What is a Knock Sensor on a 1997 Pathfinder LE?

[MJBBMANO]

What is a Knock Sensor on a 1997 Pathfinder LE? What is it for?

[88pathoffroad]

It detects cylinder detonation due to lean mixture or advanced timing and allows the ECU to readjust timing or fuel mixture to get the stoichiometric ratio of gasoline to air correct for best operation.

[MJBBMANO]

It detects cylinder detonation due to lean mixture or advanced timing and allows the ECU to readjust timing or fuel mixture to get the stoichiometric ratio of gasoline to air correct for best operation.

 

Do you happen to know the actual part number and name so I can get at an auto parts store? Is it hard to change? When I have my car in drive and I'm stopped the trucks knocks. It does it more when the AC is on. This started happening when I had the timing belt/waterpump and 3 belts changed.

[GhostPath]

Do you happen to know the actual part number and name so I can get at an auto parts store? Is it hard to change? When I have my car in drive and I'm stopped the trucks knocks. It does it more when the AC is on. This started happening when I had the timing belt/waterpump and 3 belts changed.

 

I think someone got your belt timing off or screwed up your ignition timing.

 

A bad sensor will not cause the truck to knock at idle (in general)

[MJBBMANO]

I think someone got your belt timing off or screwed up your ignition timing.

 

A bad sensor will not cause the truck to knock at idle (in general)

 

The mechanic that changed the timing belt said it was the Knock sensor because the computer told him. They cleaned it and I still have the same problem. What do you suggest I tell them?

 

Thanks

[GhostPath]

The computer is saying "knock sensor" because the sensor is telling it that the engine is knocking, the computer is trying to adjust it out, and nothing it is doing is working. So, it's guessing that the knock sensor is bad - but it's not.

 

Have the mechanic check the thing's timing. It is probably a couple of teeth advanced. Hope he didn't bend your valves.

[XPLORx4]

The mechanic that changed the timing belt said it was the Knock sensor because the computer told him. They cleaned it and I still have the same problem. What do you suggest I tell them?

 

Thanks

 

That's pretty funny. Ask the mechanic what he did to "clean" the knock sensor. The knock sensor is basically a piezoelectric device (microphone-like sensor) attached to the top of the block that "listens" for the sounds of engine knocking. It's time-consuming to replace, since getting to it involves removing the entire upper intake system. The part itself is relatively inexpensive.

 

FYI, I have had the knock sensor error code (P0325) for several years now, and my truck does hardly ever knocks/pings. In fact, the only time I've ever heard pinging or knocking is under heavy acceleration when I towed a boat in 105° weather after having refueled with cheap 87 octane gas. After driving for about 20 miles, I topped off with 91 octane, and the pinging disappeared.

 

I concur with the other people who have said that knocking at idle is due to the timing belt being off by one tooth, or that possibly the timing itself (should be 15°BTDC) is too far advanced.

 

If the mechanic insists it's the knock sensor, tell him that you will let him replace it, but if the knock still exists afterwards, you'll only pay the parts cost, not the labor cost. And if it turns out to be an incorrectly installed timing belt, you shouldn't have to pay anything at all for him to correct that mistake.

Edited February 3, 2008 by XPLORx4

[MJBBMANO]

Thanks for the info. I took the truck last Friday and he changed my Dis, cap and rotor (paid for parts only) which were bad. Still same problem. I might have described the problem wrong. When the car is at a full stop in "DRIVE" The RPM are at 1 (Example) and they drop a bit and come back to one. This happens a lot more when the A/C is on.The mechanic said its not a knocking but he called it Skipping a beat. Its like if you pull one of the Spark Plug wires out. I was thinking of replacing the spark plug wires since they have never been changed. What do you think? I have to drive 4 hours on Wednesday to Miami, Do you think the vechile will make it? Thanks so much for helping me out.

 

That's pretty funny. Ask the mechanic what he did to "clean" the knock sensor. The knock sensor is basically a piezoelectric device (microphone-like sensor) attached to the top of the block that "listens" for the sounds of engine knocking. It's time-consuming to replace, since getting to it involves removing the entire upper intake system. The part itself is relatively inexpensive.

