Crossfire O2 Sensor and Throttle Position Sensor
Thread Starter
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Crossfire O2 Sensor and Throttle Position Sensor
Hi All
Thought I would share my recent experiences to get my 84 Corvette to run a little better. I recently took ownership of this car and I have been working away at making it a reliable driver.
The engine was using quite a bit of fuel and running quite rich as indicated by the black soot on the spark plugs. The Engine was throwing a code 44 indicating a lean condition. Also the idle was all over the place and the engine would occasionally slow right down and stall. The engine was running in open loop.
i replaced the EGR valve with a blanking plate but there was little if any improvement. I purchased a ALDL cable so I could run winALDL and gather a bit more information. Unfortunately I somehow accidentally ordered the 16 pin cable instead of the 12 pin one. While I was waiting for the correct cable I decided to put my old electronics skills to use and I made a cable. I had already replaced the O2 sensor by this stage because for $25 dollars I may as well know it’s good. Anyway as soon as I could see the telemetry I could see a problem. The TPS was reading 2.1 volts confirmed with a fluke with the throttle closed. WinALDL reported that the 2.1v equals 39% open throttle. No matter how I tried I couldn’t adjust the TPS to 0.54v. The TPS was clearly showing the signs of age, when I wiggled it from side to side the voltage bounced all over the place.
Ok so I need a new TPS and living in Brisbane Australia that does pose some problems. After a bit of a google search I found Corvette Australia Express Parts who were local. The guy that owns the business has a beautifully restored 1968 427 Tripower four speed corvette with side pipes absolutely gorgeous.
Anyway back to my story. I have replaced and adjusted the TPS, replaced the O2 sensor and blanked off the EGR valve. The 84 Vette is now idling smoothly accelerating and cruising nicely and my fuel economy has improved by about three liters per 100kms. No engine codes happy days.
Its amazing how easy things become when you can interrogate the ECM. Hope this is useful to someone else.
Regards Greg
Thought I would share my recent experiences to get my 84 Corvette to run a little better. I recently took ownership of this car and I have been working away at making it a reliable driver.
The engine was using quite a bit of fuel and running quite rich as indicated by the black soot on the spark plugs. The Engine was throwing a code 44 indicating a lean condition. Also the idle was all over the place and the engine would occasionally slow right down and stall. The engine was running in open loop.
i replaced the EGR valve with a blanking plate but there was little if any improvement. I purchased a ALDL cable so I could run winALDL and gather a bit more information. Unfortunately I somehow accidentally ordered the 16 pin cable instead of the 12 pin one. While I was waiting for the correct cable I decided to put my old electronics skills to use and I made a cable. I had already replaced the O2 sensor by this stage because for $25 dollars I may as well know it’s good. Anyway as soon as I could see the telemetry I could see a problem. The TPS was reading 2.1 volts confirmed with a fluke with the throttle closed. WinALDL reported that the 2.1v equals 39% open throttle. No matter how I tried I couldn’t adjust the TPS to 0.54v. The TPS was clearly showing the signs of age, when I wiggled it from side to side the voltage bounced all over the place.
Ok so I need a new TPS and living in Brisbane Australia that does pose some problems. After a bit of a google search I found Corvette Australia Express Parts who were local. The guy that owns the business has a beautifully restored 1968 427 Tripower four speed corvette with side pipes absolutely gorgeous.
Anyway back to my story. I have replaced and adjusted the TPS, replaced the O2 sensor and blanked off the EGR valve. The 84 Vette is now idling smoothly accelerating and cruising nicely and my fuel economy has improved by about three liters per 100kms. No engine codes happy days.
Its amazing how easy things become when you can interrogate the ECM. Hope this is useful to someone else.
Regards Greg
Last edited by GregMartin; Jul 17, 2018 at 05:14 PM.
