Using TTSdatamaster and tunercats... I'm getting some hefty knocking from 4K rpm to redline-5200rpm (ECU pulling 7deg timing). I want to start modifiying the tables but I'm not exactly sure what to do. I've searched a little and get confused quickly because there are so many opinions on how to change. How do I change values in the BLM cells themselves- I don't see anything in tunercats to do it?

Also, did a couple WOT runs- opinions on this data.....
1. 4th gear- BLM 15, starts knocking at 4k
2. 4th gear after cruising- BLM 18, knocking pattern the same
3. 3rd gear pull- BLM 15, slightly less knock.
4. 4th gear CUTOUTS open-BLM 15 significantly less knock, down on power though
5. 2nd gear pull- BLM 11, car ran very smooth, no knock, torque/HP curve looks perfect

 

Why do you feel you need to change the Cell boundaries (RPM and MAP)? Are you doing that to eliminate knock?

The values stored in the BLM cells are the "learned" values for the long term fuel corrections. The PCM creates those number, based on O2 sensor feedback. You can "lock" the BLM's... but again, it would help to understand what you are trying to accomplish.

 

the boundaries only have 3 values. I'm not trying to change that.

GOAL: I'm trying to eliminate the knock and spark retard that I'm getting at 4k+rpms.

I see that people are playing with P.E. modes ?? (I have not found a table for that yet). I also see that people are talking about being in "cell 15" and modifying it. If thats a WOT cell how do I up the fuel??? Are you saying I cannot modify the 16 cells???

One other thing: I have seen people talk about MAF calibration. I searched, read for 30 mins, and never found a write up of HOW TO actually do it.

Thanks,
James

 

The cells have jack crap to do with knock or knock retard. You do not adjust the cells. There are certain times you want to adjust the cell boundaries but knocking is not one of them. If the fueling is correct, then there are two things you can do for knocking, remove timing when the knocking first shows up, or get better fuel. In my opinion stop hammering it to the floor in fourth gear or pull timing out from the transition of cruising to wot, or take it down another gear if you can. Since second gear is perfect, you don't have too much timing there just too much load on the engine or too much timing on the way to wide open throttle.

In your research about tuning, tackle one subject at a time. For example how a maf sensor works and with the data the pcm gets how does it decide how much fuel to add. Then move on to blm locker how it works and why you want it. At some point you will get enough general knowledge about it to start putting things together. You have a whole bunch of things you need to read and understand very clearly.

The best advice I can give you, don't change a damn thing unless you fully understand exactly what you're doing, why, and how much along with other things that may be affected by the changes.

 

Thanks for the input. Maybe I'm saying it wrong...

I already know how to pull timing, I found that table. I do plan on doing that, but I need to know how I can add fuel too. Also, my MAF is descreened (bought the car like that), so I'm not sure if I need to calibrate.

Here is the pulls- 4th top, 2nd bottom. Basically, I'm trying to find the difference between cell 11 and 15. I've never seen anybody refer to 11... so I'm trying to figure out why its in 11, but runs good in that zone. Does anyone have a GOOD writeup on this tuning software and functions with FACTS and not opinions? I'm getting confused reading all the "in theory".

 

Have you read this info yet?
http://www.lt1pcmtuning.com/tips/
Just trying to help.

 

for starters your BLM's are perfect in both your screenshots so you can forget about what cell your in. Do you have roller rockers? maybe you just need to desensitize the knock sensor for them if you do or get an lt4 one. 2 degrees of retard is not much, perhaps your expecting too much from your engine. If you floor it in 4th I would expect the load to cause some timing to be pulled.

 

koolaid kid: that's what I'm looking for thanks!

Rockers are stock. 2deg is towards the end, at 4k its 7deg

 

onefastmx5:
It's actually NOT the LT4 knock sensor (in the engine block) you might want ... It's the LT4 knock module that plugs into the back of the PCM. This is an electronic filter that helps keep noisy exhaust and/or roller rocker noises from being falsely interpreted as engine knock.

 

To get down to basics on the air/fuel control system, and the BLM's.... read this:

http://www.injuneer.com/ScanMast.html

When you put the throttle on the floor, the PCM enters power enrichment (PE) mode. The target A/F ratio is richened significantly to produce more power/torque. The target A/F ratio is determined mathematically from the PE tables. That's where you change WOT A/F ratio.

But right now, you don't know why its knocking. Do you have any evidence that it is running lean? Have you tried using a higher octane fuel to verify that it is "true" knock, and not "false knock"? As poor an indicater as the stock O2 sensors are at richer A/F ratios, the numbers showing in the screen shots above (mid 900mV's) do not indicate its running lean.

As noted in the WS6T3ERROR post above, I wouldn't touch the tune until you verify the cause of the knock. You will start screwing the timing and fuel up, and it may not be related to timing and fuel.

 

Thanks for the input all. I understand the ACTUAL BLM cells are untouchable. I now understand P.E. mode = WOT tables. I now understand I can correct fueling through the MAF calibration with the AGFS value. I'm using 91oct- the best you can get at this altitude. Filled up twice, same results. I do have an autometer wideband, and the ratio is 13.1-13.3 WOT. 1st,2nd,3rd gear have always pulled nice. 4th has always felt slow, I know its more load... but dam its slow in 4th, 5th, 6th.

The Datamaster shows the PCM is trying 40deg advance through the whole powerband, but in the timing table it is set at 34deg @ 80-85KPA MAP. I'm thinking there may be another table trying to give it more timing? I'm very certain now this tune is NOT for this altitude (5200ft). The values in 95-100KPA seem more along the lines of what I need, but the best it does at WOT is 83. I have plans to hit the dragstrip next season and I don't want to blow the motor because the tune is too aggressive. I also don't want too conservative and run 14's either.

I haven't played with EFI tuning in a decade and the last time I did it was a boosted mx5 with LINK-- so easy a caveman could use it!

 

The computer adds timing incrementally at high rpm, the higher it goes the more timing it adds. What you put in the timing tables is most certainly not what you get out on the scanner at high rpm. There is no other table for it, change the one you're looking at in the 80-85kpa zone and it will respond accordingly.

If thats the readings you're getting for wot air fuel ratio then you need to fatten it up a little. Try adding a little fuel until it shows 12.7 a/f, as a side note there is nothing wrong with running 13's at wot if your engine will make max power there quite a few drag race only engines make max power that lean. From your sig you will be better off in the 12.7 range though for max power and to keep knock down and parts alive.

You can't achieve 100kpa because your barometric pressure is not that high. As long as the wot map readings are close to the barometric pressure you're doing good and getting all you can get. That is the problem with high altitude, no atmospheric pressure results in no air density and it costs you a bunch of power.

 

Cool I'll setup for 12.7. At idle and cruise its doing like 14.6-15.2, and I'm happy with that. Ya this altitude is horrible, about a 20%loss HP up here. The GOOD news is that with lower cr's up here, this car will like 6-7psi of boost when I can afford to buy a supercharger! As I estimate actual compression ratio of this motor at 9:1 up here.

 

how would altitude have any affect on compression ratio? Compression ratio is based on volume. Altitude doesn't affect volume, just density.

 

Well, simply put- there is less air up here. On the terminology you may be correct, but if you take a compression test at sea level on a cylinder and get 150psi, up here you will only make around 120psi.

So what I'm trying to get at is if you have 1000cc of air to compress at sea level, up here you only have 800cc of air. So a 10.5:1 motor up here is equivilant to a 9:1 at sea level. Its the reason the best fuel you can get up here is 91, if your lucky, because less compression = engine less likely to ping. Most gas stations are 86 regular, 88 mid, and 90 premium here.