QuestionHi, I have a 97 seabring with the 2.5 6cyl. I recently replaced the water pump, messed up the timing, blew the timing belt and then replaced the timing belt. I'm 97% sure we got the timing correct. While we were doing this I replaced the spark plugs and thermostat. Now it idles very ruff, but seems to drive down the road ok. Check engine light is on w it's trouble codes p0118 and p1391. Any suggestions?
AnswerHi Gregg,
The 0118 code is reporting that the signal voltage output of the engine coolant temp sensor is too high, which means that there is something the matter with either the sensor itself or with the wires of the sensor. The sensor is located on the coolant manifold directly adjacent to the coolant filler tube/cap. Remove the connector on the sensor (lift tab on edge to release)
and measure the sensor resistance. When cold it should read 7,000 to 13,000 ohms. When the engine is warmed up it should read 700-1,000 ohms.
If that checks out then check the wiring from the plug to the engine control module. The black/light blue wire should read 0 ohms between pin B of the connector and pin 43 of the ecm plug 1, and the tan/black similar should read 0 ohm between pin A and pin 26 of the same ecm plug. Turn the key to run position and check to make sure that the tan/black wire reads much lower than 12v (but varies with the temp of the coolant) when connected to the sensor (you can probe through the insulation of the wire with a fine pin to make the connection for your meter. It may be that that wire is shorted to 12v due to damage somewhere along its pathway.
That problem would affect the fuel/air mixture and might be the cause of rough idle.
The 1391 says there is an intermittent loss of with the crankshaft or the camshaft rotational sensor signal. The crank sensor is less expensive to replace because it is a separate part, while the cam sensor is part of the distributor and it is difficult to get that unit without replacing the entire distributor. You would want to check the wiring of the two plugs at the distributor along their visible pathway, and similarly check the crank sensor wiring. It is located just below the distributor and above the vehicle speed sensor at the seam between the engine and the transaxle housing. The crankshaft sensor has 3 wires: a black/light blue which on pin 2 is also connected to pin 43, an orange wire on pin 1 with 8V on it that is connected to pin 44, and a gray/black on pin 3 which is connected to pin 32 of the ecm. The distributor has a black/light blue on pin 1 connected to 43, an orange on pin 2 connected to pin 44, and a tan/yellow on pin 3 connected to pin 33 of the ecm. Check those wires for continuity while shaming the harness. Only after verifying would you want to consider replacement of either sensor.
Thanks for the rating and nomination.
Roland
