335i....strange surging feeling on the highway?

[IQraceworks]

I was driving home the other day on the highway...constant speed (75mph), on flat road. I started feeling a weird pulse, or split second lack of power from the motor....almost like a missfire. You could just barely feel it......it would do it about ever 3-4 seconds. It was almost like you just killed the ignition for a few milliseconds....just enough to feel it, but not really enough to affect anything. It did this for a few miles, and then I pulled over to plug my cable in so I could pull a log.

Got the cable hooked up, and MHD logging....got back on the highway, everything is normal again (crap!). I checked the log when I got home........everything looked fine. No faults, no codes.

Any idea what would cause something like that? A failing injector? Failing LPFP or HPFP? Missfire? Vanos issue?

No codes where saved, and the car has new plugs and coils as of a few months ago. I did a wide open throttle 2-3gr pull...and everything looked fine except my LPFP is starting to get weak.

Any ideas?

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[NoGuru]

It's your LPFP.
Might want to change the LPFP sensor while you are at it. I think they run about $50.

 

[IQraceworks]

I did get a chance to log it when I got back on the highway....was it was running fine, and the LPFP pressure was right around 70psi at cruise. Maybe when it was acting up and had that ignition cut out type bobble....the pump was starting to die?

I guess I will know as soon as I get that new Walbro 450 in next week. Not planning on driving the car until then.......

And thanks....I will get a sensor also.

 

[NoGuru]

It might have got too hot and started to shut down. I have also heard this about the EKP2.

Do you know what EKP you have? I have a spare I am getting ready to setup with Active cooling soon, I might be able to make you a Beta tester if you want? I already have it setup on my car but I was trying to improve on the design.

 

[IQraceworks]

Not sure what EKP I have....where is it located? I'm assuming it's got a number or rag on it?

 

[NoGuru]

Pull the passenger seat and then pull the corner cushion and it should be right there, it will say EKP2 or 3

 

[IQraceworks]

It might have got too hot and started to shut down. I have also heard this about the EKP2.

Do you know what EKP you have? I have a spare I am getting ready to setup with Active cooling soon, I might be able to make you a Beta tester if you want? I already have it setup on my car but I was trying to improve on the design.

Hopefully I will have some free time this weekend to mess with the car and find out with EKP I have. I'd love to test out the active cooling design you are developing. I'll let you know what I find out.