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taaron

Megasquirt Base Tune

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So I finally have my car up and driving a little bit (no where near road ready but enough to move under her own power). The problem I'm having right now is my base tune. The car is smoking like a fiend and I'm fairly certain I'm running rich. Plus I'm an utter novice at all this. I was wondering if anyone had a base tune they could share with me, just a 78 NA with 265cc injectors (but living in Denver [5000ft]). Any help would be appreciated, I'm tired of fouling plugs after a few minutes. 

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I do have a wideband installed, just not the ability to really drive around at the moment (15 feet in the alley is about as far as I can go). I know that Tunerstudio has the auto tune functionality, I'm just not sure how much you need to give it as a base. Like I've heard it auto tunes out that last 5% but you can't rely strictly on that. 

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If it runs and is getting solid AFR data, that's enough of a base. You might have to babysit it for a little bit, but it should get you in the ballpark. It won't be perfect, but unless you are taking the car to a dyno, you're not going to have a fully optimized tune. If you're fouling plugs, it sounds like something is way off. I'd go back and make sure your initial injector settings are correct, and use the test modes to ensure that they are opening/closing correctly, rather than stuck open.

 

Other things to do if you can: Look at your AFR reading when you're at idle to verify you're running rich. Then, look at your VE and AFR Target tables while it's idling, there might be some obvious changes you can make. You can also do some searching over at MSExtra and see if someone there has a base tune. 

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So I've had some luck using the auto generating Fuel tables. However, I'm noticing that my idle MAP sensor is about 60kpa. Every thing i've seen online shows people typically idling near 35kpa. Is this plausible? At ambient, imat  like 83kpa which seems right for Denver. 

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Do you have a stock cam?   My aftermarket cam idled around 10-12”s pending how well I had tuned it.   Stock is probably more like 16-18”.   Id use Kpa but it’s been a while since I used megasquirt and I forget which was it measures idle kPa. It’s different then my Haltech.

 

tossing a mile high of elevation is going to throw everything out the window anyway.  If it’s idling nicely, take that as your baseline.

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800 rpm, looks like 10.1.  I can't seem to get it to drop below 10.1

 

Does the MAP effect the AFR or vice versa

 

Edit:

So I'm making progress. The TPS was reading pedal inputs completely wrong. Got that wiring corrected and is happy again. I then realized that 10.1 may not be a reading and instead a fault. And it was. Power wasn't connected to the O2 sensor. 

 

So now I'm getting readings around 11 at idle and still near 800 rpm. I try and run the auto tune and it doesn't seem to be changing anything/ afr isn't really coming up. 

 

Edited by taaron
more info

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In Tuner Studio, be sure to set Baro to Initial MAP Reading.  My L28ET idles at around 35kpa.

 

The default settings in Tuner Studio will likely not make changes at idle. Check the "Advanced Settings" tab and see what limits are set. Autotune will only make changes to the table within those parameters which generally include a minimum engine temperature, a set kpa (load) range, and a set RPM range. I think idle normally falls outside the default ranges.

There is also an Idle VE Table you can work with. If you have followed the "Setting Up" steps in the documentation, you really should have a fairly safe usable starting point. You may also want to look at Andy Whittles YouTube videos. He has some decent videos up on Megasquirt and using Tuner Studio.

 

If you do a lot of mountain driving up there with substantial elevation changes you should probably look at a dual MAP sensor or a secondary MAP sensor open to the atmosphere for a barometric reading.

Edited by cgsheen

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Tune your idle manually. Once fully warmed up, set your base timing 15-20 degrees (I’d go 15 if stock cam, higher with a larger cam, you can adjust this once you have a stable idle. Adjust for best vacuum).  Lock all idle regions with the same timing.    Then dial in your VE table to get your best stable idle. Change all VE cells in the area of your idle at the same time with the same number. Once it stabilizes you can fine tune from there.   

Edited by HuD 91gt

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Thanks everyone who keeps responding! I'm absolutely making progress. My rich smoke is gone. 

