Hey guys,
I’ve been trying to help solve this problem on an S14 for a long time and have searched a lot but so far I haven’t seen anyone else with a similar problem.
The following are the conditions when the problem occurs:
S14 SR20
GT2871R - .64
Tomei 740cc injectors
Tomei fuel pump 250 LPH
AVC-R set at 16 PSI
PowerFC D-jetro with air temp sensor installed on FMIC piping right before the throttle body
PowerFC D-jetro running RS Enthalpy stock map
Greddy oil catch can (just installed today)
Water temp: 80
Air temp: 35ish
A/F ratio is 12.0 at full boost by 4500rpm and beyond 5500rpm it hits 11.0.
The problem:
When cruising at highway speeds and stomp on the gas in 3rd or 4th to build up boost, it will read 100+ knock at around 4-5500 rpm. However no knock all the way to 7200rpm from 5500 even with the same boost at higher RPM.
No knock at all in any gears below 3rd, at same boost level.
If you do a standing 1/4 mile run, it does not register knock at all since it does not it the rpm range between 4000-5500 rpm in gears above 2rd.
Any thoughts? I am all stomped out of ideas.
John
Do you feel a diffrence in power when it registers the high knock count?
bogging of any kind? and what are you running for Ignition? stock coil packs?
sorry i forgot to mention, the coil packs are stock, and spark plugs are NGK PFR7G-11’s gapped to .8 mm
There is a loss of power but that could be caused by knock feedback from the PFC to reduce timing?
John
timing. fuel, shit spark plugs.
check all.
The problem with Scott’s base is that it is too linear.
You need a tune…PM me. My PFC tunes are $500+tax which at this point may be the best money you can spend.
Timing at point of knock is 8 Degrees BTDC at boost of 16psi, 4500rpm
Timing at idle is 15 degrees BTDC - verified with timing light
Fuel - A/F is at 12.0 at 4500RPM.
Shit spark plugs, checked and they look fine still. Perhaps i could try a different set at a colder temp range?
Hey Dan,
I started with Scott’s base and added fuel in the mid range where it now knocks. Also pulled the timing. Fuel correction is now at 1.46 at mid range now which is the maximum that the FCEdit allows and it still knocks.
I want to tune it eventually but first thing first is to solve the problem of knock.
You need to determine if it is actually knocking or if it is just making noise. The knock value on the PFC is just a graphical representation of knock sensor voltage. Just because the number is 100 does not mean it is knocking.
Is this a stock block?
Stock block. How would you determine if it is really knocking vs. noise?
John
Well now Happy240sx involved im outa my leage, but i was gona say possably ignition breakup if you using stock coils at 16psi on that turbo? what do you think Happy? same issue you found when tuning my car (and compensated for). I couldnt be more satisfied with my tune. specificly because he found the issue with my car.