WebJun 15, 2024 · From a cold start without touching the gas, as soon as the O2 sensors start reading, the STFT start pulling fuel and adding to the negative LTFT until they get to around -18%. Each time the STFT hits the most negative point, it will reset to 0 causing a bit of idle surge, before going negative, then resetting back to 0, it continues to loop ... WebFeb 6, 2024 · Since the long-term fuel trim seems to go high at idle, a vacuum leak is the thing I would suspect. ... As soon as you hit the leak the STFT will go negative and in a hurry. Then replace what you find is wrong. Share. Improve this answer. Follow answered Feb 5, 2024 at 20:38. vini_i vini_i. 16k 1 1 gold badge 38 38 silver badges 59 59 bronze ...
STFT and LTFT/Short Term & Long Term Fuel Trim
http://www.boosttown.com/electrical_system/stlt_fueltrim.php WebWHAT CAUSES HIGH LTFT - Answered by a verified Chevy Mechanic ... If you notice a change in idle, you've found your leak. Be careful not to spray this stuff around ignition components (distributor, wires, coils, etc) as a spark leak can ignite the spray. ... HI BRAD CARLZ 136 RPM 670-710 /ECT 198/IAC 36/BARO PRE 31/ENG LOAD 3 /IPW 4.6-4.7 /LTFT ... cube battery replacement
Fuel Trim Data: A Powerful Diagnostic Tool MOTOR
WebJul 21, 2024 · If so, it automatically provides 5% more fuel (or whatever LTFT adjustment is stored). When reading a scan tool, LTFT won’t change as rapidly as STFT at or near idle. However, if you drive with the scan tool … WebJan 9, 2024 · Restriction on fuel filter or fuel ines will cause lean mixture at higher loads and RPM generally not so much at idle. Low fuel pressure from a bad pump usually affects crank time at cold start but less than 0.5 bar (7psi) drop can have a big effect on fuel trims. " We're trying to plug a hole in the universe, what are you doing ?. " WebJun 29, 2024 · The LTFT on a cold engine at idle starts at +1.6. As the engine warms to operating temperature the LTFT creeps up to 21.9 at idle. This seems to go up in line with … east chester auto group kingston ny