Need a little assistance on CAS calculations...Q45Tech?

[qsiguy]

...The CAS has 360 pulses per rpm650 rpm = 10.83333 x 360 =3900 pulse per secomd = 0.000277 or 2/10% accuracy.

With an accurate frequency counter 3.9khz = 650 rpm.

I'm working on an Excel spreadsheet with formulas to calculate my TP so I can pinpoint trouble areas easier on my fuel and timing maps. The guide I found has the CAS formula but it's for a different engine and doesn't work (at least I don't believe it works).

Here's the formula I have which I believe is for a 300ZX Turbo.CAS= RPM / 50 x 256

The problem I have with this formula is that when I run the numbers the TP comes out way too low and I don't see how it could be right. At the MAF voltage and RPM I'm at the map should be in the high load area. With this formula it comes out in the middle and can't be right, the MAf is almost maxed out. If I change the 256 to 360 using the numbers the TP is actually lower so that's not it.

This is the complete formula I'm trying to calculate. In case you don't know, TP is the Theoretical Pulsewidth used in the ECU for the maps.TP= (VQ x K Value / CAS Value) / Number of Cylinders

The only variable I need to make sure I have correct if the CAS Value. Anyone have any ideas?

[qsiguy]

If these TP numbers are correct then I'm tuning totally wrong. I don't think so because the changes i am making to the high load areas are effecting the AFR's and timing.

[qsiguy]

I guess I'm just having a conversation with myself on this one...

I've been crunching more numbers and did a log on the way to work this morning. I can still make it detonate if I do a rolling start from 2nd gear at 40 mph. I've been calculating the TP so I can plot the map to see where the detonation is and it comes out right in the middle of the map. I think it should be further right, into the higher load areas but I could be wrong. That may explain why I was having so much trouble getting rid of the detonation w/o methanol.

I have to get this fixed before Saturday. On the dyno the TCU will be unplugged and it will be in 3rd gear for the whole thing. I guess I need to do a road test/log with the TCU unplugged to see were it's at and try to get a rough tune in before Saturday. Can't have detonation on the dyno!

[Q45tech]

I pointed out that the easiest way is to read the frequency of the pulse from CAS and compare to rpm of engine to arrive at number of slots in each separate section.

The FSM STATES 1 degree so the only possible 2 conditions are 360 or 180 since the CAS rotates at 1/2 crank the question is 1 degree of cam or crank?

[qsiguy]

That's a good question. I don't know. I'm assuming cam but that's just a guess. I thought CAS referred to the cam angle sensor or is it crank angle sensor?

Well here are the results of my number crunching. IF the formulas and numbers are correct this chart shows the potential detonation area (mostly the center of the orange). I had been pulling timing in the far right columns assuming thats where it was at. Seems to me the load would be higher at WOT and full boost. Anyone have any knowledge of this? I guess it wouldn't hurt to pull some timing in that area and check the results.

[John Dixon]

Its easiest to get an eprom emulator with an address trace then use that to see which map points are being accessed. Not romulator as the latch on it isn't quick enough.The actual TP used is stored in RAM, on the 300zx you can modify the code to pass it out via consult but I think on the Q45 ROM there isn't room to fit in the extra code? Try the http://www.ztechz.com forum and search on there, some useful info.

[qsiguy]

Thanks for the link, I'll check it out. I have to do something, this is ridiculous and tedious tuning this way and sorta blind.

Just to update this thread, the TP formula above was NOT correct. I tried redoing the maps based on the TP info above and it was terrible. Lean and detonating.

I went back to the previous maps and pulled some timing but I'm still fighting some detonation at around 4-5K. Just can't seem to get rid of it. It's only in 2nd and 3rd gear. 1st gear is perfect. I keep pulling timing to try and fix it and I can tell power is down but I just can't make it right. Getting angry...

[John Dixon]

I don't think any of the TP formulas I've seen worked when I checked them against the actual values. Try having a word with 'Eric' on that link, he developed the conZult software for the 300ZX so may be able to help with TP extraction. Also, there is a link somewhere on there to the nissan patent for the TP type load scale with some info on it.

I tried for ages with the 300 mapping like you are but honestly it's best to just get the emulator and do it that way.

Also it is possible that the ECU is detecting det and dropping onto the knock maps, if you're not adjusting them too then your changes to the main maps may have no effect.