 

Basically this morning, went in and confirmed my timing was correct. Not sure if it matters, my offset was set to 363 degrees for some reason, brought it back down to 3 degrees. Confirmed with a light I was at 10degrees btdc. Also was thinking, what could make my idle MAP reading so high, and I started thinking about vacuum leaks. I realized that my intake manifold was littered with hoses I had forgotten to tighten up. After I did that, I checked my connection to the Megasquirt, and realized that the air fitting I have on there is way incorrect. The hose was a bigger ID than the fitting OD. Using some tape and a hose clamp, I was able to tighten that guy up in the mean time. Got in the car, fired it up, and my MAP was reading right!! Hanging out between 30kpa and 40kpa (I don't remember exact numbers). I need to order some better air fittings to finish everything up. 

 

I also went ahead and lowered a bunch of Fuel VE values near where I should be idling, and low and behold it brought my AFR closer to 14.7. It brought it close enough that I was infact able to actually run the engine and use the auto tune to smooth things out a little bit. 

 

Honestly, today went so well, that I decided to drive the car. For the first time in 3 years, it was on the road. The engine sounded strong and healthy, yet smooth. I even managed to capture a shot with my daily and other side project. I feel totally reinvigorated after today. Thanks everyone whos helped!

 

Obviously I still have a far way to go, next task is to figure out why it doesn't always like to come back down to idle.  It tends to sit up at like 1100-1300 rpm after driving just a little and never come back down. However, thats fine tuning. 

20200126_125203.jpg

20200126_125219.jpg

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Super possible its an air leak. I'm waiting on some new fittings this weekend to try and get all my air situation sorted out. Theres a few different idle control settings, but I'm definitely limited by not having any kind of controllable input. I was planning on playing with this Idle Advance settings once I'm sure theres no air leaks left this weekend. 

 

image.png.1621ef23da952e64eff03ccb9001561c.png

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My guess would be a vacuum leak too.

 

But since your map is probably a bit of a mess, pending your IGNITION advance at idle is quite low, it’s possible coming down the RPM range the car is quite a bit happier at the higher ignition advance in the higher rev range. Basically establishing a higher idle.... until it eventually stumbles and falls down further to your original “idle”.


 

Setting ignition advance below your planned Idle speed, a couple degrees higher is a way to stabilize your idle so when it falls in RPM, it automatically bumps up to your planned idle.
 

Eg.

500RPM - 20 degrees

800RPM - 17 degrees (Planned idle)

1500RPM - 25 degrees

 


If things are really out of whack, your engine could be much happier at 1300RPM and 20ish degrees of timing to the point where it just stays there.

Edited by HuD 91gt

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So. My exhaust manifold was absolutely loose. Like badly. Definitely wasn't helping things. Unfortunately now I also have some pretty bad knock I can't get rid of, and definitely can't get the car into a lower idle. Does anyone know of any tuners that could take a look and tell me where I'm being dumb. I'm hoping that the knock isn't fatal. 

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Engine RPM are controlled by air flow.  If you cut off all of the air the engine must die.  Close off your idle speed screw until the idle speed drops.  If you close it all the way and the engine keeps running you have an air leak in your intake system.  You should verify that before getting carried away with other stuff.

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All is good with the leaks. It seems like everyday theres something new. So I had recently been experiencing some knocking sound. (Car sits in my garage, not road worthy so engine isn't getting really abused). Finally took the valve cover off last night and was greeted by this sight. Turns out I had a rocker arm completely jump ship. I'm going to get this all back into place then re-set my clearances. Hopefully fixing the knocking. Then I can check timing again, then get back to tuning properly. 

2020-02-23.jpg

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6 hours ago, taaron said:

All is good with the leaks. It seems like everyday theres something new. So I had recently been experiencing some knocking sound. (Car sits in my garage, not road worthy so engine isn't getting really abused). Finally took the valve cover off last night and was greeted by this sight. Turns out I had a rocker arm completely jump ship. I'm going to get this all back into place then re-set my clearances. Hopefully fixing the knocking. Then I can check timing again, then get back to tuning properly. 

2020-02-23.jpg

 

Uhhh, that could be bad lighting...but your oil looks pretty milky. If it is, might also have something to do with your knocking sound. You should do a solid mechanical once over before you try to tune. You'll be chasing your tail trying to fix mechanical problems in the tune.

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