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Megasquirt tuning fun... (UPDATE)

Posted: Jun 21, 2012 9:51 PM
by clongo
I'm pretty new to MS. I have my E28 running pretty well at partial and full throttle. However, getting her to idle properly has been a bit of a issue.

I'm running MS2 extra that Peter Florance built with his P&P harness. He has been a great help with all of my questions. I just figured i would post here to get some other feedback.

I'm attaching my msq and a data log from this morning. When it's cool outside the car would run perfect. But when it would get over 85 degree's outside the car would idle really lean and hunt a lot. I tuned for a smooth idle yesterday when it was near 90 degree's outside. The idle was perfect at 13.2 when I was finished tuning it. However, when I drove it this morning 75 degree's it idle'd really rich in the low 11's.

I can't seem to get my idle consistent between cooler and hot weather. Also, if I try to restart my car while the engine is warmed out it doesn't want to idle at all without me cracking open the throttle for the first 10 seconds.

TIA!

2012-06-20_17.38.44.msq

I tried uploading the data log but it said the file size was too big. Can anyone host it for me?

Posted: Jun 21, 2012 10:03 PM
by M. Holtmeier
You need to tune your MAT correction table. Also, set your MAT correction value to 50 from 100. I assume your IAT sensor is plumbed after the intercooler really close to the engine.

Posted: Jun 21, 2012 10:09 PM
by clongo
IAT sensor is on the cold side of the intercooler as far from the engine as possible.

I'll look into tuning the MAT correction table.

Posted: Jun 21, 2012 10:19 PM
by M. Holtmeier
Do you have a good shot of the intercooler setup?

Posted: Jun 21, 2012 10:27 PM
by clongo
Image

Best photo I have right now. The sensor is on the end tank of the intercooler next to the fender.

Posted: Jun 21, 2012 11:13 PM
by M. Holtmeier
I can't believe the sensor is still heat soaked next to the fender. Here's a shot of my table. Don't start at 6, try to have the table come off a zero percent change to the map and add fuel as the temp rises and your afr leans out. I had my sensor mounted in the actual intake manifold to monitor the effect of water injection but since moved it to the location in your pic. (I have the TCD w/a that sits over the valve cover)

BTW, I see you have a tial bov- I just got my adapter welded on and am anxiously awaiting to hear it!

Image

Posted: Jun 22, 2012 8:42 AM
by clongo
M. Holtmeier wrote:
BTW, I see you have a tial bov- I just got my adapter welded on and am anxiously awaiting to hear it!
I love my Tial BOV. I switched to it from a HKS SSQ and its much better/less annoying.

As far as tuning MAT correction. Should I first tune the VE table at cold start, then mess with the MAT correction table once its warmed up to richen it up as the temp increases?

What do your AFR's look like when your car is started cold. I was always under the assumption its supposed to run rich for the first few min then lean out as its warmed up. But im not sure how rich it should after a cold start.

Posted: Jun 22, 2012 9:00 AM
by Jeremy
clongo wrote:As far as tuning MAT correction. Should I first tune the VE table at cold start, then mess with the MAT correction table once its warmed up to richen it up as the temp increases?
No. All of those changes should be made with the engine fully warmed up. If you're going to change VE, do it with the engine fully warm. MAT is there to compensate for environmental temperature changes and intercooler heat soak, not to tune engine warmup. Warmup Enrichment is the part that you tune to get the cold running settings correct. It modifies the fuel requirements based on coolant temperature.
clongo wrote:What do your AFR's look like when your car is started cold. I was always under the assumption its supposed to run rich for the first few min then lean out as its warmed up. But im not sure how rich it should after a cold start.
Give it whatever it likes. :laugh: The m30 runs real smooth rich, and that's probably where you want to be when the motor is cold. 12-13:1, I usually shoot for 13:1, but targets are a little harder to hit at idle because the air speeds are so slow.

