I have a 1999 chevy truck with a rebuilt engine 4.3L V6. The engine has about 3000 miles on the rebuilt engine. But I keep getting code p0327 which is the knock sensor. My cuz works for Firestone and he check it out and it was working. The problem that I am having is that the engine light will come on for awhile and then it will turn itself off for awhile. Can't figure out why. Anyone have any ideas?

What engine?
The code is for a front knock sensor circuit problem.
It is coming and going.
You need to test it when the light first comes on?
Lot of wiring problems on them and always us dealer oem sensors.
Get a factory repair manual or all data online sub.
http://www.alldata.com/products/diy/index.html


A repair flow chart for that code will take you threw the test for repair.
Good Luck
MT

have you tryed resetting your computer? but it could be your thermostat or the sensor in radiator.but i would take it to autozone or some where when check engine lights on.just one little sensor can throw it off on your computer...good luck...

My dad gave me this truck back in Feb 2008 and I had for less then a month when the engine spun a rear main bearing. My dad had the engine replace with a rebuilt one. When my dad had the truck for 8 years he never had the engine light do this.

According to my cuz at Firestone my truck only has one knock sensor.

CEL normally has nothing to do with parts and issues outside the emissions system. i do not think knock sensor is one of them. to me, it souns like you have 2 seperate issues - one for CEL, and one for knock sensor.
i'd start with resetting error codes and replacing fuel tank cap before you start the engine after that.
apperently, you need to replace knock sensor or, at least, check for good contact.
on V6 engines it is located in the transmission mounting flange portion of the engine block below the oil pressure sending unit. looking at the pic, it is across from the large white tag on the firewall, with the transmission disptick to the left of it, with 2 hoses between the dipstick and sensor. it looks like a cylinder with a nipple and lays horizontally.

I have already replaced the fuel cap and had the computer reset 5 times already. And still the same.

I had a 1996 Chevy that did the same thing when I towed my boat (not a big boat, was a fiberglass bass boat). Everytime I towed the boat the service engine light would come on. It finally dawned on me to try 89 octane instead of the 87. Low and behold the problem ceased. I would have bet against that fixing the problem, but I know for a fact it did. Try it and let us know.

I had this very same problem with my 4.3 where the SES light would come on and go off. Everytime I had the cold checked it said knock sensor. After about 3 years I found the problem...bad sparkplug wires. They finally started breaking down badly under load. Replaced with a set of good wires and the problem was fixed. The "missing" under load and the SES light. I'd try it if I were you. It makes sense to have a knock sensor code if your "spark" isn't as hot as it needs to be. Let us know.

I have a 1999 chevy truck with a rebuilt engine 4.3L V6. The engine has about 3000 miles on the rebuilt engine. But I keep getting code p0327 which is the knock sensor. My cuz works for Firestone and he check it out and it was working. The problem that I am having is that the engine light will come on for awhile and then it will turn itself off for awhile. Can't figure out why. Anyone have any ideas?

it is possible that the engine is making noises under load setting off the engine light...I would inspect plugs measure plug wire resistance,,,,and posssibly the engine is running too lean....could also be carbon in cylinders from engine breaking in...causing preignition..check for vacuum leaks...

When the rebuilt engine was installed it was installed with new spark plugs, wires, distributor cap, and rotor. Checked for any vacuum leaks and there were none. I have already done the things you'll are saying and even carried it back to the shop where the engine was installed an they are stomped. And so am I.

When the rebuilt engine was installed it was installed with new spark plugs, wires, distributor cap, and rotor. Checked for any vacuum leaks and there were none. I have already done the things you'll are saying and even carried it back to the shop where the engine was installed an they are stomped. And so am I.

did they measure resistance of wires??? new don't mean anything...I've found plenty of new wires that were defective...also are you sure the wires have the oem resistance or some other value....???? what type of plugs oem or some other brand????

To be honest I don't know the brand plugs they put in there. I don't know if they are regular plugs or platinum plugs.

