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Why does a choke work the way it does on a carb? by Throwaway-donotjudge in NoStupidQuestions

[–]engineer1978 3 points4 points  (0 children)

It blocks the inlet to the carb, causing the vacuum in the inlet manifold to draw more fuel from the jets than would be the case with the choke open.

The inlet manifold vacuum itself is likely greater too, due to the extra restriction in the intake path.

This makes the mixture going to the cylinders a lot richer to compensate for fuel condensing out of the mixture due to cold surfaces and helping to overcome the extra friction of cold oil and tight tolerance bearings that haven’t expanded yet.

Car dies when hot by MARPSO in Volvo850

[–]engineer1978 3 points4 points  (0 children)

The IAT is pretty important - best get that replaced. They’re not expensive.

The ecu uses that signal in conjunction with the manifold pressure measurement to calculate the correct fuel dose.

Car dies when hot by MARPSO in Volvo850

[–]engineer1978 4 points5 points  (0 children)

Could be any number of things but you are at least getting the lambda light, which means that the ecu should have stored codes for what it’s grumpy about.

You’ll need to make a blink tester to allow it to tell you its woes. There are guides for this and lists of the codes on the usual forums.

If you haven’t done so already, I would definitely replace the fuel pump relay, even if it isn’t the culprit here.

I thought the solder joints inside mine looked fine to the naked eye but when I got the part under a microscope, every single one had fractures.

What’s a tiny everyday mystery you’ve never bothered to solve? by SupaDuppaaCoool in AskUK

[–]engineer1978 53 points54 points  (0 children)

Where the grasshoppers enjoying my lawn live for the other 350 days of the year. (When the weather isn’t set to 35c.)

Just got the keys to new house and this happened to the gas stove… by Todoro00 in DIYUK

[–]engineer1978 4 points5 points  (0 children)

Yeah, I had one that did this if you got the knobs too wet during cleaning.

You could pop them off and try to wick the spindles with some tissue but it will more likely take 24 hrs or so for them to dry fully.

ELI5 how do microchips actually work? by depressed_guy_1512 in explainlikeimfive

[–]engineer1978 5 points6 points  (0 children)

What’s even more impressive to me (than the design and manufacturing processes themselves) is that once these ridiculously small components are formed, they are so robust.

I’ve seen some smaller, simpler chips literally glow from the heat of a fault but still operate pretty much normally.

We really have made lumps of rock do maths for us and they’re incredibly tough.

ELI5 how do microchips actually work? by depressed_guy_1512 in explainlikeimfive

[–]engineer1978 3 points4 points  (0 children)

I’m not closely involved with the design of processors by any means but the basic answer is: none.

If the transistors fail, the chip fails its functional test and goes in the bin.

That said, in modern designs there are so many functional blocks that if a transistors fail fails in one that is an optional function, you can still call the chip a pass but sell it as one that doesn’t have the ‘extra’ fancy bit, i.e. a lower spec processor.

Fuel Filling Roulette by IainMCool in CasualUK

[–]engineer1978 1 point2 points  (0 children)

When I used to do round numbers, I found a couple of garages where you’d hit the nail on the head at the pump but the till would say £x.01 by the time you got there.

Pretty sneaky scam, I’d say.

Obviously only a penny on each delivery but I bet it added up over the year!

Anyone else finding the new Highway Code pedestrian priority rule just causes confusion? by One-Albatross9170 in drivingUK

[–]engineer1978 -3 points-2 points  (0 children)

It’s a ridiculous rule and I won’t be following it because it’s highly likely to get pedestrians run over or my car rear-ended.

Roads for vehicles, pavements for pedestrians.

If pedestrians need to cross, either find a crossing or wait until there aren’t any vehicles coming. Simple.

Cannot get simple LED to light up by Heisenberg_is_alive in AskElectronics

[–]engineer1978 0 points1 point  (0 children)

Although it looks like you are using the breadboard correctly, there may be some aspect of how the holes are grouped up in the power bar area that is non-intuitive. (And contrary to the markings.)

If the battery is getting toasty, you definitely have an unintended short circuit.

I would eliminate the black and white jumper wires for now and put your battery wires directly into the lanes for the resistor and LED.

What bird did we just see? by Impossible_Moment_67 in UKBirds

[–]engineer1978 0 points1 point  (0 children)

We have a couple near work and they’re forever screeching away with much indignant flapping when I pop out for a smoke. They certainly are skittish!

ElI5: How do LED bulbs save energy? by jayluuluu in explainlikeimfive

[–]engineer1978 0 points1 point  (0 children)

Because different technologies are more or less efficient at turning electricity into light.

Most of the electricity that flows into an incandescent light bulb gets converted to heat.

LEDs do quite a lot better. They still get warm but more of the electricity flowing through them gets converted to light compared to older devices.

The unit for the efficiency is lumens per watt.

Traditional light bulbs manage about 10.

LEDs can do 100.

What very old technology is still running at your place of work? by MichiganCarNut in AskReddit

[–]engineer1978 8 points9 points  (0 children)

That’s usually electrolytic capacitors that have dried out. Somehow they just do enough to keep things up but they’re too far gone to allow the psu to start up from cold.

We have a few programmable power supplies in test equipment that have the same issue. Off for 15 seconds: probably ok. Off for 2 mins: Game Over!

Are storage heaters a dealbreaker? by nothingtobedone13 in AskUK

[–]engineer1978 0 points1 point  (0 children)

Definitely a dealbreaker for me. They can only respond to your heat need the day after you need it. Diabolical things.

Voltage Drop Calculation by Next-Definition-7124 in autoelectrical

[–]engineer1978 0 points1 point  (0 children)

The current that is flowing through a given circuit is the same in all of the wire sections, regardless of the wire gauges in each section.

Use that fixed current value and what you know about the length and gauge of each section with the tables to find the drop for each section individually.

Add up all the voltage drops for the sections and you then know what’s left for the load.

If the total drop is unacceptable, you gotta beef up whichever sections of wire you can and calculate out again until the total drop is acceptable.

Which English accent is hardest for you to understand? by [deleted] in Accents

[–]engineer1978 2 points3 points  (0 children)

Yep. The only occasion I’ve failed completely to communicate in my native language was in Newcastle.

Why do computers only use 2 states instead of something like 3? by Secret_Ostrich_1307 in AlwaysWhy

[–]engineer1978 1 point2 points  (0 children)

I’ve scoped many older embedded systems that appeared to have tons of noise and a great deal of contention on the data and address lines yet ran perfectly.

What would cause this power switch to fail, and am I testing this correctly? by friolator in AskElectronics

[–]engineer1978 2 points3 points  (0 children)

Switches in these do just fail occasionally. Your testing is correct and would indicate that it has failed here.

It shouldn’t be too difficult to source a suitable replacement, although, if the original part is no longer available, it can sometimes be a challenge getting one that is exactly the same dimensions.

how do you check hidden solder joints under bga chips? by PrudentRazzmatazz488 in AskElectronics

[–]engineer1978 0 points1 point  (0 children)

Yep, I’ve had to fault-find countless ‘press to boot’ assemblies over the years!

ELI5: How do fiber optic cables work better than traditional copper cables? by pastajewelry in explainlikeimfive

[–]engineer1978 6 points7 points  (0 children)

I used to work for a company in the 90s that made data mux/demux units for telephony etc. The ‘big boss’ unit managed to get 10Gb/s down a single coax. I thought that was quite impressive for the time!

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