Posted: Jun 22, 2012 10:18 AM
by clongo
How should the warmup enrichment curve look? I understand how it works in theory, but im unsure of the values that i should use to make it to run better. Is it just trial and error until you get it right?

Posted: Jun 22, 2012 11:45 AM
by M. Holtmeier
My particular setup starts with about 150% enrichment at 20 degrees and ramps down to 100% at 160.

If your wideband isn't set up to stay on during a start, I would make temporary changes so it does. Datalog the entire start-up and warm-up process. During warmup, just keep bumping the curve so it runs well. Mine starts and idles at 12.0 in pretty much any temperature. It doesn't idle perfectly, but the 62lb high-imp injectors and big cam have something to do with that. When I had the stock cam(b35) and 42lbers, that thing idled like a brand new car.

Posted: Jun 22, 2012 2:20 PM
by clongo
M. Holtmeier wrote:My particular setup starts with about 150% enrichment at 20 degrees and ramps down to 100% at 160.
Thats exactly how mine is setup. I'll play with turning the wideband on during cold start and tweaking the fuel. I'll take some data logs. Thanks for all the help so far!

Posted: Jun 23, 2012 9:19 PM
by marc79euro645
It will also help to level out your idle area as a flat plateau.
This keeps the idle from hunting around, do the same with spark map.
good luck
marc

Posted: Jun 26, 2012 3:16 AM
by ianwood
How does MAT correction know that it's heat soak and not just really high ambient air temps? Isn't there a difference between sitting in traffic at 80F vs. driving on the highway in Palm Springs where it's 110F outside? Wouldn't MAT correction result in a very rich mixture in the latter case?

One more question: would slowly rising AFRs at idle indicate the need for MAT correction? Say starting at 14.2 and ending up at 15.5 after 10 minutes or so? IAT steadily rising by almost 25F.

Posted: Jun 26, 2012 11:40 AM
by Jeremy
Intake air temperature is intake air temperature. Changes in fuel requirements are the same regardless of what causes the change in intake air temperature. The trick is making sure you're reading the intake air temperature accurately. Proper placement and mounting of the sensor are critical.

Posted: Jun 26, 2012 1:34 PM
by ianwood
Jeremy wrote:Intake air temperature is intake air temperature. Changes in fuel requirements are the same regardless of what causes the change in intake air temperature. The trick is making sure you're reading the intake air temperature accurately. Proper placement and mounting of the sensor are critical.
So, I get that IAT is IAT. But I am still a little unclear on what the MAT correction table is meant to do. Is it simply an adjustment on an adjustment used to fine tune how much fuel to add or subtract based on actual IAT? Or is it an an adjustment to compensate for IAT readings that are different from actual IAT (e.g. heat soaked sensor)? Or both?

Posted: Jun 26, 2012 1:38 PM
by Jeremy
The terms IAT and MAT both refer to the same thing AFAIK. Interchangeable terms. There might be subtle differences, but they're both accomplishing the same thing.

Posted: Jun 26, 2012 2:07 PM
by Brad D.
Jeremy wrote:The terms IAT and MAT both refer to the same thing AFAIK. Interchangeable terms. There might be subtle differences, but they're both accomplishing the same thing.
In this case they are the same thing. In a test cell we usually refer to IAT as the temp of the conditioned air entering the filter. MAT would be the temp in the manifold after heating from a turbo and cooling in a CAC. For our argument, use them interchangeably.

Posted: Jun 26, 2012 2:47 PM
by ianwood
I assumed they were interchangeable. To answer my own question from above, it appears according to MS2 Extra documentation that the MAT correction table is an adjustment on an adjustment (a fine tune if you will) and it is used to compensate for heat soak. So, it's both. Still wrapping my head around some of these concepts!
MSEXTRA wrote:MAT Correction

The MS2-Extra code also allows the user to fine tune the amount of correction given for the Air Density calculations that is worked out using the air temperature sensor. This compensates for some heat saturation from the plenum, or intake if the air sensor is in a particularly prone position to heat up due to heat saturation from the engine. This should be set to Zero for starters so the standard Air Density correction factor is used.