To be honest I don't know the brand plugs they put in there. I don't know if they are regular plugs or platinum plugs.

The forum members have had plug problems most recommend ac delco...also the wire resistance is very important must be close to the OEM value....


there is the posibility that the knock sensor connectors are bad....this is common...

Several TSB's on the knock sensor check engine light to deal with the problem.

99-06-04-036 sept 99

Later revised 02-06 04-023A June 02.
Get a copy of them and see if they fit your truck and problem.
They deal with reprograming The VCM.
Good luck
MT

on the intermittent p0327 torque the ks [knock sensor] to 14ft lbs...leads to KS must be clear of plug wires high voltages will cause this problem so plug wires run near these are a problem the resistance of the KS is 100k ohms check connection for issues as well as wire for chafing and continuity..

as you know your KS is very close to the distributor so that KS wire must be run correctly or it will pick up the distributor EMI..........

maybe this will be of some help. i know, it's P0325, not 0327, but both codes are virtually identical:
http://www.obd-codes.com/p0325

as you know your KS is very close to the distributor so that KS wire must be run correctly or it will pick up the distributor EMI..........

just out of curiosity - as i have 2000 5.3V8 on mine - the 99 V6 has a distributor? not ignition modules? i mean, it might as well, i have seen stranger things...
haynes says it has ignition coil and ignition control module, not a distributor. of course, both are high voltage devices, indeed. it's just that there's so much basic difference between distributor and module...

j Cat is right, new does not mean that they are good. I failed to mention that when my truck started missing under load I immediately went to the local parts store and bought the cheapest set of plug wires they had. That didn't help my problem. About, 10 labor hours later it was found that the "new" wires were just as bad as the old wires. So I replaced with the premium wires and all was good.

The V6 engines STILL use a distributor as it's old Gen-i small block V8 based, specifically it's 6 cylinders of a 350. The Gen III engines (your 5.3) all have individual coil packs.

Anyways, put an OBDII scanner on it and drive it around for a while. Pay attention to the data the scanner is showing. Have a friend drive the truck while you pay attention to the data under acceleration, while coasting and while idling. This will reveal a lot.

Clearing the code on the computer will do nothing but put the computer in 'not ready' mode. Plus, the problem still exists and the light will be back! You won't have to worry about 'not ready' mode unless you are trying to pass a vehicle emissions inspection. If that's the case, you will fail the test hands down. It's best to find the problem, fix it and then go from there. You generally have to have 50 start/stop/drive cycles on the computer after it has been put in 'not ready' mode in order to have it inspected.

This is the code that I am getting - DTC P0327 Knock Sensor 1 Circuit Low Input (Bank 1 or
Single Sensor.

This what my code is telling me. DTC P0327 Knock Sensor 1 Circuit Low Input (Bank 1 or
Single Sensor

just out of curiosity - as i have 2000 5.3V8 on mine - the 99 V6 has a distributor? not ignition modules? i mean, it might as well, i have seen stranger things...
haynes says it has ignition coil and ignition control module, not a distributor. of course, both are high voltage devices, indeed. it's just that there's so much basic difference between distributor and module...


the 2000 v6 has a distributor and even an air pump!

This is the code that I am getting - DTC P0327 Knock Sensor 1 Circuit Low Input (Bank 1 or
Single Sensor.


I forgot to mention If they dropped the sensor its n/g....this is a fragile componet...have fun...

So where should I start?

on the intermittent p0327 torque the ks [knock sensor] to 14ft lbs...leads to KS must be clear of plug wires high voltages will cause this problem so plug wires run near these are a problem the resistance of the KS is 100k ohms check connection for issues as well as wire for chafing and continuity..

as you know your KS is very close to the distributor so that KS wire must be run correctly or it will pick up the distributor EMI..........


this is were I would start!!

Hey there I pulled 1 plug out and it is not a platinum plug it's a champion copper plug.

i'd put ngk in in..say missing under load and you replaced plug wires. missing under a load i do a compreson test..

