intake plenum blew up

[Mtaghoe]

Hi everyone, This is my first post here tonight, I am hoping someone might be able to tell me if I may have bigger issues than I am seeing. I have a 96 Tahoe 5.7l, with 150,000 miles.
I have been fighting a p0300 code for the past few months, p0305 will appear about once every 2 weeks. I have already replaced my plugs, wires, cleaned my maf which cleared 2 other codes p0172 & p0175 but didn't help the hesitation. 3 days ago I had purchased a new distributor, pcv valve, egr, coolant temp sensor and was going to install them over the weekend.
Just the next day I was leaving work, turned the key and BOOM!. I mean it was like a shotgun went off under the hood type backfire and the rpms shot up. Than some smoke followed. Popped the hood and I saw small orange flames on the top back of the engine, panicked and ran for the fire extinguisher but by the time I got back it there was nothing. I spray one puff anyway in case something was burning I couldn't see. Since it was dark decided to wait and got a ride home.
The next day I popped the hood and see a piece of cracked plastic under the air silencer box and was able to pull a piece out (first pic). Knowing this was bad led me to do some searching online, decided to order a new plenum and lower intake gasket set, valve cover gaskets and fuel pressure regulator which arrived yesterday, but as i took apart the top of the motor i was able to see it the plenum was cracked into five pieces and most of the bolt holes had cracks around them. There is a strong gas odor from the pieces as i remove them. Pic 2 shows new vs old , and the white coating is from fire extinguisher.
I am assuming either the spider or the fuel pressure regulator was leaking fuel and it somehow backfired through the intake igniting the gas. My question is will replacing my intake manifold gaskets, spider (mpi) with regulator fix my issue or what else could have possibly been damaged from such an explosive force. Could a bad egr valve cause a spark to ignite the gas vapor and possibly be responsible for my p0300 code as well? I am just trying to eliminate the possibility that its a valve issue. Sorry for the long story but I am looking for some input
thanks

 

[rockenthebowtie]

Well if the fuel pressure regulator was leaking enough with a combination of a restricted injector (s) will cause a P0171 & P0175 fuel trim lean and rich and if the FPR was leaking enough its going to allow fuel vapors to escape through the throttle body plate and fester under ther hood while your working for the day and all it takes is a small spark leak through the ignition system to make it go BOOM !!

 

[lesterl]

Wow, sorry to hear that happened to you......

P0300 is Random Cylinder Missfire

P0305 is Cylinder 5 Missfire.

Perhaps what rockin was coming up with isnt too far off, you had a good leak and something like a plug wire to cyl 5 ignited it?

But it does look like it was blown out from the inside so maybe a real good backfire? Due to bad Cap on Distributor causing crossing of the spark durring an intake stroke even on Cyl 5 perhaps?

You said you did the Dist, how did the drive gear on the bottom look?

 

[rockenthebowtie]

Good points lester you stop seizing to come up with good suggestions

 

[lesterl]

seizing?

 

[rockenthebowtie]

Whatever.. you know what I mean.. you come up with some good points ok ? Lol

 

[lesterl]

Just wasnt shure what you meant with the term.....

 

[miuwu208]

Hi everyone, This is my first post here tonight, I am hoping someone might be able to tell me if I may have bigger issues than I am seeing. I have a 96 Tahoe 5.7l, with 150,000 miles.
I have been fighting a p0300 code for the past few months, p0305 will appear about once every 2 weeks. I have already replaced my plugs, wires, cleaned my maf which cleared 2 other codes p0172 & p0175 but didn't help the hesitation. 3 days ago I had purchased a new distributor, pcv valve, egr, coolant temp sensor and was going to install them over the weekend.
Just the next day I was leaving work, turned the key and BOOM!. I mean it was like a shotgun went off under the hood type backfire and the rpms shot up. Than some smoke followed. Popped the hood and I saw small orange flames on the top back of the engine, panicked and ran for the fire extinguisher but by the time I got back it there was nothing. I spray one puff anyway in case something was burning I couldn't see. Since it was dark decided to wait and got a ride home.
The next day I popped the hood and see a piece of cracked plastic under the air silencer box and was able to pull a piece out (first pic). Knowing this was bad led me to do some searching online, decided to order a new plenum and lower intake gasket set, valve cover gaskets and fuel pressure regulator which arrived yesterday, but as i took apart the top of the motor i was able to see it the plenum was cracked into five pieces and most of the bolt holes had cracks around them. There is a strong gas odor from the pieces as i remove them. Pic 2 shows new vs old , and the white coating is from fire extinguisher.
I am assuming either the spider or the fuel pressure regulator was leaking fuel and it somehow backfired through the intake igniting the gas. My question is will replacing my intake manifold gaskets, spider (mpi) with regulator fix my issue or what else could have possibly been damaged from such an explosive force. Could a bad egr valve cause a spark to ignite the gas vapor and possibly be responsible for my p0300 code as well? I am just trying to eliminate the possibility that its a valve issue. Sorry for the long story but I am looking for some input
thanks

I replaced my MAF sensor and it cleared up my codes.

