What did you do today?

Talk about your cars etc here
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Drum
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Re: What did you do today?

Post by Drum » Sat Jul 25, 2020 9:36 am

I had a p38 briefly. I did that key thing, needing a secret coded handshake with the ignition to wake it up. I bought it with a fucked HG and sold it with the same.

It was a bonnie car though
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Drum
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Re: What did you do today?

Post by Drum » Sat Jul 25, 2020 10:36 am

Trying to get onto Eddie's crash bang thread
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MLOR
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Re: What did you do today?

Post by MLOR » Sat Jul 25, 2020 11:26 am

@Panhard65, Those battery leads are err... "interesting"!
Looks like he used meter tails, did he buy the wrong battery?

Are there any more bits of household wiring in use?
Bathroom cord switch to turn on the fog lights perhaps ;)
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Scruffy Bodger
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Re: What did you do today?

Post by Scruffy Bodger » Sat Jul 25, 2020 12:09 pm

Pretty sure I've read battery voltage on the P38's is absolutely critical or it'll do what CLINT mentioned. They are such a good looking truck and I'm sure values will soar at some point, mostly because there will be virtually none left because of slipped liners and electrical gremlins.
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mercrocker
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Re: What did you do today?

Post by mercrocker » Sat Jul 25, 2020 12:26 pm

My friend Dave who got the Cowley from scrapper to MOT for me had a P38. In fact, he towed the Cowley in with it and at the time I joked that the old Morris would outlive his Rangie. Within a year it had pulled the key trick, flattened its battery, lost its suspension and ended up stranding him in the Dartmoor cottage he had rented for Christmas. Dave is a seasoned car fondler, having revived dead Silver Shadows and S Type Jags for fun but that thing damn near broke him.....
South's gonna rise again.....
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chadders
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Re: What did you do today?

Post by chadders » Sat Jul 25, 2020 12:47 pm

I'm curious about P38s.
I've seen loads of problems reported about them but why are they like that?
Bad design, poor quality parts, inadequate development, poor maintenance or whatever?
As Drum says it's a good looking car but for someone of my mechanical and electrical ineptitude it's a complete no no. I might be able to buy one but sure as hell couldn't afford to run one.
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Scruffy Bodger
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Re: What did you do today?

Post by Scruffy Bodger » Sat Jul 25, 2020 1:30 pm

chadders wrote:
Sat Jul 25, 2020 12:47 pm
I'm curious about P38s.
I've seen loads of problems reported about them but why are they like that?
Bad design, poor quality parts, inadequate development, poor maintenance or whatever?
As Drum says it's a good looking car but for someone of my mechanical and electrical ineptitude it's a complete no no. I might be able to buy one but sure as hell couldn't afford to run one.
IIRC they have an early Can bus system that fails and means they can be fraught with problems. I know someone who's smoking round in an early diesel one at the mo. It was an Ebay buy and he put in a stupidly low bid and no-one else bid against him so much to his surprise he won it. That was just before the lockdown, dunno if it's failed on him already? The TD's are the old BMW engine fitted to 325's and Omegas so I'd have thought their reliability wouldn't be so bad?
SiC
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Re: What did you do today?

Post by SiC » Sat Jul 25, 2020 2:07 pm

CAN bus/Multiplexed systems always gets blamed for electrical issues but that's not the problem. Protocol and bus itself is extremely robust and fault tolerant. The issue is badly written software/inexperience.

In the example of low battery corrupting the immobiliser, when programming flash memory you need to ensure you have a rock solid power supply. If power is interrupted during the write or erase cycle of that chip, you end up with corruption all over it. As flash erase is quite slow (100-600ms, depending on size), it's quite a large window where it can be affected. I imagine in the P38 case, it probably writes the next rolling code or ignition starts, etc around when the engine is cranked. Also at risk if there is a glitch in the power supply that causes a data error and thus accidentally triggering a rewrite cycle. All at risk of corruption if the power supply voltage sags.

To stop this being an issue, the software should take a number of strategies to mitigate the risk of corruption. Multiple banks that you only unlock individually and each bank having a copy. Enough bulk capacitance to allow the software to run long enough without power to abort the erase/program cycle. Finally only reading/writing when you know it's perfectly safe to do so.

It's not only the P38 got this wrong. PSA BSI body computers are notorious for it and require a dance before disconnecting the battery. Honda got it wrong with the spaceship Civic where the immo data would be lost if you disconnect the battery with the ignition on. Etc, etc.

Shit software that manufacturers find out these issues but can't be bothered to fix. To fix requires going through an approval and documentation exercise that costs money, when the issue can be resolved by telling and selling a customer a new car battery with the occasional recode of the immo.
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Eddie Honda
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Re: What did you do today?

Post by Eddie Honda » Sat Jul 25, 2020 3:21 pm

SiC wrote:
Sat Jul 25, 2020 2:07 pm
The issue is newfangled tosh/French.
FTFY
Alf892
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Re: What did you do today?

Post by Alf892 » Sat Jul 25, 2020 9:08 pm

Spent the day helping a mate put the gearbox back in his Chevy pickup. He had put the selector housing on wrong which cost a few minutes. Then we found the output splines were different size which cost a couple of hours.

Topped off by it being torque tube so had to get the axle back in. 6 hours just to get the box back in!! I've still got to go back and bleed the brakes as well
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