# Knock Sensor?



## Twoods (Sep 18, 2009)

My MIL light has been coming on and the engine is running sluggish. When I put a bottle of seafoam in the tank the light goes out and the engine runs fine, but when I refill the gas tank, without seafoam, the light comes back on and the eninge runs rough again. I got the MIL read. Says knock sensor and #4 cylinder mis-fire. Does the temporary fix of the seafoam offer any clues to what my first step of action should be?


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## mitsuspyder (Feb 27, 2009)

the knock sensor is prolly due to poor quality fuel, so because of that the knock sensor will retard the timing some what in order to save the engine from damage, that might also be tied to your misfire


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## Twoods (Sep 18, 2009)

I've tried gas from several stations with the same result. I've replaced my fuel filter and ran my tank dry. Still no improvement. I've been experimenting with different things for 2 months now. The only thing that will make the MIL light go off is seafoam or lucas. As soon as I refill the light cames back on and the engine goes back sluggish. I've ran 4 bottles of fuel additive through the system in the past 2 months. Just can't understand why the seafoam is only improving it temporarily...


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## mitsuspyder (Feb 27, 2009)

well that is a bit strange tat only the seafoam would be able to cure the problem, did try changing the fuel pump or the filter and see if tat makes a difference


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## vrefron (Dec 18, 2007)

Fix the #4 miss and the knock sensor code will go away.


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## Twoods (Sep 18, 2009)

I changed the filter with no improvement. I really doubt its the fuel pump since the engine runs fine with seafoam in the tank. Would fouled spark plugs or bad spark plug wires cause this? I guess the seafoam is increasing the octane of the fuel?? But what would cause the engine to run rough with regular 87 in the tank and not with seafoam? Anybody got any ideas?


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## mitsuspyder (Feb 27, 2009)

well the spark plugs would be a gud idea to check out, because when i use use 87 octane here in jamaica my van runs rough also, it only runs smooth if i use 90 octane, u can check the plugs and prolly try like cleaning the injectors. When was the last time u changed plugs and what brand plugs u got in the van


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## Twoods (Sep 18, 2009)

Well I replaced them about 50k miles ago. Don't remember the brand. I'll repalce them again. then go from there.


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## mitsuspyder (Feb 27, 2009)

yea and let me know


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## Twoods (Sep 18, 2009)

Update:
Haven't had a chance to replace the plugs yet, but I took the battery cables off for a few hours yesterday then put them back on. Since I've done this the MIL light has not come on and the engine runs perfectly with plenty of power. I can't make it hesitate. Got any ideas on how or why this improved the situation?


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## mitsuspyder (Feb 27, 2009)

because when u took the battery off it resets the ECU, so any stored codes on it would be erased, jus watch it and see how long before the MIL light comes bak on


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## Twoods (Sep 18, 2009)

Sorry i'm new to sensor problems, but why would clearing the codes cause the truck to run better? Could clearing the codes also somehow fix or reset the sensors?


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## mitsuspyder (Feb 27, 2009)

wat happens is that there is a constant supply of current goin to the ECU, even tho the van is off there is a small amt goin to it, so when u disconnect the battery it resets the ecu. Also when the ecu detects a problem like in ur case the knock sensor there is a fail safe system tat is activated so as to save the engine from damage, the fail safe is to retard the timing. so caus u pulled the battery off it reset the ecu thus removing the fail safe until the ecu picks up any error codes


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## Twoods (Sep 18, 2009)

Update:
Got my codes re-read. 
here they are: P0325 (Knock Sensor) and P0172 (mixture too rich)

Got any ideas for my first steps to fixing this?


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## azrocketman (Oct 5, 2005)

Clean the Mass Air Fuel (MAF) sensor. Use a spray radio tuner cleaner that leaves no residue (see Radio Shack). Be gentle with the MAF as it is delicate. A cotton swab may be used to gently wipe the sensor. A contaminated MAF sensor is more likely if you have a K&N filter that has been over oiled.

By the way, it would be helpful if you indicated the year, which engine, transmission type, 4 wheel drive or 2 wheel drive, and how many miles total.

Steve


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## Twoods (Sep 18, 2009)

Hmmm I'll try cleaning the MAF sensor and let you know the results.

BTW the truck is a 2000 crew cab V6 manual 2WD with 150,000 miles


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## Twoods (Sep 18, 2009)

update:
OK I got some CRC MAF sensor cleaner and sprayed down the sensor real good last weekend. I've been running the truck all week with no issues! No hesitation, no rough idle and no SES light. The truck is running perfectly!
thanks for all the help!


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## mitsuspyder (Feb 27, 2009)

no problem, gud to hear u up and running again


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## azrocketman (Oct 5, 2005)

Sounds great!

Steve


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