{"id":858,"date":"2009-12-31T07:22:35","date_gmt":"2009-12-31T07:22:35","guid":{"rendered":"http:\/\/www.n5hrk.com\/blog\/?p=858"},"modified":"2018-08-24T17:16:25","modified_gmt":"2018-08-24T22:16:25","slug":"good-question","status":"publish","type":"post","link":"https:\/\/www.n5hrk.com\/blog\/mega-squirt-efi\/vw-trike\/good-question\/","title":{"rendered":"Good question"},"content":{"rendered":"
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A friend emailed me asking for clarification in the “big step” update:<\/p>\n

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Did you get the stepper motor working correctly? In the vid it went to full open then I wasn’t sure if that was the secondary’s @ 60% or the mains.<\/div>\n<\/blockquote>\n

I replied:<\/p>\n

Yes, working well. At least working as well as I can test with it removed from a running engine.<\/p>\n

The video depicts the subthrottle’s opening all the way under MegaSquirt control. This, via the cam, opens the main throttle a bit. MegaSquirt then works it back towards about 60%, by which time the main throttle is closed, as I manually adjust the CLT knob on the stimulator. CLT is megaspeak for coolant temperature, intended to represent the running temperature of the engine.<\/p>\n

The engine would (likely) not warm from freezing to 160F in 15 seconds, so the throttle would close in many smaller steps instead of the 3 or 4 big jumps shown here as I manually turn the CLT knob on the stimulator. Also, the actual throttle opening needed for warmup will probably be less than the full amount provided by the subthrottle cam. I wont know that for sure until it’s on the engine and the engine is running<\/p>\n

Perhaps obviously, neither Buzz nor the VW have “coolant”, at least not a self-contained recirculating coolant. Sometimes people use oil temp for this, but the engine is usually well into operating temperature before the oil gets very warm. Cylinder head temperature is a better representation of CLT on aircooled engines. On Buzz, I JB Weld’d the CLT sensor<\/a> between some cooling fins<\/a> cylinder #2.<\/p>\n

\"\"<\/a><\/p>\n

I was lucky that the fins on Buzz’s head were spaced similarly to the size of the default MegaSquirt CLT sensor. What’s more appropriate, especially for a VW, is something more like this cylinder head temperature sender<\/a> which goes under the spark plug like a washer. Trouble is that this is a thermocouple, which produces a small voltage based on temperature. MegaSquirt wants a thermistor, which varies resistance according to temperature.<\/p>\n

I may hack an IAT (intake air temp) sensor, which is electrically the same at the CLT, and see if I can get it crammed between some fins.<\/p>\n

Another complication with the VW is that you not only have to deal with the cooling tins, but what they represent: cooling air forced over the cylinder head, cooling the fins while you’re trying to read their temperature.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

A friend emailed me asking for clarification in the “big step” update: Did you get the stepper motor working correctly? In the vid it went to full open then I wasn’t sure if that was the secondary’s @ 60% or the mains. I replied: Yes, working well. At least working as well as I can … Continue reading Good question<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"class_list":["post-858","post","type-post","status-publish","format-standard","hentry","category-vw-trike"],"_links":{"self":[{"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/posts\/858","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/comments?post=858"}],"version-history":[{"count":4,"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/posts\/858\/revisions"}],"predecessor-version":[{"id":2019,"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/posts\/858\/revisions\/2019"}],"wp:attachment":[{"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/media?parent=858"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/categories?post=858"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.n5hrk.com\/blog\/wp-json\/wp\/v2\/tags?post=858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}