454 knock retard

[bigpapiray]

Okay so I have. 97 K2500 burban 454 bbc 7.4l...

I put Gibson headers, new 02 sensors up stream cat delete, 3” exhaust to a black widow muffler 3” single out the back, egr delete err o2 delete. Full tune up, reprogrammed/tuned(sinister performance), FPR, motor man 4squirt injectors, new knock sensors. With doing all this my mpg went from 10-11 all the way down to 6-7..... not sure why. That’s why I’m asking...

PC says knock when you are in over drive going up a hill under a load if it’s on flat land or going around town doesn’t do it. Truck has 168k miles.. runs fine, ran fine before I did all this, all the time the mileage was 10-11...

Any and all help is amazing.....

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[Mangonesailor]

Might need to retune and put in some AFR correction or lower your spark advance in the base table. I can't get above 10-11° around 55-70kpa/2k-2800rpm without getting KR and it not being in PE mode.

 

[Christian Steffen]

Okay so I have. 97 K2500 burban 454 bbc 7.4l...

I put Gibson headers, new 02 sensors up stream cat delete, 3” exhaust to a black widow muffler 3” single out the back, egr delete err o2 delete. Full tune up, reprogrammed/tuned(sinister performance), FPR, motor man 4squirt injectors, new knock sensors. With doing all this my mpg went from 10-11 all the way down to 6-7..... not sure why. That’s why I’m asking...

PC says knock when you are in over drive going up a hill under a load if it’s on flat land or going around town doesn’t do it. Truck has 168k miles.. runs fine, ran fine before I did all this, all the time the mileage was 10-11...

Any and all help is amazing.....

You must be registered for see images attach

Is it possible you have a wire to the o2 sensor that is partially broken? If the a knock sensor low voltage code is thrown the computer assumes the worst and goes max retard. Can you datalog the live spark advance, map, rpm, and watch actual knock retard? If so do that and report back when the knock is showing up. Another thing you can try is pump it full of the highest octane gas you can get and some octane booster and see if it shows up still.

Check for the headers contacting the frame or anything too. It could be false knock from something. It would likely not register at lower loads, because the knock threshold is different at different loads.

 

[bigpapiray]

Is it possible you have a wire to the o2 sensor that is partially broken? If the a knock sensor low voltage code is thrown the computer assumes the worst and goes max retard. Can you datalog the live spark advance, map, rpm, and watch actual knock retard? If so do that and report back when the knock is showing up. Another thing you can try is pump it full of the highest octane gas you can get and some octane booster and see if it shows up still.

Check for the headers contacting the frame or anything too. It could be false knock from something. It would likely not register at lower loads, because the knock threshold is different at different loads.

The front o2 sensors are new did them when I did the exhaust. Driving until over drive it runs fine overdrive 50/55-70 is when it does the KR.

 

[bigpapiray]

The front o2 sensors are new did them when I did the exhaust. Driving until over drive it runs fine overdrive 50/55-70 is when it does the KR.

Is it possible you have a wire to the o2 sensor that is partially broken? If the a knock sensor low voltage code is thrown the computer assumes the worst and goes max retard. Can you datalog the live spark advance, map, rpm, and watch actual knock retard? If so do that and report back when the knock is showing up. Another thing you can try is pump it full of the highest octane gas you can get and some octane booster and see if it shows up still.

Check for the headers contacting the frame or anything too. It could be false knock from something. It would likely not register at lower loads, because the knock threshold is different at different loads.

I just bought a snap on ultra. So I can use it all the time to check this dang thing out and post videos etc

 

[Christian Steffen]

I just bought a snap on ultra. So I can use it all the time to check this dang thing out and post videos etc

Some data will be useful for sure.

 

[L31MaxExpress]

Might need to retune and put in some AFR correction or lower your spark advance in the base table. I can't get above 10-11° around 55-70kpa/2k-2800rpm without getting KR and it not being in PE mode.

That is substantially less than I found I could run in a 454 K3500 Dually pulling a 6,000 lbs trailer. At my suggestion he did the basics on his truck and fixed his leaky injectors before I tuned it. Ran GM Top End clean through it, installed OEM plug wires, plugs, cap and rotor, new fuel filter, LS1 injectors, new intake gaskets and a 170°F thermostat. On 87 octane, running 12.4:1 air/fuel ratio it is running 24° total advance at WOT.

 

[Christian Steffen]

That is substantially less than I found I could run in a 454 K3500 Dually pulling a 6,000 lbs trailer. At my suggestion he did the basics on his truck and fixed his leaky injectors before I tuned it. Ran GM Top End clean through it, installed OEM plug wires, plugs, cap and rotor, new fuel filter, LS1 injectors, new intake gaskets and a 170°F thermostat. On 87 octane, running 12.4:1 air/fuel ratio it is running 24° total advance at WOT.

24* at what rpm? 11* does seem pretty low, even on 87 octane. I'm going to have to go review some logs.

 

[L31MaxExpress]

24* at what rpm? 11* does seem pretty low, even on 87 octane. I'm going to have to go review some logs.

I have maximum timing at 20° in the main timing map at 2,800 rpm. 4° more in PE. The smallest value in the table is 8° BTDC at 1,000 rpm. It has 16° @ 2,000.

 

[Mangonesailor]

I have maximum timing at 20° in the main timing map at 2,800 rpm. 4° more in PE. The smallest value in the table is 8° BTDC at 1,000 rpm. It has 16° @ 2,000.

Screenshot?