Trey's *Twin Turbo 5VZ* Mid-Travel Build +Haltech Tips

Haltech Tips & Tricks

This is going to be a placeholder for everything Haltech Elite 2500 related on a 5VZ non-California edition with SNP PnP harness that I've learned and have to say about it, mainly from the context of advice for people planning to add one to their truck...most will be relevant to any First Gen, with the exclusion of ECU pin numbers. Efforts will be taken to retain factory configuration on the backend for emissions passing.

I anticipate linking to this post and you may wish to also. Note that I am learning as I go, so not all information here may be perfectly accurate! Make sure you double check anything I say and ask questions!



~ Optional Parts ~

Wideband O2 Sensor

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The SNP kit comes with the WB1 unit, which is a fancy Wideband O2 sensor controller that operates via 4 pin CAN connector to the Haltech ("HT"). You need this sensor at the bare minimum.

O2 Bungs

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You obviously also need an O2 bung for the wideband sensor itself. I would recommend leaving the two narrowband sensors in place for the time being. I bought these because for the price of 2-3 I could get 10.

Wideband Knock Sensor (2500)

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The HT 2500 is the only model available to us now that the 2000 was discontinued that provides knock control. Knock control's necessity is debated, but I find it important. Unfortunately, the Toyota knock sensors are an old style resonant type, and completely useless - go ahead and try to get them to provide meaningful feedback if you want, I'd love to see it done. So what you want instead are "wideband" knock sensors as well. These are available from Haltech for $101 as of writing, or you can do a little research and find them as low as $10, both genuine Bosch. You need two.


You'll want to make sure you get them with a known connector type to be able to make/add a harness with; the one above is the EV1 standard (coincidentally the cheapest one). You can find those connectors all over Amazon.


You'll need the proper mounting bolts (Toyota P/N: 90126-08046(?)) and nuts as well, and make sure to look up the torque spec (it's low). I'll update once I figure this all out.

Extra Harness Pins

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Once you're set up and start tuning a bit, you'll probably find you want more control over certain things. For any additional function, you'll need to add pins to the HT. The part # for these pins are TE's AMP 3-1447221-4 Superseal. They look like this:

I've found them cheapest on eBay but they can be found at any electronics parts storefront like Digikey, Mouser, or Arrow. You'll be hit with a high shipping charge though. The cheapest I've found are 26 for $4.20 delivered from eBay.

I also have some for sale here.

Flex Fuel Sensor

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One such example of an inexpensive addition is a Flex Fuel (Ethanol) sensor. Most US gas has some concentration of ethanol (up to 10% legally) and being able to measure this can theoretically improve internal calculations. It can also allow you to add an ethanol axis to your maps, in case you ever want to run E30 or E85. Again, Haltech has rebranded and marked up one. They are $209 as of writing, or you can do a little research and grab the same one from ACDelco/GM for closer to $55 (Amazon is good too). These come in many part number variations but from what I can tell they're all the same internally. Some reviews make mention of having fuel temperature sensors built in also which communicate on a different frequency using the same pins, but that's not as important to me.


If you order from someone other than Haltech, you'll need the connector as well. Search Amazon for "gm flex fuel sensor pigtail" and you'll find all sorts of options.

Map Switch

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You can also add a Generic Switch as another dimension to most tables, or generic condition correction tables, which would allow functionalities. For instance, you could do a low boost or low octane tune and flip between them on-the-fly.

These are available from HT in a multi-position potentiometer version with 24 positions for nearly $200.

I can't imagine why I would need that many options given the tables and dimensions available to me (only 3 (they call it 4D but whatever)), so I opted for a 3 position switch for $6 on eBay, which would only require 2 pins and a conditional input configured.

You could easily find the analog Haltech version by searching for a "12 position potentiometer". In fact AEM has one for under $40 (model 30-2056).

Gear Position Converter

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As you start to tune certain maps, you might find you want to have some sort of gear input. There are 3 levels to this:
1. Park/Neutral sensor input
2. Gear Selector input (P, R, D, 2, L)
3. Park/Neutral + Shift Solenoid inputs

ECU pin info:



1. As you can see below, Park and Neutral are coupled to one ECU input. STA on pin E8-13 can be tapped for this input. STA is not activated after start - it cannot be used.. The only reliable way to get any gear read is directly from the gear position switch on the transmission itself under the vehicle. This can be extremely helpful for idle control, where you have a large variance in load between in gear and in park.


