My truck is still running really rough, here is what I have figured out so far:

-I have spark, and new plugs & wires
-I'm getting good fuel pressure
-I just replaced the O2 sensors
-I just ran a bottle of carb cleaner through the intake manifold

After all of this, I'm still getting the same codes:

-P0118 Coolant Temp Circuit
-P0125 Closed loop Fuel
-P0113 IAT Sensor
-P0183 Fuel Temp Sensor
-P0340 Camshaft Position Sensor
-P0103 MAF or VAF

Any ideas of what I should do next? Could all of these really need replacing? Know of any test proceedures for me to check any of these sensors with a meter?

 

Maybe they all share a common ground or wire of some kind?

 

http://www.roverparts.com/TechTips/g...l_problems.cfm

A bad fuel temp sensor can cause a rough idle.
A bad coolant temp sensor can cause the ECU to think that the engine is to cold and over fuel the engine.
A bad intake air temp sensor can tell the ECU the wrong incoming air temp which can cause rough run issues.

Start with the sensors, coolant temp, fuel temp and air intake temp.
The ECU uses all of those to help figure out how much fuel the engine needs.
If it is getting a wacky reading from the IAT it could set off a MAF code.

The ECU takes readings from the engine temp, air intake temp, coolant temp, throttle position, O2's and RPM to determine how much fuel the engine does or does not need.
Any one of those is sending a bad signal then it will throw things out of wack.
Several of them sending bad readings and you have a nightmare.

The cam sensor tells the injectors when to inject fuel and the cam sensor tells the spark plugs when to spark.
But you have a distributor so that is what tells the spark plugs when to spark on your truck.

 

I don't think I have a distributor, since 96' was the first year for the 4.0, but I know what you mean. I'll get to work on those sensors, thank you!

 

Sorry, I always get the '96 and the '95 confused.

 

OK, so I replaced 3 of the sensors, the IAT, Fuel Temp, and Coolant Temp sensors. That should improve things, right? Wrong.

Not only does the truck still not start without spraying some carb cleaner into the intake, but it's still throwing all the same codes, including the ones for those sensors that I replaced.

New ideas anyone? Wiring? ECU?

 

will it stay running after it starts on the carb cleaner ??? do you have code reader to clear the codes ??? Just a thought.....It seems highly unlikely that ALL of those sensors could be "bad" at the same time, but......the wiring harness feeding info from the sensors to the ecu may have issues, disconnect the battery and check all the connections as well as the ones at the ecu, try to follow the harness from the ecu as it winds around the motor, it could be rubbed or chewed through some where. I went through a similar situation a few months ago......and yes some of the sensors share the same ground...and if memory serves me , a couple of them even share the same power feed.

 

It depends on how much carb cleaner I spray in. The more I spray, the longer it runs, but never very long.

I do have a scanner, and I do clear the codes after each time I check them. I'll locate the ECU and start following the wiring. I just loooooove playing that game. Thanks for the help.

 

one problem at a time..... you said you had "good" fuel pressure.....the fact that the truck will only run on the carb cleaner says that either there's not enough fuel pressure ( clogged filter ,or bad/weak pump, or no power to the pump ) do you have a fuel pressure gauge to test the actuall pressure ? it should be 32-36 psi. turning the key to the second position will run the pump and if all else is quiet you should be able to hear the pump run......this should prime the fuel system at the above pressure, try priming the system like this a couple of time and read the pressure....let us know

 

ECU is on the passenger side by the fender, just in front of your washer tank. There is a plastic cover on it.