Minor knock in 3rd, hit 4th and 40+ counts!

[el aguila]

Ok, info on the car first. 92 AWD with 3" turboback, Walbro 190, GM MAF-T w/ 3" MAF in blow through, 3" Intake. Decided to retune the car for summer to get it ready for the track. Reset the ECU, tuned and got all the trims into spec. I recently put Sunoco 93 into the car because it was cheaper and the car was running good at WOT with little or no knock and O2's at .87, and timing between 19-23. When I shift to fourth, the boost creeps a pound or so to 16 or 17. EGT's reach near 1500. Then this week I filled the tank with Sunoco 94 (I usually do) and made a WOT run yesterday and as soon as I hit 4th gear, knock counts went all the way to 40+! Timing dropped to 6 degrees and O2's were .89 through 3rd and 4th. In 3rd gear, I got some 10-12 counts of knock.

I richened WOT one click hoping this would alleviate the knock. Didn't do much. Here's the settings on the MAF-T

Base 1 click lean (475cc injectors I think)
Idle 3 clicks rich
Mid at 0
WOT 1 click rich.

All trims are in the 95-105 region. I'm gonna run this tank dry of 94 and try some more of Sunoco 93 hoping it will solve it. Sucks cuz the car was tuned awesome before and pulled so hard.

 

[yo2001]

With my old sidemount, mine did that sort of thing. I think it was heatsoak

 

[el aguila]

With my old sidemount, mine did that sort of thing. I think it was heatsoak

That doesn't make sense. The day before the car ran with no knock through 3rd and fourth. Just last night and this morning it was doing this in 4th gear.

 

[HighPSI TSi Guy]

bad gas maybe? i would think it unlikely from a sunoco but you never know

 

[LandoAWD]

...

Please resize your sig. Thanks.

 

[1fast97gsx]

well if one day it's warmer out then another day it could heatsoak one day and not heatsoak another.

 

[el aguila]

Temperatures were similar on both days.

 

[el aguila]

Threw in some Sunoco 93 this morning and made a run through 3rd and fourth. There was no knock in 4th gear. Needless to say, I won't be putting in anymore 94.