[qsiguy]

That thought crossed my mind this morning when I was driving to the office. I haven't touched the knock maps yet.

[John Dixon]

Probably best when tuning to set the knock and high gear maps to the same as the primary ones. The high gear maps are quite easy to disable if the Q is the same as the 300.What software are you using to edit the maps?

[qsiguy]

Tunerpro primarily. My detonation issues are around 4-5k and I thought the maps had really high numbers where it watched for knock and would access the knock maps? The high numbers on the maps are fairly low on the map, 3200 rpm and below. The timing on my current bin is more advanced on the knock map so that could certainly cause a problem. Will the ECU access the knock map even out of the high map blocks? I'm talking about the ones that are in the 140-150 range.

I'm definitely going to remember those maps now, as soon as I get a bit of detonation now and it switches to the knock map it would get worse! Sheesh. Learn something new everyday.

What's considered high gear? 3rd gear or 4th/overdrive?
Modified by qsiguy at 5:34 PM 4/23/2008

[John Dixon]

The way I understand it, the ECU is looking for det with a higher sensitivity in the areas with a timing figure >&h80 (or 128 decimal) so timing value of 148 is actually 20deg. When knocks are counted they are referenced against a table that dictates how many knocks can be detected in a certain TP/RPM block before the switch to the knock maps is made.After this switch is made then the knock maps will be used at all times until the ignition is cycled off and on again.I'm not 100% but I think there are 2 3x3 tables in the 300zx ECU for the knock limits at high / low sensitivity - either way the knock maps are latched across the entire operating range once set.Also, there is a seperate ignition retard parameter which looks to be applied as a timing retard for every knock detected, I set this to 0 when tuning.High gear is some sort of calc performed using a coefficient set in the ECU, again you can set it to disable this function when tuning.

I had started to make a ROM editor before I decided to go aftermarket, it had map trace and everything but the romulator didn't work as planned!!

Heres the definitions section which should show you the maps and parameter locations I knew about at the time. I'm sure Wes and Robert on here may know lots more by now!

'Set Up byte datablnErrors = blnErrors Or Not BA_RevLimit.Setup("Rev Limit", 1, &H7FB4, 50)blnErrors = blnErrors Or Not BA_SpeedLimit.Setup("Speed Limit", 1, &H7FA5, 1.25)blnErrors = blnErrors Or Not BA_Latency.Setup("Injector Latency", 1, &H7F88, 0.01)blnErrors = blnErrors Or Not BA_Feedback.Setup("Injector Feedback", 1, &H7F91, 1)blnErrors = blnErrors Or Not BA_VTCRelease.Setup("VTC Release Point", 1, &H79F6, 50)blnErrors = blnErrors Or Not BA_TPFuel.Setup("Fuel Map TP Scale", 16, &H7AF0, 0.125)blnErrors = blnErrors Or Not BA_TPTiming.Setup("Timing Map TP Scale", 16, &H7B10, 0.125)blnErrors = blnErrors Or Not BA_RPMFuel.Setup("Fuel Map RPM Scale", 16, &H7B00, 50)blnErrors = blnErrors Or Not BA_RPMTiming.Setup("Timing Map RPM Scale", 16, &H7B20, 50)blnErrors = blnErrors Or Not BA_TTPMin.Setup("TP Minimum Limit", 16, &H7E80, 0.125)blnErrors = blnErrors Or Not BA_TTPMax.Setup("TP Maximum Limit", 16, &H7E90, 0.125)blnErrors = blnErrors Or Not BA_TPLimit.Setup("TP Minimum Limit", 16, &H7960, 1)blnErrors = blnErrors Or Not BA_Recovery.Setup("Recovery", 16, &H7970, 1)blnErrors = blnErrors Or Not BA_ThroEnrich.Setup("Throttle Enrichment", 16, &H7E20, 1)blnErrors = blnErrors Or Not BA_IdleSpeedTemp.Setup("IdleSpeedWithTemperature", 32, &H76B0, 12.5)blnErrors = blnErrors Or Not BA_StartPulseIncTemp.Setup("StartPulseIncTemperature", 16, &H7E20, 1)blnErrors = blnErrors Or Not BA_DTS.Setup("Latency Change mS/V", 1, &H7F87, 0.00048828125)blnErrors = blnErrors Or Not BA_DRET.Setup("Detonation ign retard", 1, &H7FB8, 1)blnErrors = blnErrors Or Not BA_HGMC.Setup("High gear map coefficient", 1, &H7FC8, 1)

