1987 AMC Renault GTA 2.0 - Gone to a new home.

Ooh, looky looky! What's in my mailbox today?


Is it? No, it can't be, but yes! It is a Colortune!



heh.

Got the thing unpacked, checked it was all there. Kindly my old man has included a few more instructions photocopied (In colour, nontheless!) from his Colortune. The things have changed over the years but the theory is identical.



It's all in there. You get a different assortment of parts than you used to. The original from the 60's you had to improvise and put the middle of a bog roll over it to be able to see what was going on if it was the slightest bit light out. This one comes with a little tube with a mirror, so you're not staring right at something that could potentially blow out into your face. Nice touch.

For the young'uns who might read this and have never seen it before, this is the most important bit, the plug:



Looks like the banjo-playing half-brother of a real spark plug, but for a reason:



Unlike a normal spark plug, this one has a chunk of Borosilicate glass set into it, with the ceramic centre going down the middle. you can see all the way through it.

Most of you will probably have had the opportunity to play with a Bunsen burner at some point in school, and you'll know that if you block the air duct off the flame goes all bright yellow and sooty, and if you open it up it burns pale blue and clean.
Petrol does the same inside the cylinder, so if the mix is too rich it burns bright yellow, if it is stoichiometric (perfect ratio of air:fuel, petrol is about 14:1) it burns with that "Bunsen blue" colour. The plug allows you to see this and adjust the fuel mixture accordingly. It kinda went out of fashion with carburettors, but it's still a useful tool. They sell 'em here, but not in metric, and they roll off the shelf for about $90... go see what Halfords sells them for heh, and you'll see why I had my father ship one from the UK!

Got that lot packed up, and set aside the other part of today's odds and ends:



The three-legged creatures are on the march across the plains to destroy everything in a *ZORT* of bright green light!
aka I got another couple of transistors to try build this circuit again

--Phil

Didn't have much time to do anything tonight, as by the time I get home it's dark already. Daylight savings time sucks on the changeover.

Either way the wife wanted to stop in and check for mail at the MIL's so I picked up one of the spare plugs from my toolbox when we stopped to compare it against the Colortune;s threads.



Thankfully they are identical in diameter and thread pitch.

This weekend might see some testing. I did notice last time I ran it up that the thermostat was sticking, opening, sticking, opening. I guess it doesn't like being sat up. Might be time for a replacement.

--Phil

i used a colourtune on my vw 2.0 aircooled when i fitted weber idf carbs, i used the gunsun colourtune, a gunson cheapo gas tester i got of ebay, a carb airflow balancing tool, & i got mine running absolutely spot on, i wanted it as good as it could be before i had it on a rolling road-the rolling road guy was super impressed!!! one of the jets on one my carbs was wrong from the factory / but other than that being changed & a few experianced tweaks for smoother running the rolling road guy said my mixture was right on the money!!!!
i think the colourtune is a good tool-even better with a gas tester!!!!!!

We are due to freeze tonight, so I made a trip down to the car after work tonight.

Decided to take the Colortune down to check it out.
Removed the no4 (yes, I know it's at the pulleys end but Renault number their plugs from the flywheel end. Yet another oddity) spark plug and cleaned up the hole:


Stuck the Colortune in


And wired it up to the ignition lead


My camera can't handle really dark, but I fired it up and poked the lens towards it, hoping to capture something:


Really cold it runs better than not so cold, suggesting I have the baseline wrong somewhere, or a sensor is maladjusted.

Stopped that, forgot to put the old plug back in and started it up on a whistly-wheezy 3. Oops. At least it starts and runs on 3 though. Get-me-home

Decided then to actually drain the coolant and put in some antifreeze.


The radiator has a drain tap on it, helpfully.

Car took a leak all over the driveway. Antifreeze has been on the "must-do" list since I rebuilt the engine. thankfully it is clean as it had boiled up a while back, and I think a large amount of the oxygen in the water outgassed, so there wasn't much to make it go rusty.


Stuck $19 of Prestone's finest Alugard-II compliant antifreeze in:


Started the engine and let it draw the stuff round.

Mmm, fluorescent yellow goodness!

Let it come up to temperature and open up the thermostat- the heater works really very well

Idling nicely, although the flash made the fan and belt appear stationary


One thing I did notice though was that when it was idling on a slight load (fan, heater, headlights etc on) the voltmeter was dancing about and the lights flickering:


Not too sure what causes that, but the battery is a)knackered b) low on charge.

