PR Coils with Motiv Flexfuel?

fmorelli

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Someone just told me that PR coils cannot be run in tandem with Motiv Flexfuel. Is anyone doing this? Is that correct? I've never heard of this. Thanks!
 

fmorelli

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Aug 11, 2017
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I figured this would get a pretty quick response. Anyone know?
 

proboner

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Sep 13, 2020
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I'm very interested in this answer as well. I'm currently running PR coils and just hooked up the Motiv Flex Fuel and am having issues. Under normal driving the ethanol content reads just fine at 32%, but at WOT and specifically when turbos are fully spooled the ethanol content jumps to 100% and stays there until I let off. I reached out to Motiv and they told me it was because of my PR coils and that the only way to fix it was to replace them with Delphi style coils.

I've since done some research and found a couple posts indicating they were having the same issue and that moving the power source for the flex fuel fixed it:
I Tried doing that today but unfortunately no luck, it actually made things even worse and numbers were all over the place. Also tried cleaning up the grounding post and a different ground location, but neither made a difference. It also seems like some people have no problem at all, running Motiv Flex Fuel (Not ReFlex) and PR coils.
 

martymil

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Sep 6, 2017
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Running reflex with PR coils now on our single turbo setup with no issues except we are chasing a persistent misfire on one cylinder but has nothing to do with reflex, otherwise everything works as it should but I'll double check the logs
 

proboner

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Sep 13, 2020
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Running reflex with PR coils now on our single turbo setup with no issues except we are chasing a persistent misfire on one cylinder but has nothing to do with reflex, otherwise everything works as it should but I'll double check the logs
I think this question is specific to the Flex Fuel box, not ReFlex, or at least that's my interest.
 

martymil

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Sep 6, 2017
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I was running it with motiv flex fuel before hand with no issues at all but switched to reflex due to needing more fuel via pi.

Dont know why your getting issues with it but our cars run eu tunes which are a little different As we dont run DTML.

Maybe time to run reflex if that helps.
 

zomski101

Private
Dec 28, 2019
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335i
Been running this setup for almost 2 years with no issues regarding pr coils and flex fuel module, probably the 2 most reliable aftermarket parts on my car.
 

zomski101

Private
Dec 28, 2019
47
8
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Ride
335i
I'm very interested in this answer as well. I'm currently running PR coils and just hooked up the Motiv Flex Fuel and am having issues. Under normal driving the ethanol content reads just fine at 32%, but at WOT and specifically when turbos are fully spooled the ethanol content jumps to 100% and stays there until I let off. I reached out to Motiv and they told me it was because of my PR coils and that the only way to fix it was to replace them with Delphi style coils.

I've since done some research and found a couple posts indicating they were having the same issue and that moving the power source for the flex fuel fixed it:
I Tried doing that today but unfortunately no luck, it actually made things even worse and numbers were all over the place. Also tried cleaning up the grounding post and a different ground location, but neither made a difference. It also seems like some people have no problem at all, running Motiv Flex Fuel (Not ReFlex) and PR coils.
I used to have that problem, sometimes it would jump up then back down sometimes it would stay at 100 during a pull. Then, my alternator randomly died after doing a 2nd gear launch while I was 60 miles away from home but I managed to drive it back. Bought an alternator off rockauto for like 200 bucks and it has been stable since.

 

proboner

Specialist
Sep 13, 2020
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I was running it with motiv flex fuel before hand with no issues at all but switched to reflex due to needing more fuel via pi.

Dont know why your getting issues with it but our cars run eu tunes which are a little different As we dont run DTML.

Maybe time to run reflex if that helps.
Been running this setup for almost 2 years with no issues regarding pr coils and flex fuel module, probably the 2 most reliable aftermarket parts on my car.
This is so curious to me. It sounds like people run this setup without issue. Why is Motiv telling me the reason I'm having problems is definitely the PR coils and the ONLY way to fix it is to replace them? I don't want to replace them, they have worked well for me, and I don't want to spend money on superfluous things.

I used to have that problem, sometimes it would jump up then back down sometimes it would stay at 100 during a pull. Then, my alternator randomly died after doing a 2nd gear launch while I was 60 miles away from home but I managed to drive it back. Bought an alternator off rockauto for like 200 bucks and it has been stable since.

Thanks for the suggestion. I think my case may be a bit different, as it doesn't fluctuate at all. It's very predictable... 32% ethanol while driving, idling, stopping, etc. Then it jumps to a stable 100% when at WOT and in boost. If I go WOT at low RPM in 3rd it won't peg 100% ethanol until the turbo is spooled.

Plus I only have 55k miles on the car, which seems low for the alternator going bad.
 

jzx_andy

Corporal
May 22, 2019
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Perth, Western Australia
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2008 E92 335i 6MT
This is so curious to me. It sounds like people run this setup without issue. Why is Motiv telling me the reason I'm having problems is definitely the PR coils and the ONLY way to fix it is to replace them? I don't want to replace them, they have worked well for me, and I don't want to spend money on superfluous things.

These questions are best answered by Motiv.

That said, I suspect there is an underlying electrical or grounding issue somewhere, perhaps worth testing the battery, and checking the alternator voltage regulator to see it still has life left in it. I don't see how coils can have any effect in this particular instance, provided the car has a healthy electrical system.
 

proboner

Specialist
Sep 13, 2020
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This was an issue before that was isolated to the relay in a secondary pump activation harness. The relay pack just needs to be replaced with a Diode Relay
I don't have a secondary pump. Glad you posted this here for posterity though, for anyone that does have a second LPFP and is having the same problem!

And to continue with the diagnosis, I tried wiring power and ground for the Flex Fuel, directly to the battery. Started off with just the ground to the battery, with no luck. Then tried ground and power directly to the battery, also no luck. Each time, once the turbos spooled, ethanol would pin to 100% and hold until I let off the gas.

I guess I may have to bite the bullet and try downgrading my PR coils to Eldor...
 

proboner

Specialist
Sep 13, 2020
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As an update to this, I replaced my PR Coils with stock style Eldors and the issue is now gone. So basically, YMMV. You may be able to get away with PR Coils or you may not... doesn't seem to be a method to the madness here.
 
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veiss335

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Apr 24, 2023
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Reroute the ethanol sensor harness as far as you can away from the coils.
I ran mine into where the strut rod brace goes under the windshield and drilled a hole in the firewall and dme box and routed the wire through the cowl. It eliminated my ethanol spikes.