Category Archives: Electrical


Good Electrical Ground

A good electrical ground.

How many times have we read about the need of having a good electrical ground in classic cars?  Well, I’ve had my fair share of bad electrical grounds through the years and this weekend I fell victim to one.

Weekends are my time to enjoy driving bowtie6 and this past Saturday was no exception.  At a red light not far from the house some dipshit was fiddling with his phone instead of paying attention to traffic.  I reached down below the dash and tapped the single-pole momentary-on switch that controls the horn…

Nada.  Nothing.  Horn did not work.  At this point I had the default Whiskey-Tango-Foxtrot expression on my face.  Damn!  Electrical gremlins.  Fist thing that pops in my head is failure to have a good electrical ground.

And so, when I get back home I check the fuse panel under the dash that I made and controls all electrical circuits under the bonnet (click here for a more detailed post).

IMG_2825I checked all fuses and they all passed with no issues.  Then, I pulled each one out and made sure all connections were in order.  I know, the wiring is a bit busy – but this is rather hard work to do especially in the tight confines of the passenger’s side footwell.  I suppose this is what “bespoke” is all about!  😉

So, next was to go through the main power box.  This is located in the engine compartment (click here for more details).

IMG_2824As you can see, here is the main power distribution block in bowtie6.  The six red-capped affairs on the bottom are circuit breakers.  They feed hard voltage to each purple relay.  In addition there is another fuse panel located behind the relays as well as the engine’s PCM.  After careful inspection all this checked out just fine.  When I flipped the switch under the dash for the horn, the “horn” relay clicked as expected.  Still no horn – rats!

Which brings us to the next photo (a closeup of the featured image above):

IMG_2826 closeupThe entire circuit governing both horns relies on the ground made by the connector to the body.  As it turns out, I pulled this connector and ensured there was no rust.  Sure enough, after cleaning the connection, adding a little de-electric grease, and plugging the connector back in place all worked just fine.

And there you have it, the root of all evil… The lack of a good electrical ground.

ECOTEC ECM Tuning – Changes So Far

I mentioned in the last post I’d go into more details about HPTuners.  This time I want to talk about the Ecotec ECM tuning changes done so far.  I’m far from being an expert however one needs to start somewhere…

Vehicle Anti Theft System (VATS)

The first and most important task is disabling VATS.  This is a prerequisite when doing an engine swap such as what we did here.  Failing to disable VATS renders the engine inoperable.  On earlier ECM’s GM devised a system by which the ignition key had a special resistor that would match a receiver in the ignition key tumbler.  This “match” would enable the ECM to fire the engine.  With those early ECM’s it was possible to wire an inline module and basically fake out the key resistor.  With modern ECM’s such as the one controlling the Ecotec, the VATS became more advanced.  With the aid of HPTuners though, this is a simple change in the flash file burned into the ECM.

Mass Airflow Recalibration

In bowtie6, we replaced the stock plastic intake with a smaller, more direct intake manifold.  The reason was not for performance but because the stock intake was too big and got in the way of the steering shaft.  The air filter housing was also replaced with a cone-shaped K&N air filter.  There is simply no room under the hood of the TR6 for the large box that holds the stock air filter.  These changes forced relocation of the Mass Airflow (MAF) sensor.  As expected, the stock settings for the MAF did not match the new configuration.  This manifested itself in a rather rough idle and poor performance.

Tuning the MAF took some doing.  I won’t go into all the details but suffice to say it took a few hours worth of driving down the road and logging data with the VCM Scanner.  Using the VCM Editor I was able to dial in the low and high MAF tables to more desirable values.  This resulted in smoother idle and better performance.

Seeking Professional Advice

This is where the tuning process gets a bit pricey.  After going through several  books and reading many long hours’ worth of posts I decided to find a local expert.  Sure enough I found a person with a great knowledge and familiarity with HPTuners and tuning GM engines. However this came at a price.  The results though, made a huge difference.

As expected, fuel efficiency is the ahead of pure performance in the  stock ECM.  This shows up the way the commanded air fuel ratios are pre-set across the RPM range, spark tables and the way that power enrichment activates proportional to throttle angle – among other things.  After quite a few alterations the ECM is delivering more performance at the expense of fuel efficiency.  The results are astounding:  throttle response is much more livelier resulting in more power being delivered and overall the engine is much smoother across the entire rev range.  It is now very easy to make the Ecotec reach its 7000 RPM redline.

