Help me identify this sound

[pmesfun]

Hello,

Whenever I go WOT in second gear about 3 seconds after the is a loud pop sound coming from the engine. I took a video two days ago of what it sounds like. I assume it to be backfire because I drove last night and after the pop sound the engine was running really rough and today after checking every random thing I found the intake plenum(dog house) gasket blown out.

I put in a new Turbo Tweak chip last week with the old chip the CEL would come on until I restarted the engine. I have the fuel pressure set to 43 psi running 20 psi of boost and the was no knock when it happened. Any help is appreciated.

 

[Chuck Leeper]

Lean backfire...Doesn't have to register knock.
20#?? alky? If not, suggest you turn the boost down, b4 you drive over the crank, or just before you blow the head gaskets out.
Where's the fuel psi at 20#?
What are your Scanmaster readings?

 

[TURBOELKY]

Keep in mind a pretty simple rule of thumb I guess you can call it. For every 2 psi of boost, it equals 1 point of compression. If you're running 20psi of boost, that's 10 points of compression. So if your engine is say 8.5:1 plus 10:1, you're roughly at 18.5:1 CR. If you are runnin that on pump gas alone, that pop is going to be the sound of your wallet being sucked dry.

 

[278cikiller]

Sound's like you already hurt the motor.

 

[GNRick]

What's going on with your oil pressure gauge?

 

[pmesfun]

I'll turn it down to 16. Installing the power plate tomorrow. I'll post scanmaster readings then. The signal wire is not hooked up for the oil pressure gauge. I'm missing the plastic nut thing, not sure where to find it.

 

[Phoneguy]

Doesnt sound good.....Is there still a cat on the car ? sounds like a lot of back pressure before the backfire, like the engine is straining hard and you keep pushing it

Bryan

 

[TURBOELKY]

Doesnt sound good.....Is there still a cat on the car ? sounds like a lot of back pressure before the backfire, like the engine is straining hard and you keep pushing it

Bryan

I paid better attention to the sound and you are right. Sounds like it's building up before it pops.
Maybe someone stuck a banana in the tailpipe.

 

[pmesfun]

I got the car running again. I installed a power plate and loosened the actuator rod 4 turns, max boost I saw was a little under 16 psi. It doesn't have much of the back pressure you guys metioned anymore, feels more free revving. Although I still can't go WOT, it will backfire but it is very faint compared to the video.

Here are the scanmaster readings a minute after starting the engine.

02 Millivolts 370-400
AF 10
L8 44
Int 128
BL 128
CLT 71
ATS 58
rpm 1225
IAC 02
cc 104
MAL 23

I also noticed a weird noise either coming from the fuel pressure regulator or injector next to it. Is that normal? I plan to change the fuel filter and plugs today.

Thanks

 

[TURBOELKY]

Your 02 is way low, you should be up in the 700's. Is that a metallic rattling sound or a vacuume leak? You also have a sensor unplugged or missing with that engine code 23.

 

[TURBOELKY]

http://www.vortexbuicks-etc.com/Scantool_Readings.htm

Here is some reading. Very informational.

 

[626gn]

Take readings after the engine is warmed up.

 

[pmesfun]

Your 02 is way low, you should be up in the 700's. Is that a metallic rattling sound or a vacuume leak? You also have a sensor unplugged or missing with that engine code 23.

It sounds like a sucking noise from the fpr or injector next to it. If I shut off the fuel pump it will stop.

Here are the readings after the the engine is warmed up. I didn't drive it.

CLT 167
ATS 84
RPM 750
TPS .42
IAC 00
CC 254
MAL 00
02 Millivolts 578
AF 05
L8 35
BAT 13.9
INT 128
BL 137

I changed out the plugs, they didn't look bad.

I'm about 14 miles away from Jack Laswell, thinking it would be easier for him to take a look.

 

[TURBOELKY]

If you turn key on but engine not running is it making that sucking sound? Maybe you have a bad FPR and you're leaning out under boost.

 

[pmesfun]

Yes that is what I did, key on/engine off and if I shut off the fuel pump switch the noise goes away. It has a walbro 340 with the hotwire kit and 36 lb injectors(they are kinda old though).

 

[pmesfun]

If you turn key on but engine not running is it making that sucking sound? Maybe you have a bad FPR and you're leaning out under boost.

I believe I have a fuel delivery problem. While cruising, fuel pressure is around 40 psi, if I start to accelerate and build boost fuel pressure does not rise but the needle just shakes back and forth around 41 psi. I already plan to replace the filter, but is there a way to test if the fuel pressure regulator or fuel pump are working? I read on a thread to crack the flare nut on the fpr and if the fuel pump is good the pressure should rise to 100 psi?

Thanks

 

[TURBOELKY]

I'm not sure. I'll leave that for someone with experience doing that. I've never ran into any fuel issue, I never left it to chance. I replace fuel pump, filter, injectors and FPR on whatever I own it I'm not 100% positive they are in good working order. It's cheaper than a new engine.

 

[bison]

Intake valve not closing? Exhaust valve opening late? You can use any nut that's the correct thread on the oil pressure sender


Sent from my iPhone using Tapatalk

 

[gusszgs]

I'd be suspicious of that regulator. Going lean and popping. That sound is like it's leaking internally. Is it home made?
Your FP should instantly rise with boost.

 

[pmesfun]

It is a ATR fuel pressure regulator which is probably as old as me.