OK, I think I finally found the correlation. I think it has to do with Maf Hz. I logged 2-byte Maf Hz and went for a cruise/log today. When I zoom in on Maf Hz to provide sufficient resolution, Maf Hz seems to almost completely correlate with the jumpy IPW.

I will have to re-read John's thread on the full path to IPW to see if he talks about it, but how is the Maf Hz calculated with the SD patch? John, if you read this, and know off the top of your head, let me know. Mrfred, if you read this and know as well, any help would be appreciated.

I'll try to post some screenshots to show what I see after I am done looking over this entire log.

OK, here is a screenshot that shows what I am referring to. I have the Hz zoomed in quite a bit, so that may be exaggerating the correlation, but the jumps/dips in Hz are about a swing of 10Hz in the 150 Hz range. It may just be a combination of everything: map, map ve, rpm ve, hz, stft, all playing their own part. But, I don't understand why it happens in this one specific map/rpm range though:



The Maf Hz is the jagged line on the bottom...the IPW is the jagged line just above it.


Eric

 

Eric, I'm noticing the same hesitation/jerkiness that you are experiencing as well.
I'm going to play with it some more before I post a log.

 

That actually makes me feel a little better and gives me hope that it's not my ROM or something that I have done to it.

Maybe it's something just with 96530006 since John hadn't noticed anything in his ROM. I'm curious if others using SD have experienced something similar. I think Creamo3 in the other thread may be experiencing something similar with a different ROM, but I haven't seen any logs yet.

 

Well, I made some progress today, still have a ways to go though.

Eric, attatched is a DMA log saved as .log file that can be viewed in Logworks if you want to see if the same problem is there. I can defanitely feel cruise is rough in the same RPM window that you are describing, kpa in that window is a bit lower than yours probably due to altitude.

 

Any chance the jitter in the MAP is just the cylinder pulses?

A lot of guys that run speed density tend to get the MAP off the manifold and onto a line. The flexibility in the line combined with the volume of air in the line help damp out the pressure variation generated by the dynamic nature of the IC engine.

The pulses are likely to be most prevalent in mid throttle conditions where the pulses are strong from higher engine speeds, but the throttle still posses as a throttling device to drop average plenum pressure but not greatly reduce pulse transportation.

 

Eric, I'll have to read the other thread as well to remind myself what filters are on it and the exact calculation, but MAF Hz is part of the IPW correlation. MAF Hz is calculated from the MAFSOURCEMAINxMAFMULTIPWARMUP, so I suspect you'll also have some jitter in the load value as well when you look closely, but maybe the MAF Hz calculation amplifies it if RPM also starts to jitter.

I think at this airflow/engine speed/pressure you have some resonance or you're picking up pulsations. I did not see this with the JDM MAP sensor in its original place. Perhaps it has a slower response time, perhaps it has a different diaphragm arrangement to the MAP sensor you're using.

So, we'll look at the MAF Hz calculation & filters, you can think about your MAP sensor. I doubt that mrfred has done anything different with the code, otherwise you'd have a systematic offset or problem, rather than a resonance at a certain point.

 

https://www.evolutionm.net/forums/ec...tor-pulse.html

From the first post in that thread:
AIRFLOW=MAFSOURCEMAIN/TIMEBETWEENCASPULSES, used to lookup MAFSCALING, MAFSMOOTHING, TEMPBAROAIRFLOWLOOKUP to give MAFsmthsclgfactorxINJSCALING

AIRFLOW is like LOAD*RPM then.

MAFSCALING is doing part of your VE compensation, but it doesn't seem steep at about 150Hz, but any RPM fluctuation induced could amplify the problem.

The filtering is done before load is calculated, we could change the filter level and make it smoother, but this may reduce transient response elsewhere - CORRECTION - see next post.

Since I no longer have my car (although I am adoring the new one ) I cannot do detailed logs in this area to prove categorically that the JDM 3 bar sensor fixes it.

Do you have an option to borrow or try or switch to a JDM 3 bar or do you want to play with the filter which I can find for your ROM?

 

The filtering is done based on previous and present MAF sensor pulse counts, but it is done BEFORE we replace the values with our SD calculations, so there is NO FILTERING with SD, so no filter to adjust.

So two options, you could use Tephra's MAP averaging (if he has made it adjustable, I never tried it) and see if there is a good compromise that makes it smooth without killing throttle response, or you could look at the MAP sensor hardware you're using and if you don't need more than about 30 PSI you could use the JDM sensor (need to confirm with other's logs that it doesn't do this) or identify other sensors that don't jitter like this.

 

Gear head - thanks for the logs. I will take a look later today when I get a chance.

John - thanks for the help and insight. I actually re-read that thread and was going to ask about the filter for Hz.

I have another thought, that may or may not help much at all. I was thinking about flattening the maf scaling and maf smoothing table (maf smoothing is already just about flat) in the area of concern. Since we have the map VE and RPM VE tables to adjust, we shouldn't need the maf scaling table (which is basically another VE table) to add in another source for error. Sort of like the reverse of your easy speed density thread, except just target the 125-225Hz range.

As far as the map sensor: I have tried tephra's map averaging and the issue was still present. I have also logged 16 bit map and the variation was subtle during this...maybe 1-2 kPa deviation. The only thing that remotely seems linked so far is the Maf Hz. RPM does seem jittery as well sometimes, but I think this is a side effect of the IPW being jittery, so an effect rather than cause.

So, I'll give the maf scaling thing a try and see if that helps the issue at all. I hope this doesn't scare people off though. I have been running this patch for more than a week now and daily drive the car with it. Everything works fine outside this small range, but obviously something is a amiss and I would like to figure it out.

Thanks for your help, John, as always. Enjoy your GTR.


Eric

 

Thanks for the log. I just took a look and you seem to have the same issue as me, in pretty much the same exact area as me. I also noticed one example in your log at a higher RPM/kpa as well. But, for the most part, that same exact RPM/kpa range seems to give you a jumpy IPW as well.

I will be a bit busy today, but I will try some things out and keep reporting back with any results. I think my next round of tests will involve the maf scaling table as mentioned in my previous post.

 

Eric, I think you need to see if Tephra's averaging is adjustable, or whether he has hard coded it.

Can you really perceive no more jitter in the MAP signal when the IPW jitters? Just a wild thought, make sure your coolant temperature is steady during the jittering.

I didn't see much gradient in the MAF scaling table at around your problem point, but it is worth a try certainly.

 

Are you thinking that a remote mounted sensor may give different/better results?

No problem, just trying to help get all this stuff sorted out.

I forgot to mention that log was on a 5.10 ROM. For some reason I have not been able to write to RAM with the v7t6 so I haven't switched yet. I'm going to double check everything & try to get that working today....So tired of flashing small changes

 

I am having a problem with writing to RAM. Everytime I try to make a change, and hit write on the data page it fails. I can read from RAM just fine. Anyone know whats up with that?

 

There was an update to the instructions that corrected a problem with writes; you might be running the original version of the instructions. Instructions on patching, and instructions on fixing the problem if you already went through applying the patches, and just need to fix this issue.

 

I wanted to share, I was logging boost before with a GM 3-bar and the values I'd get would be very jumpy. I got the JDM 3-bar and the values I log are WAY smoother (not even using MAP averaging)

The gm 3-bar was plumbed off a line, not on the manifold.

Also I want to say to l2r99gst great job on the charting addition to Evo Live Map.