98.5 Auto with Quadzilla and adjustable Boost Elbow only getting 24 PSI of boost?

[Joey.G]

On my sons 98.5 Auto we added a Quadzilla and adjustable Boost Elbow but are only getting 24 PSI of boost with the screw all the way in, this is being checked with the Iquad gauges. The only other mods to the engine are a intake horn, S&B cold air intake, Fleece intake Lift pump and a 4 inch exhaust with no muffler. I have not tapped the VP yet but I do have a stealth cover coming for it. Just looking for some thoughts.


Thanks

 

[NIsaacs]

Sounds about right. You will need more fuel to get more boost. Since you have a boost elbow, I assume your turbo is HX35?

 

[petersonj]

A couple of things come to mind.

Are you getting black smoke while under the 24 psi boost? If not, the Quadzilla may not be supplying enough fuel. Try giving it more fuel.

You could try disconnecting the boost elbow temporarily. Cap off the supply and leave the wastegate side open. Give it a test drive.

If none of this changes anything, it is possible that the wastegate may be not be fully closing.

When I had the OEM injectors with a Smarty S03 mild tune, I was easily able to attain 30 psi boost by 1800 rpm.

@NIsaacs , did the 98.5 automatic transmissin truck come with an HY35, or did that happen a couple of years later?

- John

 

[Joey.G]

So will tapping the VP help with that, I would like to try and get at least 30 LB , The turbo has the elbow in the front. Can I pinch off the line going to the waste gate to try it? I have not adjusted anything on the Quad, plugged it in and selected 3 and 4 to try , I believe it is a HX35.

 

[Chief USA]

You should probably be talking to Mopar1973Man. This area is his forte. I am sure Mike can help you with this and more.

https://mopar1973man.com/forum/174-quadzilla-power/

 

[petersonj]

You should easily attain 30 psi without tapping the VP44. I have no experience with the Quadzilla, but others that do have experience recommend to make small changes and then test drive. The Quadzilla is not an easy tuner use if you are not familiar with its operation.

I wouldn't pinch off the boost elbow hose. Besides the possibility of damaging the hose, you may unknowingly trap air pressure on the wastgate side.

Something I recall from Quadzilla users is that boost pressure is not accurate under all driving conditions. You may want to temporarily install a mechanical gauge.

And, do what @Chief USA suggests.

- John

 

[Joey.G]

Okay so its better to pull it off the waste gate side and plug the hose? Leave waste gate open? I am new to the diesel world and trying to figure it all out.

 

[petersonj]

Yes.

 

[NIsaacs]

@NIsaacs , did the 98.5 automatic transmissin truck come with an HY35, or did that happen a couple of years later?

- John

Thats why the question mark, I am not sure. I think the HY35 has a mechanical boost adjustment, so I figured if he had a boost elbow, it would be an HX.

 

[NIsaacs]

You should probably be talking to Mopar1973Man. This area is his forte. I am sure Mike can help you with this and more.

https://mopar1973man.com/forum/174-quadzilla-power/

Keep in mind, he has a $100 price tag for a subscription, I had to drop out.

 

[Joey.G]

The truck does not smoke, When my son gets home I'll bring the I quad inside and call Support, to go over some of the settings, he showed me something that says max boost 24 LB, so maybe I need to adjust something.

 

[Mikey-KE7LBB]

If it's reading boost via the OBDII, the numbers won't be accurate at all. You need to use a separate gauge since boost fooling is skewing the data from the MAP sensor.

 

[Joey.G]

I believe it reads off the Map.

 

[petersonj]

I believe it reads off the Map.

I also believe this is true, but I also believe that the MAP sensor has limitations and is only good for stock fueling and not for reading a wide range of boost pressure.

Anytime the value of boost pressure is questioned , the use of a mechanical test gauge is the best solution.

- John

 

[Joey.G]

Is there a good write up and a suggestion and a mechanical gauge? Even if i hook it up temporary to get a feel for how the digital one reads. If I am over boosting the truck at the moment is that bad?