2. As you can see below, the gear selector is limited in its helpfulness. D(rive) and P(ark) actually never make it to the ECU. You do get R, 2, and L, however, which would be wanted for transmission control if you're into completely eliminating the factory ECU someday.


My ECU pins are E5-15, E5-1, and E5-10, respectively.


3. Finally, we have the shift solenoid outputs listed below. These operate in combination to produce the 4 gears. This is the ideal scenario because you get the actual gear you're in, not just the gear you're limited to. SL, the lockup solenoid, is not needed yet.



As you can see from the truth table above, we likely need the Overdrive pin as an input to verify we are truly in forth gear via this method. (I don't currently know if Park/Neutral goes 0-0). Otherwise you could use the P/N sensor as a feed and treat 0-0 as 4th if P/N is LOW, or P/N if HIGH.


Note that ODMS and ODLP are both related to the O/D switch. ODLP appears to be a pull down transistor to operate the O/D off light when the switch is depressed. So if you tapped this for input you would pull down the bulb and only ever get +12V or some non-0 voltage when activated. ODMS is likely the better option to tap; it will pull low when the O/D switch is engaged, but I'm not sure what a disengaged voltage would be yet. Because of this, the Park/Neutral switch would be my first priority, but O/D will need to be fed in for transmission control later.

From my FSM for the ECT:


Here is a summary of all relevant pins on my ECU (updated 5/8/2023).



All this is to say, you'll probably want some kind of multi-input converter to save on HT pins. Haltech takes the CAN approach and expects you to pay $400 for this. This is the digital approach which is nice if you don't care about money and have the space for it.

Another option since we're dealing only with ON/OFF states is a simple converter that takes a pinset and converts them to an analogue range on a single pin. HT NSP tuning software accepts this type of input as a "PRNDL converter" with up to 12 voltage levels between 0 and 5 volts to tell it what drive state it's in.

The absolute cheapest way of going about this is to buy a bunch of LM317 converters (~$1.50/pc) and wire them all together and shove them in a box, one for each input. I would not recommend a resistor array as they will respond linearly to input voltage and could easily create false output voltage in suit. (eg: 14volts to 10volts would swing a 5V setpoint to 3.6V, which will severely limit your options since you have to account for that swing between inputs)


Alternatively, there are PRNDL converters you can buy for around $250, or Haltech now has one for around $150 (if stocked).

Alternatively still, I have developed an inexpensive universal 6 channel converter which I make and sell on-demand.

~ Extra Features & Adjustments ~

Current Gear Axis

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It should be possible to set up solenoid gear reading through the following process (I have not tried yet). We're actually lucky to have only 4 gears or this would not be possible with the current HT firmware due to limited selector positions, or at least we'd have to rely on improper naming which could get confusing later. This requires 3 inputs and doesn't work with a converter due to gear 2's need of two simultaneous inputs. Though, you could technically feed two of them in via a converter, and the 2nd solenoid from either another converter, or on it's own and do some conditionals.

1. Set Gear Detection to "Use Selector Position" and Enable Selector Position.


2. Go to Selector Position tab and make sure only Park, Overdrive, 1st, 2nd, and 3rd are enabled.

3. Go to the Selector Position Wiring tab. We will be treating "Overdrive" like 4th gear (which it is). Both gears Overdrive and 2nd will be purely conditional statements. Park doubles as Neutral, to state it explicitly.

4. Give 1st and 3rd the wires of your choice that connect to their respective solenoids in the truth table above. In this example I am using AVI10 for S1 (1st) and AVI9 for S2 (3rd). Assign Park to your Park/Neutral pin, which I have done as AVI3.

5. Assign 2nd the "Conditions Only" (2 operations) that "AVI10 Switch State is Equal To On" AND that "AVI9 Switch State is Equal To On"

6. Assign Overdrive the "Conditions Only" (3 operations) that "AVI10 Switch State is Equal To Off" AND that "AVI9 Switch State is Equal To Off" AND that "AVI3 Switch State is Equal To Off". This will ensure that the HT will not think 4th gear is enabled if we're in Neutral or Park and no solenoids are active. I'm not sure if it's actually smart enough to make a decision or present an error if the same conditions are met for multiple gears. NOTE this assumes P/N switch is high when in P/N, but it could be opposite (testing required).





