You can type here any text you want

Knock at modest Boost

Welcome!

By registering with us, you'll be able to discuss, share and private message with other members of our community.

SignUp Now!

krazy86t

Member
Joined
Jun 21, 2009
Messages
388
This car still has a number of performance issues to fix - hard to find the time to work through them all. I recently replaced the stock fuel pump with a Walbro 340 from FTSS. The pump is hotwired. Weird thing is that i now get knock retard of a few degrees at 8-10 psi boost, but did not with stock pump. fuel pressure regulator is 40psi vac on, 43psi no vac. Fuel pressure comes up to ~50-52psi with the 8-10 psi boost, so that seems ok. I cannot go to WOT at all anymore without seeing few deg of knock retard. O2 sensor voltage is 820-850mV under these conditions.

I did not change anything else to the set-up. I know the car has some issues left to fix, but figured these were more or less the same prior to FP replacement. I hope to go through the list in the next few days:

Replace stock injectors with new 42.5's
Replace old vacuum lines
Check plugs (NGK's in there now)
REplace plug wires
Replace valve springs and seals (unrelated but still want to do this once i figure out the tool puzzle)
put in TT chip (calibrated for 42.5 injectors)

Scanmaster data at idle is not great, Int ~127, but BL is in 130's to keep the Int near 128. IAC is pretty low 00-06, TPS = 0.46, WOT = 4.45.
 
You need to determine if the knock is real or false. True knock will rear its head in third gear when the motor is under the most load. False knock shows up quite often in 1-2 gear when something is hitting or tire spin is occuring. Im not ruling out that your knock is false...just letting you know that the odds are more for real knock in third gear WOT.
 
my 3" DP rattles the firewall, but 1) it has been that way for several weeks without KR, and 2) no KR in park when @3000-4000 RPM. DP rattles the firewall differently in park vs. drive. maybe i have a bad motor mount.

need to fix the DP rattle for sure with some weld changes.
 
Back
Top