Car Still Knock @ 1/4 Throttle

[1QWIK6]

I'm bout to sell the freakin car!

Ok here it is...

When I GRADUALLY ease into the throttle, 1/4 or less. I HEAR (and scanmaster reads) KNOCK! I also get this when I slam a WOT. I see 10 or less degrees of knock. I get this at 1-10# of boost. It gradually goes down (knock), but I hear it and see it!!
Ok, the engine.

Coolant temp is 175 or less
M&A heads (plugs FR3LS6)
22 degress of timing
39 FP@ idle and the pressures goes up 1 to1 with the boost.
72 # injectors (CLEANED AND FLOWED!)
NO EGR
TPS is .46 @ idle
110 octane fuel
2 307 F/P's.
MaxEffort Chip

NOTHING IS MOVING! I HEAR IT. THIS IS NOT FALSE KNOCK

What and why am I getting KNOCK at such a low boost/RPM?

 

[UNGN]

When you say you "hear" knock is it a violent "whamming" sound or a metallic pinging?

It may be compressor surge (especially at 5-10 psi and 1/4-to 1/2 throttle) that is causing enough noise to set off the knock detector. A properly set up blow off valve will reduce compressor surge. Compressor surge would give you false knock.

If you here metallic pinging I'd make sure the chips know the EGR has been disabled. But that's just a guess.

 

[1QWIK6]

I hear the metalic pinging.

I'm not sure what compressor surge means, but, when the turbo starts "getting into the boost" i.e. 1+ PSI and up I hear and see the knock.

Chip knows there is no EGR...




TTT
ANY other suggestions?

 

[OKTurbo]

Don't get too discouraged. You really need to get a scan tool to record what's going on....like TurboLink or Direct Scan. That way you can look at the BLM's/INT's when the knock is happening.

It may be as easy as a reprogram on the chip.

Part throttle can be tricky on these cars....especially when you have the boost set higher than stock. I have a TA49 turbo on my car running ~19-20 psi boost using a SMC alcy kit.

WOT is GREAT! no knock....but the turbo spools so well that even 1/8 throttle will get it spinning enough to make boost. This is where you get into trouble.....barely any throttle (low TPS voltage) the boost comes up, but the computer thinks you're taking it easy (TPS volts)....the engine needs more fuel, but it's learned in a BLM without the boost. It takes a while for the computer to compensate for the low 02's and by that time the knocking has already started.

I would send a TurboLink file to you're chip guy and try a re-burn.
At least look at some more data....the Scanmaster is great for watching o2's and KR, but it's hard to keep a close eye on the BLM's etc.

Good Luck,
John

 

[Dan Thompson]

Your fuel pressure seem low at 39. It should be up around 42 when checked with the vaccum hose off.

 

[1QWIK6]

I tried the 42 base line fuel setting. No difference.

TTT

 

[rob nolan]

I had the same problem and i chased the problem for about 6 months. What i found out is i had a blown head gasket. I happen to see it was blown when i changed the intake to a ported one. My car never ran hot or used water. The one that was blown was the drivers side in the middle. That was my problem and it doesn't do it anymore. Good Luck!!!

 

[crazygn]

I had the same thing when i blow a intercooler hose, make sure its not off and they look ok.

 

[OKTurbo]

Any way to record data?

The big question is when did it start doing this???? gradually go worse or did it start happening overnight?

Have you worked on it recently? Do any "tweaking" on the MaxEffort?

John