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Old 06-18-2013, 12:31 AM   #1
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Default 90-93 DIY MS (START/IDLE ISSUES)

So I bought a used "brain-built" Megasquirt standalone, and I've run into a few issues in my install.


Here are some pictures for perspective, so you can see what I am referring to.
MS - Imgur


And Car-information:

92 NA, with a tdO4 greddy-Frankenstein kit, begi 2.5'' downpipe, 2.5" test-back, big intercooler, 315cc Supra Green-top Injectors, Walbro 190 Fuel Pump, MTX-L wideband.


MS Specific: I am using both the STOCK AFM and the STOCK TPS. (I will be getting an IAT/TPS I know...)



So,


The MS appears to be ready for shift light & EBC, but that's about all I really know about this board.

I do not have an EBC, so I don't use the exposed grn/white wire, and I'm unsure about the "relay" brown wire, or the yellow unknown wire (coolant down side). I've pulled the TPS, removed SIGN fuse, wired my WBo2 to the pink wire pictured, double-checked guides for editing a basemap (incl injector options), and managed to get the car to start!

Currently, it starts but barely holds idle..its rough and my AFRs are super lean (~20+). If I touch the throttle the rpms dip, it almost dies, and then it kind of "catches up" for a second. The radiator fan also seems to kick on immediately following start-up (I've uploaded easytherm data for stock AFM(iat) and CLT) It behaves like it is only running on a few cylinders. I've downloaded a base-map for similar setup, and double checked the settings to make sure they match, and I have adjusted timing/injector size for my vehicle.
I've got WBo2 readings, Clt, Air, RPM and MAP/bar on TS Dashboard. They even appear ~accurate.

Plugging my stock ECU back in completely fixes any issues, so I know I didn't fry anything on the car .

I'm not sure if I need to be re-wiring anything additional, changing software/tune, or fixing something broken. I've been staring at a wiring diagram for the MS, but the point of buying it built was to avoid this process, although I am growing impatient enough to tackle it.
Do I need to ground anything on the MS since I have the stock TPS? I've unplugged it and I've got mixed advice coming in. Also, I am not sure if I need to calibrate the TPS with it removed (dumb concept) but a few values seem to rely on TPS. I've got acceleration on MAPdot in TS.

(I also have a Cartech RRFPR installed, the last of my bandaids. It keeps my afrs down when I need to use stock ECU to drive between working on the MS. Could this be the culprit? It will be removed anyway, but I've heard of people keeping them on)

Last edited by gompers; 06-18-2013 at 01:07 AM. Reason: More info/Specificity
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Old 06-18-2013, 08:20 AM   #2
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the yellow wire should be in the harness, are you not getting a CLT reading? What is the current Req_fuel value, you should be closer to 12.0 now, I'm sure Tyson had it much lower on larger injectors.
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Old 06-18-2013, 10:12 AM   #3
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Quote:
Originally Posted by Braineack View Post
the yellow wire should be in the harness, are you not getting a CLT reading? What is the current Req_fuel value, you should be closer to 12.0 now, I'm sure Tyson had it much lower on larger injectors.
Currently req_fuel is ~9, after setting injector size. I took the time to redo VE and AFR target tables according to DIY pnp suggestion/basemaps and several user-posted maps (I ignored Hustler's ), so I'll tweak req some more.

I am getting CLT, but I will verify its accuracy.
So I should be intercepting the coolant wire from the stock harness with the floating Coolant Wire (in middle of your harness)?. I am unsure of the exact build-specs that Tyson originally requested, but I assumed the harness was built to intercept the coolant sensor through its harness. I'll go fool around with it more since the fan kicking on is an odd sign, and see if I can decipher more wiring diagrams.

Any clue what "V???" (vtps??) wire is on the harness, and what the "RELAY" is for? I assume its for mods I don't have, but I didn't build it haha.
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Old 06-18-2013, 10:27 AM   #4
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I couldnt get the pics to work earlier, now they are. let me review. It's been close to 5-6 years since I touched that ECU.

But your req_fuel should be much higher. I used to use ~13.0 for stock 230cc injectors on an MS1, using 305s should bring it to clsoer to 10. I'd keep increasing it until the loaded fuel map gets your AFRs that make more sense. He that that map for a while and it should be a good jumping off point for you the actual req_fuel value doesn't really matter--it's just a multiplier.


Can you tell me what pins on the db37 connector the green/white, blue/white and black wires go back to?

Last edited by Braineack; 06-18-2013 at 10:38 AM.
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Old 06-19-2013, 02:05 AM   #5
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Heres a better shot of the connector too.

Http://imgur.com/ZUmL1Zw

http://imgur.com/OP2EQEk

http://imgur.com/iRzJMrU

http://imgur.com/eGSiK0i
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Old 06-19-2013, 08:32 AM   #6
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The yellow and gray wire on the middle connector are unimportant. IIRC it was done for water injection.

The Gray wire labeled "relay" is a simple circuit that can trigger a ground at a given trigger, unsure what output it's on, as I'd need to see the bottom of the board or your msq. But it be left unused, it was to activate the relay to turn on the water injection pump.

The Yellow wire was most likely labeled "valve" for the water injection fast acting valve.

If you look at your codebase options and settings, im sure JS0 is set to water injection.

to learn more: MSnS-Extra Hardware Manual




The two wires coming out the side of the case are the seq. shift light grounds. He was able to set two different RPM points for lights as seen here:




Other than that, everything else is business as usual. The only thing being there isn't anything to activate the a/c if you have it, if you have a/c let me know and I can tell you how to add it to the harness, it's a simple jumper to two unused pins on the yellow connector.
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Old 06-20-2013, 01:15 AM   #7
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After tweaking req_fuel, associated VE tables, and fixing the timing the car idles great. Gotta fool around with some idle settings, VE, and timing, but all looks good
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