89 Firebird Turbo 3500 Build

[caffeine]

Car was not moving but rear end was jacked up with the trans in neutral the tires were turning a bit. Just realized I need to hook up A20 to the fuel pump power for reference voltage.

Injectors are 52 lb/hr at 44.5 psi. I started with the BPC at 104 but it seemed super rich so I kept reducing it.

Thanks for noticing the issue with the boost multiplier at 100kpa I didn't even realize it was at 0. Shouldn't cause problems at idle though.

[robertisaar]

52 lb/hr.... bigguns. by my calculations, i would have started at 81. to comp for injector size: 52/16.7 = divide existing BPC by 3.11. to comp for displacement difference: 3.5/3.1 = 1.129. so with the existing BPC of 224:

224/3.11 = 72
72X1.129 = 81

of course, that will get you a rough idea of where to start. if your entire VE table looks too low, raise it. if the entire table looks too high(or you get to ~100% VE), lower it. not much else you can do with a BPC based fueling scheme.

the fuel pump voltage DTC got set pretty quickly after cranking, so the entire log is skewed by it.

i need to check my bench and see something.... the flag for firing the injectors on every reference pulse was set.... IIRC, that is supposed to go away after cranking and actually only happens when cranking at VERY low temps. i also need to see if applications like this would benefit from only single-fire fueling.... your BPWs were tiny in double-fire... enough so that the injectors may not be acting as consistently as expected.

[Mars]

Blair, hammer out a good tune with this thing cause I might borrow it.

[caffeine]

I REALLY want a 2-step, so I wanna get this tune working but for now ill settle for an idle with all cylinders firing

[caffeine]

Oh btw the regulator appears to be working fine I think the pressure was just jumping because the MAP was all over the place. Unplugging the vacuum port maintained constant fuel pressure nicely.

[TGP37]

i need to check my bench and see something.... the flag for firing the injectors on every reference pulse was set.... IIRC, that is supposed to go away after cranking and actually only happens when cranking at VERY low temps. i also need to see if applications like this would benefit from only single-fire fueling.... your BPWs were tiny in double-fire... enough so that the injectors may not be acting as consistently as expected.

Limp home mode triggered by the 0v ref to the FP? I know there is a way to trigger LHM with a resistor across two points on the ALDL connector for many OBD1 cars. I think it was a 4k ohm resistor but forget the terminals.

Oh btw the regulator appears to be working fine I think the pressure was just jumping because the MAP was all over the place. Unplugging the vacuum port maintained constant fuel pressure nicely.

That's good to hear......no doubt it was from less-then optimal combustion.

[pocket-rocket]

I know there is a way to trigger LHM with a resistor across two points on the ALDL connector for many OBD1 cars. I think it was a 4k ohm resistor but forget the terminals.

I want to say 8 or 10k, and it puts the ECM in ALDL transmit mode.

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[TGP37]

I want to say 8 or 10k, and it puts the ECM in ALDL transmit mode.

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could be both, but I can't be sure.....My study is OBD2.

[robertisaar]

connecting ALDL pins A to B directly(no resistor) with the engine off will cause code blink mode. with the engine running, it causes field-service mode(the SES light will turn on and off based on O2 sensor readings, possibly some other effects). 3900 ohm resistor from A to B along with some odd voltage levels on the battery voltage and fuel pump voltage circuits will cause Factory Test Mode(all outputs are cycled rapidly, along with a bunch of other stiff). 10,000 ohm resistor from A to B will transmit the 160 or 8192 baud datastream on certain ECMs.

not all ECMs support all modes though. factory test and code blinkout are definitely present, but i'm not sure if i've ever gotten into field-service mode. no 7727/7730/9396 application i know of uses the 10K mode either.

keep in mind this, is all off of memory, so i could be forgetting stuff.

anyways, if it were limp-home mode, then no datastream would be able to be acquired, along with a fan being triggered on and other stuff.... i actually don't think the engine would run at all since the limp-home mode is VERY dependant upon correct injector size and displacement. running injectors 311% larger than what it was setup for will definitely cause issues.... running at 13:1 AFR with regular injectors would cause a 4.2:1 AFR to be commanded. running the 3BAR will negate a lot of it though... since instead of there being ~2 volts coming out of the MAP sensor(at idle) and into the limp-home fueling chip, there is more like ~.7 volts.

tuneable limp-home mode is something people have been trying to crack for years.... and i can count on one hand the number of people i've seen get far enough to make a testing board. simulating and improving upon the NETRES chips are difficult and since it will only ever get entered if there is a significant failure internally to the ECM(basically, either the PROM or the 6811 processor itself have to fail), it doesn't happen enough to be dealt with.

[TGP37]

Wow Rob, you know your shit ehh!

Tunable LHMode, something I never considered until now. 4.2:1 is crazy rich, lol......I would be surprised if there was no hydrolock w/ that much fuel being dumped.


Hope to hear this beast idle on her own soon.

[robertisaar]

also, took a look at the VE tables.... for the lower table, you may want to use values a lot closer to stock.... i'm not sure how big of a cam or headwork you're running, but a lot of that VE table is implying to inject roughly half the fuel compared to a stock engine at the same RPM/MAP.

needing to constantly move the TPS to keep it running is implying that you need AE fuel to keep it alive due to how little fuel is being injected otherwise.

[caffeine]

I got it to idle (sort-of) on a code59 tune but I have an intermittent misfire I can't figure out. Swapping out the coils/ICM for known working ones did nothing. It has to be a wiring issue. Any ideas where to start?

Edit:
When I hook up a spark tester all the posts test fine except for #5 which sparks intermittently. It's #5 on both coils I've tested. Seems strange...

[robertisaar]

#5 on both ICMs bad?

[caffeine]

#5 on both ICMs bad?

The ICM/coils I have on now were working perfectly on the Fiero this morning.

Edit: it's weird because #2 which is on the same coil seems to test fine its just #5. It also still fires intermittently with the ECM unplugged so I doubt it's tune, trigger wheel orientation, or wiring to the ECM. Bad grounds are the only thing that makes sense to me but I'm using the same grounding location as on the Fiero. I've also tried a different IGN+ wire to power the ignition as well...

Voltage also tests good across the two terminals on the two-wire pigtail. I'm running out of things to test this doesn't make any sense to me

[caffeine]

Just tested resistance on the 5-wire pigtail and none of the wires are showing resistance. Also tried the crank sensor and crank sensor wiring from the Fiero. No difference. This is driving me crazy!