quote Originally posted by dskebo: When are you going to get the paint shining like it deserves? The car is a labor of love and it should look the part.

Who knows...

I would like to get it painted, but I still have 3 more body mods to complete.
I also don't want it to be locked up in body shop jail for a year or more either.

So for now, I will just continue with more modifications/refinements and drive the wheels off it!

Got back from the HRPT yesterday.

Long Hauled with Marty, his son Steven, and Jack & Joe.
Also met up with several other Fiero owners and showed Alex4mula some pictures of the sub box he inspired from his build. Spent a fair amount of time talking about my car, and Marty and Joe helped field the many questions as well.

Only issue was some debris on the road between Indy and Joliet damaged the sidewall on one of the rear tires. They were 8 years old and needing to be replaced. Fortunately, from Joliet, we were headed to Ft. Wayne and Tire Rack has some rear tires in stock. So we nursed the car to South Bend, got new tires, and made it to the Ft. Wayne venue about 3 PM.

Also met up with some of the Haltech guys that were participating in the tour with their personal cars and they really liked the Fiero as well.

Overall is was a 1200 mile trip and the best tank of gas was 27.6 mpg. I checked the weight again as the same grain elevator, and it is still 2920 lbs, so more work needed on that front.

Now that the HRPT is over, I started with the WOT tuning.
After about 6 WOT runs with the boost controller set at 15% duty cycle I am seeing about 3.5 psi boost.
I should be within about 1-2% on the fueling with the latest tune revision.
Now I can bump the duty cycle, and start coorelating % duty cycle to overall boost pressure, and dial in the fueling at higher boost levels. Not planning to go over 8psi.

The car has been to work 1 time this year, but I will be drving it daily for the rest of the summer.

Just been driving the car daily the past 2 weeks (truck hasn't moved).

• Adjusted the End Of Injection Timing (EOIT) and saw a 2% reduction of fuel usage at idle - should be similar at cruise.
  
• Part throttle VE is within +/- 2%, but can swing up to 5% between morning and afternoon driving (fuel and air temp caused), so I disabled closed loop & LTFT below 160 degrees (it was set to 32 degrees as delivered) and lowered the LTFT gain to 5% so the STFT can take care of changes due to fuel temperature w/o having the wrong LTFTs stored the next time the car is started.
  
• I still need to insulate the hot air tube from the turbo to the intake. It is heat soaking too much and I see about 125 degrees in city driving - granted it was a 95 degree day.
  
• Cut the cold start enrichment in half, since it is now running open loop and the supplied gains were much too high.
  
• With the change of the cold start enrichment and the raising of closed loop to 160 degrees, I can start the car in the morning and go. Before I needed to let it warm up about 60 seconds, and feather the throttle more on the first 2-3 accellerations from a stop.
  
• Roughed in the max throttle opening by RPM x Gear so that 1st and 2nd gear hook vs. spin (atleast at 15% wastegate duty cycle)
  
  

The car now has about 8,500 miles on it with the turbo, and about 2000 miles this year.

Waiting for a 195 thermostat to come in, then I will swap out the 180 in the car. Warmer engine temp should help with fuel economy and my quest to get to 30 MPG.

Still need to work on the cruise, front wheel speed sensor, and flex fuel... but free time has been limited.

I accepted a promotion to the Asset Manager (Plant Manager) position and will be covering my duties as the Engineering Manager until that position is filled.
Anyone with significant engineering exxperience looking for an Engineering Manager position with a public utility in the middle of IL and surrounded by corn/soybeans, please send me a PM.

quote Originally posted by fieroguru: Just been driving the car daily the past 2 weeks (truck hasn't moved). The car now has about 8,500 miles on it with the turbo, and about 2000 miles this year. Waiting for a 195 thermostat to come in, then I will swap out the 180 in the car. Warmer engine temp should help with fuel economy and my quest to get to 30 MPG. Still need to work on the cruise, front wheel speed sensor, and flex fuel... but free time has been limited. I accepted a promotion to the Asset Manager (Plant Manager) position and will be covering my duties as the Engineering Manager until that position is filled. Anyone with significant engineering exxperience looking for an Engineering Manager position with a public utility in the middle of IL and surrounded by corn/soybeans, please send me a PM.

Where is the Tstat on your setup? is it under the filler neck?

edit:

I think I answered my own question. I'm guessing it's in here.



congrats on the promotion. Not so much on the dual responsibly. You're not selling anyone on being surrounded by corn.

[This message has been edited by KissMySSFiero (edited 06-30-2025).]

quote Originally posted by KissMySSFiero: Where is the Tstat on your setup? is it under the filler neck?