 

FYI, I have had the knock sensor error code (P0325) for several years now, and my truck does hardly ever knocks/pings. In fact, the only time I've ever heard pinging or knocking is under heavy acceleration when I towed a boat in 105° weather after having refueled with cheap 87 octane gas. After driving for about 20 miles, I topped off with 91 octane, and the pinging disappeared.

 

I concur with the other people who have said that knocking at idle is due to the timing belt being off by one tooth, or that possibly the timing itself (should be 15°BTDC) is too far advanced.

 

If the mechanic insists it's the knock sensor, tell him that you will let him replace it, but if the knock still exists afterwards, you'll only pay the parts cost, not the labor cost. And if it turns out to be an incorrectly installed timing belt, you shouldn't have to pay anything at all for him to correct that mistake.

[laxman0324]

Thanks for the info. I took the truck last Friday and he changed my Dis, cap and rotor (paid for parts only) which were bad. Still same problem. I might have described the problem wrong. When the car is at a full stop in "DRIVE" The RPM are at 1 (Example) and they drop a bit and come back to one. This happens a lot more when the A/C is on.The mechanic said its not a knocking but he called it Skipping a beat. Its like if you pull one of the Spark Plug wires out. I was thinking of replacing the spark plug wires since they have never been changed. What do you think? I have to drive 4 hours on Wednesday to Miami, Do you think the vechile will make it? Thanks so much for helping me out.

 

Well how many miles do you have on the current plugs/wires? It could be whats causing the problem

[MJBBMANO]

Well how many miles do you have on the current plugs/wires? It could be whats causing the problem

 

The plugs were replaced December 2007 and have maybe 1000 miles. The wires have never been replaced and I have 160,000 miles on the truck.

[csutke]

that could defenitly do it. I would make sure to change the wires before going on your trip

[02silverpathy]

Yes, change the wires first and foremost...those new plugs don't stand a chance of working their best with the old wires. Does the truck miss a beat under acceleration or just during low RPM crusing? But don't answer that until after changin the wires! If the wires work, great, if not it may have a clogged injector...my 98 had this problem.

[MJBBMANO]

Yes, change the wires first and foremost...those new plugs don't stand a chance of working their best with the old wires. Does the truck miss a beat under acceleration or just during low RPM crusing? But don't answer that until after changin the wires! If the wires work, great, if not it may have a clogged injector...my 98 had this problem.

 

I haven't got the wires yet. I'm getting them this weekend. It does it when I'm stopped and the truck is in 'DRIVE' and a lot more when the A/C is on.

I decided to drive my Honda to Miami instead because I don't want to take the risk the truck stalling on me.

I'll post on Saturday if new wires do the trick (I Hope they do).

[MJBBMANO]

I haven't got the wires yet. I'm getting them this weekend. It does it when I'm stopped and the truck is in 'DRIVE' and a lot more when the A/C is on.

I decided to drive my Honda to Miami instead because I don't want to take the risk the truck stalling on me.

I'll post on Saturday if new wires do the trick (I Hope they do).

 

I changed the wires and it was great until an hour later it started doing the same thing. Except this time it does it a bit less. It will only do it when the truck temp gauge is at half / In Drive @ a complete stop/ A/C on. I did notice I have a bit more power when I step on the gas. Any ideas?

[MJBBMANO]

Would changing the fuel filter help?

[XPLORx4]

Would changing the fuel filter help?

 

It couldn't hurt. Has it ever been changed?

 

You might need to also check the coolant temperature sensor. It could be operating out of spec, and that would definitely contribute to poor drivability.

 

Read how to check the ECT sensor on page EC-127 here. The sensor is physically located on the top of the engine where the upper radiator hose is attached. Of the two sensors there, the ECT sensor is the one whose connector has multiple wires. The other sensor there is for the temperature gauge; it has just one wire.

[MJBBMANO]

Fuel filter has never been changed.

I had the temperture gauge changed when they did the timing belt and water pump (Jan 2008). Are you refering to the same thing?

[XPLORx4]

Fuel filter has never been changed.

