LLY: Popping at WOT.....?

[SSchmi5519]

I get a poppping when im at WOT, but not at other times or even at 3/4 throttle.

Its a popping sound that happens about twice a second.

Normally, when at WOT the exhaust hazes, but now when it does this popping thing, it puffs a little poof of black smoke at every pop.

(I can see it well with the stack out the back window.)

Fuel starvation? Timing?

Running Nick's race tune.

 

[McRat]

That's called bursting. Remove any harness boxes you have (if any). Many add timing even when you have them turned off.

If that doesn't do it, remove some timing at the affected RPM, or fuel pressure.

 

[sweetdiesel]

That's called bursting. Remove any harness boxes you have (if any). Many add timing even when you have them turned off.

If that doesn't do it, remove some timing at the affected RPM, or fuel pressure.

X2 That certainly sounds like a bursting condition

has it always done this? Is it possibly ECT related?

 

[SSchmi5519]

Nope, just with this new tune.

Ill talk to Nick.

 

[SSchmi5519]

Niiiiiiicholaaaaaasssssss.

(Rhymes with the Ricola commercial.)

 

[SSchmi5519]

Pat/sweetdiesel/everyone, could lack of fuel (lack of lift pump) cause bursting on a demanding tune? or is it just the timing?

 

[McRat]

Not that I've seen. Lack of a liftpump causes gentle laydown with no smoke, not sudden kill + smoke.

Bursting happens when the air in the cylinder is not hot enough to ignite the fuel. The piston starts to come up, the air gets hotter and hotter, and when it's almost to the top, the injector opens and sprays fuel into the superheated air. Normally the fuel burns as soon as it comes out of the nozzle, and it runs smooth. If the fuel doesn't ignite at first, it turns to a white explosive vapor and cools the air down. If it ignites as the piston continues upwards, it makes a "ping" sound, with poor combustion and black smoke. If it doesn't ignite at all, it comes out white if nothing ignites it first. As the rpm fall, the fueling amount drops, and the engine relights, "bursting". Bursting will often blow both black and white smoke depending on how severe. It will always blow some black when it relights because it wetted down the cylinder walls and exhaust system with fuel.

To stop bursting, anything that gets the air hotter before you spray fuel in will work (retarding timing), or you can spray the fuel in slower by reducing fuel pressure.

 

[vortecfcar]

LIIIIIIFFFT PUUUUUMMMP

The timing in this tune is no more aggressive than any other.

 

[sweetdiesel]

LIIIIIIFFFT PUUUUUMMMP

The timing in this tune is no more aggressive than any other.

WOW! I never would of thought Nick,I wasnt trying to say your tune was off
Just that I have personally experianced busting and those where the same symptoms

 

[McRat]

LIIIIIIFFFT PUUUUUMMMP

The timing in this tune is no more aggressive than any other.

I've driven a lot of LiLLY's with and without lift pump, and even had one fail at the dragstrip during a pass (Holley). So far, none them has popped and blown black smoke.

I've also driven a lot of trucks that have popped and blown black smoke too.

Not saying your wrong, or I'm right. Just posting based on the symptoms.

 

[vortecfcar]

I think part of the troubleshooting difficulty has to do with trying to describe/analyze symptoms without seeing it in action. I've heard the popping that Pat mentioned, and I've heard trucks 'break-up' from running out of fuel, low pressure, long pulse. I think the popping on this truck is late combustion gas when the exhaust valve opens, I don't think it's a ping like Pat described (on this truck at least). Of course I have the benefit of knowing the file on the ECM.

I sent him another tune geared toward a 'no -lift pump' combo. That should work in the meantime until he's able to get a pump on the truck.

Nick

No hard feelings Simon or Pat.. :hug:

We just do the best with the info we're given. That's all anybody can expect.

 

[McRat]

I think part of the troubleshooting difficulty has to do with trying to describe/analyze symptoms without seeing it in action. I've heard the popping that Pat mentioned, and I've heard trucks 'break-up' from running out of fuel, low pressure, long pulse. I think the popping on this truck is late combustion gas when the exhaust valve opens, I don't think it's a ping like Pat described (on this truck at least). Of course I have the benefit of knowing the file on the ECM.

I sent him another tune geared toward a 'no -lift pump' combo. That should work in the meantime until he's able to get a pump on the truck.

Nick

No hard feelings Simon or Pat.. :hug:

We just do the best with the info we're given. That's all anybody can expect.

The rattle or ping is the first indicator you are about to burst. But some bursting will not even give that warning, like too much nitrous will burst without pinging at first.

 

[SSchmi5519]

When the popping happens, the sound it all in the exhaust...theres no motor rattling noise to go with it. Just pop,pop,pop,pop...

No white smoke, and the truck continues to pull strong, with little baby poofs of black smoke at each pop.

I talked to Nick and im going to use his other tune until the AirDog gets here..then i'll load up the other tune again and post results.

Thanks guys!

 

[SSchmi5519]

I know this thread is old...but for what its worth:

After i got that lift pump put on, the tune ran well with no popping. Still all good to this day.