Barking sound on deceleration

[jeep haller]

I have an 04.5 LB7 with a Predator set on 2 and a turbo boost stick and every time I get on it and then start to back off I get a barking sound from under the hood. I believe it is from the EGR valve and I think if I remove the boost stick it would stop, but is there a way to fix it without removing it. I know Kennedy sells some kind of kit but I am not sure where the EGR valve is or what it looks like and not sure this is the problem.

[DmaxMaverick]

First off, you either have an 04.5, or an LB7. Not both. 04.5 began the LLY engine. Unless you have a California emissions truck, EGR means LLY, or later. CA smog started the EGR in 2002 LB7's.

Raising boost pressure does a couple things, aside of adding an ability to burn more fuel (more power). The increased pressure also increases the force against the EGR valve, and can cause it to "bark" once it opens (no pedal input). It could also be a traditional sense of "turbo bark", which happens after a period of high boost, when fueling is stopped (no pedal input), and the boost pressure in the intake is forced backward through the turbo. This is what "blow-off valves" are for, and common in competition applications, when higher boost pressures are used (they dump intake pressure before it blows back through the turbo compressor). More common on competition gasser turbo engines, as the throttle is more abrupt, and increases the opportunity for the blow-back.

If your "bark" is EGR related, blocking the EGR will eliminate the condition. It won't help if you are experiencing traditional turbo bark. Your condition could be either, or both. More likely EGR related, if you have EGR.

[Kennedy]

Blocking the EGR would be the way to cure this. Looking at what you have there is one thing I would like to point out. You are approaching $200 in "band aids" to fix weak tuning. Even with these band aids it will not be as good as a good tune doing it all. Yes I know I sell those band aids, but I just wanted to point out before you go any further that there is a much better way. Look in the Perf forum at mjammer's mpg report.

[jeep haller]

Thank both of you for your reply, yes I was looking at something else when I mis spoke on the LB7 I have an LLY engine.

Thanks, I will seek more info on the perf forum.

[jeep haller]

Kennedy,

Not sure what you mean by week tunning?

I have looked at your web site and the kit is 55.00 what other band aids are needed?

The tuning that is on the perf forum looks to be more complicated than I am wanting to get into. I could just pull off the boost stick and the barking will stop but I would like to keep it.

I have 4" exhaust, AEI air intake, EGT gauge and the predator with the boost stick, I had an edge with additude on it before the predator but it decided to stop working 1 month after the warentee ran out and they refused to replace it. It did the same barking sound with the edge so what makes this new tuner capable of curing this problem.

Sorry for all the questions but I am not on top of this stuff as much as some of you.