Under boost, loud pop!

[HRobertson1]

I have finally got my car back on the road with the help of Scott Atkinson. I snapped my stock crank in half last December and its been a whirlwind of parts and money since then. When I broke the crank it was under boost, between 10-15 pounds, and I heard a loud pop, the engine looses power for a sec, I let off the gas, and it just picks right back up. I was hoping since almost everything in the engine bay is new now, that issue would have dissappeared, but no. I took it out for its maiden journey around midnight last night, gave it about half throttle, and POP!, same thing again. I checked all of the IC hoses, all are still secure. Other than that one thing it seems to run awesome. I have a powerlogger I still need to install, but I have the scanmaster on and running, nothing looked funky. Is there anything that comes to mind that would cause that?

 

[Lil Truck]

I am not an expert yet but I am sure everyone will ask you the running conditions first, Engine temp, Air temp, how much Alky, fuel pressure check, AFR and O2 volts etc?

I had a Pop recently through the intake, the engine was cold and the air at 75 deg. I believe the alky at low temp was my problem. I have not had the problem since I made sure the car was fully warmed up.

 

[1QuickGN]

Maybe sounds like bad ignition coil,wires. Wrong spark plug wire on wrong plug. Check the basics.

 

[HRobertson1]

I will try to install the powerlogger tonight to get some numbers. Everything on/in the engine is new except the coil and crank sensor

 

[gnpoweredrail]

I have your cherry picker...lost your number call me

 

[SHADOWII]

Some suggestions, maybe raw fuel or alchy getting into the exh. system, by a leaky inj. or siphoning of alchy. Loose reluctor ring, crank sensor, etc.

 

[Scott Atk]

stop by and grab my coil pack / module, its an easy swap.

 

[nickygn23]

I had the same problem. It was my M.A.F. At least that what it sounds like. If you have a friend close that you could borrow M.a.f. Fixed my problem.

 

[highboostgn]

Do you have a wideband?

 

[HRobertson1]

No wideband. I got the powerlogger in, just need to install on the laptop. I hope to have some numbers up soon. After doing some thinking, I need to check the MAF and the translator (horsepower in a box). It was one of the first things I switched when I got the car, I remember opening it and having to flip switches around. I wonder if I did it right?

 

[Scott Atk]

ding,ding,ding

 

[highboostgn]

No wideband. I got the powerlogger in, just need to install on the laptop. I hope to have some numbers up soon. After doing some thinking, I need to check the MAF and the translator (horsepower in a box). It was one of the first things I switched when I got the car, I remember opening it and having to flip switches around. I wonder if I did it right?

Id check that first thing then

 

[HRobertson1]

Ok, Finally got the PL in, heres the file. You can see where the pop is the rpm goes from 5k to 1250then back to 4k, any help is appreciated

 

[gnpoweredrail]

did you try another coil and module??

 

[Chuck Leeper]

If I'm reading the log correctly:
Boost is 15psi
Rpm is 6025
tps is 2.44
Maf is 203 G/S

Looks fishy...

 

[Scott Atk]

can someone post up a screenshot? I can't figure it out

 

[Richard]

One of the worst backfires I ever had was because of a loose cam sensor. At wide open throttle, it moved and caused a back fire that sounded like a shot gun. Dented the up pipe and cracked the paint of the hood

 

[HRobertson1]

No I havnt tried that yet Burt, I will try to hunt one down. Scott I can bring the laptop over to see the file, or I can email it to you. I dont know how to take a snapshot.

 

[HRobertson1]

I got a new coil and module on its way. My chip was burned by Eric for 24lbs of boost, I am running about 12-15 until I can get this figured out. Would that have anything to do with anything? I have been doing a lot of reading but the PowerLogger is still confusing to me.

 

[gnpoweredrail]

if your only running half the boost you need to turn the fuel down....call me 702-683-9429