Attention: TDR Forum Junkies Yesterday I stacked my Dr. P 100hp fuel pressure box with my TST. Before, smoked like a locomotive, power surged on higher settings, and egt's were through the roof. Trapped as high as 1650'ish on my digital X-monitor--pre-turbo. 7hp/4tq max practical.
Now, can run on 9/9 no surge, also raced a "Bimmer" M-3 or M-Something today on 7/4--max EGT trapped was 1560'ish. Max boost, 32. 8. Needless to say at the next stop light the kid picked up his jaw to muster a congratulatory "unbelievable!"
Think I have a good hypothesis:
Pressure box and TST both plug into the MAP sensor. Isn't MAP an acronym for Manifold(intake) Atmosheric Pressure? If so, then that sensor tells the OEM ECM how much turbo boost if present at intake. So my Dr. P pressure box, and also the TST intercept the MAP sensor signal to lower the numerical value so you don't throw an overboost code. Makes sense. Both box's, on their own, will tell the computer (ECM), via being placed between stock MAP sensor and stock MAP sensor harness, lower turbo boost than actuallity. So if your making 32 lbs. of turbo boost with either box, the MAP output side of the box which plugs into the stock MAP harness will tell the ECM you only have 22 lbs. (or whatever, just a number to make a point), . . . everything's fine, keep fueling, no codes. That, I believe, is what manufacturer's refer to as "boost fooling". Otherwise the ECM will defuel, logically.
So both boxes will lower the actual boost # it sees before presenting it to the stock ECM via the MAP sensor harness.
Now, both boxes require map input, so I hooked the pressure box up to the actual MAP sensor itself first, then plugged the output of the pressure box into the "MAP sensor" in receptacle on my TST, then TST "MAP out" plugged into the OEM MAP wire harness.
So here's my guess: MAP sensor reads 32 lbs. boost, Dr. P pressure box intercepts and changes that number to 22 lbs. (or whatever) to make it more presentable to the computer. Only it's not going into the ECM, it's going into the TST. Now the TST sees this lower boost number so it doesn't fuel as heavily (Mark told me his box fuels proportional to boost, more boost=more fuel added). Then of course the TST will lower the numer to make it presentable as well, doesn't know the number has already been washed by the pressure box.
Now I dyno'd at 413 hp a long time ago. About 150 hp over stock, I imagine. Ran that for awhile, so have an instinct of what a "150 hp" feels like. My TST alone feels as fast, or faster on 7hp/4tq oppesed to my old "413/835" setup. A few people have said TST's ratings are on the convervative side. Now that I've added a pressure box, on setting 7/4 it's more powerful than anything yet. Whole truck shuddered today as the torque converter locked up.
Wonder if I swap the order of the MAP sensor plugs, so the TST sees the "actual" high boost and fuels more . . .
Will try tomorrow . . .
Now, can run on 9/9 no surge, also raced a "Bimmer" M-3 or M-Something today on 7/4--max EGT trapped was 1560'ish. Max boost, 32. 8. Needless to say at the next stop light the kid picked up his jaw to muster a congratulatory "unbelievable!"
Think I have a good hypothesis:
Pressure box and TST both plug into the MAP sensor. Isn't MAP an acronym for Manifold(intake) Atmosheric Pressure? If so, then that sensor tells the OEM ECM how much turbo boost if present at intake. So my Dr. P pressure box, and also the TST intercept the MAP sensor signal to lower the numerical value so you don't throw an overboost code. Makes sense. Both box's, on their own, will tell the computer (ECM), via being placed between stock MAP sensor and stock MAP sensor harness, lower turbo boost than actuallity. So if your making 32 lbs. of turbo boost with either box, the MAP output side of the box which plugs into the stock MAP harness will tell the ECM you only have 22 lbs. (or whatever, just a number to make a point), . . . everything's fine, keep fueling, no codes. That, I believe, is what manufacturer's refer to as "boost fooling". Otherwise the ECM will defuel, logically.
So both boxes will lower the actual boost # it sees before presenting it to the stock ECM via the MAP sensor harness.
Now, both boxes require map input, so I hooked the pressure box up to the actual MAP sensor itself first, then plugged the output of the pressure box into the "MAP sensor" in receptacle on my TST, then TST "MAP out" plugged into the OEM MAP wire harness.
So here's my guess: MAP sensor reads 32 lbs. boost, Dr. P pressure box intercepts and changes that number to 22 lbs. (or whatever) to make it more presentable to the computer. Only it's not going into the ECM, it's going into the TST. Now the TST sees this lower boost number so it doesn't fuel as heavily (Mark told me his box fuels proportional to boost, more boost=more fuel added). Then of course the TST will lower the numer to make it presentable as well, doesn't know the number has already been washed by the pressure box.
Now I dyno'd at 413 hp a long time ago. About 150 hp over stock, I imagine. Ran that for awhile, so have an instinct of what a "150 hp" feels like. My TST alone feels as fast, or faster on 7hp/4tq oppesed to my old "413/835" setup. A few people have said TST's ratings are on the convervative side. Now that I've added a pressure box, on setting 7/4 it's more powerful than anything yet. Whole truck shuddered today as the torque converter locked up.
Wonder if I swap the order of the MAP sensor plugs, so the TST sees the "actual" high boost and fuels more . . .
Will try tomorrow . . .
