This is starting to fustrate me, Its clean in 3rd but knocks in 4th gear, i keep pulling timing, but I don't want to go any lower.

Is this knock something I should be concerned about or just live with it?

fuel is shell 93(but I think its 92 or 91) Houston gas has always suxored
cams 264/272
3inch tb, no cat

tomei arms turbo and supporting mods.

Ive attached 2 back to back logs and my timing map, any help is greatly appreciated

 

i have the same problem i fixed it to day(i was gonna post it lol).. i think its because of the longer duration of 4th and how hot the engines getting there for gas is less stable... but you have to reduce timing....i didnt want to but i rather lower a few power that start have damage done to my engine, i got rid of my 4th gear knock and now i have random 5th gear knock which i will not tune for because i rarely do 5th pulls..

 

I would pull more timing, shouldnt need to pull much more than 1 degree.

 

i just pull 1 as well and 2 at peak load

 

You guys mean pull 1 degree around 6k amd 6.5k rpm?

 

Id pull 1 degree 6500 to limiter to start off with.

 

This is where tephra's v7 patch feature that offers gear dependent boost control is so useful! (for ECU controlled boost cars)

Why make 3rd gear weak to make 4th powerful when you can have both Just keep the timing as aggressive as you can in 3rd and drop boost 1psi in the top of 4th where the knock kicks in. Your 1/8th mile trap speeds will stay strong and your car won't fall on its face in the top of the 1/4 mile anymore. Gotta love these patches!

Otherwise, you just need to lower the timing up top and make sure you have a fresh set of spark plugs gapped correctly since fouled plugs always fall flat on their face first in the 6K+ RPM range. Fourth gear is longer and allows the car to sit in certain cells in the map a lot longer,where is 3rd gear it just breezes past those cells quickly. That, combined with the fact that you can sometimes get slightly higher boost levels in 4th than you may see in 3rd, more so on MBC cars.

 

Tephra v7, is great news . If I could just get the timing part it would be great...I use the 2 boost control tables and works like a champ in 1-3 and 4-5.

Also, I'm using the perrin WG solenoid and not liking having the open port1 to atmo. It's like having a boost leak. I'm going to try routing it back and see if that helps too.

 

your not alone, I've been having the same problems, 0 knock in 3rd then bout 4 counts of knock in 4th, trying to track down possible problems, I'm thinkin a small boost leak most likely but idk for certain, running 23-25psi on 91 oct and my timing is a little higher than yours

 

make your timing smoother you have a step of +2 degrees of timing in 500 rpm in 6,5-7Krpm/220-260load cells.

- begin with pulling 1 degree in 6,5-7,5Krpm/220-260load cells, to make the transition between 6-6,5Krpm rows smoother.

= switch to TephraMod V7. It has hi resolution BIGMAPS (25x30) that allow you to make much smoother timing map.

 

This is 100% normal to get knock in 4th but not 3rd. 4th gear imposes longer durations thru each cell and causes more strain on the engine to withstand the same amount of timing 3rd gear can since it just breezes thru those cells in 3rd gear. This is nothing new, thats why most reputable dyno shops will do a few 4th gear pulls after tuning 3rd to ensure it is knock free. Thats the beauty of Tephra's v7 gear dependent boost control patch, get the most out of 3rd gear, then tone it down a hair for 4th.

A 2 degree jump will NOT be the cause of knock, in his case if dropping it down 1* solved the problem it would be from actual knock, not interpolation in the ECU. The ECU can make a small jump like that with EASE. When you start making jumps 3* or larger it becomes more of an issue.

 

What other mods do you have? Boost looks consistent between the two gears, but if you're on the stock FMIC it may be getting heatsoaked pretty quick in 4th.

 

yeah timing looks conservative to me. What FMIC do you have like scheides asked? Pull timing or taper the boost off just a bit. Another future patch request would be low/high gear timing/fuel tables (timing more desired than fuel).

 

I have the AMS intercooler,and the LICP. My car has always been knocky, running always a bit less timing but still making decent power. So far I've left the timing alone and running load based dual boost tables (80 rpm/mph cross over) running agressive boost in 3rd land ower boost in 4-5, and has helped lower knock in 4th.

 

kool i hope it works for you. what program is that you use to log? i like it is it free? lol