MAP/Boost Bypass Tested and Operational

From: Bernd D. Ratsch (bernd@texas.net)
Date: Wed Nov 08 2000 - 20:24:44 EST


Ok...for all of you with blowers on your Daks...here's the parts list:

All of these parts can be found at AutoZone (or PepBoys)
1 - Vacu-tite #47356 Vacuum "T" - $1.49
1 - Vacu-tite #47334 Vacuum "F" - $1.49
2 - Borg Warner #EC601 Check Valve - $3.99/ea
1 - 10" 1/4" Vacuum Hose - $1.00
1 - 3/16" Vacuum Cap for the MAP Sensor Port ($.25)

Total cost: $12.25 + tax

(Or...you can pay $450+ to have your computer reprogrammed) ;)

Here's how you build it:

(1) Remove the MAP Sensor and plug the vacuum port on the TB (You don't have
to remove the connector)
(2) Flip the rubber adapter under the MAP around so that it faces away from
the TB
(3) Install the vacuum "F" (Long side) into the rubber adapter on the MAP
(4) Reinstall the MAP Sensor
(5) The outside connector on the "F" gets one of the check valves (Black
Side facing away from the "F") (You'll need a 2" piece of vacuum hose for
this)
(6) The inside connector on the "F" goes to the FMU vacuum line with a check
valve and a "T" (Black side of the check valve goes into the "T"). This is
where you'll use up the rest of your vacuum line.

Once this is done, fire up the truck and see if it stumbles or dies. If it
does, you've got one, or both, check valves in backwards. This is important
that you install them properly!

I'm working on a diagram/picture to make it easier to see how it's installed
so if you can't figure it out, just hang tight...i'm working on it.

The initial results are very promising and there's been no more stumbling,
surging, or any sorts of problems with part throttle (or even 3/4 throttle)
boost performance. Some of you may have felt this when driving around town
and hitting about 3psi of boost. What's happening is the MAP is registering
30.8" of vacuum due to the fact that it doesn't know what to do with boost.
I've checked my Dak (V6 Supercharged) and a '99 R/T (Supercharged) and they
both show this on both my Actron OBD-II Scanner and my OBD-II Cable (tied
into my laptop). Under WOT, the MAP is also registering 30.8" and we all
know that under WOT, it should be close to, if not, 0". I'm still taking
some readings to see if the TPS cares if the MAP is close to 0" under 3/4
throttle...but so far, there's been no problems at all.

Regards,

- Bernd



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