THe thermostat rests inside a rubber o-ring type seal and fits in the machined groove right under the coolant fill point. When the coolant fill is bolted down, it compresses the seal for the thermostat.

This means that my LS4 coolant path is now like the SBC with the thermostat on the hot coolant exit from the engine vs. the cold coolant supply to the engine that typical LS engnes use.

quote Originally posted by KissMySSFiero: congrats on the promotion. Not so much on the dual responsibly. You're not selling anyone on being surrounded by corn.

I have been covering 2+ postions for most of the 3 years I have been at this location, so it isn't anything new... I just know that a local food mfg has been posting for an Engineering Manager for 6+ months and my last 2 engineer postings took about a year to fill, so it will be a slow process.

If being in the corn doesn't sound appealing, how about no emissions testing within 2 hrs.

[This message has been edited by fieroguru (edited 06-30-2025).]

Do you ever make it to Chicago? I'll be there through the weekend.

quote Originally posted by fieroguru: I have been covering 2+ postions for most of the 3 years I have been at this location, so it isn't anything new... I just know that a local food mfg has been posting for an Engineering Manager for 6+ months and my last 2 engineer postings took about a year to fill, so it will be a slow process. If being in the corn doesn't sound appealing, how about no emissions testing within 2 hrs.

I live in Florida. No emissions anywhere around, and you may taking a beating if you suggest it. Nowhere in FL is more than 74 miles from the ocean. Negative: We have a few crazy people and hurricanes.
We have 7-8 engineering req's open for my program alone. We're always understaffed. But at least we're not underpaid, most of FL is. My last job took a year to find a suitable replacement for a Communications systems engineer.

How's product development for your water pump and accessory drive coming? Is it something you're still considering selling?

I'm currently running the SC3800 in my choptop but I'm wanting another 100HP.

I found an alternator that may work for a flipped cantilever setup for the LS4 but I'm not a big fan of the look and worry about belt squeal.

I think I can use aluminum plate and spacers welded together. I should be able to pivot the alternator for tension.


------------------
SSFiero@Aol.com

[This message has been edited by KissMySSFiero (edited 07-01-2025).]

quote Originally posted by Will: Do you ever make it to Chicago? I'll be there through the weekend.

I sometimes have meetings at the AON center in downtown, but normally don't get to Chicago unless I have to be there for something.

Cruise control now works through the stock 1988 Pontiac Fiero cruise stalk!

Several must haves that are burried across several Haltech technical guides:

• DBW
  
• Vehicle Speed - from a wheel speed input
  
• Brake Switch wired into ECU
  
• Gear detection or neutral switch
  
• If Manual Transmission - Clutch Wired into ECU
  
• 1 or 2 input wires, must carry all the signals, voltage or resistance must vary based on resistors for each circuit

Now my Fiero did not have stock cruise, but I added the stock cruise stalk. So all the wiring terminations start at the clutch switch, brake switch, cruise stalk, 203, and Haltech ECU and Haltech 12 I/O Expansion module. For all the Haltech connections, I list the pin location. It is starts with an A or C it is the Haltech ECU, if it is IO12 then it is a pin location the expansion module - many of these could originate at the ECM depending on how many I/O you have:


Now there are a couple gotchas in this chart.

VSS Input:
You will need to know the teeth count per 1 revolution for your VSS (F40 3.091 Final Drive = 68 teeth)
You will also need to know the rotations per mile for your drive wheels (275/35/18 rear tires = 815 rotations per mile)
The field for DriveShaft RPM Sensor - Number of Teeth is maxed at 50, so just enter 50 as it really does not matter.

The key is the Drive Train Sensor - Pulses/Mile = this is # VSS Teeth for 1 rotation x # Tire rotations per mile.
For my setup with the 3.091 final drive it is 68 x 815 = 55,420. From there you can bump it up and down to make the ECU match GPS.


Now you have the Vehicle Speed into the ECU, but it needs to get to the Fiero Speedometer.

VSS Output:
The Rebel LS does not come with a VSS output, so you have to make your own using one of the Generic Outputs.
ON this page, you give the output a name = "Speedometer Output", select the signal type = "Frequency", and set Mode = "Table"


Next is to setup the "Frequency" table. We need to know the frequency (cycles = pusles per second) for a 4000 pulses per mile (most older electronic GM speedometers need a 4000 PPM input) @ 100 miles per hour.

