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Birth of my Home Made ECU

Old 07-21-2005, 12:37 PM
1.0 BAR
Thread Starter
Join Date: Apr 2005
Posts: 375
Default Birth of my Home Made ECU

Ok cant afford the Megasquirt.
So on a shoe string budget building something to help me run some good boost. On my cheap-arsed 8 valve 1.3ltr Suzuki. CARBED ENGINE

Initally it was I just want an acurate Digital Boost gauge.
This then became let me set what PSI my WG will open at.
That then became let me fire an injector for alky/watter at a certain PSI.
Then somebody found an Old narrow band sensor. And said why not fire the injector if we go lean. Anyway as posted elsewhere.

Its shaping up to be a Digital gauge that shows the Boost, the O2 Output as a ratio or as a lean / rich bar. That controls the wg and the Cold start injector.

If condition = lean and Boost exists fire injector.
Store min / max values for boost and O2 readings.

Plan of action.
1. The PCB for the Display and pic is done.
2. Develop seprate PCBs for the map sensor. And for the O2 sensor. Test on bread board and then convert to a single PCB.
3. Make a parts list and the PCB avalible as a free download for the HMT guys.

Help Im looking for
1. How does the Cold start Injector's working varry from a regular injector.
2. I have a single MPX4250AP which is working. I have 5 numbers of MPX4250DP but the DP shows a PSI reading of 1.2 why when both the DP and AP share the same data sheet is one working and the other not.

Ps: My 10$ Display budget only affords me this cheap 2 line display for 20-30$ you can have a graphical LCD display which would allow you to plot graphs etc. Pics of the breadbord are the Map sensor circuit. With two mosfets to triger two devices. Next will be the Narrow band o2 pre-amp circuit.

chinoy is offline  
Old 07-21-2005, 10:18 PM
0.5 BAR
Join Date: May 2003
Posts: 152
Default Re: Birth of my Home Made ECU

your crazy, just drop another $100 and buy the rest of the parts to build a Megasquirt! haha

You must have way too much time on your hands, interesting concept tho I must say

neil85ae86 is offline  
Old 07-21-2005, 11:53 PM
1.0 BAR
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Join Date: Apr 2005
Posts: 375
Default Re: Birth of my Home Made ECU

As discused elsewhere Megasquirt not my cupa tea. As well as imposible for where I am.

Anyway I figured why Im geting the diffirent readings on the DP. vs AP
AP is say showing 12.7 DP is showing 1.3 which is correct cause 14-12.7=1.3
So the DP is actually showing me my vacum value due to elevation.
It hit me while falling asleep. Problem solved.
For the injectors will just setup a test jig.
For the O2 have got some samples LM9044 neat stuff. Check it out.
chinoy is offline  
Old 07-22-2005, 12:04 AM
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Join Date: Jan 2003
Posts: 4,403
Default Re: Birth of my Home Made ECU

thats nuts but i know the cold start injectors squirt purty much in a strait path as if you where pising while regular injectors make a mist like a shower. ehh thats all i know. blame osama
RENR is offline  
Old 07-22-2005, 02:06 AM
1.0 BAR
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Join Date: Apr 2005
Posts: 375
Default Re: Birth of my Home Made ECU

Megasquirt makes me feel like ive been put in a straight jacket. i.e. you cant customize anything. You cant say hum I want to do this. And then I want to do that and then I want to tie in my Ignition like that.

I have a problem with anything that makes me feel clutophobic Blame it on osama

Im sure its a great kit just not my cup of tea.
And knowing my experience with kits. Probally wouldnt even be able to get it to run. Megasquirt must have its applications. Just not too sure its the best solution to my carbed engine and turbo setup.

The cold start I have gives off a nice mist. Remember this is just a booster shot to what the carbs allready feeding the engine. Am loking into driving regular injectors as they are easier to find at the wreckers.
Lastlly Megasquirt=170+40(SH)=210 + 180% Import duty. You may be able to smugle in one kit as a gift. Not more than that. vs this kit what will probally land up costing me less than 40 bucks.

Besides isnt this place all about DIY the pride and satisfaction Ill get when this is done will pale vs soldering together some other guys bits and bobs.

chinoy is offline  
Old 07-22-2005, 04:31 AM
3.0 BAR
Join Date: Aug 2003
Posts: 3,930
Default Re: Birth of my Home Made ECU

how about you get a job so you don't have to ---- around with 1.3 liter CARBED engines and toyotas throw away cold start injectors. Why would you want to run a extra injector? just tune the ------- carbs. and then use a regular old vacumn canister for boost control with a 9 dollar home made manual boost controller.

I really don't understand why you are overcomplicating everything for some ****** little susuki engine that might put down 140whp.

hahahaha, im just kidding, just bustin your chops. That thing is gona be really sweet, you must be really into that stuff, looks like a fun little project, that anybody could use. Can't wait to see the scetches and ---- after.... o by the way if im acting weird its cause i just took some crazy mush.
Spenser is offline  
Old 07-23-2005, 01:25 AM
1.0 BAR
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Join Date: Apr 2005
Posts: 375
Default Re: Birth of my Home Made ECU

Actually in this part of the world. The Suzuki "Esteem" as its called is acutally what the rich uperr class guys ride.
When it was purchased it was one of the best cars avalible in the market.
Cheap cars are the Maruti 800 and the Fiat 1100.
In a country where the avrage motorcycle cc is 100cc. The largest bike being produced is 220cc and most cars ae 800cc. A 1.3 Ltr is quite the catch.

Besides this is the perfect learner car to experiment with. Once we have it all sorted can get a fancier imported car and turbo that.

If your still on that good mush. Try and contemplate the world beyond USA. Its a big world. Diffirent countires. Diffirent life styles. Some countries where the number of bullakarts still exceed the number of cars bla bla bla.
chinoy is offline  
Old 07-23-2005, 03:20 AM
3.0 BAR
Join Date: Mar 2003
Posts: 4,219
Default Re: Birth of my Home Made ECU

what country is that? congratulations anyway if it were'nt for people like you we would'nt have uberdata, and all the other free diy ideas out there.
rudebwoy is offline  
Old 07-23-2005, 11:32 AM
1.0 BAR
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Join Date: Apr 2005
Posts: 375
Default Re: Birth of my Home Made ECU

Can we try and have some constructive posts on the subject.
Im still not sure about one issue why does the AP and the DP give out diffirent readings. When they both share the same data sheet.
Also is the reading of 12.74 or whatever we are geting right. WHen nothing is hooked up. Anyway since the Map circuit is done. Busy trying to finish the O2 part.
I get the feeling if some Yank had made this post the responces would have been diffirent.
Ive seen more excitement over a Radiator cap for BOV post.
chinoy is offline  

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