What next?

The next step will be to take bowtie6 to a dyno.  Been there, done that before but this time we will be tweaking the ECM  This will allow even more accurate dialing in for extracting that last bit of power.  Also, something that is yet to be modified are the VVT tables.  The 2.4 Ecotec has variable valve timing and this first tuning did not touch VVT.  Who knows what we can do with this?

Another avenue left for exploration is E85 Ethanol.  I’ve been intrigued for a long time about this source of fuel.  FlexFuel vehicles have a special metering device that allows the ECM to calibrate itself on the fly.  I don’t have that metering device but I have HPTuners and this will allow a special E85 calibration flashed into the ECM.  Where I live E85 is very easy to find – there is a very large fuel station just down the street from my house – so this will be a fun experiment.  Granted, flashing the ECM to run E85 without a metering device means E85 has to be burned exclusively.  However, changing back to straight fuel is easy to do, simply by reflashing the ECM.

In Summary

I realize to each his own and this is not for everybody.  However, having all this technology at your fingertips (literally) is remarkable.  Why would anyone want to waste time on those relics of fuel metering called carburetors is beyond me.

Stay tuned…  Soon bowtie6 will be the first E85 Ethanol powered TR6…  🙂

ECOTEC ECM Tuning – Intro

Gone are the days of “burning a chip” for engine computers.  Modern Engine Control Modules (ECM’s) can now be monitored real-time and then modified based on readings done after driving down the road.  Pretty cool stuff indeed but it adds a whole new dimension to engine performance adjustments.

The factory install of the Ecotec in a Pontiac Solstice at its core consists of the engine, wiring harness, ECM and the Body Control Module (BCM).  The ECM reads and controls engine signals while the BCM controls such things as gauges, door locks, lights, etc.  In addition, the BCM supplies data used in the information center on the instrument panel showing fuel consumption, engine temp, outside temp, etc.  Furthermore, the ECM and BCM talk to each other via a digital high-speed bus integrated into the factory wiring harness.

So, one of the challenges in getting the Ecotec to run in bowtie6 was making all this work outside of the factory install.  After doing a ton of research and reading the Factory Service Manuals, we were able to figure out what wires actually control engine sensors and what goes to the BCM.  This enabled us to change the factory harness to fit our needs.  Since we did not run the factory instrument panel and did not need to control lights and such, we did not use the BCM.

A disadvantage of this approach is the lack of cruise control.  In the Ecotec the throttle body is electronically activated – there is no cable in the traditional sense.  Instead, the electronic “gas pedal” inside the car sends a signal to the ECM via a small wiring harness.  This gets accomplished by coarse and fine potentiometer readings of the throttle pedal position (Click here for my Drive by Wire article).  There is also no Idle Air Control (IAC); instead idle is now controlled by the ECM cracking the butterfly angle as needed.  This is very amazing stuff.  As a side note, it is interesting to pay close attention when turning the ignition to the “on” position:  there is a very short “click” heard from under the hood.  It is the throttle body going through its pre-check.  But I digress… Bottom line:  my goal is to be able to integrate the BCM into bowtie6‘s wiring and by doing so, have a fully operational fly-by-wire cruise control.

Among the wires going to and from the ECM is a group that end up in a special plug called an ALDL connector.  This special connector is normally found in production GM cars under the dash on the driver’s side.  It is by the ALDL that the GM TECII scanner/programmer gets connected to the car’s ECM.  In my case I use my laptop along with an interface made by HPTuners to read and change the ECM’s settings.

Enter HPTuners

HPTuners is a commercially available ECM tuning package.  It consists of a Windows-based software running on a laptop and an interface with a USB connector on one side and a matching ALDL connector on the other.  This software package is quite remarkable in what it does; equally remarkable is the lack of documentation.  Sure it has online help but it is very lacking in detail and content.  In the hands of a newbie it can spell disaster to the engine; in the hands of an expert it makes an already great engine even more remarkable.