4000 cycles/mile x 100 miles/hour / 60 minutes/hour / 60 seconds/minute = 111.11 hz @ 100 mph. This output is linear for all speeds, so some simple math and you get this table:


Now we have to assign the "Output" to a pin location and configure it:


Working Speedometer:
Now that everthing is done in the Haltech for the speedometer output, it still didn't work for me. So I added in the typical speedometer buffer circuit that is needed for any OBD2 ecm to drive the Fiero speedometer. It is shown at the bottom of this schematic. With this circuit between the Rebel LS Speedo output and pin G on the 203 connector, the speedo will now work:



Once you have a working speedometer, now you can start working on getting cruise to work.

Cruise Speed Reference:
From what I gather, the drivetrain speed within the ECU is not good enough for the Haltech speed signal for cruise, so I enabled a Left Rear Wheel Speed Sensor. You don't actually need to install a wheel speed sensor, you can "T" off the VSS Output signal going to Pin G of the 203 (and your speedometer) and send it back to the Haltech ECU once you have setup a SPI input for it.

LR Wheel Speed Input:
Basically just turn on the Left Rear Wheel Speed toggle and enter "4000" pulses per mile since that is what we set the output driving the speedometer to.


I used an SPI input, set it for "Digital - Frequency", Edge Select = "Falling", Sensor Type = "Hall Effect", Pull Up = "Disable"


This should get you a working wheel speed for cruise.

Gear Detection:
Since the F40 is a manual transmission, I need to enable Gear Detection:
First thing to note is that the FWD F40 6 speed manual didn't make the cut in the available lists of transmissions (neither did the 2005-2009 LS4 for that matter - L33 FTW), so I used a T56 manual.
Transmission Type = "Manual"
Gear Detection Type = "Gear Ratio"
Funtions = Toggle "Gear Ratio" to the ON state


Since the F40 has the VSS on the differential teeth, I went ahead and chose the km/hr per 1000 Engine RPM.
From there you then have to calculate (or use the calibrate function for each gear)
Formula is: 1000 RPM /(Gear ratio * Differenial Ratio) * (Tire Dia (in) * 3.14 / 12 / 5280) * 60


Now the ECU should know what gear the transmission is in.

Brake Pedal:
The brake pedal is easy as the brake wire in the pedal harness just needs spliced into the +12V from the brake switch on the brake pedal.


Clutch Switch:
The clutch switch is an available function, so it needs turned on and assigned to an input. I chose to use an AVI input for this. Since I was using a 5V feed for the clutch and cruise inputs, the clutch sends a 5V back to the ECU when it is pressed. This could have just as easily been a 12V circuit.
Input Mode = "State/Switch/Button Input", Switch On Voltage = "4.0V", Switch Off Voltage = "2.0V", Pull Up = "Disable"


Cruise Control:
Now at long last we are ready to setup the actual cruise control inputs. This takes some pre-planning and some trial and error (at least for us non-electrical engineering types).

You can use either 1 or 2 inputs for the cruise commands. The 2nd input can only be to Engage/Disengage cruise
All other cruise commands need to share the same input and have varying voltages based on which button was pressed.
Since I was using 5V for the cruise commands, I used the 2nd input for Engage/Disengage as it was one less resistor and voltage splits I would need.
Here is the first Cruise table, most of this is pre-populated. The one thing I did change was the Maximum Wheel Speed Difference = 100 mph. This was due to troubleshooting my front wheel speed sensor for traction control. If you have any other wheel speed sensors that are not working (and calibrated), then you need to include this setting or Cruise will not work.


The cruise buttons page really had me stumped for a while. For a mid 80s Fiero, Input Type = Analogue - Voltage
Then you need to setup available cruise commands. Typical 80s GM application will just have 3: Set/Coast -, Resume/Accell +, and Resting Position. Resting position really isn't a command, but an absence of a command. Now
Set/Coast - & Resume/Accel + will need to come in on the same wire, so before they join, you need to add in a couple of resistors. Since I have 5V to work with, I installed a 220k Ohm resistor on the Set/Coast - wire and a 1M Ohm resistor on the Resume/Accel + wire. Once wired up, you press the lever for the command, then press calibrate. Then move to the next. Last while not pressing anything calibrate the resting position.


Here are the input configurations. The separate input toggle is switched on.
Input (these are the cruise commands on the buttons page), is an AVI, Pull Up = Disable.
The Separate Engage Input = AVI input, Switch ON Voltage = 4.0, Switch OFF Voltage = 2V, Pull Up = "Disable", Button Mode = "Momentary"


It was a fair amount of work to get figured out, but having working cruise is AWESOME!

[This message has been edited by fieroguru (edited 07-09-2025).]

Thanks for much for posting all of this. I probably won't be using Haltech now that I've spent a lot of time learning MegaSquirt on my Mustang. But, the logic should be very similar for other systems. This should be a huge help to me and I'm sure several others. Great work as always! And I'd be in that small market for your mechanical water pump solution for the LS4.