Zener boost fooler kill low end??

[Dudenhymer]

I've seen some rumors floating around about the zener diode boost fooler setup robbing some of your low end power. Does anyone have any experience or proof of this? Can anyone explain how the mod would reduce low end power?

The zener should just be basically invisible to the system until the 4.7 volts is reached. What does everyone think?

[Dudenhymer]

Anybody know where this loss of low end power nonsense came from?

[harley1rocker]

cant say for sure if there is a loss of power,i mean,unless there is just a dramatic loss to were there is no boost,and just no guts or azz... the only way to really tell is #1 a dyno...#2 a good scanner. i have a mt2500 snap-on that reads all the sensors. not accurate on som things.but on most it is

[Dudenhymer]

I've wondered about how the A/F ratio can be correct at higher boost levels if you are truncating the MAP feedback to the ECM. For instance the mechanical solution of putting a valve or regulator inline to cut the feedback at 21-23 psi... Doesn't the ECM need to know how much boost pressure is being made in order to dump the correct amount of fuel? For example if you are acually making 28-29 psi and the ECM thinks you're only making 21-23. How does that work? Are MAP readings not as vital in a diesel engine vs. a gasser? Does a chip account for this missing information?

Thanks guys, still pretty new to diesels.

[Southpaw]

Without a fooler of some type your truck will defuel at higher boost psi. In stock applications your truck only makes about 23 or so psi IIRC.

With a chip (increased injection pressure, oil pressure and boost pressures), the truck will try to build higher than stock psi's. Once the psi gets over the factory set limit(I forget what it is, I think it is like 23 psi) it will start defueling. You'll lose boost pressure fuel and power.

With a boost fooler, it simply tells the PCM not to defuel. The injectors, HPO system, and the turbo will continue to deliver the parameters the chip is asking for.

As for the first question, I have never heard that theory that it will rob low end power. It makes no sense that it would

[dereku]

I have it and it works great. I see 40psi regularly and it never goes off

[Dudenhymer]

So does the MAP sensor feedback have any function on our diesels OTHER than over boost protection? Because if so, putting the zener in parallel there or installing a regulator/valve will fool more than just the overboost protection function.

[Southpaw]

That's all the boost fooler will affect is a de-fueling situation.

[zpd307]

i thought that i read anything over 17 psi, the computer sees it as max fuel.

[CT Performance, Inc.]

There is no defuel on the Super Duty trucks regardless of boost amount. There is an overboost code that reduces the cycle time of the IPR. The result is a slower gain in acceleration, not a reduction of fuel. The way to see if you are setting this would be to scan for the code. This is off the top of my head and it may be wrong, but I think it is a P0236 that is the code. You can set them on 94-97's, but it is a higher differential than the 99-03's. I run a MAP Pressure Relief Valve on my 95.

However, I've seen various configurations of MAP sensor alterations and I would warn that most are ill conceived. The majority of the pressure relief set ups I've seen blow off actual boost and do not isolate excess boost to the MAP side only, leaving the manifold pressure able to rise. The electric modifications don't allow MDFR (Mass Desired Fuel Rate) on the low end early enough since they mitigate the overall boost by a percentage.