HPTuners has two main software components:  the VCM Scanner and VCM Editor.  The Scanner is the means by which the engine’s parameters get monitored real-time.  There are a number of different ways to display data:  charts, a gauge panel and tables.  Scanning is accomplished by connecting the laptop to the ALDL connector via the interface, starting the engine and pressing the “Scan” button on the Scanner.  Then you drive down the road and start logging data – the more, the better.  This data can then be saved to a log file for further analysis.  Another feature of the Scanner is to load a log file and play it back – this is very helpful in determining what to change.

The tool used to re-flash the ECM is the VCM Editor.  The process is quite simple:  read the ECM, make adjustments and re-flash.  The hard part though, is figuring out what to change and in what order.  It has been my experience so far this is a bit of a black science.  Information on the interweb is vast about tuning.  However, discerning truth from fiction is the true challenge.  There are several books on the subject and then there are tuning courses available, however they are pricey.  HPTuners is the tool but what to do with and how to use it, is a very time-consuming task!

In the next installment I’ll go into more details about HPTuners…

bowtie6‘s Custom Wiring – Inside the Cab

The last and final installment of the bowtie6‘s custom wiring takes us to the inside of the cab.  This will be the last on wiring – I know this is getting boring but I just want to show what can be done with a little creative thinking.

So what do we have here?

The picture above shows the quilted maple dash we made, it is mounted to an aluminium backing dash which in turn is bolted to the stock TR6 mounts.  The vent is fully operational with a bit of a twist – I’ll have to write about this later…

Behind all this you can see what I call the “cab” wiring.  Here are two spade fuse housings holding 7 of 8 fuses.  The ones on the left side are constant “on”; the ones on the right are switched.  In the middle you can see four relays.  Here is a closeup:

Why the missing fuse?  I am not completely done with the interior wiring and this circuit will be used at a later date when I add the final details to the inside:  fully operational door activated interior lighting.

Relays & Fuses

Four relays are mounted on this plate.  They control the following:

  • Heater and windshield wipers.
  • Turn signals – one relay controls “left”; the other controls “right”.
  • Parking lights.

As with all the other switches, the heater and windshield wiper switches make “ground”.  They in turn activate the electromagnet on the relays.  The B+ to the electromagnet side of the relays are fed by the fuses on either side.  I did not use circuit breakers here, I just used the spade fuese.

The turn signals are controlled by a stock TR6 turn signal stalk.  The turn signals feed goes through a “blinker” switch and from there, a wire is sent forward to control the front signals and a matching wire is sent rearward to the back turn signals.

The same process is done for the parking lights.  The parking lights and headlights are both controlled by a universal park-light/headlight switch.  I bought this from the same supplier I bought all the wiring from and is commonly used in street rods.

Two banks of fuses flank the relays.  The left ones are constant “ON” and supply power to the ignition switch, ECM and dash clock.  Yes, we have a clock in bowtie6!  I’ll have a writeup on the VDO gauges soon.

On the right, the fuses are switched “ON”.  These fuses supply such things are the control side to the relays as well as instrumentation lights and such.

In Summary

Once again, I guess you must be saying “this guy has a lot of time on his hands”.  Then again I wanted to make this flawless and 100% reliable.  I imagine you are asking yourself if this can be “seen”.  Well, I made sure to hide this as best as possible.  You have to get on your knees to see the fuse panel.  If you don’t know about it, you will never see it.  Finally it is mounted high enough that it does not get in the way of your knees and/or feet.

Another great advantage about all this is that all three panels are very easily accessible.  If for some reason a fuse blows it can be easily found and replaced.  When I built bowtie6 the first time, the fuse panel was in one central location.  It was VERY difficult to get to and was not easily serviceable.  I made sure to make it this time very “user friendly”.

And Then There is More…

See anything “unusual” in the pictures above?  There are two small details that do not exist in a stock 1972 Triumph TR6.  See if you can spot them.

If not, stay tuned and there will be more about this soon…


bowtie6‘s Custom Wiring – Trunk

The last post talked about the harness and fuse box under the hood.  Today’s post shows the wiring in the trunk.

Since we are far from “original”, I wired up bowtie6 in a practical way.  There is a fusebox in the engine compartment (as discussed previously), one in the cab compartment (to be discussed) and one in the trunk (discussed here). Why go through all this trouble?

