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What Causes an Overboost Condition?


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Spent the afternoon at the shop doing some data logging and changed my spark plugs. Added a can of seafoam to an almost full tank of fuel for the 60 mile ride home, for the injectors. About halfway home, my boost gauge was showing higher than normal for cruising speed. I give it some gas, staying in 5th gear and not WOT and the boost jumps to 11psi and the needle is flicking(right word). I back off but am curious. So I downshift to 4th and floor it, boost jumps to 16lbs and the check engine light starts blinking. I immediately move to the slow lane and continue home at 60mph, scared I broke something. The car is tuned for 9psi, and the needle has always been spot on until today.

Could clogged or damaged cats cause the overboost? Reason I ask that is, once I got off the freeway and lost the wind noise, the exhaust note sounds different.

Did the Seafoam fuck my car up?

What other things could cause the boost to go so high?

SMD Super Seller


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I doubt the seafoam messed your car up. But clogged cats for sure would cause you to boost higher then normal it's restricting your exhaust flow which means more boost will build in the engine. Whatever it may be I would get it checked out ASAP.

That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals.

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If you feel up to it, and don't directly sniff if but see if the exhaust has an eggish smell to it. Ive seen a few fords start to stink when the cats begin to plug up, my moms van with the 5.4 would stink pretty bad because my mom always drove it like a grandma and the cats got packed with carbon. Or take it for a drive and when you park, check for excessive heat coming off the converters.

Brandon

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I couldn't imagine the seafoam doing anything to the engine...especially if you just dumped it in the tank. The overboost is weird though. I could see if your cats are plugged up that your boost would increase but I don't see how it would all of a sudden start during a drive. Have you checked the CEL code?

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check blow off valve see if a setting got moved around

Could be stuck closed, ill check it out.

Doesn't explain the change in exhaust note though, unless there are two different problems that conveniently decided to arise at once. Wouldn't be all that surprised.

SMD Super Seller


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