Would the regulator be having a fit like that because it has a load and the battery is shot, or is that symptomatic of something else? Adding a load makes it smoothly drop down in volts, then rise up again and begin to wiggle.

There's always something. That and I packed up and forgot to lock my toolbox- I remembered when I got home- so had to drive all the way down there and back again with dinner in the oven, afraid it was going to singe... haha.

--Phil

Four pot drone lol
The battery is a Walmart (n)Ever-Start, and it was in the car when I got it, dead flat. I'm surprised it even took a charge. You can see how good it is from one of the previous videos. I go to start it and RAKRAKRAKRAK of the solenoid lol
It's had it, so a new one is on the list. I know the battery is a large part of smoothing the voltage out on the car too.

Probably going to be doing a bit more research tonight on the electronics, SWMBO wants me to bake bread and clean house.

--Phil

I had the alternator checked locally and they said it was good and didn't need to have anything changed. A rebuild here usually ends up into three figures- it's often cheaper to p/x out the old one as a core against a rebuilt one.

The belt has done about 3 miles, but may have to be changed again. Someone I know has kindly donated a spare idler pulley (the piece making all the racket in the bonnet-up videos) to the cause.

The voltmeter appears to be quite accurate- the headlights were pulsing in time with the gauge
I've checked the meter against what the battery reads at and it is accurate. I'm thinking Sven is right- a decent battery would help.

--Phil

I tried doing the paint/sand thing but it didn't work out too well- the paint is very thin, the plastic bends under the pressure of your touch and you end up showing all the high areas.

It isn't as pretty but with this method I would at least be able to put on a layer, sand it flat, put another, sand it etc, until the paint was totally flat.

In this case it's going to be pocked with stones and bugs so it's adequate

I learned also that the European lights are slightly different in dimensions to the standard USA spec 4666 bulbs. That's probably why...

--Phil

At idle it widdles everywhere, flowing about as much as that pipe can handle.
I had checked that before. I need to repair the tank or replace it because it is cracked but not yet leaking. Another item on the list of things, but flow of coolant is superb, thankfully. It even fills up with just the radiator top plug unscrewed and pouring coolant into the header tank. I did find it easier to take the heater pipe off the intake manifold and fill it from there in the past...

--Phil

I've been busy, me. Inbetween baking bread for SWMBO and cooking dinner, and work (bah) I managed to verify a few things.

Firstly, I set up my fully stocked electronics workshop:


Fired up my trusty oscilloscope, wiped the crud off it and discovered something my nephew had spilled on the bezel had eaten at the plastic



I set the little USB RS232 device I bought off Amazon to work, outputting a series of 1's and 0's. This is the output from the computer, the "ideal" waveform, if you will (basically what the computer would be expect to be fed).



Not too bad. I notice my scope needs adjustment for this new location, or possibly it just didn't like being sat on top of the dog's kennel but the waveform is nice and uniform, with some good rising edges.
Now, if I actually liked math I could look at the markings on the screen, the width of a pulse, the timebase of the scope and work out the frequency the thing was pushing at. Given that I try to avoid sums where possible, I decided on an easier route, seeing as I was equipped.
My concern was that the serial device was lying to me and the program that was driving it, and that it was running at 57600 baud, a standard speed, not the 62500 I had set it to.



62505. That'll do. I actually did a sum here and came up with 0.000064% error rate in timing. That is well within the 0.050000% by several factors. Joy. My cheapy device actually works!

I decided to feed the output into the input and look at what the circuit was actually generating.

In theory it should smooth out any ripples or wibbly noise that the car may spit onto the line (think interference from spark plugs etc.) and create a brand new waveform from that.



Nice sharp rising edges. A little bit small perhaps (I fixed that since by introducing a smaller resistor into the output stage to bring up the voltage) but a good shape.

I'm actually quite proud that the waveform I have created is cleaner and a better shape (compare the bottom of the squares on each picture, the bottom one is better than the computer was making!) than the input...

Decided to drive it at about 4 times the speed it is designed for- and stuck a file through it for good measure. It read the file back perfectly at 26kb/s- that is the same speed as slow DSL- so 6.2kbps should present it no problem.

The bits are inverted in this circuit- that is, a 1 put in makes a 0 and vice versa so I'm hoping the car is trying to make a 1 when it turns the output on and not a 0 else I'll have to make a hasty addition to the circuit to amend that but hopefully all is well.

Wish me luck with this one. I'm going to need it.

--Phil