Not going into closed loop
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Not going into closed loop
I was scanning my '85 today to see if I could find out why the idle increases all by itself if I let off the brake, I realize it will come up some just because the car is rolling but it comes up over 400 rpm and will go along without me touching the accelerator. I found a code 24 which is the speed sensor so I figure I have that one solved. However, while I was scanning I also noticed the car was in open loop while idling. I could rev the engine up & hold it & it would eventually go into closed loop until I let off the gas again. It seems like the O2 sensor is cold but I have a heated one on the car because of headers. Apparently it is working since nothing else shows up wrong so what is your guess as to why it will not stay in closed loop?
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
I was scanning my '85 today to see if I could find out why the idle increases all by itself if I let off the brake, I realize it will come up some just because the car is rolling but it comes up over 400 rpm and will go along without me touching the accelerator. I found a code 24 which is the speed sensor so I figure I have that one solved. However, while I was scanning I also noticed the car was in open loop while idling. I could rev the engine up & hold it & it would eventually go into closed loop until I let off the gas again. It seems like the O2 sensor is cold but I have a heated one on the car because of headers. Apparently it is working since nothing else shows up wrong so what is your guess as to why it will not stay in closed loop?
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Good point, I plan on going out later when it cools down & see if it is getting power or if it just dead. When I re-read my first post I realized I goofed. (First time)
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
If I checked the sensor correctly I think it is bad. It has 3 wires, 2 white & 1 black. The black one is the signal wire. I put an ohmeter lead on each of the white wires and it went from infinity to 0.00. Shouldn't there be some resistance? I then put power to the one white wire & grounded the other and the sensor did start getting warm but it took some time and it never got too hot to hold. Unless I hear different, I am going to get a new sensor in the morning.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
If I checked the sensor correctly I think it is bad. It has 3 wires, 2 white & 1 black. The black one is the signal wire. I put an ohmeter lead on each of the white wires and it went from infinity to 0.00. Shouldn't there be some resistance? I then put power to the one white wire & grounded the other and the sensor did start getting warm but it took some time and it never got too hot to hold. Unless I hear different, I am going to get a new sensor in the morning.
Racer
Joined: Sep 2004
Posts: 323
Likes: 1
From: Muncie Indiana
Tps
Yesterday I had a problem with the car not restarting after it was run 6 miles in 99 degree heat and sat for 3 hours soaking up the heat under the hood and the sun on it. It gave me a service engine soon message and I got the paper clip out and had code 15, code 21, and code 23. After the car sat for a few min. I tried to start it and it started without showing the service engine soon. Drove it home and when I got here I checked the TPS voltage I had .63 closed throttle and 4.1 WOT. This morning I again checked it cold and got .52 closed throttle and 3.99 WOT. From what the manual says I should have 5 volts WOT. Since the codes are for a lean condition could this lower voltage in the TPS cause a lean condition? Do I need a new TPS? I have checked the circuit grounds and cleaned the frame grounds in the last 2 days. All the grounds checked good.
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Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
You are correct that there should be some resistance, I checked several spares and all tested between 7 and 16 ohms. I have to wonder what scale your meter was on, if the reading was truely zero ohms you would pop the fuse on the power side assuming your ground side connection for the heater circuit is good. Make sure you verify that you have a good ground to the heater circuit when you are checking it for power, good luck