Well here is what is going on with my engine light. First I had code cleared. Second I have replaced the spark plugs, wires, knock sensor, the connector, and used unleaded plus gas. I drove about 100 miles and the code came back. Any ideas? I am stumped and ready to pull my hair out. Just wondering if I should carry it back to the place I had the motor installed.

Well here is what is going on with my engine light. First I had code cleared. Second I have replaced the spark plugs, wires, knock sensor, the connector, and used unleaded plus gas. I drove about 100 miles and the code came back. Any ideas? I am stumped and ready to pull my hair out. Just wondering if I should carry it back to the place I had the motor installed.

what about the KS wires? did you route them away from spark plug wires and distributor? also what type of gas do you usually use ....?


the possiblity that the computer is bad or the connectors at computer/ecm/pcm......


IT's a long shot but since this KS voltage is very low in amplitude the possibility that they did not secure the ground wires is common ...this will make electronic noise....

No I have not change the KS wire yet. But I noticed that the wire is not even close to the spark plug wires. I use 87 octane. All these problem started after I had the motor rebuilt.

No I have not change the KS wire yet. But I noticed that the wire is not even close to the spark plug wires. I use 87 octane. All these problem started after I had the motor rebuilt.

It helps to know this stuff! If that's the case, your engine may now have slightly higher compression, considering it was probably bored, decked and the heads milled. All 3 of these things can raise compression.

Try running 89 octane in it and see if that helps.

Well I changed the KS wire and I noticed that the existing wire was slightly greenish and copper looking. Looks like the wire might have been bad. After changing the wire connector and driving around for about 5 mins. the light turned itself off.

Well I changed the KS wire and I noticed that the existing wire was slightly greenish and copper looking. Looks like the wire might have been bad. After changing the wire connector and driving around for about 5 mins. the light turned itself off.


you most likely fixed it... the KS output is a very low a/c volt...if you have a corroded connection this will happen and this is very common...

good luck

Man I really hope so.

Well guys guess what? You'll know I changed my KS connector. I put about a half tank of unleaded plus in it and drove about 95 miles, then the light came back on. Now what do I do?

Well guys guess what? You'll know I changed my KS connector. I put about a half tank of unleaded plus in it and drove about 95 miles, then the light came back on. Now what do I do?


it is possible that the computer has to relearn the Ks voltage output...the KS produces a/c voltage when shocked as in engine detonation..


can you hear engine noises...maybe the engine has mechanical noise thats creating the KS output to be incorrect...95mi then it comes on is strange unless something else occured..

if your engine is running too hot this can cause detonation..what temp does it run at ???

I don't hear anything that is knocking or pinging anywhere. My engine temp is about 195 F. Which I believe to be normal. When the light comes on I dont hear anything different.

I don't hear anything that is knocking or pinging anywhere. My engine temp is about 195 F. Which I believe to be normal. When the light comes on I dont hear anything different.

this I feel is a bad connection then as the engine appears to be running at normal temp and does not make any noises...

are you very sure you checked all the grounds ???? this will also cause all kinds of problems such as yours...battery , frame rails, engine etc...there are many and with the job they did it is very common for the rebuilders to forget to secure and clean surface before securing the grounds...

I checked everything that I can see. I am about ready to go buy some C4.

I'm not 100% positive on this, but I recall reading somewhere that knock sensors use a special sealant (silicone?) or no sealant at all on the threads. This might be worth a shot checking into since the engine has been replaced and maybe the shop put the wrong stuff on it. Other than that, I suppose it's possible during the install that a wire got pinched somewhere in the harness and it is causing your trouble. Good luck, and I'm sure you'll figure it out soon.

Took the knock sensor out and there was no sealant of any kind on it.

Took the knock sensor out and there was no sealant of any kind on it.

replace the KS sensor they probably dropped it.....

Is it possible the engine block was painted and the threads for the knock sensor have paint in them? Also, you really need a manual for your truck to follow the troubleshooting steps for checking the circuit as well as the sensor. It's possible the new sensor you bought was dropped and it's bad as well. Do you have a scanner that you can watch the knock sensor with?


