Mercury Villager '97, P0305 & P0325 issue

Hi,
I'm new here, but have searched this site for similar problems. From what I can see, a basic tune up (wires, spark plugs, cap & rotor) can fix the P0305 problem. In the past this has worked for me, which has been required every 18-24 months to correct both codes. However, this time the basic tune up is not working. From what I have read, a fuel injector may be a problem and the knock sensor on this vehicle is problematic. Is the P0325 a symptom of the P0305 problem? Could something other than a fuel injector cause a P0305? Could both trouble codes be valid?

BTW: This Villager has about 155k miles.

Thanks,
Nick D.

ant vaccum leaks?

Are vacuum leaks a problem with the Villager? If so, where should I look? I'm aware of the Saturn SL series having vacuum leaks with the intake manifold, but that usually causes a high idle problem. Could a vacuum leak cause rough idling issues that I have?

It's a good possibility on any vehicle 11 yrs old and those vans and engines had some intake gasket issues as well as ports plugging, etc!

What do you mean by "ports plugging"? Intake manifold ports?
Also, is there a good way to test the knock sensor?

Your knock sensor will not work anymore for sure ¡¡ Just buy an original new one.

Ahh,, and also I was forgoting: The codes are not related, you have 2 different problems, also check the intake gaskets and ports as Jeff says.. could be leaking..

some ford vans had a tsb explaining how the egr ports carbon up causing some cylinders to misfire etc, as well some had vaccum leaks from around the intake bolts, pcv hoses, plugged converter etc! The knock sensor is hard to test without at least a scan tool. Check the basics like the wiring from the senor to the pcm but it may just be time for a new one.

Duh... EGR port, wasn't thinking. I'll check that for build up. That could be a problem getting to it though.

The knock sensor, according to the Haynes manual, says that this sensor can be tested. So I tried it last night, but I'm not sure if I did it correctly. Its simple, disconnect a connector on the left side of the upper intake manifold, probe a pin (according to Haynes), ground the other lead of the DVM, set the DVM to the lowest AC volts range, then tap the intake manifold with a hammer. Supposedly, the DVM should respond every time the hammer hits.

I think I remember doing this 6 or 7 years ago, and it was OK at the time. But now, I'm either doing it wrong or this knock sensor is really bad. The Haynes manual isn't very clear as to which connector to back probe.

Does anyone know if a resistance check is a valid test? If so, what values should I be measuring?

Not the most accurate way because of the possibility of it going open as it heats up! On alot of vehicles after the work involved to access it just for checking and the wirinig up to it was good then I'd just replace it.

helo

The resistance of the knock sensor has to be 500-620 kohms at (77°F)
But even though you should have these readings when measuring the sensor it doesn´t mean it is working properly. The best way is replacing it. Believe me, those knock sensors fail on millions of nissans (the sensors were faulty build) and the Villager is at the end a Nissan quest.
Just buy a new one, just buy the original one (with the nissan dealer it is made in Japan others might not work exactly).
Also how is your EGR doing ?? have you checked it ??

Sorry for the late reply, its been a busy weekend sending my kids off on their missions trips.
Thanks for the resistance values, I'll check that tonight.
Found the right connector for the knock sensor (KS) and was able to perform the test described in the Haynes manual (as stated in my prior post). This test suggests that my KS is good. But, I'm not a 100% convinced.

This weekend I performed a fuel pressure test, and according to the Haynes manual, I may have a possible leaky injector. My neighbor (mechanic) says that a leaky injector could cause a misfire. I never heard this before, but I never had injector problems in the past, on any of my vehicles.

I had plans to check the EGR, but time ran out. Did check for a vacuum leak by spraying engine starting fluid at the intake manifold gaskets, but the rear section may not have properly tested. Nothing suggested that I had a vacuum leak. Hoses all connected and look in good shape. Amazed at the number of hoses on this engine.

The engine runs very rough, so at the moment we're unable to drive it. Picked up a 6mm hex socket so I can take off the intake manifold, but I'll check the EGR first. It's such a pain to get to the EGR on this Villager.

Question, could leaky injectors cause a misfire?

helo
Yes, a malfunction of an injector can cause a missfire, could be your problem; but be sure the injector has a problem, because bad fuel pressure readings don´t mean necessary a injector is working bad.

Keep posted

Actually, the fuel pressure and fuel regulator tested fine. It was the second half of the test that failed, which tests bleed down pressure for the injectors and bleed down valve in the fuel tank. The bleed down valve was within spec, but the fuel injector test was out of range. Which, indicates a leaky injector or injectors, according to the Haynes manual.

I have never used the Haynes manual trouble shoot guide before to diagnose a problem like this, so my trust level is not very high at the moment, which is why I'm on this forum. Tonight I'll check the EGR and resistance of the KS. Hopefully I'll discover something there.

Had my injectors cleaned & tested and two failed. I should have checked the resistance on these injectors. The #5 that I suspected was trouble ohmed out at 0.5 ohms, but I wasn't expecting #6 to ohm out at 34 ohms. Normal range is 10-14 ohms. Had to order them, should be here this Saturday.

Mean while, I looked into the KS by checking the resistance while it was still install, buried underneath coolant pipes. I was getting something like 35M ohms on my Fluke 77 DVM. Compared the resistance at a local parts store, which was in the range of 500-620k ohms, so I ordered one at another store where I get a discount. Now that its ordered, I have to further disassemble this engine. Once out, I checked the resistance again, still high. I now tested it for knock by connecting both leads to the KS, place it on the garage floor, and then tap the metal section (bolt hole). I was able to see my meter react to every tap. Puzzled that it worked with 35M ohms of resistance, I tested the resistance again. It now reads 540k ohms.

What gives? Only one pin is used on the connector, the second pin which is ground is also the metal section of the KS. Could there been corrosion between the block and KS? Could I have knock some sense into this KS when tapping it with the hammer? Should I use my old KS and save the $100+ for a new KS?