How to set up safe map in case of TPS/MAP failure?

General Topics for configuring, operating and tuning the Megajolt. Also see the <a href="http://www.autosportlabs.net/MJLJ_V4_Operation_Guide">Operation Guide</a>

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Lazeum
Posts: 74
Joined: Mon Sep 17, 2012 3:03 pm
Location: Paris, France

How to set up safe map in case of TPS/MAP failure?

Post by Lazeum »

I'm trying to make sure if something goes bad in my system, I can still drive the car home safely.
My TPS sensor is plugged on carbs linkage, wires are running close to heat shield which is sharp, exhaust headers that are running hot, etc.
This is a very hostile area that could lead to failure. Same goes for MAP that can go bad: punctured hose, defective sensor, power going bad, etc.

Of course, I've managed to protect my wires the best I could. They are inside a thermal resistant hose, some clamps hold wire harness tight to avoid movements/vibrations, etc.

Still, I was looking at how to set up ignition map for bad event.
2 solutions come to me:
- Secondary map with switch with no load input effect. If something bad happens (including switch itself), safe map would be enabled.
- 0 load raw needs to be set conservatively. A new raw with low load needs also to be created to get back to "normal" with very low load (2% TPS in my case).

Here's an example of current running map on my setup and the one modified with low timing with 0 load (sensor inactive)

Image

and modified map with safe timing at 0 load.
Issue with this solution is that I'm losing 2 raws of resolution in my map to create such feature. So 0 & 2% load have been created, 90% & 100% TPS load are gone.

Image


What do you think about it?
Is there any simpler solution?

I haven't tested this map yet, so I don't know either if it would make a difference during decelerations since this is the only state where those new timings could affect my setup.
Mathieu

brentp
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Posts: 6277
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

20 degrees is probably a safe choice. You will want to test with the TPS disconnected (a common TPS failure mode) or with the MAP sensor disconnected from the hose (Common MAP sensor failure)

If the MAP sensor is disconnected your MAP reading will be about 100-103. You can fix the MAP in this area to be safe. Double check with wide open throttle because you will be near that value under those conditions as well.
Brent Picasso
CEO and Founder, Autosport Labs
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