I have a 93 LT1 5.7l 350 stock. I'm getting horrible hesitation to it completely just dieing on any type of throttle pressure soft , hard don't matter. Also I get this weird internal popping/ banging noise if I free rev and it doesn't become an intake backfire almost though. Also get a horrible exhaust emissions, poor fuel mileage , as well as motor running a lot warmer than it should fans come on a lot and stay on?! Anyone have this or is my shade tree mechanic mind over taken my logical one?!! 😂 Oh and my timing is in constant retard and this problem just occured one day and I've changed map, IAC, coil pack with zero changes at all.

 

A faulty knock sensor should set a code in the ECM (DTC 43). When the code sets, the ECM retards the ignition timing based on engine load, RPM, throttle position, etc. The engine will feel more sluggish, may knock a bit under very heavy load, or when using low octane fuel.

Easy to check - 1) scan it for codes; or 2) pull the single dark blue wire off the knock sensor, key on/engine off check the voltage between the blue wire and the engine block (ground). Should read 5 volts. Connector still of the sensor, probe the resistance between the single pin on the sensor and the engine block. Should be about 4,000-4,500 ohms.

The knock sensor isn't causing the problems. It may not be working so it can't correct the problems, or the problem is so severe it can't correct even if it's working. The worst you should ever hear is a sound like ball bearings rattling in a tin can. What you are describing seems way more serous than that.

See if the MAP sensor is working correctly. The ignition timing is determined by a table with RPM on one axis and MAP on the other. IF the MAP sensor is "off" the timing is off.

 

Thank you very much! So I did make those checks to the knock sensor and I do have the 5v just get nothing when I checked the resistance. I ordered a knock sensor already so I'll swap it out upon arrival. Your saying it sounds like a map sensor issue maybe? I replace the map about a month ago as I thought the same thing and it did nothing at all stayed exactly the same? I recently looked at some live data on my small hand held scanner besides the bog/ either it just dies or hesitates real bad then moves up the dial like it should don't matter cold , hot whenever don't matter. I noticed the timing advance is retarding in the negatives especially from free revving or from idle in n gear. Thanks for helping me sir I very much appreciate it!

 

I misread you first post… thought the problem started AFTER playing parts replacement roulette. I read it a few hours after cataract surgery and my vision was limited.

Is your scanner showing advance or knock retard? Some scanners report advance as a negative.

When the knock sensor fails, and the code sets, the ECM will retard the timing under many circumstances, even at idle. Have you used a paper clip to scan for codes?

 

No worries Injuneer thx for the help sir! It says spark advance for the colomn.