'Set up wordArraysblnErrors = blnErrors Or Not WA_KValue.Setup("KValue", 1, &H7F2B, 1)blnErrors = blnErrors Or Not WA_VQTable.Setup("VQTable", 64, &H7A70, 1)

[John Dixon]

'Set up Fuel MapsblnErrors = Not FM_Primary.Setup("PrimaryFuel", 16, 16, &H7D00)blnErrors = blnErrors Or Not FM_PriKnock.Setup("PrimaryKnockFuel", 16, 16, &H6C00)blnErrors = blnErrors Or Not FM_5th.Setup("HiGearFuel", 16, 16, &H6D00)blnErrors = blnErrors Or Not FM_5thKnock.Setup("HiGearKnockFuel", 16, 16, &H6E00)'Set up timing mapsblnErrors = blnErrors Or Not TM_Primary.Setup("PrimaryTiming", 16, 16, &H7800)blnErrors = blnErrors Or Not TM_Knock.Setup("KnockTiming", 16, 16, &H7C00)

[qsiguy]

Here's what I have for the knock settings. I guess I should change the knock retard degrees. Any idea how to convert 307*? Obviously can't retard that much so there must be a conversion factor. This value is the same as stock. Any idea what the values in the knock filters represent?

[qsiguy]

Any details I can get on these items would be appreciated. If I get back home from my business trip early enough Saturday I will be heading to a dyno day at a local performance shop.

I want to get my rough tune as good as I can before I get on the dyno. I'd hate to have to pull the plug because of too much detonation or something. I don't think I will have time to go get some race gas before the dyno. Best pump gas here is 91. Should I at least pour in a bottle or two of octane booster?

[John Dixon]

I think those tables are the knock limit tables used to decide when to switch the maps but I'm not 100%.Again, try Eric on ztechz, he's spent a lot of time looking at the ECU code.I think the scale should be rpm in 3600 increments vertically and TP horizontally.Failing any other info, I'd try setting them to 0

[T45]

A tank of 100 octane will be plenty. Boosters are....I'm sure you've read about them before.

[John Dixon]

Just did a bit of digging around and it looks like on the Z32 then those tables are scaled 0,1000,3600 rpm and 0,32,64TP.The values seem to represent some sort of sensitivity coefficient for the knock sensor. One when running on the primary maps, one when running on the knock maps. I guess you still need one on the knock maps so the ign det retard can still be applied if further knock is detected.I think setting them all to 0 should effectively disable knock detection.Failing that, you could link your knock sensors out with a 1Mohm resistor for tuning?

[ultrapulse]

That resistor to bypass the det sensor may want to be 0.5Mohm. Pretty sure the donut tests at 1meg accross an Ohmmeter but the ecu wants to see approx 500kOhm..Maybe thats the impedance at the particular resonance of detonation...

[qsiguy]

Yes, it's 500k ohm. I had one of mine bypassed for about a year until I just recently replaced them both.

Missed my first flight home from my trip and didn't make the dyno today. They said they do it every month which I didn't know. Also, they offered to give me the dyno day price any day of the week if I could make it in. I'll have to take them up on that offer.

Just did a bit of digging around and it looks like on the Z32 then those tables are scaled 0,1000,3600 rpm and 0,32,64TP...

I found a note regarding the High Octane Knock Filter. "Rows should be marked 0 RPM, 1000 RPM and 3200 RPM, but it won't let me" I believe this is a comment from Robert Bowen. So the values on the left are supposed to be RPM's.

Here are a couple more knock settings I found. Looks like to effectively disable knock detection you could also change the RPM and/or TP points where knock detection starts. Crank up the RPM or the TP to where it will never reach and I believe it would never be an issue. Even the minimum temperature could be increased. Not sure if that's IAT or coolant temp.


Modified by qsiguy at 9:29 PM 4/26/2008

[qsiguy]

I think I have the map trace data sorted out. deviousKA on the hybridKA boards disassembled the code and found the addresses I needed.

I still have to road test it but I ran it in park and revved it and all looks good so far.

I want to move this over to my tuning thread here:

zerothread/330027

I'd like to make it a single stop for VH45DE tuning info. I'll post the addresses over there.