CSL MAP Sensor Function

[Slideways]

Recently, I have been reading and watching a few videos on how modern engine management systems work and one topic that came up was TPS and MAP tuning for ITB setups. I remember that there was a thread on M3F about the CSL MAP sensor, but I cannot find it in the google cache.

I'd like to understand more about the function of the CSL MAP sensor. I found on the E9XM S65 aftersales manual that the MAP sensor has two purposes: "ensure emergency operation in the event of TPS failure and used for plausibility checks in filling and load in normal operation." This goes into a bit more detail than the CSL aftersales manual which leaves out the part about plausibility checks in filling and load. What does it mean by plausibility checks in filling and load and how would an MSS54HP CSL setup run in limp mode during a TPS failure without a MAP sensor? I believe SliM3 and Olza had some detailed info on the MAP sensor operation in the old thread..

[terra]

Olza had some good information which I really wish I saved now. From the gist of what I remember, the TPS is the primary, MAP and EGT sensors are used to create correction factors of sorts.

MAP sensor can also be used to guesstimate throttle position in the event of total TPS failure (MAF is used for that purpose in normal M3s)

[Slideways]

Olza had some good information which I really wish I saved now. From the gist of what I remember, the TPS is the primary, MAP and EGT sensors are used to create correction factors of sorts.

MAP sensor can also be used to guesstimate throttle position in the event of total TPS failure (MAF is used for that purpose in normal M3s)

Yeah, I periodically looked at those old tuning threads trying to make sense of it all. Any chance liam821 was able to save the entire Comprehensive DME thread?

I guess it would be easy enough to test the engine operation without the MAP sensor by unplugging it temporarily.

[liam821]

Yeah, I periodically looked at those old tuning threads trying to make sense of it all. Any chance liam821 was able to save the entire Comprehensive DME thread?

I guess it would be easy enough to test the engine operation without the MAP sensor by unplugging it temporarily.

That thread had 500+ pages, I was able to save 24. 😪

[jbfrancis3]

SliM3 made some overview comments related to the MAPS when helping me with an issue. I saved:
Hi jbfrancis, this could be an issue with the MAP sensor. It's only active when one or both TPS sensors fail and/or if there is an implausible value calculated that falls outside the pre-programmed mass air flow estimator. The later would be more a function of how the MAP scalar was programmed in the tune. I would disconnect it and try reading AFR's again.

Based on your thread title I'm guessing you watched HP Academy's recent video? Andre's comments summarized: manifold pressure post-ITBs is going to be just about ambient pressure at part ITB opening which could be as low as 30% throttle opening, generally speaking. So in terms of dictating load, MAP usefulness falls away quickly.

[Slideways]

SliM3 made some overview comments related to the MAPS when helping me with an issue. I saved:
Hi jbfrancis, this could be an issue with the MAP sensor. It's only active when one or both TPS sensors fail and/or if there is an implausible value calculated that falls outside the pre-programmed mass air flow estimator. The later would be more a function of how the MAP scalar was programmed in the tune. I would disconnect it and try reading AFR's again.

Based on your thread title I'm guessing you watched HP Academy's recent video? Andre's comments summarized: manifold pressure post-ITBs is going to be just about ambient pressure at part ITB opening which could be as low as 30% throttle opening, generally speaking. So in terms of dictating load, MAP usefulness falls away quickly.

Hah, yeah I was going to link it in the first post, but I thought it would be better in another thread -

I believe SliM3 posted something similar in that lost M3F thread. I'm just curious what the DME does if there is no MAF or MAP sensor when a TPS fails. Does it go into standard limp mode?

[terra]

I believe SliM3 posted something similar in that lost M3F thread. I'm just curious what the DME does if there is no MAF or MAP sensor when a TPS fails. Does it go into standard limp mode?

It assumes it has no idea where the throttle is and tries to control power purely by fuel flow rate and ICV. Basically limp mode on steroids.

[SliM3]

I'm just curious what the DME does if there is no MAF or MAP sensor when a TPS fails. Does it go into standard limp mode?

It will then reference driver demand torque (accelerator pedal position) + engine speed & try to down-regulate fuel/ignition so that only the idle control valve is active during limp mode.

[joz]

I experienced it before. It was not a pleasant experience to try to limp it back home.

[Slideways]

Thanks terra SliM3, good to know. I believe Olza mentioned something about stages of failure for each of the different conditions.

[x Spades x]

Hey Terra,

Does TTFS use the CSL MAP sensor, or the GM sensor? Not sure which one I should be checking, in Martyns tool.

[terra]

Hey Terra,

Does TTFS use the CSL MAP sensor, or the GM sensor? Not sure which one I should be checking, in Martyns tool.

Unless they've changed something in the last few years, they were using GM sensors.