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Breaking up in boost

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Old 08-05-2018, 02:11 PM
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Default Breaking up in boost

car runs fine but breaks up as soon as the boost kicks in. Fuel pressure drops 2lbs@WOT.Checked the fuel filter , looks fine. Plugs? I guess what Im Asking is what are the main causes? Ly6/whipple2.9 running 93/water/meth. Plugs are TR7ix gapped @.42
Old 08-05-2018, 03:51 PM
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gap the plugs tighter and figure out why fuel pressure drops it should increase with boost not drop
Old 08-05-2018, 04:14 PM
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I ordered plugs . I’ll try swapping them out . If it don’t work, I will swap out fuel pump(Walbro 450) . The FPR is not boost referenced. Mast motor sports tuned it. They set the fuel pressure @65lbs . I think they control fuel with injector timing? What ever they do, it’s been working fine for 10-12k. Plugs and fuel pump been in about the same. Pretty sure it’s a modified ls9 tune.
Old 08-06-2018, 07:24 PM
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Is this a new problem or has it ever ran correctly ?

How much water/meth ?

42thou is on the large side for a boosted build unless it has extremely powerful coils.
Old 08-06-2018, 08:13 PM
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It’s been together running my fine since 2015. Im hoping I accidentally put 100% water in meth tank? Seems to be not getting fuel up top but pressure seems ok . If plugs were bad wouldn’t it run like **** all the time? I ordered new TR7ix what should I gap them at? I’m only running 13-14 lbs. 50/50 water meth progressive snow kit I think it’s the biggest nozzle they have , a 6?
I’ll look it up
Edit. it’s a number 6. 625 ml/min


Old 08-06-2018, 08:30 PM
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Certainly too much water and the engine will be less happy although it's a relatively small nozzle.

Any plug/performance issues are more likely to show under load than with no load....same as anything really.

Always be careful gapping precious metal tipped plugs, never touch the tips themselves, so gap carefully. I prefer the round wire type gauges over regular flat feeler blades.

I'd doubt you'd need to go as low as say 25thou, but it would do no harm either. Anywhere 25-30thou should be fine.
Old 08-07-2018, 08:43 AM
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I'd gap between .028 and .032... How much boost are you seeing?
Old 08-07-2018, 04:06 PM
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13-14 lbs
Old 08-07-2018, 04:22 PM
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.020-.022 gap
Old 08-10-2018, 01:04 PM
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Originally Posted by jimmyg
13-14 lbs
PD blower.... 13-14... I'd try .028 and see how she reacts.
Old 08-10-2018, 07:36 PM
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It was fine on the stock gap .42? For a year or so. I think the plugs are junk. They finally showed up in the mail, so I’ll put them in in the morn @.28 and see what’s up.




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