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Old 06-23-2008, 12:24 AM   #1
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Default Ahhh, squirtin'! Got some ?s

Bone stock '94. DIY MSIv3, parallel install with a boomslang following Brain's writeup. Hires 10g firmware, currently using the .msq from DIYautotune and their fuel & spark maps. The car started right up, and it just took me a couple minutes to dial in the trigger angle.

I easythermed it using the appropriate values in the writeup (in my case, 1450 bias for both) and the IAT and CLT readings look good in Megatune. MAP at idle is in the vicinity of 28-30 kPa, tach works fine (I did the cap mod).

I'm getting a CEL, not blinking an actual code, just staying solidly on, all the time. The MAF itself is disconnected and I have the IAT sensor plugged into the two pins in the MAF plug per the writeup. I did a search and it seems the CEL could be due to no MAF signal to the stock ECU. There were some ideas tossed around (resistor between two other pins in the MAF connector?) but I didn't see what I thought was a nice tested & proven resolution to the problem other than A) pulling the bulb or B) going standalone. Is there a simple way to spoof the stock ECU, assuming this is what's causing the CEL?

Other than the CEL, no problems. I drove around the neighborhood a bit and it ran fine. Nothing has really been tuned yet but it seemed fairly smooth all things considered. It's responsive and smooth when I get on the gas, although it seems a little more "sudden" and less smooth on decel compared stock. I just took it easy, didn't go WOT or much above 4000 rpm since I've got 87 octane in the tank at the moment.

I still have the stock NBO2. Yes, an LC1 is in my future. Is there any point to running either autotune or the VE analyzer in MLV, using the stock O2 sensor?

Thanks to all you guys for lighting the way. I'm really stoked that the car runs off a computer that I built! It's like the first time I fired up that tube preamp I built, or the first decent batch of beer I brewed. Sure there's lots of room for improvement, but I've got a touch of the proud poppa syndrome.
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Old 06-23-2008, 01:18 AM   #2
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You should just go to the autostore instead of stabbing in the dark.

Free code checking.

As far as I have heard, pulling MAF should not throw CEL.
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Old 06-23-2008, 01:55 AM   #3
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Those of us with OBDI don't need auto parts stores to check our codes, just a paper clip.

When verifying that I was using the correct tick mark on the crank pulley for my timing, I had put things back to stock temporarily (remove MS & boomslang, just run the stock ECU with the IAT sensor removed and the MAF hooked back up) and had jumpered GND and TEN in the diagnostic port. The CEL blinked code 8 which is a MAF code. It didn't blink any other codes. I can clear the code and be CEL-free with a stock setup, but when I run the MS with the MAF unplugged (IAT pins in the MAF connector) it throws a CEL again.
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Old 06-23-2008, 02:07 AM   #4
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Pulling the MAF throws a CEL on your car, just how it is. A simple resistor will not fake the signal, the circuit is "smarter" then that. Deal with it or figure out how to use EBC to fake it like arkmage was hoping to do someday.
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Old 06-23-2008, 02:32 AM   #5
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My CEL is very intermittent and I can not figure out what triggers it. I really don't care that much. The MS on laptop is showing me alot more of whats going on in the motor than a yellow light ever will.
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Old 06-23-2008, 07:22 AM   #6
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I had the same issue on my 94. It gives you the code saying your maf is missing if you choose to look it up. I was to lazy to pull the bulb out so instead I jsut cut the wire for the CEL in the wiring harness. It easily solved that problem.
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Old 06-23-2008, 08:48 AM   #7
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go standalone.
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Old 06-23-2008, 11:27 AM   #8
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Quote:
Originally Posted by shuiend View Post
...I jsut cut the wire for the CEL in the wiring harness.
That sounds like the easiest solution. Based on the wiring diagram in the FSM, it looks like 1E out of the ECU should do it.

Quote:
Originally Posted by paul View Post
go standalone.
That is the plan eventually. I wanna make sure I've got everything running as is and get more familiar with MS before I add in the other necessary mods. I think my future directions are:
1- get wideband
2- mod MS for standalone (fans, idle/TIP120, and A/C because it gets hot here and there's no reason to live like an animal)
3- install those RX-7 550s I've got sitting around
4- turbo
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