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Discussion Starter #1
I'm having a strange issue with my 2005 Elise. When driving over expansion joints in road or pothole the engine seem to shut off for like a have second, does not stall. I've done some checking and can't located problem. Does this sound like a MFRU???
 

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Yes, and ground from battery too. All grounds.
 

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Discussion Starter #4
Thanks for the advice. Drove again today and did same thing-like a cylinder dropping out just over a bump. Checked all mentioned and performed wiggle test with nothing. I've heard the MFRU will cause intermittent hard/no start since . Does it cause any other problems? They are cheap, I should just buy one.
 

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IIRC, there is an intermediate battery connection. Ck that too.

How clean are terminal & cables?
 

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Is it possible for the battery to have an internal short over rough roads? Stock battery or gel-cel?
 

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Discussion Starter #7
Thanks, will check other battery cables, it is a gel battery. I don't think it's the battery since lights don't flicker when this happens, seems like a fuel or ignition issue. I know the MFRU controls fuel. I did die on me twice today when coming to a stop and started right back up, no codes stored.
 

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I had a similar problem. I had larger injections installed. The splice was bad on one cylinder and I would get blip of power loss at full throttle going over a bump.
 

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also check the inertia switch. could be bad.
 

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Discussion Starter #10
All stock injectors. My second thought was to look at the inertia switch. I guess the only way to check is to tap it while running.
 

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Years ago I installed a radio in my car. It would go on and off over bumps. It was down to a loose connecting wire.
 

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All stock injectors. My second thought was to look at the inertia switch. I guess the only way to check is to tap it while running.
Better yet, unplug it and wire in a jumper wire. Check the junctions blocks though at the bottom of the firewall below the ECU and the ground near the ECU, too.
 

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Wiggle wires when the engine is running. Especially coil pack and injector wires/plugs.

I had a couple of coil wires break just before the plug. The harness was quite hard around there.
 

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My 06 did something similar but only with the AC on. Found a TSB from Lotus that the AC control module had a short and would reset the ECU. TSB said it only effected a few early 06 cars but thought it was worth a mention.
 
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Discussion Starter #15
Fixed it!! I ordered MFRU and Inertia switch. The inertia switch arrived first so I installed it. I drove the car for 4 days on the same road where I know exactly when it will happen and it has not happened at all since replacing the switch. The connectors were clean and don't know how this simple magnetic switch will cause the issue without tripping. I will replace the MFRU this weekend just because. Thanks everyone for your help!!
 
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