Posted: Jul 30, 2012 7:04 PM
by clongo
Can someone send me a pic of their warmup enrichment settings? I'm making some good progress so far. I still need to iron out a few kinks, but I think im on the right path.

Posted: Aug 01, 2012 10:47 PM
by marc79euro645
No pics but mine are as follows
-40f to 40f = 140% (but it rarely gets that cold here,so who knows)
60f = 130%
80f = 115
100f = 110
130f = 105
160f = 100

Posted: Aug 24, 2012 4:52 PM
by Russianblue
Jeremy wrote: No. All of those changes should be made with the engine fully warmed up. If you're going to change VE, do it with the engine fully warm. MAT is there to compensate for environmental temperature changes and intercooler heat soak, not to tune engine warmup. Warmup Enrichment is the part that you tune to get the cold running settings correct. It modifies the fuel requirements based on coolant temperature.
is there a sticky or other high level guide which shows the chronological order suggested for each aspect of the tuning process? this is one of the things i find most frustrating about tuning...getting along well into the process and then finding out i should have tuned X before i tuned Y.

Posted: Aug 24, 2012 10:51 PM
by clongo
Russianblue, The issue is there is no definitive answer as to what to tune first. A lot of changes you make to one part of the tune will require you to go back and tweak other parts of the tune.

And on a side note my wife and I have a russianblue. She got a kick out of your sn and avatar, lol.

Posted: Oct 23, 2012 1:02 PM
by clongo
Update time!

I've got my idle and cold start issues figured out. My only issue at this point is restarting the car once its warmed up. I have updated my firmware to pre3.3alpha with the gslenderv2.8 software. Peter Florance advised me to give this update a go as it has a option to ignore MAT signal during the first 10 second's the car run's upon hot restart. I have managed to get the car to restart ok a few times since this update without having to give it any throttle input, but most of the time it still run's way lean and wants to die within the first 10 second's. I have tried maxing the MAT correction to 130% and it still lean's out. Anyone have any idea's what could cause this? I attached my msq.

2012-10-23_12.24.38.msq

Also, what are you guys running for timing at idle? I lowered my timing to 18* and it seem's to not hunt as much at idle.

Thanks again for everyone's help!

Posted: Oct 23, 2012 6:26 PM
by clongo
Here is a datalog that I did when I got home. I turned the car off and immediately restarted it. It did not stall this time, but if I were to let it set for 10-15min it will stall upon restart as it heat soaks more.

2012-10-23_18.21.18.msl

Posted: Nov 23, 2012 2:24 PM
by espeed
clongo wrote:Here is a datalog that I did when I got home. I turned the car off and immediately restarted it. It did not stall this time, but if I were to let it set for 10-15min it will stall upon restart as it heat soaks more.

2012-10-23_18.21.18.msl
Interesting.. is that consistent with other users?

Posted: Nov 26, 2012 9:35 AM
by Lulu66
clongo wrote:Update time!

I've got my idle and cold start issues figured out. My only issue at this point is restarting the car once its warmed up. I have updated my firmware to pre3.3alpha with the gslenderv2.8 software. Peter Florance advised me to give this update a go as it has a option to ignore MAT signal during the first 10 second's the car run's upon hot restart. I have managed to get the car to restart ok a few times since this update without having to give it any throttle input, but most of the time it still run's way lean and wants to die within the first 10 second's. I have tried maxing the MAT correction to 130% and it still lean's out. Anyone have any idea's what could cause this? I attached my
2012-10-23_12.24.38.msq

Also, what are you guys running for timing at idle? I lowered my timing to 18* and it seem's to not hunt as much at idle.

Thanks again for everyone's help!
Under iddle control check the start value steps and the crank to run taper time. When you first start up your iac pintle will automatically go to this position(start value) then taper down to the correct position within the specified time(crank to run taper time). That might be causing your lean spot upon startup.