@AuroraGirl,
I'm still hung up on the alum. intake being isolated electrically. How? It's got about ten or twelve or more bolts in it that go straight into the head!! If you connected a ground wire on it, I don't know why, are there engines that have that?, it couldn't help but be grounded. I see your post about ECM ground strapped to intake bolt. Do these computer trucks need extra ground wires?
My old '74 has three on it. I just cleaned them all last week, like removed them, cleaned the spot with a wire brush, sanded the terminal end and reattached to wherever. Then sprayed them all with that red anti-corrosive battery terminal spray. After reading some post on here by people talking about grounds I got paranoid about it.
I think the possibility that the gasket material or design doesnt touch conductive material to either surface or just at least to bridge any eleectrical, and then the studs are done in such a way or coated or something like that, and I cant rememebr if it was related to just an accident of other engineering or just happened and then was problems or if it was isolated for the sensors stuff and grounds get bad and people dont put them back. I cant remember tho.
I wouldnt worry about your grounds you are prob better than most of those old 90s trucks with bad wiring or botched stuff. Those trucks had a lot more sensitive electronics, ones that often used grounds on what they mounted to if possible. Often the case of a sensor or something grounds to surface and then the PWM wiring is back to the computer as proper, and then the computer is the thing is then grounded at a spot not as likely to be a problem with ground fluctuations or other things finding their path through that ground which when such low signals are used for engine management it can pull things low or high enough to be huge driveability issues.
Your truck doesnt have that stuff to worry about on engine bay as long as cables are good, clean ends, and no breaks.
One to chassis, firewall, from head is a good policy. both heads better. then One from the engine block to battery neg. that is how that strap is now ground in line to the battery, but once you add a ground from the fender to the battery, it now has that path assuming bolts arent all crusted bad. then you add a ground to the frame itself. so then you have a route for the gas tank senders. but thats still all going through a couple places either through others or in paths which may be resistance prone. But Its not hard on a system with no electronic demands compared to now. Then you can also just do good things like a dedicated battery to frame and i also forgot starter before. thats a huge one. the starter shouldnt ever need to use other ground paths. if that ended up going through an engine block, to head, to intake that was not isolatied, then to a firewall strap or just went to there from head, you could potentially do damage to, say, a... uh... Idk what tbi electrical is like. Anyway. Now lets say you have sensors on that intake grounded to tbi or the intake, and then the path for that starter happened to cross rightr where a fine sensor was, it might pull the small signals high or low and the pcm would compensate. worst thing would be if your stuff starts using a PCM To ground like a starter RIP. But dont have a tendancy to daisy chain, keep connnections and cables good. And stack battery lugs in the right order OR use a syhstem of some kind where t hey donbt have to stack if possible. Oh. I forgot, often the block ground is instead the alt bracket, I forgot about that. Then of course, chassis grounds like the rear lighting depends on the path from the bed to the battery then, and sometimes those crusty bedsides and bad bolts or rusted floors can become too much. somehow my bed is offering good chassis ground for myy tail lights.
Oh wait, I made that to frame as well lol