Oh also I have changed spark plug wires, spark plugs, gas filters, air filters, oil filters

 

I am sorry to just jump in the middle of your headache, but I am having the same P1540 code. At first it threw a PRC Solenoid code. I have replaced it and now this P1540 code shows up. Can you tell me from the picture if the vacuum line is connected correctly on the PRC Valve. The vac line on the right is from the Map Sensor Solenoid valve and the vac line on the left goes to the fuel regulator. When I first bought the car there were 3 vac lines going to the PRC Valve, which is kind of weird from all the diagram I have seen. thank you in advance.

 

none of the vacuum lines to/from the prc solenoid are connected to the abv circuit. one line goes to the fuel pressure regulator, the other goes to the map sensor solenoid, and also to both intake plenums. and, just because a prc solenoid code is thrown, does NOT mean the solenoid is bad. it means something in the prc CIRCUIT is bad, most commonly, a vacuum leak. since the prc solenoid only has 2 vacuum line ports, how can a 3rd line be on there? unless it was tee'd in. and there ARE 2 tees on this circuit, and from your description, they are correct. from the pic, the lines look to be new. 1540 is abv control system malfuntion, and there are like 5 lines going to/from the abv, a couple of them are one way only. i suggest you start by checking each line coming off the abv, then following where each line tee's, and look for vacuum leaks. not a difficult job, but a very time consuming one

 

Hi Keninn, thank you so much for your help. That's how the vacuum lines were connected when I bought the car. And at that time it threw a different code stating the Map sensor was bad. I than check the Map sensor and it was ok. Than I look up the vacuum diagram and it shows only 2 vac lines are suppose to hook up to the PRC solenoid. That just threw me off. Now that I connected correctly, since you have confirmed it, it threw the P1540 code. I will go and check for leaks like you suggested before i go buy a new ABV solenoid. These are a pain in the butt. Thanks again!

 

you can ohm the solenoids. there is a vacuum and a vent. you need an ANALOG multi/0hm meter, NOT digital. iirc, new is like 26-30 kohms. if you get 0, or above like 38, they are bad. also, they can ohm good, but when they heat up, they can fail. where they are placed gets a LOT of heat. this is why in the beginning stages, after about 15 min, the car will go "limp home". then, when it cools down for a long time, like overnite, it will start and run normal, then after 15-20 min, it goes limp home again. this means the solenoids are heating up. i always change the solenoids in pairs, vacuum and vent, most of the time, the vacuum goes. but the vent is generally not far behind. again, from the pic, the vacuum lines appear to be new. this can mean the prior owner was chasing a vacuum problem, too.

 

ken you have been helpful to me- I hope you can occasionally peek in at the board to share your wisdom