iQuad Boost Readings Lower than Boost Gauge

[6cyl$$pit]

Just curious if anyone has experienced this before. I recently installed a Adrenaline with iQuad on my truck. When monitoring the boost reading from the iQuad on my phone it reads about 3psi lower than my other boost gauge. I have a 0-60 Autometer elite, its not a junk gauge and has never been over pressurized since my truck is mostly stock so I would expect it to be accurate. Could this be a conversion thing with how the Iquad produces its boost number or a sign of a failing MAP sensor? Truck runs great no weird issues I have noticed just curious since if it is low all my fueling will be thrown down 3psi levels.

Thanks 

[Mopar1973Man]

Known problem mine is the same way. I'm also running expensive ISSPro EV2 boost gauge.

[6cyl$$pit]

Interesting, I assume the root cause ins't known? Is the quad is fueling based on this? Thanks for the info it was bugging me. 

[bcbigfoot]

Mine is this way as well at low boost pressures Autometer boost gauge reads 2 to 3 psi and the Quad shows 0 psi.  By 25 psi both gauges read the same. 

2 minutes ago, 6cyl$$pit said:

Interesting, I assume the root cause ins't known? Is the quad is fueling based on this? Thanks for the info it was bugging me. 

 

The Quad spokesman has explained why this is, in the Quad forum of this site about 2 months ago,  I can't recall the reasons off hand, I believe it had to do with ECM, or factory boost sensor, inaccuracies. 

[Me78569]

The quad is reading what the ecm is seeing until 16 psi then it starts to add on top of it.   

 

late trucks appear to have this issue more so than early trucks, but I have only ever been able to chalk this up to odd ECM behavoir. 

 

as long as the reading is stable and not jumping you will not see an issue.  

[6cyl$$pit]

I have a 98.5. Reading is stable, so as you said truck runs fine I was just curious, thanks for the info guys.

[Me78569]

Yep don't worry about it.  You might have a aging Map sensor causing the issue.  Early trucks pass a KPA value directly, which is easy to read, late trucks have a weird offset that I dont need to bored you with explaining.

[Cummins4life]

So I have the same problem in my truck except that the reading is off by 10 psi I’ve tried two different boost gauges and three map sensors and they are all off  I’m reading my boost off the horn. I’m going to get another sensor and higher quality boost gauge to tey and see if that’s the problem. Were would I check readings on the wiring? 

[Me78569]

10 psi offset sounds like the difference between a early and late gen truck map reading.  Inside the box what is the jumper setting set to ?

[Cummins4life]

You will have to explain to me what you mean by inside the box what is the jumper  setting set to? I’m having a brain fart haha

[Me78569]

Look at the quadzilla tips and tricks article in the articles section.  It has pictures

[Cummins4life]

So I didn’t check the jumper on the box but I did hook a scan up to the obd and the computer is reading 36psi at wot and the gauge is reading 44psi so my computer is what’s off the sensor is reading good the tps is reading good all the ohms check out there’s no brakes in the wires took the truck into a shop had them check the computer over and reflashed and they said everything was good but it’s still reading 7 to 8 psi off. what could cause this bad computer? A non ho computer (wrong computer was put on it?)

[Me78569]

9 hours ago, Cummins4life said:

So I didn’t check the jumper on the box but I did hook a scan up to the obd and the computer is reading 36psi at wot and the gauge is reading 44psi so my computer is what’s off the sensor is reading good the tps is reading good all the ohms check out there’s no brakes in the wires took the truck into a shop had them check the computer over and reflashed and they said everything was good but it’s still reading 7 to 8 psi off. what could cause this bad computer? A non ho computer (wrong computer was put on it?)

please check the jumper on the box.

FYI it is impossible for the ecm to see 36 psi at wot, that boost fooling curciut will not allow it.  

Edited October 23, 2018 by Me78569

[Cummins4life]

4 hours ago, Me78569 said:

please check the jumper on the box.

FYI it is impossible for the ecm to see 36 psi at wot, that boost fooling curciut will not allow it.  

So the jumper is not in place so I put it in place.  Update installing the jumper didn’t not work when I build 35 psi the quad is only showing 5 now

Edited October 23, 2018 by Cummins4life

[Me78569]

jumper remove = 98-00 jjumper installed = 01/02    

 

If it was removed when you checked it is setup right.  

 

 

edit;

 

Was your ecm or motor ever swapped?  the obd reading 36 psi tells me your code reader isn't reading boost correct.  With the quad plugged in you should only ever see ~16psi from the ecm due to boost fooling.  

[Cummins4life]

25 minutes ago, Me78569 said:

jumper remove = 98-00 jjumper installed = 01/02    

 

If it was removed when you checked it is setup right.  

 

 

edit;

 

Was your ecm or motor ever swapped?  the obd reading 36 psi tells me your code reader isn't reading boost correct.  With the quad plugged in you should only ever see ~16psi from the ecm due to boost fooling.  

Yes it was removed so I installed it because after reading the artical it said some of the older ones needed jumped so I was just checking it so I’ll swap it back. As far as I know the engine was never swapped I’ll double check with a snap-on scanner for sure. Should a manual  gauge read higher than the quad or the ecm?

[Me78569]

1 minute ago, Cummins4life said:

Should a manual  gauge read higher than the quad or the ecm?

that is impossible to answer.  The mech gauge will be more accurate, generally, but one may be higher or lower than the other.  

[Cummins4life]

12 minutes ago, Me78569 said:

that is impossible to answer.  The mech gauge will be more accurate, generally, but one may be higher or lower than the other.  

So how much of a difference tho will 7-10 difference make and with it being that much will it result in damaging something?

[Me78569]

no issue.   

[Mopar1973Man]

I don't rely on the Quadzilla for gauges. This is why I like going headless. Boost (varies as boost climbs), pyrometer (+50*F to my ISSPro EV2 gauge) or vehicles speed (-1 MPH always compared to GPS). In my truck, all 3 of these gauges are off.