Brian

I have already ran all the checks for the knock sensor and they were ok.

I have already ran all the checks for the knock sensor and they were ok.

the only way to check the KS without any doubt is to use the oscilliscope.... this will show the high speed dropouts that a bad KS can produce,, that a meter will never see /read,, and this is one way to troubleshoot intermittent problems ....the reason I did not mention this is,, most vehicle owners on this forum don't own a tool such as this...


this is why I suggested the replacing of this part....your dtc is saying that it has lost a signal...from it..

I wondering if changing the negative wire from the battery would help?

Well guys after really looking over my truck I noticed 2 things. 1st was the negative wire off the battery to ground was in bad shape (wire was replaced) and 2nd the o2 sensor connector on the passenger side had some corrison on it so I cleaned it with electrical contact cleaner. Started motor and within 1 min. the light turned off. Keep your fingers crossed. I will let you guys know.

Well the light came back on!!!!!!!!!!!!!!!!!!!!!

Well guys the light came back on again with 3 codes now and they are p0174, p0171, and p0327. I know what these codes are cause I have checked all the possible causes for them and there is nothing wrong. I am lost.

System running lean on both banks,
Could be many things.
MAF sensor dirty.
Air leak in intake air.
02 sensors bad.
Or even fuel pressure low.

Start with a good fuel pressure check.
Check and clean MAF sensor for starters.

Get some good repair info and go threw the repair flow charts for the codes.
http://www.alldata.com/products/diy/index.html

MT
MT

Everything you are requesting to get check have been already checked and passed.

Have you went threw the repair flow chart for the codes?

My cuz works at Firestone and he ran all the checks ( Smoke test, fuel pressure check). The scanner my cuz has at Firestone shows exactly what happened when the light came on. The only thing I can remember that he found was low voltage in vacuum.

My cuz works at Firestone and he ran all the checks ( Smoke test, fuel pressure check). The scanner my cuz has at Firestone shows exactly what happened when the light came on. The only thing I can remember that he found was low voltage in vacuum.


the problem with this extensive post repair is the fact that you do not give detailed readings....cuz checked this and that... next post start talking some figures and specs... maybe the cuz don't know these things....


if the scanner showed what caused the light to come on ,, why is it he can't give detailed info....????? or repair this minor issue????

Because everywhere I have taken it everybody is puzzled. Cause when there is no vacuum leaks, fuel pressure 59 to 60 psi.,MAF sensor new, and the O2 sensors were changed last December. Like I said all these problems started after the engine was replaced and the reason it was replaced cause it spun a rear main bearing. Is this enough info?:mad:

you don't by chance have a k & n air filter in it do you? if so theres yor ploblem you can get to much of the red grease on it will mess up your maf and your 0-2's..and if your thinking if you take 0-2 sensor and cleaning them your wasting your time.

No I don't have an K & N air on my truck. To be honest I wouldn't on my truck period.

Because everywhere I have taken it everybody is puzzled. Cause when there is no vacuum leaks, fuel pressure 59 to 60 psi.,MAF sensor new, and the O2 sensors were changed last December. Like I said all these problems started after the engine was replaced and the reason it was replaced cause it spun a rear main bearing. Is this enough info?:mad:

As J-cat says wen need info.
Fuel pressure 59 -60 may be one problem.
Specs is 60/66 lbs of fuel pressure.
A good engine capable scanner will point you to the problem.
But you need someone trained in engine running problems and someone that can read out a scanner and.
Good repair info is your best friend.


When looking for a good repair shop.
Check around Ask around
Word of mouth.
Family friends coworkers neighbors business people and delivery people.
Mailmen and parcel delivery people get around and notice a lot of stuff.
Even a good parts house knows what shops are good and not good.
Chamber of commerce and better business bureau and city hall.
If you find a good referral to a repair shop go look them over and talk to them.
Look for a clean looking busy place with nice people running it.
Ask a few questions and ask about their qualifications and training.
Not all places have trained tech/mechanics.
If they do not find a place that does.
Even all dealers do not have all trained techs/mechanics.
MT

I really appreciate all the help. But the only thing stopping me from having a professional looking at it is $$$$$$$$$$. My money tree is empty.