7. You can now add Gears or "In Gear State" to your tuning tables.

Vehicle Speed(o) Calibration

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It should also be possible to correct your factory speedometer for use with larger tires with no additional hardware. You will need to break your harness though to intercept the PnP signal back out to the factory ECU though. The HT is configured to parallel the speed sensor for the factory ECU; we want to re-write it.

All this should take is cutting the correct PnP wire to the factory ECU pin, and wiring a new pin from the Haltech to that output. The wire that used to feed the factory ECU will be tied into our HT directly, instead of the PnP harness. The other will float.

1. Look at the main table related to the speed input (Sensors -> Vehicle Speed). Go for a drive and calibrate the Drive Train sensor using a GPS speed phone app. I chose 45mph and got 3,542 pulses/mi for my 35" tires. The faster you use, the lower error you'll have due to a higher sampling rate. Congrats! Your HT now knows your proper speed, but the factory ECU, and therefore speedometer, still does not.



2. Create a new Generic Output (Generics) with Frequency Type and Table mode, and a 50% duty cycle. Set its output pin.



3. Navigate to the new table. Theoretically you should only need three cells, the Vehicle speed you calibrated at, 0, and your max vehicle speed. You'll need to extrapolate the max speed calibration from the speed you took. The HT will then interpolate anything in between. But you can add as many speeds as you want and linearize.

The formula to get Hz should be: (Pulses/mi)*(mph)/(3600sec/hr) * TF (tire factor). If we assume TF is 1.0 (stock tires), then the result is 44.275Hz. I will round up so that the factory ECU thinks I'm moving slightly faster than I am at a HT read 45mph, so 45Hz @ the HT's calibrated reading of 45mph (conviniently, or coincidentally? Cool design Toyota?). Note this is table only takes whole numbers.

I'm running 35" diameter tires, and my factory ECU is calibrated for P225/75R15s as shown on the door sticker, which are 28.3" in diameter. That's quite a difference.



To get "TF", tire factor, we just get the two circumferences and divide new/old, or since 2pi/2 cancels, it's just the new diameter/the old diameter: 35/28.3 = 1.23675. Multiply that back in with the result above to get your corrected frequency to feed the ECU.

Sanity check: with bigger tires we were traveling faster than the ECU was reading notches on the VSS, so frequency was slower than it should have been. Therefore, frequency now should be higher than we calculated the base rate at. HT was calibrated at the proper pulse rate so it reads our actual vehicle speed, now we need to feed the factory ECU a faster signal because it is calibrated to need more pulses to travel the same distance.

44Hz * 1.23675 = 54.417Hz, and we will round UP again to 55Hz for error. Test this later with the GPS speedometer (or you could also use the HT itself at this point), and make corrections as needed. Increase Hz if your GPS reports over your speedo, decrease if it reports under.

To make the final cell easy, choose a multiple of your calibration speed. I chose 45mph*4 = 180mph. Then extrapolate the frequency the same way: 55Hz*4 = 220Hz.



Finally, we need to select the proper interception point. For this you need an understanding of how the transmissions handle speed. There are 2 Vehicle Speed Sensors (VSS) on your transmission if you have an Auto, and 1 if you have a Manual. I will attach the relevant documentation to this post (bottom).

VSS #1 is raw fed through the combination gauge cluster, where it undergoes a correction to a "squarer" waveform, which then goes to SP1 on the ECU. SP1 on the ECU is completely unused unless VSS #2 on an A/T malfunctions. We want to force this because VSS #2 is a reluctor sensor and cannot be simulated very easily, so disconnect VSS #2 if you have an Auto. SP1 is a failover for auto transmission shift points.

Now, you can either intercept before or after the gauge cluster. Before will impact both the speedo and transmission (after VSS #2 is "malfunctioned"). After will only impact the A/T once VSS #2 is "malfunctioned". A good splice point is either behind the gauge cluster, or at the VSS #1 sensor. The latter will have you disconnecting both VSS sensors on an A/T.

Voltage from VSS #1 square wave is an active low (defaults to 5V when not moving). On the HT we cannot simulate a 5V active low, so we need to splice a 5V rail into the splice point as well, and let the HT do the pull down at the interval we have determined above.

Again, this has not been tested, so don't cut anything unless you want to take the risk and report back .

