Hi, so Ive been having some spark knock on my 82. Ive had everything else check and so far the only thing that i can find is that the knock sensor is bad. Ive done some research but i havent been able to find a oem replacement. Is it needed to allow for my car to function? if so, could i convert my 82 sensor to a 84 since there somewhat similar? maybe from a different model of car entirely?

 

You will NEVER find a new knock sensor for the 82...ANYWHERE. They are like hens teeth and NOT made anymore. Best bet is a wrecking yard and no, you can not use the 84 sensor, it is a different frequency and different sensor. Are you absolutely sure the sensor is bad? You may have some carbon build up in a cylinder causing your knock issue. OR you are going very lean under load. What is your fuel pressure?

 

I wonder if a late 80's early 90's 5.7 TBI knock sensor and ESC module would work? The knock sensor/ESC module combination works together and the ESC module only gives a analog signal to the ECM to retard the timing. I'm still using the 82 CFI knock sensor/ESC module with 92 TBI ECM and they all seem to work together. I don't see why it shouldn't work. 5.7 TBI knock sensor and ESC modules along with the 4 wire ESC harness are all over the place at pick and pull yards. To the OP, is your EGR system working correctly?

 

What's the '82 frequency?

 

So, for clarification, I replaced the fuel pump about 6 months ago and at the time the car was running at a cool 12 psi. ive checked it and so far its remained at 12 psi. Its summer here in Oregon so my car is running a bit hotter than normal, and the temp gauge is reflecting that. Ive tried to clean the carbon the best i could with many of the tools around local autoparts stores. Seafoam, gumout, etc. My direction to the knock sensor came from a local chevy mechanic who believes that the knock sensor isn't signaling the car to advance and retard correctly so under load, the car isnt able to adjust accordingly. I thought about a way to test this. My car has almost 90000 on my engine and everything beside a few basic stuff like alternator, vacuum lines, etc, are all stock. could it be something to do with the water pump? heat? ive replaces the CTS at the front of the engine. New wiring and everything. and the car is running a little warm. Though i guess in the cold months the car doesn't do the knock as much, but is still prevalent when its warm, but the temp does stay at correct levels.

 

Just for the record, there is this on Ebaymotors . BTW, I'm NOT the seller ! 1 of 2 for sale.

 

only 600 bucks! what a bargain!

 

It's $600 because the seller knows that an 82 CFI car is a paper weight without it. This is speculation on my part and I haven't tested it out. I did a little research. It seems that all the OBD 1 GM cars require around an 8 volt signal to the ECM's spark retard circuit. The 8 volts comes from the ESC module. When a knock is detected the ESC module stops sending voltage to the ECM causing the timing to be pulled back. If the ECM doesn't see 8 volts upon startup it sets a code 43. I have the ability to tuned this out on my car but for those of you who still have the original ECM I don't see why a later 5.7 TBI knock sensor and ESC module wouldn't work. Another solution would be a voltage divider circuit consisting of two resistors to provide the 8 volt signal to the ECM and eliminate the knock sensor and ESC module. There are voltage divider calculators online to figure out what resistors you would need. And like I said I haven't tried any of this out, but if someone does try it and it works, please let the seller of that $600 sensor to shove that sensor where the sun don't shine.

 

Well, there's always the " bargain " one if that's too much . ( Both of these have been on Ebay for a year or more !) For obvious reasons. But I have never run across an EGR purge valve solenoid. No I'm not payin $600 bucks for one ! ( At least the shipping is free! )

 

I think your previous post reasoning, and this one, are well thought out, and the parts swap is worth trying. The '82 and '84 engines are both L83 RPO code engines, and should share the same internal noise signature and knock frequency. The '84 knock sensor is pretty common, and the knock filter (ESC module code HKR, along with ANUC and CXX used in some other engines) is somewhat common, and not overly sensitive, so it should be tolerant of any slight noise variation between the '82 and '84 powertrains.

 

That's a great suggestion. We know that the 84 ECM works with the 82 knock sensor/ESC module so vice versa should work also.

 

If you feel that you can use a different sensor on your 82...Go for it! Myself and an engineer on the forum spent a lot of time on this issue for the 82 and ended up getting nowhere in the end. Good luck with your mod...out!

 

Tom, were you using the corresponding ESC module with the knock sensor you were testing with?
To the OP, your car shouldn't be knocking regardless if you have non working knock retard system. If you're not getting a code 43, I wouldn't start modifying it yet. The knock retard system is reactionary, it doesn't cause a knock, it just there in case.

 

The knock sensor is a piezo electric devise. It makes an oscillating, very low amp signal. To test it, you'll need a scanner or scope. Watching the scope/scanner for a signal while tapping near the sensor with a hammer and punch. Since it's such a low amperage signal, connections are very critical and must be tight and clean.,

 

I retract this solution. Having to doing some more research and I come to find that the ECM performs a self check on the knock sensing system. The ECM periodically advances the timing to the point of spark knock to see if the system is working. So the voltage divider circuit won't solve this. I still think the later knock sensor/ESC module combination would work.

 

I know the later 80s ECMs did that, but I don't recall when that was first implermented. Have you seen some documentation that indicates that function is in the '82 ECM?

 

You are correct. Particularly in the later non-'82 type sensors. IIRC, the connector there is only "guaranteed" to be reliable up to five connects and disconnects (which is usually fine for the working life of the great majority of vehicles), but can be a problem if the later sensor is frequently plugged and unplugged due to vehicle repair or diagnostics.

 

I haven't. I just assumed they all worked the same way. You may be correct because the 82 ECM's doesn't self check the EGR system ether.

 

[QUOTE=Buccaneer;1605435555]If you feel that you can use a different sensor on your 82...Go for it! Myself and an engineer on the forum spent a lot of time on this issue for the 82 and ended up getting nowhere in the end. Good luck with your mod...out![/QUOTE]

Um, okay.

How 'bout actually contributing some technical input here instead of just poo pooing everything. This can be a constructive and interesting discussion.. I've twice tried to engage you in a technical discussion, and you have ignored my posts both times.

 

can these proms be flashed to ignore the knock sensor? carb cars run just fine without a knock sensor...