My 96 disco is throwing the P1316 code, Misfire causing excessive emissions. Upon clearing the code and a cold engine the truck runs properly for 3-4 miles then a distinctive change occurs in the running with misfiring. Eventually the code is thrown. The freeze frame indicates the short term fuel trim - bank 1 value is -25% while bank 2 is -3.91 and the long term fuel trim for both banks is 3.13. The truck has new wires, plugs, timing gear and rebuilt heads. The spark plugs on bank 1 appear to be running lean as indicated by the freeze frame. I replaced the O2 sensor on the left side in front of the converter. This did not help.

The problem becomes worse after running for a while with the cruise control is set.

Does anyone have an idea as to which sensor or other component might be causing this problem?

 

Sounds like the truck is not coming out of cold mode into a closed loop, which can take 2 or 3 miles to happen.
Past that, I need to scratch my head a little.
Mike

 

Thanks for the input. The freeze frame for this error shows Fuel Sstem 1 and 2 are both in a closed loop condition. The engine coolant temp was 169 degrees, with a calculated load value of 78%, RPM 1724 and 44 mph.

Do you think a bad O2 sensor down stream of the catylitic converter would cause this fuel bank to lean out?
Does the coolant temp of 169 seem realistic? The truck was going down the interstate after a 15 minute in-town driving interval when the code was thrown. Could a bad temp sensor be telling the engine control to lean out on one bank?

Just some questions which come to mind trying to figure this out.

 

First of all the temp sound about right. A failing O2 sensors could lean out the engine but should show a code for thparticular O2.
A bad temp sensor, if failing would only allow the engine to run too rich to long, trying to warm up the engine, or cut off too soon leaning the engine out while it is still too cool.
Mike