1993 Chevrolet S-10



July, 18, 2008 AT 11:12 AM

Engine Performance problem
1993 Chevy S-10 6 cyl Four Wheel Drive 198K miles

My 'check engine light' is on.&Amp; I finally found access to a computer and a get 'Code 43' (indicating a faulty 'Knock Sensor'). Apparently someone (who had worked on the vehicle previously) had broken the Knock Sensor ' Connector (END)'. And had 'taped it into position'. The Spark Knock is quite bad & after doing some research, I found the Knock Sensor Connector is part of the EST (Electronic Spark Timing System), consisting of the 'distributor HEI module' and the ECM (Electronic Control Module).

I would appreciate some direction on 'finding' the Module and replacing the Knock Sensor Connector's wire (where it's connected at the Module.
In other words, The Knock Sensor 'Connector' may be my 'entire' trouble, but I need some help on locating the 'module' and then instructions on wiring it into the system (wiring harness/module).

I thought I'd start by replacing 'just' the connector/wire. Then replace the Knock Sensor, if replacing the connector/ wire doesn't correct the problem.I just cant locate the module or any direction on wiring the connector's wire into the harness and how it connects to the module.
I guess the 'check engine light' will 'go out' after correcting the knock sensor issue(?).

Thank for your time and any assistance in this matter.



4 Answers



July, 19, 2008 AT 2:05 PM

You should be able to replace JUST the end connection on the wire. The HEI module is inside the distributor and the ECM is the main computer located behind the dash. If you want to replace just the wire to the knock sensor you will need to remove the dash, strip the tape off the wiring harness and have the special tools needed to remove and replace the pin connection in the ECM multiple connector. Then you need to strip the harness in the engine compartment to replace the other end as well.
FAR simpler and just as well to replace just the connector. The knock sensor is a simple item. However just disconnecting it will cause a code 43.

92-93 GM 4.3 OBD1 Code 43: The ECM did not detect a knock signal during near wide open throttle operation with coolant temperature above 194� F or the knock signal was present for 5 seconds or more during normal engine operation.

If you have constant spark knock that is not good either. Could be related to carbon build up in the cylinder. I would repair the connector and then run a batch of top cylinder cleaner through it to remove the carbon.



July, 22, 2008 AT 10:03 AM

In answering your question: 92-93 GM 4.3 OBD1 Code 43: The ECM did not detect a knock signal during near wide open throttle operation with coolant temperature above 194� F or the knock signal was present for 5 seconds or more during normal engine operation.

The engine was at operating temp when the computer was hooked up (code 43). And the check engine light has been on since getting the tranny rebuilt. Apparently someone broke the knock sensor 'connector-end' off for me and kindly 'taped' it back into place. But I don't see how it could make a good connection (considering the design of the connector). It's the original knock sensor. Should I go ahead and replace the $30 sensor and splice the 'NEW' connector's wire into the harness, or just start with the new connector (splicing the wire into the existing one and see if the knock goes away. The knock definitely corresponds with the check engine light as it wasn't present before the sensor connector was broken.
Also. To keep the engine in best shape (best gas mileage!). Any recommendations on replacing 'original' O2 sensor or anything else (maintenance-wise)?

-Relating to: " a batch of top cylinder cleaner".
Are you referring to a good fuel system cleaner.I do 'reg'.-Valvoline (10-40) oil changes. And the only (oil) additive I've done is a can of 'Restore' about 8K ago. Seemed to make a difference in engine-'smoothness'. Other than that I put a bottle of STP (or similar)gas-treatent in 'every so often'.

This vehicle needs to last me a while.(Unless I hit a lottery). So any addtl. Suggestions are greatly appreciated (as well as the time you've already spent) assisting me. THANK YOU.



July, 22, 2008 AT 8:07 PM

If they broke it off while it was still connected I would replace the connector itself and look over the sensor itself REAL close. If it isn't damaged then it should be OK.

If the O2 sensors are stock then I would replace them. They have a few miles on them.

The top end cleaning is done using either GM's top cylinder cleaner OR Seafoam.
Just follow the directions on the can. Basically what you do is get the engine running, let it warm up. Then disconnect the brake booster vacuum line and stick it into the bottle of cleaner. Let the engine draw in about half the can. Then pour the rest into the tube. The engine will stall because of the cleaner. Now let it set for an hour or so, that lets the cleaner work at softening the carbon and crud up. After an hour or so start it up and drive it around. That is needed to blow the carbon and crud out of the engine.
NO it will not hurt the converter or muffler.
HOWEVER the smoke that the cleaner makes might kill you if you try running the engine in the garage or near someone else's car! It creates a HUGE cloud of smoke and spits out a lot of carbon.
Once you get the treatment done you will want to change the oil and filter. It will have carbon and cleaner in the oil.
I do that every other year to keep the engine cleaned out.



September, 14, 2008 AT 6:44 PM

I replaced the Knock Sensor and the connector but the engine still has the classic 'spark knock-rattle' when under any throttle load on the interstate. You really can't tell in city driving but it's very apparent on the interstate in high gear (especially when there's any load put on the accelerator - climbing even slight grades, etc.

I am wondering what the 'next step would be(?)' To resolve this. As I stated earlier, the spark knock seemed to start right after having the auto-trans rebuilt (coincidence?).I'm even running premium fuel to try to alleviate the knock but it's really not making a difference (plus I've never had to run higher grade fuel before to get good performance from this engine.
I need to commute on the interstate approx. 65mi. Each way, 2-3 times per week for the next few months and definitely need to resolve this ASAP. So any helpful advice here is greatly appreciated.

Also, there is a very small exhaust leak (at the muffler) I don't know if that could contribute to the spark knock in any way.

The check engine light is still 'on' as well. Even though the only code that came back when checked was code 43. Is there any 'trick' to making the light go off. Or will it go off after the issue is resolved.

Thanks again for your help and any advice.

93' S-10 Blazer
4-door, 4-WD

Lastly, I recently charged the AC and have cool air again, but noticed the line that runs from the compressor to (in front of) the radiator has a small bulge in it. Do I need to go to the dealer for this hose or is there an alternative source for AC hoses?

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