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Old 01-03-2013, 05:45 PM   #1
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Default Car won't run with throttle open (even a crack)

The basics if you didn't see this in the engine performance section. 94 miata 99 motor, just rebuilt with Eagle/Weisco ID1000's. FM2. DIYPNP used from a member here who was running the exact setup (including ID1000's). Total newb to tuning. Pretty good with a wrench, but three kids and job plus other hobbies limit time in the garage. Love long walks on the beach.

Initially I couldn't even get this car to start for more than a few seconds, but with the addition of a proper AIT sensor (GM), getting it running enough to get an initial time on it (10deg), and going to PWM warmup mode for the idle, I've managed to keep the car running long enough to warmup completely. It idles.. sort of.
If I step on the accelerator at all (just a bit or all the way or anywhere inbetween) it richens up and revs for just a moment, then the WB shows it running to full lean and it dies (like two seconds). It reacts the same no matter what the coolant temperature is, so I doubt that the after start enrichment/tapers have anything to do with the big problem.
My goal here is to get it to work even just a little bit. And I'm at the 'completely new and pretty much clueless' stage of tuning. I have a little bit of sense though, so here's what I tried: 1/ Could it be reading incorrect manifold pressure? Unplug the vacuum hose, engine quits. Apparently that's working, and it should be since the ecu came off a working car. 2/ Add fuel to VE1. I selected all and increased in increments of 10. The mixture richened, and now it 'idles' at 2000 rpm and 12.0 AFR. Didn't make a difference when I tried to rev the motor. AFR goes to 18+ and it dies. You can feel it take the acceleration enrichment and right after that the pedal feels dead (motor doesn't react to it).

Thoughts: The VE table certainly will need tuning for this car, but I don't think that's the problem. Likewise with timing and IAT temperature. TPS has been calibrated. I probably need to mess with that again as I turned the screw on the throttle body, but it works. Probably not the problem. Fuel filter: Could be, but it runs and gets gas. A clogged filter might mess with things, but it would be more likely under load. Plus, the motor reacts the same if I even just crack the throttle.

IAC needs tuning, but again, I don't see this being the root of this problem. Could I be wrong there?

Fuel pressure: I'm a little unclear how this is working. It's a 94 with a 99 engine, so I'm using the 99 rail and the 94 fuel pressure thing turned upside down on the end of the rail. Should work.

This whole damn thing is complicated by a military move that is taking me to HI (from Washington state)... Sunday. It will suck to leave this car parked for years.

Anyone know anyone in Seattle that knows miatas and how to deal with MS?
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Old 01-03-2013, 06:21 PM   #2
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post msq.
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Old 01-03-2013, 08:39 PM   #3
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Can someone please tell him and me that the fuel pressure setup is correct or not? Isn't the '99 a returnless system? But since he's running a '94 FPR, it'd be turned into a return system?

And where are you tapping in for your MAP signal? Post some engine bay pics, that might help those of us who are currently blaming your mechanical setup (me) instead of the MS (everyone else).
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Old 01-03-2013, 08:50 PM   #4
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Curly.. I agree... I think there is a high probability/possibility that this is mechanical.. that's why I originally posted to Engine Performance.

The 99 is returnless, but it's a 94 fuel system, so it's been converted to a return system by adding the return line and the 94 fuel pressure regulator to the 99 fuel rail. The system looks ghetto right now, but the plan is to sweeten it up later.

MAP vacuum is coming from a nipple under the manifold towards the back. They should all be the same right?

I know it sounds crazy to richen up to the point that I'm idling at 2000+ and rich fuel ratio, but the point of that was to prove to me that the engine and fuel system could supply fuel to do that (ie, fuel filter not so clogged that it could only support minimal flow). With the idle at normal parameters there was no way I could reach and maintain 2000 rpm (as previously stated).

I'll work on posting the msq file (haven't done that yet either), and some not so pretty pictures. Thanks for the help gang... This should be simple right?
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Old 01-03-2013, 10:38 PM   #5
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Ok, here is the msq file. I have TONS of extra gas across the board in VE1, but other than that I haven't tweaked too much (well, I've tried things in the idle field and put them back).
Attached Files
File Type: msq 2013-01-03_18.33.33.msq (83.9 KB, 53 views)
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Old 01-04-2013, 12:09 AM   #6
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Why run a FPR at all if u're running a stand alone?
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Old 01-04-2013, 12:37 AM   #7
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Triple.. Please explain? I just have the stock little vacuum actuated regulator that goes on the end of the fuel rail. I've never heard to get rid of that. Plus, with a return system, how would we keep any pressure in the rail? I'm seriously asking since I feel really behind on knowledge.
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Old 01-04-2013, 12:43 AM   #8
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Oh my bad, i thought u meant like an fpr from begi or something which is what people use on fail aid systems.
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Old 01-04-2013, 02:18 AM   #9
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Ok, fixed it.. I think. Added some coolant, switched out my oil pressure sender (inoperative), moved my MAP sensor vacuum line to a different nipple, and disconnected a vacuum driven solenoid (no idea what it does, but my egr is gone).
First time it's turned a wheel under its own power in well over two years. One mile. It boosts and pulls hard (no boost control yet, so six psi). I'll take it out and run a tune on it tomorrow, but the main thing is getting it reliable enough to drive 100 miles to the shipping yard for its trip to Hawaii!
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