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Discussion Starter · #1 ·
I have 1991 Turbo
I have a turbo smart boost controller installed and am boosting at 16lbs
the boost controller displays the amount of boost but the factory boost gauge does not work
is there a way to have both working at same time?
its annoying me that the needle on the factory boost gauge doesnt move anymore
took it to a shop and they say its one or the other
 

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What did you do to install the boost controller? If you have it set to 16psi and it's a GEN2 then you've disconnected the MAP sensor. The MAP sensor is what drives the factory boost gauge.
 

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And to add to GDII's point - if you aren't seeing any fuel cut (bc the pressure sensor is disconnected) then you don't really have any fail safe in an overboost condition
 

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Discussion Starter · #4 · (Edited)
it was installed when i did the swap so i dont know
the guys at prime mr2 did the swap for me
i have a gen 4 swap done to it
i know it has fuel cut cause it happened to me before in the winter when it was really cold outside and i was driving like an idiot when i first got the car back after the swap
 

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You would need to reinstall a gen2 map sensor and run the signal wire to the stock boost gauge to get it to work. The shop is wrong it's not one or the other.

If you just want some activity out of it you might get by sending the gen4 map sensor signal to it but it is different.

The sensors work by outputting a certain voltage based on how much boost or vacuum it is reading. Gen2 sensors are on a different voltage scale than the gen4 ones.
 

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One could argue that the stock boost gauge never really "worked" to begin with...
 

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Discussion Starter · #7 ·
You would need to reinstall a gen2 map sensor and run the signal wire to the stock boost gauge to get it to work. The shop is wrong it's not one or the other.

If you just want some activity out of it you might get by sending the gen4 map sensor signal to it but it is different.

The sensors work by outputting a certain voltage based on how much boost or vacuum it is reading. Gen2 sensors are on a different voltage scale than the gen4 ones.
so i need to get a gen2 map sensor and take out the gen4?
 

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so i need to get a gen2 map sensor and take out the gen4?
no, you absolutly need the gen4 map sensor to run the gen4 engine. You would need to add an additional gen2 map sensor that would do nothing except run the boost gauge.

But the point is, why? The factory boost gauge is beyond worthless.
 
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I found a chart that should explain the differences better than I could explain.

Rectangle Slope Plot Font Parallel
 

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I found a chart that should explain the differences better than I could explain.

View attachment 77075
That might be the GEN2 vs GEN3 MAP sensor. The GEN4 is different again.

But quite right. GEN4 MAP sensor is needed to run the engine. And yes the stock gauge does nothing useful and is very delayed vs a real gauge with actual numbers.
 

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Discussion Starter · #11 ·
It annoying that it just doesn't move like a limp **** just sitting there. Just want everything to work. I'm just a little ocd I guess
 

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It annoying that it just doesn't move like a limp **** just sitting there. Just want everything to work. I'm just a little ocd I guess
Get one of the 45mm aftermarket gauges that can be retrofitted into the cluster. Done right it looks 99% OEM, and actually works and provides useful information.
 

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It annoying that it just doesn't move like a limp **** just sitting there. Just want everything to work. I'm just a little ocd I guess
If you really really want it to work there is a bit of work involved. But it's a useless gauge that tells you nothing. At 5psi boost it still reads vacuum.

Essentially you need the GEN2 3SGTE MAP sensor, a vacuum reference hose, a 5V power supply from the GEN4 ECU, a ground to the engine, a signal wire to the correct pin on EA1 plug in the trunk and done.

Sounds simple if you know the wiring and way it work but if you want to do it cleanly you've got to think about it and also understand your ECU and how to wire it up safely.
 

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Discussion Starter · #14 ·
Thanks everyone for the response. I think I'm gonna go the 45mm route. Trying to find one that is lid up red as I just changed all the backlight to red
 
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