Anyone else get that annoying PM?
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By soviet_merlin · Posted
Thanks! Supercheap has a sale on this weekend so might be a good opportunity to get a new one. I do have a decent multimeter so I'll give it a try either way. Hah, you got me! I do not. All I know is that the battery holds charge and sits at an okay level before I start the car. Doing the full charge and rejuvenation cycle on a trickle-charger seems to not really make a difference to the cold start behaviour. I'll try and measure it during cranking and see what it does. It's likely terrible; it certainly feels terrible. I'll be happy if it is really just the battery and I don't have to dick around with the alternator or starter motor. -
By No Crust Racing · Posted
how do you know voltage is fine? quick easy test is connect DMM up and put it on max/min mode, remove fuel pump fuse, crank car for 3-5s, go check min voltage You'd be surprised how many "healthy" batteries are showing under 10v during this test in cold weather. -
Not properly. You need to be able to dissipate 100 amps or so to doing it meaningfully. You can do it indirectly by watching to see how far the voltage falls during cranking. Unplug the coils or something else to prevent it from starting so you can get a good couple or three chugs. It also helps if you have the multimeter set up reading before you start, and that it has max/min functions. So you can catch the real minimum without having to watch the screen, which often doesn't update fast enough to show the real max/min in dynamic situations. Or use a digital oscilloscope, which can be obtained for <<$100 from Aliexpress (although I'd argue for paying up to ~$200 for a nicer one). A >4 yr old battery will very likely be well down the path to the knackery. Many only last 5-6 years these days. The cold weather lately will definitely make it worse. -
By soviet_merlin · Posted
Hmmm, what do you mean by getting weaker? And where did you get that test done? I've been wondering about my battery because the cold starts crank super slowly. The voltage is fine. Not sure if cranking amps can be checked at home. Battery is 4+ years old. -
No. The simplest wastegate hookup, with no solenoid or other form of "boost control" (ie, control over your boost control, if you know what I mean) is a single hose, direct from the turbo outlet/hot pipe, straight and only to the wastegate actuator. It is that pressure signal that drives the wastegate to open, providing the boost control (and by "boost control" here, I mean, limiting how high it can go, which is essentially the spring pressure of the actuator). You only end up with tee pieces and alternate flow paths once you start adding things to the boost control system to allow you to determine how much of that boost signal makes it to the actuator. There are so many ways to do that that there is no single way to run the hoses and tees and the like. If you have a stock boost solenoid, then all it does is either allow all the boost signal to go to the actuator, or open up to allow some of it to bleed off. There needs to be a restriction in that bleeder to allow only a small amount to bleed off. And in a stock system, that would then be plumbed back to the turbo inlet (for "emissions control" reasons). That is actually what that nipple on your BOV return pipe could/would be for. If you have an aftermarket boost controller and solenoid, then the above is mostly true, but there is no need for a restrictor in the bleed, because the solenoid is pulse width modulated to create a variable bleed off. The air that escapes from the bleed can either be vented, or also returned to the turbo inlet. For emissions reasons it should be returned to inlet, but the amount of air being vented is so small that it really doesn't matter (either from an emissions perspective, or from an air-fuel ratio affecting perspective).
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