I had the temperture gauge changed when they did the timing belt and water pump (Jan 2008). Are you refering to the same thing?

 

They changed the temperature gauge (on the instrument panel) or the temperature sender? Why did you have it changed?

 

The part I'm referring to has nothing to do with the temperature sender or the gauge. I'm referring to the Engine Coolant Temperature (ECT) sensor, which tells the computer what the coolant temperature is. It's not the same part as the gauge sender. If the sensor is sending the computer an incorrect voltage, the computer may change the fuel mixture or timing. It's just something to check. If it tests OK, then look elsewhere for the problem.

[MJBBMANO]

They changed the temperature gauge (on the instrument panel) or the temperature sender? Why did you have it changed?

 

The part I'm referring to has nothing to do with the temperature sender or the gauge. I'm referring to the Engine Coolant Temperature (ECT) sensor, which tells the computer what the coolant temperature is. It's not the same part as the gauge sender. If the sensor is sending the computer an incorrect voltage, the computer may change the fuel mixture or timing. It's just something to check. If it tests OK, then look elsewhere for the problem.

 

I meant to say the thermostat was changed. How do you test a ECT?

[XPLORx4]

I meant to say the thermostat was changed. How do you test a ECT?

 

Read how to check the ECT sensor on page EC-127 here.

[MJBBMANO]

Is this something that I can change and if so where exactly is it located?

[XPLORx4]

Is this something that I can change and if so where exactly is it located?

 

Uh, no offense, but do you even read all of the text in the posts in this thread? That's the second time you've asked a question that has already been answered in a previous post, and this thread is starting to sound like a scratched CD.

 

The sensor is physically located on the top of the engine where the upper radiator hose is attached. Of the two sensors there, the ECT sensor is the one whose connector has multiple wires. The other sensor there is for the temperature gauge; it has just one wire.

 

I would recommend TESTING the sensor first, rather than just replacing it. It may not even be causing your problem.

 

However, before throwing random parts at your truck, start off by replacing the fuel filter, especially since it apparently has never been changed before.

Edited February 19, 2008 by XPLORx4

[MJBBMANO]

Uh, no offense, but do you even read all of the text in the posts in this thread? That's the second time you've asked a question that has already been answered in a previous post, and this thread is starting to sound like a scratched CD.

I would recommend TESTING the sensor first, rather than just replacing it. It may not even be causing your problem.

 

However, before throwing random parts at your truck, start off by replacing the fuel filter, especially since it apparently has never been changed before.

 

 

Thanks for the info. Sorry for sounding like a scratched CD. No offense taken. I'll try the fuel filter first. I had another mechanic tell me to put high octane gas in it for a week to see if it helps. He said it can also be an injector and that the problem will not cause me to break down. Hey thanks for all your help and I'll keep you posted.

[MJBBMANO]

UPDATE:

 

Has anyone ever heard of Sea Foam? Well I added Sea Foam to my tank and filled up with Shell V-Power 93 Octane. After running for 100+ miles it hasn't missed a beat. Yesterday it did it slightly, but only twice(before 100 miles). Today it hasn't done it at all (after 100+ miles). Do you think it could have been my Fuel sysytem and injectors that needed to be cleand since I have never cleaned them since buying the truck in 97? I'm having my fuel filter changed tomorrow.

Edited February 23, 2008 by MJBBMANO

[MJBBMANO]

UPDATE:

 

Has anyone ever heard of Sea Foam? Well I added Sea Foam to my tank and filled up with Shell V-Power 93 Octane. After running for 100+ miles it hasn't missed a beat. Yesterday it did it slightly, but only twice(before 100 miles). Today it hasn't done it at all (after 100+ miles). Do you think it could have been my Fuel sysytem and injectors that needed to be cleand since I have never cleaned them since buying the truck in 97? I'm having my fuel filter changed tomorrow.

 

The fuel filter has been changed. It was so dirty!!!! Its been now 4 days since I added Shell 93 V-Power and Sea Foam. one day since changeing the fuel filter and it seems like the problem is gone. I filled up again with the same gas today. I will do this for a month and hopefully it was the injectors that were dirty. I will keep you all posted. Thanks for the great help.