TMAP relocation?

veer90

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Nov 16, 2016
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Possibly a dumb question. Has anyone relocated the TMAP sensor from the charge pipe to the intake manifold? Will the DME freak out when it no longer sees pressure spikes when you let off the throttle?

Two reasons I ask:
  • More accurate manifold pressure readings for PI controllers post-TB
  • I have a 3.5 bar which in theory is good for up to 36 psi. I'm running ~29 psi currently and I've seen shift spikes up to 33-34 psi and maxing out the TMAP will put you in limp mode.
 

doublespaces

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Oct 18, 2016
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I suppose I'd have to question the ROI on doing something like this. It would seem to me that it would be better to just wait for the 4/5 bar sensors to get figured out, though I can't remember what the issue is there. I'm pretty sure I read that @MOTIV Motorsport has it figured out. If its just to squeak out an extra psi or added safety, not sure it would be worth the hassle. Also I think some of the things we think we know about PI control will be changing in the next few months.
 
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JBacon335

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good question. I wonder how it would do with seeing vacuum, since it's usually just positive pressure in the CP. that might freak out the DME as well
 
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jyamona

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The car will not run :) Without getting too deep, all of the DME modeling is centered around the 2x map sensors setup just the way they are.

That said, I have recommended many times that people running PI should get an external 3.5 bar like an AEM (which can be plumbed with a vac line), off of the intake manifold, and use that signal to go to the AIC. This will prevent it fueling 30+ psi, when in reality it is just spike from throttle closure.
 

LamboLover

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Why can you not rescale the inlet manifold sensor Jake? Is that because you lazy ass N54 guys are missing something ;) ?
 

jyamona

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Why can you not rescale the inlet manifold sensor Jake? Is that because you lazy ass N54 guys are missing something ;) ?

Haha, always a possibility. But from what I've seen in my analysis is that it mainly uses the sensor in the intake manifold for vacuum and low load, and needs the fine resolution since there is no MAF. The intake mani sensor is a 1.5bar for this purpose. It does some calibration checks before the engine starts too. Once it's ceiling is exceeded (or TMAP sees pressure > ambient, not positive), it uses the TMAP sensor directly (with mean rolling avg for smoothing), logged directly as boost mean. It then uses the intake manifold filling model, mass flow over the throttle, etc, to calculate boost pressure in the intake manifold. I'd be happy to brainstorm and toss around some ideas around on chat later :)