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Map and other sensor question for ls1

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Old 12-24-2017, 05:26 PM
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Default Map and other sensor question for ls1

I am looking at realtime data on my handheld trying to figure out my lost low end tq. Map reads when running 4.9 psi, higher when not (14.8). I'm wondering if a tb sensor is failing without throwing a code. Handheld reads 0-1% on tp angle at idle, could that be a bad tbps responding slower than normal? Or iacv? Seems like if i bypass my catch-can runs little better at times driving low end tq wise, or maybe just in my head is does lol. Car was tuned in Cali on 91, now in FL running 93. Could the winter blend gas have anything to do? Also, my k&n air filter is stained dirty, but not dirty dirty. Without buying a new air filter to see, does feel like at lower rpms could be starving for air, but higher rpms feels normal. I'm really stumped on this. I did replace 1 o2 sensor that threw a slow response code. Maybe other side is slow also but not throwing code? Rpms go up fine, but power/tq wise isn't throwing me back or squatting hard like normal just by tapping throttle at like 15-30mph. Just cleaned maf. Again, no codes. Idle is smooth... Fuel# is perfect. Newer used injectors. Car is 98 TA t56 with 410s ls6 top end full bolt on n tuned.

Thx in advance guys and happy holidays

Last edited by FU_I_AM_UltraZ; 12-24-2017 at 05:33 PM.
Old 12-25-2017, 08:05 AM
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MAP is generally referred to in KPA not psi. Everything else sounds normal, youre gonna have to dig a little deeper to figure this one out.
Old 12-25-2017, 09:20 AM
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I don't know the conversion between psi and kpa but with key on--engine off, your MAP sensor in FL should be 102-103 kpa. Running, it is less and depends on rpm-load, etc. MAP measures barometric pressure so not running it is measuring normal baro at your location, running, it is less because of vacuum in the engine. Look up the conversion from psi to kpa.
I see you said used newer injectors. Was it tuned with THESE injectors or did you add them after the tune?
Old 12-25-2017, 11:22 AM
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Originally Posted by dw456post
I don't know the conversion between psi and kpa but with key on--engine off, your MAP sensor in FL should be 102-103 kpa. Running, it is less and depends on rpm-load, etc. MAP measures barometric pressure so not running it is measuring normal baro at your location, running, it is less because of vacuum in the engine. Look up the conversion from psi to kpa.
I see you said used newer injectors. Was it tuned with THESE injectors or did you add them after the tune?
Same injectors, just from lower mileage car bc i figured after 170k, injectors might have junk built up and causing a fuel volume issue, but not case. Runs the same just wasted time!
Old 12-25-2017, 11:31 AM
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Googled conversion, its 102.042xxxxxx kpa not running. Running is 33.78kpa. So maybe lazy tps or idle air or the other upstream that didn't replace o2 as i have rears turned off, they won't be a problem... Just I'll just pull bunch of sensors from a junkyard to see whats going on



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