~ Tuning Tips ~
Moved BELOW

 

I like it, you might want these for your knockers

https://www.bmotorsports.com/shop/product_info.php/cPath/129_589/products_id/4516

 

I thought I might drop this for you just in case you decide to do full trans control before I get to it on Mike's truck...

 

~ Tuning Tips ~
I moved this here since it should be long enough to have its own section separate from the previous. Specifics will be unique to the Haltech 2500, concepts could apply to many ECUs.

Trigger & Home Arming Voltage

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Before you can do anything with your vehicle, it has to be able to start. Most of the precursor information needed to baseline your truck can be found in various base maps, but to avoid Trigger Error DTCs, you may want to look at practical voltage triggers. Useing the oscilloscope function, set up a set of probes like the following:



Here you can see I set up the actual voltage from the crank (home) and cam (trigger) sensors, and where the ECU is triggering that as a pulse based on the trigger settings. In the screenshot above, the home/crank signal is much larger than the trigger/cam to the tune of 6.2Vpk (12.5V pk-pk) vs. 2.8Vpk (~6Vpk-pk).

The important thing to realize here is that with rising RPM, frequency rises and voltage rises. This means that idle is actually your most limiting condition, so we want to set voltage trigger levels based on idle waveforms.

Ideally you want to set these to where they are most certainly real signals in all circumstances, while allowing enough margin for hysteresis (the ECU to pick up the trigger). In this case, we're around 1000 RPM and I'm looking for about 1/3-1/2 up the positive edge, which is about 1.0V:



Since home is a much larger spike, we set it higher to get away from the noise in accordance with the same methodology:

Closed-Loop Idle Control

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One of the most important aspects of tuning an engine is just getting it to behave at low load conditions. City drivers can spend just as much time in this region as actually driving, so it's important to spend the time and get it right.

Here are good base settings that I've been using for the Taco's IAC:



Once we've established the base control settings, there are several main things to access when tuning Idle:
1. Idle Air Control (IAC) Base Duty Cycle & Target RPM
2. Idle Up
3. Minimum Output
4. Start Target & Offsets
5. Ignition Correction
6. PID


1. Base Duty & Target RPM
Base duty cycle is the primary table accessed when the HT looks to control idle. Greater values = greater air = more combustion = more RPM.

Starting base duty values will vary depending on your altitude, IAC cleanliness, and throttle valve screw setting. If you're finding you need large values in your base table when warmed up, I would recommend adjusting the throttle plate screw so that it is open about 1.5-2.5% more. You can check this percentage by watching the TPS reading in real time. Then start over with the base table.

In general, you will want to start higher and let long term correction bring the percentages down. You can see from my table below that it has been difficult to tune lower temperatures so far because we are entering summer in Phoenix, AZ.
Note the Y-axis is set to Target RPM (not engine speed/RPM), and that's for good reason that we will get to. These should all be set very meaningfully, with the lowest as your lowest target (defined in next part).



The easiest table to set is the target RPM. I played with several levels, but found the following worked best for me. The lower warm RPM keeps my exhaust drone at a stop to a minimum, and with good control I'm not at risk of it stalling from dropping too low.



2. Idle Up
One of the most important parts of idling is how the ECU reacts to a sudden increase in load. The two we will be focusing on are A/C and Power Steering. I have found that RPM increase here is not nearly as important as duty cycle. In theory, you don't need to increase RPM at all as long as the extra duty cycle you provide gives the engine enough air to produce enough torque to supply the load, though your accessories may operate at greater output at higher RPM.

To set these levels properly, you need to turn off reset and long term corrections, if on, and set up a visual readout table like so:


You also should set your RPM offsets now. I would suggest 50, 75, or 100RPM for A/C, and 50 for power steering. (I chose 50 for both). We will then attempt to naturalize duty cycles to meet these. Choose 0-10% duty cycles to start. I highly recommend 0 if your idle settings will support it. If you do anything above 0% here, subtract it from the final calculation.



Once you determine these, head back to your Idle Control Base Table, and create rows for the additive RPMs for each of these possibilities. Note these are Idle Control Target RPMs, not actual engine RPM.



Since I chose a base target of 700RPM, +50 RPM for A/C = 750, +50 RPM for PS = 800. If you chose 75 for A/C and 50 for PS you would want +50 (PS), +75 (A/C), +125 (both), and since you don't have the common increment. Likewise, if you chose +100 for A/C and +50 for PS, you would want +50 (PS), +100 (A/C), and +150 (both). You should also have at least one higher RPM for starting condition correction.

