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3800 Exploding Plenum?


Senor PuffPuff

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I was just watching some random videos on youtube and came across this one...

 

Why did this plenum explode? I read one of the comments on there about the exploding intake being due to a defect in the fuel system, and I was thinking that when I changed my fuel sender unit, even with the car off the fuel pressure was super high. Even relieving the pressure through the valve on the fuel rail didn't relieve the pressure, it would just keep building up.

 

Is this something I can fix? I was at the junkyard the other day and saw a lot of 3800 GP's whose engine's caught fire, and I'm not looking to have my car join them...

 

I haven't been able to find much on google, mainly just stuff about the other issue with oil leaking on the exhaust manifold shows up.

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You carry your 3800II powered car to the dealership and have them reflash the PCM with all the latest updates.

One of those updates is supposed to prevent the upper plastic intake from exploding. The plastic motor cover is also a scatter shield so don’t remove it.

 

The problem is if an old injector leaks fuel into the lower intake and you start the car the waste spark ignition system can ignite that fuel and cause an explosion.

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backfire + plastic intake = TSHHTF.

 

the early northstars, i seem to remember having plastic intakes, but they have a valve that opens up when they have positive pressure in the intake(preventing the backfire from destroying the plenum). sometimes, if they open up, they don't want to seal again, causing a vacuum leak. i seem to remember reading a TSB about it.

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Well, I've got to take my car in to GM one day soon and find out if they've fixed any of the recalls for my car, because I know they didn't add the redesigned spark plug boots, so I would imagine nothing else was done either.

 

There's no mileage/age limit on recalls is there? Someone I know was saying that after 200,000km you can't have the recalls fixed, but I can't see that being the case when recalls are usually dangerous.

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Wierd,leaking injectors were a common issue on Fords when I was at the dealership.

Even had a "special tool" kit given to us by ford to do a leakdown test on them,I still have it and use it to check leaky injectors.

 

They generally would present with a CEL (P0316,P030x) and maybe a misfire at idle.

The injector leaks after shutdown and will drain the rail into the cylinder,causing a misfire on startup on the affected cylinder.

This was mainly on the V8 mod motors (4.6 sohc/dohc,5.4 sohc/dohc/3v,6.8 sohc) of which the cars have plastic plenums (crown vic,mustang,lincoln).

 

Never heard of any of them blowing up though.

I have had issue with them melting due to bad cats however.

The cat would raise EGT's enough so that when the EGR opened it would melt holes in the plenum directly across from the egr pipe.

This however was mainly on V6's(3.0 ohv,dohc) though all fords it seemed had an issue burning out the plastic pipes/nipples for the DPFE (differential pressure feedback exhaust sensor,what tells the computer egr flow rate).

 

Sounds interesting though,blowing apart a 3800 intake.

I wonder how many GT plenums have been blown apart by N20.

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ALSO and I've seen this with my own eyes. Those who spray carb cleaner or brake parts cleaner to get it to bust off. Well on the inside of that plastic intake is a special coating. It could happen after the first time or it could take a few times, but it will eat away that coating and explode. My boss and another guy was trying to get one to start or checking for leaks, well the intake was leaking, the other guy was checking with carb cleaneR. My boss said "hey you can't do that to these..." BOOM.

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