Hello all,

I have a 1996 Blazer with 87,000 miles on it. Its in great shape and I've recently tuned it up with new plugs, cap, rotor, cam sensor, PCV valve, etc. The problem is it pings like crazy. It does not run hot or anything, but it pings under almost any load. I was thinking the knock sensor may be the problem. Any thoughts? Does anyone know where the knock sensor is located? Thanks in advance!

 

Try a better grade of gas first.

My truck likes to run the best on 89 octane with 10% ethanol.

 

If it still pings after an upgrade in the gas for a tankful then I would look into the plugs that you used??? If you bought one of those fancy multipronged plugs then there is your problem. I know it sounds dumb but there people on this board and others I look at that have tried those fancy Bosh +4 +2 and have complained about them....when they went back to a single prong plug they did not have a problem...

 

Did you disconnect your EST wire and set your base timing?
The computer will compensate to an number of degrees, but it's a good idea to check the base timing.

 

According to the manual I have (Haynes), there is no timing to set. It does sound like a timing problem, so I'd like to try it. Can you tell me how to go about setting it? Thanks!

 

My apologies, I was thinking of an earlier model.
Because the reluctor wheel is an integral part of the crankshaft and the crankshaft position (CKP) sensor is mounted in a fixed position, timing adjustment is not possible.

The knock sensor is threaded into the block
If this pinging started after your tune-up, You may have the wrong plugs installed, or wrong gap.

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Thanks. I installed a new camshaft sensor as part of the tune up (inside the distributor). Is this what you mean by the CKP? If so, do you think it is possible this part is bad? It wouldn't be the first electronic sensor I've installed that was faulty. I'm pretty sure the plugs are OK, as the parts store I use has never steered me wrong. Also, I know I gapped them properly. I hate to pull these plugs again, especially #3!

 

Sensor, Crankshaft Position (CKP)
Below RH front of the engine near the harmonic balancer
No, I was sayiny that I was wrong about setting the timing because your engine uses a Crankshaft Position Sensor. That's in my last post.

When did the "pinging" start...before the tune-up or after?
Is that why you tuned it up?

You can't see what the timing is without a scanner.

In my last post I tried to send a picture with the location of the knock sensor.
I have tested knock sensors before by running the engine and tapping the block (close to the sensor) while watching a tachometer. If the knock sensor is working, the idle should drop. (repedetive tapping)

 

Thanks for your suggestions. I've only had this vehicle for about a month. When I first got it the "service engine soon" light was on. The lady I got it from had it diagnosed, and they told her it needed a tune up. Sure enough, after I tuned it up, the light went out. Unfortunately, I tuned it up a few days after I got it, and I never noticed the pinging before. I'll try what you suggested. It'll probably be a few weeks, as I have major house projects going on as well. I'll keep you posted.