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Discussion Starter · #1 ·
New to the forum. Just bought my second 2001 S-10 LS Ext. cab with only 49k mi's.

Truck seems to run pretty well, but the SES light came on indicating Knock Sensor Low Input, Bank 1/ Sensor 1. I cleared the code, and the truck doesn't seem to ping or be sluggish with the light out, but I did notice a change in performance when the SES light came on (retarded timing condition). I put some Chevron 93 octane with Techron in the tank to be on the safe side.

I also induced a few ounces of Sea Foam through the Brake Booster vacuum line, & discovered a minor (inaudible) exhaust leak at the manifold to Y pipe connection on the passenger side. I would have never heard the leak but saw some smoke after re-starting during this procedure. I disassembled the exhaust & checked the donut. The part didn't look bad, but the tabs that hold it into the manifold were bent in, so I bent them out a bit so that it snapped firmly into the manifold & put it all back together. The flange nuts may have been over-torqued at some time, previously, is all I can guess. Still don't hear the leak (never did) & I haven't tried the smoke test again, yet.

Is it possible the ex leak is causing the Knock Sensor Low Input code?
 

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A knock sensor has nothing to do with the exhaust leak. A knock sensor measures the "knock" or vibration in the engine, thus adjusting the timing + or - . Although OBDII PCM systems do take into account MAP sensor input, the small exhaust leak you had would not effect those readings.
Most likely your knock sensor sensed a vibration, sent the PCM a voltage signal and never reset its self back to the reference voltage. It's a piezoelectric sensor and uses a small crystal to create voltage as it "knocks", you may have a bad sensor.
I can give you some trouble tree info on your 01 if you would like, if you want to diagnose your issue. You can also use a DVOM or laab scope to see if the sensor is working by removing it or back probing it and taping on the sensor.
 

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Discussion Starter · #3 ·
Thanks for the reply. I would appreciate the trouble tree info, as well.

There is another symptom of an occassional hard start, as well, and I may need to replace the fuel filter & check the pressure.
 

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Discussion Starter · #4 ·
I found my distributor cap to be loose & was actually missing (1) of the screws that hold it down. I put a new screw in & cleared the Low Voltage Knock Sensor code. This worked for approx. 350 miles, then the light came back on. I checked the cap again & sure enough the screw I had put in wasn't holding tight. I think the screw hole must be stripped. Anyone else have this issue & what did you do to fix it? I'm thinking to just run an oversized screw in it.
 

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i saw what you did there!
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yep bigger rougher threaded screw is about the only way short of pulling the distributor and tig welding the hole shut and re drilling

cap and rotor issues and wear is basically the number one issue on these vehicles

causing bad running or hard starting

fuel issues are next
 
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