As Im sure most have read in my previous posts, I just purchased a 93 touring FD. I was playing around with the monitor setting on my PFC and viewed the knock, inj duty cyc, ect.... any way after reading the other day about knock and where it should be at. Mine read up around 165 for a little bit. That is very high compared to what I have seen on the threads. I read that sometimes the mic in the sensor just might be loose or malfunctioning. Does that number seem 2 high for det or it might just be noise getting picked up? sorry for the repost but what can i say even after searching im still new

mods:
-Brand new (not rebuilt) transmission from Mazda, added B&M shortshifter
-Brand new 99 Spec Turbos from Rotary Performance
-ECU upgraded with fully programmable Apex'i PFC
-Suspension - Koni Yellow adjustable shocks, w/ Eibach springs, and RE rear toe-links
-Exhaust - M2 Downpipe and Racing Beat Single Tip Cat-Back exhaust.
-Intake - HKS Racing Suction
-Cooling - Koyo Aluminum Radiator w/ aluminum AST new coolant lines.
-Intercooler - Greddy 2 Row Front Mount w/ Greddy Elbow and J-Spec Y pipe
-Greddy Spec II Boost Controller.
-Greddy pulley kit.

 

this is a question that i wouldnt mind getting answered myself. ive notice that my PFC will go as high as 207, but only for a sec. I think its just noise since i have a 'safe' tune. but i dunno.

 

Some people get meaningful knock numbers from their PFC - mine is just a random noise generator so I long ago gave up looking at this number.

Adding a wideband and monitoring it with a Datalogit is your best bet.

 

thats what I figured. from what i have heard that has been the general idea. i just got this car 2 days ago and have limited knowledge of it. I just dont want to blow it up.

any other idea are appreciated

 

I'll say it again - don't dismiss it. I had 120+ pre-tuning. I don't get anywhere near that now.

 

What map is loaded and what boost are you running? Peak knock values are worthless, only values under constant WOT have any value.

I would not dismiss those values either, not until I had determined the knock sensor was bad (it's only a piezo-electric microphone after all). I used to have values of 80-100 with a base map, and have much lower values now with more mods and a good tune -- same sensor.

 

dont know what map is loaded. boost spikes to 14 then drops to 12.8psi

like i said, i just got the car 48 hrs ago. trying to learn as fast as i can but this car is byfar different than what i am used to .

 

Yeah, you're definetly going to want to read up on boost spike and creep. I'm not sure about the 99specs, but 14psi with the stockers and a stock fuel system = fuel cut. I'm sure one of the more knowledgable guys will chime in here, but as for now, becareful.

 

i am being careful. just trying to figure out this damn knock sensor, it seems like many people are having the same problem, and many people arent. some say its a problem, some say ignor it. I want to be as cautious as possible but at the same time I have this beautiful car sitting in my driveway and dont want to drive it till I upgrade the fuel pump and get it tuned and get rid of those cats.
then its on

 

That's BAD! You have no idea what map is loaded and are running 14 psi? Not a good idea.

Unless you know the PFC has been tuned by someone, I would double check the map values to make sure it's the base map (or just reinitialize the PFC). You have a boost controller...use it. Lower the boost to 10-11 psi. I'm willing to bet your knock numbers will go way down.

 

Exactly, get the boost down to 10-11 range, 14 will definetly fuel cut and cause a ridiculously lean situation which means engine rebuild. So atleast lower boost for now, my guess is the knocking in your case is caused by the high boost.

 

You are mixing up how the stock ecu works with how the PFC works.

 

True, I actually overlooked the PFC mod infact. But still I remember reading a post by jimlab that describes that the stock fuel system can't take boost over 12psi without leading to cut.

 

That is simply not true. That is a function of the stock ecu, which has a table of values for overboost fuel cut. You can run a search for the table or look at www.fd3s.net. The PFC does cut fuel when you overboost your target boost level by ~3.5 psi, however, this is adjustable.

 

I want to retract that statement. Based on what rynberg said about ignoring non WOT values, I just spent an hour or so looking over my Datalogit logs and discovered that during WOT runs there is actually a pretty consistent pattern to my knock values. I'm getting values of about 60 in most of the boost area, dropping down to the 30s in the high boost, high rpm area of the map where my AFRs are very rich (10:1 or so). In the non WOT, non idle part of the map the numbers are fairly random (heading up to 100 on occasion).

Bottom line: buy a Datalogit.

 

Steve Kan told me that anything over 50-60 wasn't good. On WOT I normaly see 32-43 knock at around .84 bar. Now the only thing I'm not sure of is what PMI voltage is. When I saw higher knock numbers after my tune He told me to raise this. Ever since I have seen low numbers but I have no Idea what PMI voltage is...

 

Just had a Steve Kan tune myself this past weekend. In my case, knock is fine until I let up after a hard pull, at which point knock spikes over 100 instantaneously.

Steve said a/f was fine and that it was most likely some electronic noise, and as Rynberg already stated, consistent high readings are more of a concern.

 

This is very true... But does anyone know what the PMI voltages are?

 

The PIM voltage is the voltage from the MAP sensor....the higher voltage reported to the PFC, the more boost the PFC thinks the motor is seeing.

 

The high knock off throttle are typical of drivetrain noises, very common in older cars but not all third gens suffer from this. On most cars the knock sensor data during full throttle datalogging is very valuable and consistent, a definite plus for tuning. The occasional car seems to have too much noise from mechanical issues, rubs, clunks, etc and the knock sensor output can jump all over the place during idle, blipping throttle in driveway, to cruising around. Learn how your car is behaving before you discount the knock data.