 

[miuwu208]

INTAKE

Hi everyone, This is my first post here tonight, I am hoping someone might be able to tell me if I may have bigger issues than I am seeing. I have a 96 Tahoe 5.7l, with 150,000 miles.
I have been fighting a p0300 code for the past few months, p0305 will appear about once every 2 weeks. I have already replaced my plugs, wires, cleaned my maf which cleared 2 other codes p0172 & p0175 but didn't help the hesitation. 3 days ago I had purchased a new distributor, pcv valve, egr, coolant temp sensor and was going to install them over the weekend.
Just the next day I was leaving work, turned the key and BOOM!. I mean it was like a shotgun went off under the hood type backfire and the rpms shot up. Than some smoke followed. Popped the hood and I saw small orange flames on the top back of the engine, panicked and ran for the fire extinguisher but by the time I got back it there was nothing. I spray one puff anyway in case something was burning I couldn't see. Since it was dark decided to wait and got a ride home.
The next day I popped the hood and see a piece of cracked plastic under the air silencer box and was able to pull a piece out (first pic). Knowing this was bad led me to do some searching online, decided to order a new plenum and lower intake gasket set, valve cover gaskets and fuel pressure regulator which arrived yesterday, but as i took apart the top of the motor i was able to see it the plenum was cracked into five pieces and most of the bolt holes had cracks around them. There is a strong gas odor from the pieces as i remove them. Pic 2 shows new vs old , and the white coating is from fire extinguisher.
I am assuming either the spider or the fuel pressure regulator was leaking fuel and it somehow backfired through the intake igniting the gas. My question is will replacing my intake manifold gaskets, spider (mpi) with regulator fix my issue or what else could have possibly been damaged from such an explosive force. Could a bad egr valve cause a spark to ignite the gas vapor and possibly be responsible for my p0300 code as well? I am just trying to eliminate the possibility that its a valve issue. Sorry for the long story but I am looking for some input
thanks

Get a new MAF sensor it cleared my codes up.

 

[lesterl]

Did you see the pix in the first post?

 

[rockenthebowtie]

Hey lester im going to replace my MAF first if my upper intake blows up like that im sure it will clear it right up.. LMAO !!!

 

[lesterl]

That was my point, like WTF? Someone drinking while posting? ;-)

 

[rockenthebowtie]

Im not sure if you can blame that on drinking and if so I want some of that lol

 

[Mtaghoe]

Sorry for the delay in getting back here, but as of Mon I had every thing running again. By this point I have now replace my spider (mpi conversion), intake plenum & gaskets, plugs, wires, distributor,coolant sensor, o2 sensors, map sensor, fuel filter, and fixed all broken evap lines, pvc, cleaned egr & maf. Now it is idling smoother than it ever has. No codes have shown up yet but it was still bogging down when accelerating unless I floor it but still doesn't feel right.
I decided to take it back to the garage and I smelt a hint of fuel in the air. Popped the hood, reached behind to the fuel check valve. Now I barely even touched the thing and it sprayed fuel all over my finger. Now after searching to the ends of the internet to find the part number for this schrader valve I found it through another post but it came up with acdelco #12570619 Fuel Injection Pressure Regulator. That is what it is found under and doesn't come up anywhere if you search 1996.
So I replace the valve and lowe and behold its running like a dream now. I than fixed the small exhaust leak I had before the cat on the passenger side and its like a brand new truck now. I know I had other issues that presented themselves in an explosive way but for anyone else who has replaced their entire ignition and fuel system it might not hurt to replace this $22 valve. It also occurred to me that everyone keeps checking their fuel pressure but there is no way a fuel pressure gauge would ever pick up a bad schrader valve. I actually put my thumb over it after I primed the pump and took it off and some fuel came out after i released my thumb as well as air bubbles.