What this does is effectively create a unique set of duty cycles for each accessory operating condition over coolant temperatures to get to your target RPM (also over coolant temp). This tends to work much better than a MAP axis. Later we can add even more definition if we chose a 3rd axis of In-Gear or Not In Gear (transmission load or not).

Setting Idle Up Duties
From here we want to determine two things to minimize initial error: the corrected duty cycle without an accessory, and the corrected duty cycle with a given accessory. I used A/C first since it is very clear when it turns on, and easily controlled quickly with the dash button if you're quick, and it is more influential than PS. Make sure your engine is warmed up completely before proceeding.

To determine the correct value in each state, wait until the Idle Out stabilizes from the readout we set up in the first table (all accessories configured are off). Remember this number. Your Idle LTT should stay 0 if you turned it off. Note the STT for each state as well, as that is a good indicator of what adjustment you need to make to your base table's current cell.

The difference between the duty cycles in the ON and OFF states for that accessory is what you should put in that accessory's Idle Up %. Repeat this as many times as necessary until you stabilize RPM oscillation between ON and OFF states. Mine ended up varying from 14-16%, so I went with 15%. Recall that if you did a duty cycle above 0%, you need to add that to this number since this number already took account of it. Then apply this to the Idle Up page.

Once you're satisfied, turn Long Term Trimming back on, and let the ECU do the rest.

3. Minimum Output
Minimum Output is a sort of failsafe in case your other parameters are adjusting too wildly. It should be set just high enough that your engine doesn't die. Too high can prevent your RPMs from dropping to your setpoint, and can result in extreme negative trim values (that add up to a target of <0% - I've witnessed this)

Here are mine after a throttle plate adjustment. Note they are quite low due to this slightly further opening of the throttle plate. I'd say reasonable values in the warmed regions are 5-15%.




4. Start Target & Offsets
This maybe should have been first, but I'm assuming this guide is only necessary for people who have already gotten to an idling state and wish to improve it. These two tables should be self-explanatory at this point. The factory ECU likes to maintain a high RPM for longer than I like, so I adjusted accordingly.
Note that these are additive with Idle Up and Target RPM, so don't set your cold coolant temp RPMs too high - my max RPM is 1300 + 300 + 50 + 50, or 1700 for the first 2 seconds in sub-frozen temps, then it drops to 1300 until it starts to warm up. Before I adjusted this table, I had the ECU target over 2000RPM briefly before I moved it down.



Of course, these RPMs need to be accounted for in the Base Duty. This duty table is not nearly as important unless you're getting crazy oscillations since it will only be changing RPM for a few seconds, which the PID is decent at correcting for.

The most important thing here I found, was setting the 0 second run duty to 100%. This promotes an instant start, as it is easier for those cranking injector pulses to receive air. Immediately drop that down to reasonable values:



Since these are offsets, they will add to your base table.

5. Ignition Correction
I have not changed this table much from my base tune. It seems to work very well in what it is designed for. This table works in tandem with the PID tables to self-correct to your target RPM. I reduced the advance slightly on the edge cells near the middle and that seemed to have an overall calming effect on oscillation.



6. PID
I'm not going to get too much into this as the theory barely matches practice here. In that I mean that trial and error seems to work better than overthinking it. The goal of these tables is to reduce RPM error through duty cycle correction in a controlled manner without overshoot. P is linear, I is more influential immediately and dies off over time, D is more influential over time (note the units in each table).
Note that values don't necessarily need to grow with error because the error level itself is multiplied here. Increasing the value is "doubly increasing" the effect.

Here are my settings that work well for me. Note that I added a 0, 0 column so I could set the tiny, adjacent offset cells differently without it wanting to move at all if the + and - errors weren't the same magnitude (interpolation that would not = 0 at 0).

 

Update from a couple weeks ago I have acquired an A340F, and transmission jack last weekend. I should have everything I need for a 4x4 conversion now!

 

Some QoL updates to the bed




And some cosmetic updates to the rear lights

 

link on that 3rd brake light?

 

https://www.ebay.com/itm/354729037731

 

Those 3rd brake lights can be a pain to install but that one really does go great with the tail lights

 

Some great information here. Bump to help me remember where to find it

 

I'll have some updates to make, but glad to add more too if it'll help someone

 

I'm sure I'll be full of questions soon.