Where does TP_REL_CALC get calculated from?

Decipha's custom GUFX strategy covers all 89-93 foxbody ecu's including the 88 mass-air california ecus.
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Duke
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Location: Utah
Vehicle Information: 1988 Mustang GT 76mm turbonetics

Where does TP_REL_CALC get calculated from?

Post by Duke »

Running the newest A9L2 tune. I've been trying to figure out a closed throttle to Part throttle issue I'm having and it seems to be from the fact that I'm getting negative numbers in my TP calculation. It will start as low as -160 then after warming up it will stay around -25 at closed throttle. I'm trying to get a smooth transition from CT to PT but this negative number is making it take quite a bit of throttle to get into PT. I've done a base Idle reset a couple of times and as well adjusted the TPS. I've attached a log to help show what is happening. Any Ideas on how to resolve this?
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home2.xdl
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Duke
Posts: 7
Joined: 2023 Mar 10, 14:16
Location: Utah
Vehicle Information: 1988 Mustang GT 76mm turbonetics

Re: Where does TP_REL_CALC get calculated from?

Post by Duke »

forgot to attach the tune:
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A9L2_260307_Mustang_v2.bin
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decipha
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Re: Where does TP_REL_CALC get calculated from?

Post by decipha »

tprel is tp - ratch

if your going negative that means your throttle position sensor needs to be rotated.
red5.0fogger
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Re: Where does TP_REL_CALC get calculated from?

Post by red5.0fogger »

If it's not consistent I've seen where the throttle is somehow binding. If the blade is closed ALL the way they tend to hang up. Also then we need to find out why is it shut all the way? air leaks?
Duke
Posts: 7
Joined: 2023 Mar 10, 14:16
Location: Utah
Vehicle Information: 1988 Mustang GT 76mm turbonetics

Re: Where does TP_REL_CALC get calculated from?

Post by Duke »

decipha wrote: 2026 Apr 23, 16:39 tprel is tp - ratch

if your going negative that means your throttle position sensor needs to be rotated.
I have adjusted it several times. That's the problem I'm having is no matter where I rotate the TPS it always resets to a negative number at closed throttle. I'm trying to figure out how to get it around 0 at closed throttle.
Duke
Posts: 7
Joined: 2023 Mar 10, 14:16
Location: Utah
Vehicle Information: 1988 Mustang GT 76mm turbonetics

Re: Where does TP_REL_CALC get calculated from?

Post by Duke »

red5.0fogger wrote: 2026 Apr 24, 06:21 If it's not consistent I've seen where the throttle is somehow binding. If the blade is closed ALL the way they tend to hang up. Also then we need to find out why is it shut all the way? air leaks?
It does stay consistent after initial startup I just think that I worded it wrong. No binding and throttle blade is open slightly.
Duke
Posts: 7
Joined: 2023 Mar 10, 14:16
Location: Utah
Vehicle Information: 1988 Mustang GT 76mm turbonetics

Re: Where does TP_REL_CALC get calculated from?

Post by Duke »

decipha wrote: 2026 Apr 23, 16:39 tprel is tp - ratch

if your going negative that means your throttle position sensor needs to be rotated.
I'm seeing the correlation between TP and Ratch now. I guess what I'm asking is there a way to adjust or lower ratch? ratch stays at 250 in the log but TP is around 227 at closed throttle.
decipha
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Re: Where does TP_REL_CALC get calculated from?

Post by decipha »

oh thats RATIV then

I have custom code that allows you to clip ratch as well if you so choose, simple enable it and set ratch min to whats actual
Duke
Posts: 7
Joined: 2023 Mar 10, 14:16
Location: Utah
Vehicle Information: 1988 Mustang GT 76mm turbonetics

Re: Where does TP_REL_CALC get calculated from?

Post by Duke »

RATIV doesn't seem to change anything. Where do I find that code to clip ratch?
decipha
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Re: Where does TP_REL_CALC get calculated from?

Post by decipha »

search ratch and enable the code

then set the ratch min clip scalar to a sane value

but if tprel is going out to lunch then you either have a bad tps or bad wiring
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