Need help with a FMI/II 1.6l Hydra setup - Miata Turbo Forum - Boost cars, acquire cats.

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Old 09-26-2007, 05:32 PM   #1
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Default Need help with a FMI/II 1.6l Hydra setup

Apologies in advance for the long post, but I know you guys want all the reference and background info you can get.

BACKGROUND
A couple years ago I bought a cherry condition 1990. When I bought it, it had 30,000 miles and an old BEGi IV.2 kit with intercooler, and full FM exhaust. That's the GT25R (I think), AFPR, high pressure fuel pump, and MSD box. It was running 170hp at I think 8 psi. Ran okay, but had ping problems especially with heat soak, (the MSD box simply pulled timing 6 degrees under boost) and the stock clutch couldn't always take the juice.

PROJECT
Drove it for about 5000 miles with no real trouble. Then the ignition coil pack went out, so instead of just replacing it, I replaced it and spent about 3 grand at FM (any excuse for more power, right?). I bought the FM Clutch Happy Meal (AEM street performance clutch and FM's lightweight flywheel), RC 550 injectors, and the Hydra, as well as the O2 sensor, IAT sensor, and electronic boost control solenoid, and the newer intake with the bigger filter.

I've done pretty heavy duty work on Miatas before (NB brakes on an NA, swapped suspension, installed Torsen LSD, swapped rear subframe) so even though this was more than I'd done before, I jumped in. Had no problem with the clutch and flywheel, and although it took a while, I'm pretty sure everything else got set up and wired up properly. Yanked the MSD box and AFPR, left the fuel pump in place. Had to weld some sensor bungs and had some issues with the fuel injector o-rings tearing and leaking but I figured that out and that's all taken care of.

PROBLEM
I can connect a laptop to it and upload and download maps no problem. I've messed and fiddled and tweaked until I was ready to punch myself in the face, but the car just doesn't *quite* idle smoothly enough. The idle is just rough enough that I can't get the base timing set. It's just enough to provide an uncomfortable vibration sitting in the car.

Am I wrong to assume it should idle just as smoothly as it ever has?

I initially loaded the default map file FM sends, and then tweaked from there. The O2 sensor is calibrated, no trouble there. I haven't gotten to tuning things like the A/C stepup, or tuning it across all electrical loads, etc, because I want a smooth normal idle to start from. I've tweaked the fuel delivery maps and gotten it as close as I can but it's just not smooth. Some car guys I've described the symptoms to say it sounds like it could be a vacuum leak. The only place that's possible is where the new injectors enter the block, and I've greased the insulator rings there and don't think that's the culprit.

I don't have a cylinder misfiring, I've checked plugs and wires (they're new), and the new coil pack has been tested on another car and is known good.

I've even sent the Hydra back to FM for testing and they say it's good.

Do I need to search more intensively for a vacuum leak? How best to go about that? Any other ideas what might be wrong?

Side note re: FM and Jeremy Ferber - I've spoken with him a number of times on this project and gotten a similar response to what others here have said - his answers seemed vague and generic and not very in-depth, and he doesn't seem to remember me from one contact to the next. So I have limited confidence in getting this fixed by them short of towing the damn thing out there and dumping it on their doorstep with a big "FIX IT" sign taped to the windshield. Which I've seriously considered.

TIA for any ideas.
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Old 09-27-2007, 12:34 PM   #2
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Is there anyone here who's done a Hydra setup and has experience tuning it?
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Old 09-27-2007, 12:40 PM   #3
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Try Nester, hes the only one I can thing of who has a hydra Have you tried FM?
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Old 09-27-2007, 12:41 PM   #4
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y8s run the hydra as well.
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Old 09-27-2007, 12:42 PM   #5
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Get your injectors flow tested. EVEN if they are brand new. You blame the ECU, but you also put in different injectors.
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Old 09-27-2007, 12:50 PM   #6
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check wiring. the hydra features sequential injection right? which would mean rewiring the injector harness. did you?

if not, i would expect 550s on batch injection to not be as smooth as stock size injectors. my RC 440 injectors bump minimum on times.

also, I assume you got LowZ RC injectors. LowZ injectors take substantially more current than the original denso highZ injectors. So additional grounding between the hydra and motor would be recommended.

I had to do a lot of extra ground work to get my aftermarket ecu to play nice.
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Old 09-28-2007, 06:06 PM   #7
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The injectors came with a flow test printout that was done before they were shipped to me. They are the low impedance models FM recommends.

I've talked to Jeremy at FM, but his response has been less than helpful.

Yes, the Hydra does sequential injection, and I've rewired the injectors. Two leads from the Hydra bypass the harness and wire directly to two of the injectors, while the other two remain wired from the harness. I followed that instruction (as all the others) to a T from the manual FM supplies.

Ben, you recommend more grounding from the ECU to the chassis? Or do you mean fatter ground wires from the injectors?
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Old 09-28-2007, 07:43 PM   #8
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the ecu should switch ground to the injectors, so if you ran a lead from the injection harness to ground, it would be bad. you need to improve the ground situation between the hydra and the head. i don't understand the physics behind it, but several small gauge wires is for some reason superior to a single larger gauge. i don't know why. but add a couple or three 14 or 16 gauge wires between the hydra and the head. the engine sensors ground to the head by the fuel rail under 2 different bolts. remove those bolts and clean all the metal parts off and make everything shiny, and reattach those.
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