moto4

I have a 98 Taurus with the 3.0 duratec. It has 183k miles. I am getting 1131,1151 and 0340 trouble codes all at the same time. The car has the original O2 sensors and fuel pressure regulator. The car starts and runs as normal, except when letting off the accelerator, the revs drop quickly and the car slows more so than before, but does not stall or stumble. The fuel economy is off also. I checked for vacuum leaks, cleaned all electrical connections and cleaned the MAF sensor. The IAG valve is fairly new also. I am thinking the fuel pressure regulator may be going, The 0340 code is puzzling also, as the timing seems fine, no problem starting, running or accelerating. Anybody have any ideas on what I should do/look for?

Bert

I'd start with the P0340. Chek the connections and replace it. They aren't very costly. OBD-II Trouble Code: P0340 Camshaft Position Sensor Circuit Malfunction After that's fixed, see what codes you get after clearing them and running it a little.

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Bert

moto4

Does the timing have to be set/checked after replacing the sensor?

Bert

Just unhook the battery for 5 min. and it will clear the light. The codes will most likely stay in pending but you won't know unless you scan for codes. After about 20 warm ups and runs, they go away if they are fixed. The car will have to relearn some things but that, you may not notice.

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Bert

moto4

I replaced the cam position sensor, and that cured the 1151 code and the sudden drop off in revs when letting off the accelerator pedal. Now getting a 1131 code. Still seems to run fine, so what should I check?

Bert

That can mean too much or too little fuel is delivered. This code can be set by excessive EGR flow or engine mechanical problems. Have you cleared it and had it come back?

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Bert

moto4

It came back after disconnecting the power to replace the cam position sensor. The cam code went away, and did not come back. Some information seems to indicate vacuum issues, fuel issues and/or O2 sensor. The car runs fine, though it does have 183k miles on it, so mechanical failure seems like the least viable option. I guess the first step is to check for vacuum leaks, then move on to replacing the fuel filter and the pressure regulator, then, hopefully not, the injectors. What do you think about that plan?

Bert

I think that's a great start except for the fuel injectors. To check the presure regulator, use a pressure gauge to the system.It should read be 37 to 45 PSI when you turn the key on. Start the engine and let it idle. The fuel pressure should be 26 to 45 psi. Remove the vacuum hose from the fuel pressure regulator. The fuel pressure should rise several psi with the hose removed. If the pressure stays higher with it connected, there's a problem with either the regulator or the vacuum to it. Make sure there's vacuum in the line to it when it's running.

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Bert

moto4

Well, color me red! It seems that I forgot to reconnect the vacuum hose just behind the MAF on the intake tube! Cleaned up a few other loose connections, put that hose back on and cleared the code. So far so good. Thanks for your help!

Bert

That's great to hear. Glad you found the problem.

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Bert