Tuning: 3500, 5-speed, 1227730, nAst1, Fiero GT

[LZeppelin513]

So I finally got my Fiero started. Feels good.

I will be using Robertisaar's nAst1 code to run this 3500 through a 7730.

First things first. I am running an adjustable FPR to act as returnless and the stock 3500 line/injectors.

What pressure should I set it to? With the stock 3.1 tune it runs best at around 37ish psi.

Also, how do I change the Injector constant and what should I set it to?

I am leaving next week for Costa Rica for 5 weeks and then am moving to Oregon with the GF when I get home. I am in-between graduating this week (woohoo BS in Bio) and work so I'm hoping to make a good dent over the next 5 days. All help is appreciated from this newb.

-Blake

edit: How she sits now at dad's house. Excuse the bad pictures. It still doesn't move under its own power yet but hopefully the potential can be seen.



Love those 18s


And front c5 rotors all the way around.


And in case anyone cares, its an 88 gt. I had all the suspension powder-coated black, put in konis front and rear, poly everywhere, zero-lash front and rear sway bar links, new balljoints, tierods, and calipers. I'm excited to out handle dads '09 cts (3.6 DI not v)

[robert 1980]

Sweet car my buddy would cream his pants if he saw this whip

[robertisaar]

this should get you started at least.... can't guarantee it being perfect, but it should at least allow a J/L/N/P car w/3500 and a manual trans to scoot around without too many problems.

just copy/paste.

injector constant will be based on fuel injector flowrate, which is partially determined by fuel pressure.

[LZeppelin513]

Thank mucho Robert, that will really help.

What would you recommend with adjustable FPR and stock 3500 injectors?

Also, I have my wideband output at pin F12. How do I see it? I've done some reading but I still am VERY unsure of myself regarding this tuning biz.

[robertisaar]

i may have to throw a quick patch together, but you'll have the 0-5V WB signal placed in the datastream in place of the "corrosivity sensor" value, currently, the value will only update roughly twice per second if i have my codework done correctly, but i'll be fixing that...

EDIT: do you know how to work the tunerpro hex editor?

[LZeppelin513]

No I don't, I haven't looked at it yet. But I'm sure I could learn.

[robertisaar]

i may have been reading my own hack wrong... the WB AFR should get updated 10 times a second in it's current configuration, but the section i was looking at was referring to turning on the low coolant light... i never thought about it until now, but the low coolant light output could actually be used as a "WB is averaging way too lean" output.... all with some simple calibration changes. but you would need a light/inidicator of some kind hooked up to do so.

[LZeppelin513]

I will not be hooking up my coolant temp warning light so that circuit could be used. However, I would rather use the streaming wideband data for tuning. I won't hook up the a/c until probably next summer so for now I could use pin f14.

[robertisaar]

just keep the pin at F12 for now and see how well it works. if necessary, then move to pin F14 and make sure to disable the A/C pressure sensor flag in the tune, otherwise you could get some odd idling issues.

[LZeppelin513]

So I changed "KDISFS lbs/foot" to 24.

Is that the correct field to change the injector constant?

It runs better with the new tables but very rich. I turned the FPR way down and it runs better but still rich, so I'm thinking the KDISFS isn't the right field?

[robertisaar]

KDISFS is only used for DIS/DIC(bascially trip computers, somewhat common in the 2/3 W-bodies, not so much in other platforms) and it's fuel economy calculation.

to adjust for injectors, you'll need to play with the "Base Pulse Constant vs Desired EGR (F2" table.

quick explanation: that table forms the basis of the BPW value that eventually is used to control how long the injectors are open. for smaller injectors AND/OR larger displacement, you need to raise the values. for larger injectors AND/OR smaller engines, you need to lower the values. now a 3.1 with 16.7 lb/hr injectors has a value of 224. that's roughly 517cc per cylinder of displacement. a 3500 is roughly 583cc, which is an increase of ~12.77%, so take 224 and multiply it by 1.1277 to come up with ~253 rounded off. that takes care of displacement. assuming you're running 24 lb/hr injectors, they flow ~43.7% more than the 16.7lb/hr the tune was setup for. so now divide 253 by 1.437 to come up with 176. it's not a perfect system, but it will get you at least closer than it was. you should now be flowing 27.3% less fuel than you were.

if i were you, i would disable EGR(set it to max coolant temp for activation) and only deal with cell 0 of the BPC table.

[LZeppelin513]

Alright, that makes sense. I read about it in the "Tuning OBD1 Systems" article here but was still afraid to mess with the F28 table... I'm green and afraid of blowing up the engine. So, thank you much for the calculation using my numbers.

[LZeppelin513]

Here is a short log with the 3500 tables and f28 table set to 176. I started it, let it idle, drove it about 10 yards and let it die. Strangely, it idles worse and runs about the same with the 3500 tables than with the stock 3.1 tune. The IAC counts seem too high, which means I have a vac leak, right? I don't know where it could be as I only have the stock PCV line, brake booster and fuel pressure reg line hooked up at the moment (all other ports blocked off). Tomorrow i'll cap the bb and fpr lines to see if it makes a difference.

Robert- Is the wideband outputting at "Corrosivity Sensor"?

Its running rich still. I played with F28 and brought it all the way down to 150 while the engine was running and it didn't have any noticeable affect on how the engine would run (this was done in open loop, so no int or blm to confirm)

Anyway if anything jumps out I would appreciate any input.

Thanks,
Blake

[robertisaar]

notes: wideband looks like it's working as expected.

DTC41 is present, what MEMCAL are you using(sounds like you have it hooked up to an ostrich), and did you mess with any of the "number of cylinders" values in the BIN?

you also have DTC51 and DTC53 set....

these DTCs need to be fixed before any kind of fine tuning can be done, since they will effect how the engine will run.

[LZeppelin513]

Yes I am using an ostrich. The memcal is from an early 90's FWD car. It was the one that had a partial 3400 tune on it. I will swap it with the memcal that came with the ecm that I am using. I believe it was from an early 90's J.

As for DTC53, its charging at 13.5 volts which sounds good. I'm guessing there is a scaler I change so it won't trip the code? "battery voltage to set code 53" is 10.4. Does that mean anything above that value will trip the code?

I never messed with "number of cylinders," its C0.

If the wideband is working, changing the value in f28 did not have an effect on fuel delivery. I would like to change f28 to get 2.35 volts at the wideband before I start playing with VE tables. What could be the reason changing f28 does not affect fueling?