added EMI's, mufflers and new plugs and I'm slower!!
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added EMI's, mufflers and new plugs and I'm slower!!
Ok this sucks. my boat is a 2000 Nordic 28 Heat. To my stock 2000 502 mpi I added EMI mainfolds with thier aluminum risers, Zoomers Mufflers and changed the plugs and I lost 400 rpm and 5 mph!!!! AAAAAARRRRRRGGGGGGG! Same lake, same temp, same prop, same weight (actually lighter this time). Any one have any ideas? Bad winter storage gas - I used stabilizer. The boat ran well, fired right up but had no pull above 4000rpm. Also that sucking air sound went away at 4000 rpm as well not sure if that is significant. seems to have a stumble at fast idle 1000-1200 rpm. Plugs are the NGK BR6FS recomended by Merc. gapped to 040 - all the wires were plugged in well. I didn't have tools with me so didn't pull any plugs. I didn't really expect to gain much with the exhaust but I sure didn't think I'd be loseing anything. Last year I was 61mph @ 4900, today I was 56mph @ 4500. I'd love to hear suggestions / idea's.
Last edited by Kokopelli; 04-19-2006 at 08:16 PM.
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Re: added EMI's, mufflers and new plugs and I'm slower!!
If I were you I would start by changing the plugs again. Seems like you might be dropping a cylinder at high rpms. The higher the cylinder pressure the harder it is on the ignition system.
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Re: added EMI's, mufflers and new plugs and I'm slower!!
Did you have mufflers before last year when you ran 61 mph? Can you easily remove them now for a test run?
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Re: added EMI's, mufflers and new plugs and I'm slower!!
Originally Posted by checkmate454mag
Did you have mufflers before last year when you ran 61 mph? Can you easily remove them now for a test run?
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Re: added EMI's, mufflers and new plugs and I'm slower!!
Originally Posted by 1BIGJIM
This my sound off the wall but check to make sure all the wires are hooked up. I have seen this before and you drop about 400 RPMs.
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Re: added EMI's, mufflers and new plugs and I'm slower!!
Originally Posted by TRICK
There's a problem other than the headers. Keep looking.
Fred
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Yeah Fred I tend to agree with you. I can't imagine adding a freeer flowing exhaust and a tip rated for big HP would be the cause. It seems like its got to be either fuel or spark but I'm not sure how to test.
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Re: added EMI's, mufflers and new plugs and I'm slower!!
Its very easy and common to cross #5 and #7 spark plug wires!The engine will almost run normal except at high rpms under a load(almost)!This also could be your slight stumble!
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Re: added EMI's, mufflers and new plugs and I'm slower!!
Originally Posted by JJONES
Its very easy and common to cross #5 and #7 spark plug wires!The engine will almost run normal except at high rpms under a load(almost)!This also could be your slight stumble!
Last edited by Kokopelli; 04-19-2006 at 11:04 PM.