Vortec 5700 Ping after computer reset?

[98gmc2dr]

Hi, I have a 1998 GMC K2500 with the Vortec 5700. After putting some Summit Racing headers on my truck the engine will ping under anything but the gentlest throttle. I have never heard the truck ping before in my years of driving it, so I am confused why it would start now. The battery was disconnected in the process so my thought is that somehow that has caused the issue, though I have no idea how. I don't think the computer is still 'learning' , I have driven about 30 miles since installing the headers and it has pinged the whole time, gets worse with more throttle. The sparkplugs were replaced a couple days (and about 60 miles) before the headers since I had heard it would be a pain to do it afterwards. The TPS is a new GM OE part (213-912) I did at the same time as the sparkplugs in a parts cannon move to see if I could fix the engine idling too high when you first start it(it would go up to 1500 then come down to 1100 cold where it should be), which funnily enough resetting the computer seems to have done. I can't imagine it being the gas either as I'm at about 280 miles on this tank and you would think it would ping before this if it was bad gas I got. There is no CEL. Any ideas are welcome, thanks.

 

[Schurkey]

Damaged the knock sensor(s) or the wiring harness(s)?

Connect a scan tool, look at the knock sensor activity. If it's pinging and there's no knock activity, you know there's a problem with the sensor and/or the harness.

Beyond that, while you have the scan tool connected, you can look at fuel trims, the other sensors, etc. and perhaps find clues.

What is your fuel pressure?

 

[98gmc2dr]

Not sure what the fuel pressure is, is there a Schrader valve somewhere where I can hook up? I wouldn't imagine it would suddenly decide to be less but I guess it is possible. I'll use a scan tool tomorrow and do some digging.
Where is the knock sensor at so I can check?

 

[Schurkey]

On the 5.7L TBIs, there's only one, it's just ahead of the starter, in the block-drain hole. I don't know about Vortec 5.7L, although I suspect only one, and in the same location.

My 7.4L has one on each side, in "dry" bosses cast into the block near the block drains. (NOT in a block-drain hole.)

Yes, there's a Schrader valve for testing fuel pressure.

 

[Pinger]

My 1999 Vortec has one knock sensor doubling as a drain plug. Can't remember which side - but obvious when you get there.
Schrader test port is easily found. Points upwards and is close to the distributor on driver's side.

 

[98gmc2dr]

Ok, the fuel pressure is 56-58 psi with the engine off and 50 when running. The connection at the knock sensor seemed fine, no visible damage and it was hooked up. I'll be able to use the scan tool later this evening.
A little more background on the issue, more RPM makes it ping less per how much throttle (ie half throttle at 3k rpm is better than half throttle at 1k rpm). It might be running a little warmer but it's hard to tell.

 

[HotWheelsBurban]

My 1999 Vortec has one knock sensor doubling as a drain plug. Can't remember which side - but obvious when you get there.
Schrader test port is easily found. Points upwards and is close to the distributor on driver's side.

Should be just ahead of the starter on the passenger side of the engine? The knock sensor, that is. Schrader valve is on the fuel line behind the throttle body, driver's side; but you're tapping that for FP so you found it! If anyone has had the starter off and on, they may have damaged the knock sensor or its wiring, not much room to work down there! And mine is a C1500.....

 

[98gmc2dr]

Yeah I looked at it and it seemed fine.

 

[Supercharged111]

I've heard audible ping on my 454, but never on my 350, and the 350 has headers. My truck was totally normal after headers too. Have you retraced your steps 100%? I ended up unbolting all kinds of crap to get the headers in, they were a pain.

 

[98gmc2dr]

Only thing I can think of is somehow the EGR got messed up since I had to take the whole tube off and screw it off the manifold out of the truck. I'll look over all the connectors again but I think they're all good.