Well, for starters I wanted to keep things simple.  But mainly because there was not enough room underneath the hood!  Besides, it makes sense to control things where they belong and in the trunk there are several things to control…


The Optima Red-Top dry cell battery in bowtie6 is mounted in an aluminium enclosure pictured above.  The B+ terminal has a welding machine cable attached to it and it runs inside the TR6’s cab and ties into the firewall post.  The ground terminal is also a welding machine cable going through the body and securely bolted to the frame.  In the engine compartment, there are two more welding machine cables grounding the body and the engine to the frame. Finally, there is a B+ lead from the battery to two circuit breakers mounted in a special mount that control the following:

  1. Fuel Pump
  2. Backup Lights
  3. Brake Lights

Fuel Pump

The ECOTEC needs a high pressure fuel supply.  This comes from a GM high pressure pump as fitted to late-model Corvettes.  We used that pump because it is very small, has a filter “sock” and can be mounted in a small enclosure.  In the picture above you can see the fuel pump enclosure – that is the aluminium box resting on the trunk’s floor.  I’ve written about this before but basically that is an external tank plumbed to the main custom made all aluminium fuel tank.  We have about a 300 mile range in city driving with this setup.  I am sure it will be more once we do a long, highway trip.

The picture above shows two circuit breakers and three relays.  The fuel pump has one of the relays and one of the circuit breakers.  The control side of the relay is fed from a signal from the ECM.  When done right, the ECM sends a 5 second signal and energizes the pump.  This primes the fuel rail and gets things ready for ignition.  Once the engine fires, the ECM re-energizes the relay and that keeps the pump running until the ignition switch is turned off.

Backup Lights

The AISIN 5 speed gearbox has a built in switch that makes ground when the stick engages reverse.  I took advantage of this to make the TR6’s backup lights work.  Basically since this is a switch and it makes ground, I wired this into the control circuit of a relay.  This minimizes wear on the switch and voilà, we have backup lights.

Brake Lights

Ah!  Brake lights!! As you had guessed, I used a relay to run the brake lights.  As with the fuel pump and backup lights there is a hard voltage circuit from B+ on the battery to the relay.  This is controlled by breaking ground on the brake pedal switch.  Simple.  Brakes work flawlessly and will be there forever – the brake switch breaks ground.

 In Summary

Once again, I realize this is borderline overkill.  However, this makes things very simple and easy to fix if need be.  Setting this back circuitry together took little time and works like a charm.  As with the engine compartment fuse box, I added red “booties” to the circuit breakers.  You can also see the trunk floor is fully covered in black carpet now.

Here is a closeup of the rear wiring:

If you look close enough you will see several things here…

  • The lid to the battery box.  The box is made from aluminium and bolted securely to the side floor of the trunk.  This is mounted on the passenger’s side to even out weight distribution.  As mentioned previously, the battery is a dry cell Red Top Optima battery.  They are very durable and although they are expensive, they are very worth the cost.
  • The black plastic background.  That is ABS material pre-bent and cut to fit the sides of the trunk.  There is one on all sides, including the inside back of the trunk.  I used this because it is very easy to work with and can be shaped with simple tools such as scissors and a break.  This stuff is also very durable and looks very clean.  Much superior to the crappy cardboard “trunk liner” kits sold by the Big Three vendors.
  • The aluminium plate holds three relays and two circuit breakers.  I’ve discussed these above.
  • Finally, if you really look close you can see two rubber hoses right behind the circuit breakers.  What is this all about?  Well, my bowtie6 is from the very fine 1972 vintage.  In 1972 a special “tank” was affixed to the inside of the passenger’s side trunk.  This tank had two lines attached to it.  The first line came from a vent on the fuel filler neck.  The other line was routed to the intake.  This ensured all fuel tank fumes get routed back to the engine.  This has been retained and is fully operational in bowtie6.

Attention to detail?  Hell yes.

There are so many small details on bowtie6 that get overlooked!  However, I know they are there and this makes the difference.  With this TR6, there is not only killer looks in the form of a very shiny paint job, a powerful engine and a great handling frame but there are also countless details that separate this from even “restored” examples…