bad gas milage Help

[lodownlv]

i have a 88 supra turbo gettting the worst gas milage not sure how bad it is because my spedo dosnt work but i know i just put 20 bux in and it got me like 50 miles. no egr installed i just got the car so it could be anything i just replaced wire harness and cam position sensor. getting code 43 51 52

[Brian R.]

43 - STARTER SIGNAL--NO "STA" SIGNAL TO ECU UNTIL ENGINE SPEED EXCEEDS 800RPM

--IGNITION SWITCH/CIRCUIT

--ECU

51 - SWITCH SIGNALS IDL (tps) CONTACTS OFF, NEUTRAL START SWITCH OFF, A/C SWITCH "ON" SIGNAL TO ECU

WITH DIAGNOSTIC CHECK CONNECTOR SHORTED

--A/C SWITCH/CIRCUIT

--A/C AMPLIFIER

--TPS/CIRCUIT

--NEUTRAL START SWITCH/CIRCUIT

--ECU

52 - KNOCK SENSOR SIGNAL

--OPEN OR SHORT IN KNOCK SENSOR SIGNAL

--KNOCK SENSOR/CIRCUIT

ECU

I would check/replace the knock sensor wiring/connection, and check/replace the TPS wiring/connection - and TPS if necessary. Clean the connections with electronic connection cleaner. Knock sensor wires are commonly damaged or connections dirty.

[lodownlv]

checked codes again after 1 full tank of gas and no more codes apear. still bad gass milage. new knock sensor new tps and set tps.

[Brian R.]

What about the knock sensor wiring? That gets damaged often.

[mex.revolutionist]

you should try changing out the air filter, the fuel pump, or maybe even the pcv valve, spark plug and get a add in cleaner that you add with a tank of gas. i dont know if that would work for the supra but when ever ive had that problem with my rides thats what i have done and got great resolts.