shouldn't be broken dizzy belt since you unplugged that coil.

You can swap the plugs (front to back) at the coils too. They're supposed to fire at the same time so it shouldn't create an issue, and sometimes cars run better w/the LV leads swapped.

I think you're fine to drive on one coil, but others may have a better understanding on that...

Andy Roe

Bad primary coil? Can you swap the primary and secondary over? If it then idles better on the secondary then you'll know that's your problem. If not, may be could be bad fuel?

parsecnc4

DME relay?

Pak_37

Thanks to everyone for the feedback. We tried running on the primary coil only and had no change. We swapped the secondary and it runs fine. We had the other coil tested and it's bad even though it's only been in the car for about six months. We'll drive the rest of the trip tomorrow with only one coil.

Has anyone sourced Bosch coils that are made anywhere other than Brazil?

greg1990964

I have searched everywhere. Those Bosch coils from Brazil are no myth. We all really need to find a better alternative to those Brazilian coils..Saw genuine Porsche coils for sale on AutoAtlanta http://www.autoatlanta.com/tinydetai...l_number=28016
I think some people don't even know they are slightly bad till they put in a different coil and feel the difference. My brazilian's are already going bad after a couple months. I can feel the power fluxuations. I think they can't handle the heat. Just my uneducated guess.

RicardoD

993 coils are supposed to work
https://rennlist.com/forums/964-foru...ernatives.html

Not sure how you mount them into a 964, it's part number 993 602 071 01

sml

i bought these thinking they are the black ones .. but when they arrived they were silver. autoatlanta have some pretty bad reviews & they are definitely silver, so forget it.

go the 993 option ... if you have time to figure out a new mounting arrangement .. shouldn't be too hard for a mechanic.

Pak_37

Thanks for the additional replies. We're very disappointed with the reliability of these coils. We had no warning signs. No apparent symptoms. Just one morning it wouldnt start and when you're travelling the lack of reliability is disconcerting.

Does anyone have an opinion on whether its something in the car that could damage the coil or whether it's just likely bad product?

JasonAndreas

It could be old inventory working its way through the system. Has anybody priced these from Sunset Imports recently? The added cost OE vs. OEM might be worth the 2 year warranty from Porsche.

darth

How old and how many miles are on the other components (i.e. rotors, caps, spark plug wires and spark plugs)?

Pak_37

The rotors, caps and plugs were installed 500 miles after the coils. The rotors, caps and plugs were all replaced this spring and have approximately 5,000 miles on them. The mileage on the wires are unknown to us. We've put approx. 31,000 miles on them since we've owned the car and we don't know how much before. We have recently checked them for arcing and there was none.

darth

My advice would be to replace everything at one time. I've responded in past thread(s) the benefits of replacing everything at one time. Plug wires are kinda like oil (i.e. if you're able to shrink yourself down to the atomic level), after so many miles (i.e. at most 100,000 miles) or time (i.e. 10 years) whichever comes first, just replace them whether they look good or not. Unless you don't mind the possibility of being inconvienenced or spending the time/money throwing parts in piecemeal.

greg1990964

I agree about the wires, it is just hard to throw $500 bucks at something that doesn't even look bad. That being said, it is something I am leaning towards. I will be curious to see if my new Brazilian coils, cap and rotors and new coil wires improve my situation. It may simply be that I need a turbo..Haha.