Code 13 help
Thread Starter
Le Mans Master
Joined: Mar 2006
Posts: 7,207
Likes: 311
From: Lino Lakes MN
Code 13 help
I have an 89 car starts and runs fine in open loop, takes some time to go into closed loop (cooling temp of 200 or more). Operationally seems fine but don't care to view the warning light on the dash. In addition, the fuel economy appears better when it is running hotter than on cooler.
Earlier replaced the MAF sensor power relay and O2 sensor since I was getting both codes 13 and 34.
Ideal speed at start up is around 8000 and 6000 fully warmed up.
Not sure what direction to go. Looking for some help and/or direction
Thanks in advance
Earlier replaced the MAF sensor power relay and O2 sensor since I was getting both codes 13 and 34.
Ideal speed at start up is around 8000 and 6000 fully warmed up.
Not sure what direction to go. Looking for some help and/or direction
Thanks in advance
Safety Car
Joined: May 2001
Posts: 4,749
Likes: 1,642
From: Fairfax Virginia
The big three sensors that are involved in the closed loop are the O2 sensor, MAF output and engine Coolant Temperature Sensor. You are probably having an issue with one of the three.
While looking and thinking about this I would start at your Coolant temperature Sensor which I believe is located where mine is. The CTS is located under the throttle body and has three wires going to it. You can measure the resistance and then cross reference a chart to see what the sensor is reading.
Your MAF is probably not the problem here so I would first check the CTS and then the O2 sensor. I am going to bet it is the CTS that is making your car think it is running cooler than it really is. If the CTS thinks it is 30 degrees when it is really 80 degrees we are going to have issues starting and running faster (like on choke). It makes your car use more fuel and can trash a catalytic converter if left too long. The choke on my 1988 C4 is an additional injector which comes on near freezing temperatures for startup only. Since a CTS does not trigger a code on the older C4's it can go bad and most people would never know. It is a simple fix to replace them. I have cleaned off the terminals and got it to work more accurately.
I am not sure what you mean "Ideal speed at start up is around 8000 and 6000 fully warmed up." 800 rpm on startup (cold) and 600 on warm start would make some sense.
Before going too far take a moment and verify that your catalytic converter is working normally. If your car has been running a rich mixture for a while it could have started to plug your catalytic converter. Unscrew the O2 and see if you get pressure out of the hole, if there is a lot of air coming out of the hole then it is likely you have some kind of obstruction. On the C4's it would be in the Catalytic Converter that gets plugged first usually. You can also verify it's operating temperature with a hand held infra-red thermometers, don't forget to do all three is you have them. I have two "Pre-Cats" located in my wye pipe. I replaced my main catalytic converter with a aftermarket Hi flow unit and it made a difference in my mileage. I have been able to break into the 30 mpg range with my 1988 C4 auto with 3.07 rear.
I hope that this will help point you in the direction you are seeking!
Best regards,
Chris
While looking and thinking about this I would start at your Coolant temperature Sensor which I believe is located where mine is. The CTS is located under the throttle body and has three wires going to it. You can measure the resistance and then cross reference a chart to see what the sensor is reading.
Your MAF is probably not the problem here so I would first check the CTS and then the O2 sensor. I am going to bet it is the CTS that is making your car think it is running cooler than it really is. If the CTS thinks it is 30 degrees when it is really 80 degrees we are going to have issues starting and running faster (like on choke). It makes your car use more fuel and can trash a catalytic converter if left too long. The choke on my 1988 C4 is an additional injector which comes on near freezing temperatures for startup only. Since a CTS does not trigger a code on the older C4's it can go bad and most people would never know. It is a simple fix to replace them. I have cleaned off the terminals and got it to work more accurately.
I am not sure what you mean "Ideal speed at start up is around 8000 and 6000 fully warmed up." 800 rpm on startup (cold) and 600 on warm start would make some sense.
Before going too far take a moment and verify that your catalytic converter is working normally. If your car has been running a rich mixture for a while it could have started to plug your catalytic converter. Unscrew the O2 and see if you get pressure out of the hole, if there is a lot of air coming out of the hole then it is likely you have some kind of obstruction. On the C4's it would be in the Catalytic Converter that gets plugged first usually. You can also verify it's operating temperature with a hand held infra-red thermometers, don't forget to do all three is you have them. I have two "Pre-Cats" located in my wye pipe. I replaced my main catalytic converter with a aftermarket Hi flow unit and it made a difference in my mileage. I have been able to break into the 30 mpg range with my 1988 C4 auto with 3.07 rear.
I hope that this will help point you in the direction you are seeking!
Best regards,
Chris
Last edited by ctmccloskey; Aug 28, 2019 at 11:52 AM.