Seeing as how the engine was replaced, many connections have been disturbed. I suppose it's possible you have other main harness connectors that are dirty/loose. I'm not sure where your PCM is, but check the connectors there as well. Also, one thing that comes to mind is a bad diode in an alternator that allows ac current to leak into the electrical system can cause odd error codes to appear. Try taking it to a parts store that does free electrical testing and see what happens. Otherwise, you'll have to bite the bullet and take it to a shop or dealer.

Brian

I have a 1999 chevy truck with a rebuilt engine 4.3L V6. Engine light coming on for awhile and then going off for awhile. The engine has about 3000 miles on the rebuilt engine. But I keep getting codes P0174, P0171, and P0327. The problem that I am having is that the engine light will come on for awhile and then it will turn itself off for awhile. Can''''t figure out why. My cuz works at Firestone and he ran all the checks ( Smoke test, fuel pressure check). Cause there are no vacuum leaks, fuel pressure 59 to 60 psi.,MAF sensor new, and the O2 sensors were changed last December. Like I said all these problems started after the engine was replaced and the reason it was replaced cause it spun a rear main bearing. Right before the motor went out I was pulling a boat with cruise control on, when I was approaching an overpass the motor raved up like it does with cruise control on, but when I got to the top of the overpass the motor didn''t slow down like it should have so I had to stop it myself. An that''s when the motor spun a rear main bearing. The repair shop said that gas got into my oil and caused the oil to thin out due to the fuel regulator going out. Any ideas??? Will driving with the light on with these codes damage my motor?

did you reset comp. when it was doing this? and did you get another moter or rebuild that one? because if you rebuilt the old and never put new crank in or have it turned that can be a problem.you can go to http://WWW.OBD.COM/PO325 see if they got the codes...

did you reset comp. when it was doing this? and did you get another moter or rebuild that one? because if you rebuilt the old and never put new crank in or have it turned that can be a problem.you can go to http://WWW.OBD.COM/PO325 see if they got the codes...

Well first of all the day the motor went out the engine light never came on at all. Now to answer your question when I first got my codes the computer has been reset maybe at least 5 times and for the motor the old one shot so we had to purchase a long block to put in the truck. I am not getting a code of P0325. So how can everything for the codes that I am getting work fine before the motor went out and now its telling me there something wrong with them. Oh yeah by the way I have a 2007 chevy truck with a 4.3L and I have already swaps some parts like (MAF sensor and the tubing from the air filter to the throttle body area) with no change in both trucks.

Well first of all the day the motor went out the engine light never came on at all. Now to answer your question when I first got my codes the computer has been reset maybe at least 5 times and for the motor the old one shot so we had to purchase a long block to put in the truck. I am not getting a code of P0325. So how can everything for the codes that I am getting work fine before the motor went out and now its telling me there something wrong with them. Oh yeah by the way I have a 2007 chevy truck with a 4.3L and I have already swaps some parts like (MAF sensor and the tubing from the air filter to the throttle body area) with no change in both trucks.

Your fuel pressure is low and you have lean running codes for bank 1 and bank 2.
Does that not tell you something?
Get some good repair info and go thrwe the repair flow charts for the codes.
A factory repair manual. Or
http://www.alldata.com/products/diy/index.html

MT

I see your still not giving us much to work with....no o2 sensor readings no KS sensor readings,no vacuum readings just slightly low fuel pressure..60psi.


since you have no more money to get these readings and have a pro look at it other than free cuz service...perhaps trade in or just ignore these lights...

also earlier I suggested to check all the ground wires how many did you remove and clean....???

9 times out of 10 its a Oxygen sensor. It pops on and off when the gas to air mixture changes in side the exhaust tube. You could change it but its not really a problem unless it stays on. A bad one can effect your gas mileage.