My Microsquirt Conversion, MSQ tuning file now posted |
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My Microsquirt Conversion, MSQ tuning file now posted |
rwilner |
Sep 27 2011, 08:29 PM
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#61
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No Ghosts in the Machine Group: Members Posts: 953 Joined: 30-March 10 From: Boston, MA Member No.: 11,530 Region Association: North East States |
Ok...
I'm converting my basically stock 2.0L (stock cam, euro Ps and Cs) over to microsquirt. Microsquirt is a megasquirt-derived fuel injection computer that's robot-soldered and factory encased in a weatherproof enclosure. The I/O is implemented as a single, 35-position weatherproof connector. The whole thing is about the size of 2 decks of cards. The system I'm installing was engineered and supplied 100% by McMark. My understanding is that he usually provides these systems for motors that he builds, but I talked him into providing one for me. Below, I will document the install details here for anyone else who talks McMark into selling them a system, or who attempts something similar someday. DISCLAIMER: I won't provide model numbers, prices, or any other info like that in this thread -- please contact McMark directly for those types of details. All I can say is that you get what you pay for and this is a top-notch system that will work for the remaining life of the car. The system provides the following components new:
OK, enough babbling, on to the install! (IMG:style_emoticons/default/chowtime.gif) |
914_teener |
Nov 14 2011, 12:38 AM
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#62
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914 Guru Group: Members Posts: 5,205 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
(IMG:style_emoticons/default/popcorn[1].gif)
Thanks for the update. I was wondering what happened to this install and thread. |
rwilner |
Nov 18 2011, 08:50 AM
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#63
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No Ghosts in the Machine Group: Members Posts: 953 Joined: 30-March 10 From: Boston, MA Member No.: 11,530 Region Association: North East States |
More Progress...
I pulled a plug after my initial tuning efforts. Think it was running a bit rich?! (IMG:https://lh4.googleusercontent.com/-tgutBC2xy4o/TsZqGcFAs7I/AAAAAAAAAd0/YRfxCfBjfaw/s800/running%2520rich.jpg) So I began to investigate and found several issues. Issue 1: My intake air temp sensor was reading as 0 degrees F. This is an obvious cause of rich running. The MS calculates fuel delivery using a volumetric efficiency (VE) table, where the amount of fuel injected is calculated based on the mass of air being sucked in via the intake. If I had a mass airflow sensor, that would be measured directly. Instead of a MAF sensor, I am using a MAP (pressure) sensor and the intake air temp sensor. The MS uses these two sensors and calculates the air mass using the ideal gas law. Well, 0 deg F air is wicked dense which means lots of fuel. It was just dumping fuel into the combustion chamber. I fixed this by RTFM and discovering the MS has an internal biasing resistance of 2490 ohms. I also characterized my IAT sensor in boiling water, freezing water, and at room temp. The results are shown in the attached screenshot: (IMG:https://lh4.googleusercontent.com/-SIJ3Fh9yrWw/TsZqGPJxyXI/AAAAAAAAAdw/hks3TlwPGnQ/s800/IAT%2520settings.png) Issue 2: The CHT was reading as 0 degrees F. The stock CHT grounds against the engine block (like a spark plug). The MS has the sensor ground separated from the dirty engine block ground. Well, that resulted in the CHT reading as an open circuit, since the resistance of the CHT had no ground reference. I was left with 3 options:
(IMG:https://lh3.googleusercontent.com/-zCBXLKSUTbk/TsZqGmXeUfI/AAAAAAAAAd8/clSQwOC-bVQ/s800/cht1.jpg) (IMG:https://lh3.googleusercontent.com/-uwQ8GV3lAEc/TsZqG3FBSiI/AAAAAAAAAeQ/THsIyW9d8_Y/s800/cht3.jpg) This should arrive today or tomorrow. I will characterize this sensor the same as the IAT, program it in and we should be in business. I also had to program the LC1 (oxygen sensor brain) to scale properly. Lesson learned: make sure every sensor is reading correctly and accurately before you even turn the key to start tuning. Seems obvious, but in the complication of getting the engine started, sometimes the obvious can be overlooked. I have saturday afternoon (55 deg and sunny) reserved for getting this thing on the road and driving, we'll see if I can make it happen! |
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