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Engine Tech Technical discussion related to all relevant engines such as KA, SR, RB, CA, 2JZ , L24/26/28, VG, VQ, and LSx series.


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Old 05-17-2018, 06:47 PM   #1
Garage Skidz
 
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SR SR20det running rich everywhere

Trying to pinpoint my issue i have with my Sr. So i just got done rebuilding my s14 sr20det, (pistons, rods, jwt s3 cams, 2871r) and it runs rich no matter what its doing. sometimes it will idle high 13's low 14's AFR but that's the only time its close to where it needs to be. All my readings are coming from a brand new AEM wide band. At WOT its low 10's if im lucky most of the time it just maxes at 10. and its difficult to get close to 14 cruising. and 30 percent throttle it goes straight to 11's then 10's for the rest of the throttle. Also the other big thing is it has Rich AFR's off throttle on Decel, like 12 to 13.5. And this thing DRINKS gas bad. almost a quarter tank after 15 minutes of driving. so here is the fuel set up, walbro 255, ISR FPR (set to 43 psi with vacuum line disconnected), Dedicated Bosch relay and wiring for fuel pump, z32 fuel filter, and Five O 750cc fuel injectors. All of this is running on a RS Enthalpy Tuned ECU ( which i don't believe is the problem cause i sent it back and he tested it on a similar car and worked great). Now i have checked a few things already, switched MAF, Switched TPS with another s14 sr20det TPS, set TPS voltage at .45V and .5V measured from center TPS wire, Changed Z32 MAF's, Changed the coolant temp sensor, changed the stock O2 sensor right after the turbo, and boost leak checked the system. The Main thing i don't understand is why its getting Fuel off throttle on Decel. isnt the ECU supposed to cut fuel with no throttle input on decel? At this point im starting to think it might be a short in the TPS wiring. The car runs and drives fine not breaking up under boost or anything, only the idle is bad sometimes and it stalls if you put it into neutral before coming to a stop if i dont slowly let the rpms down ( im guessing its so rich it floods the engine or fowls the plugs). also timed it to 15 degrees BTDC as instructed by Martin and gaped NGK bk7re plugs .28. Anything to help would be much appreciated thanks!
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Old 05-17-2018, 06:51 PM   #2
nisileighty
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Check TPS voltage directly at the ECU and make sure it’s consistent with what you’re seeing at the plug. I had the exact same issue with my SR that took me a few days to track down, ended up being a break in the wiring for the TPS.
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Old 05-17-2018, 07:07 PM   #3
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ok thanks! do you know which pin on the ECU is for the TPS? also how do you probe it with the harness plugged in?
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