computer grounds?
computer grounds? i hear (read) about people talking about good grounds?
the only groung i have hooked up to anyhting on my car is the negative cable from the batt to the engine block.
what other grounds should there be (if any) because now that i have my motor running its runs like crap and it ran fine when we pulled it out (i drove the car into my garage (roasted the tires in the driveway) but now it wont idle for the life of it.
the only groung i have hooked up to anyhting on my car is the negative cable from the batt to the engine block.
what other grounds should there be (if any) because now that i have my motor running its runs like crap and it ran fine when we pulled it out (i drove the car into my garage (roasted the tires in the driveway) but now it wont idle for the life of it.
there are usually three ground wires in the harness and should be bolted to the back of the drivers side head, thats stock location. and in general the engine should be grounded to the body or frame and the frame should be grounded to the engine, basically it should all be connected. You can never have to many grounds just not enough.
There are three grounds on an electric fan harness and only two on a non. The single ground in the front is for the fan power relay. The two grounds on the back of the harness are for the clean and dirty grounds from the harness. The clean grounds are your sensor grounds, ie. the crank, cam ect. The dirty grounds are more for your coils. You do not want to have these grounded on the same bolt because the power going through them is different and the dirty ground could interfere with the clean ones. We always keep a practice of putting on one the back of either head. This ensures there will be no interference issues.
On a side note, you should always run a single ground from your battery to your engine, and one from your battery to your chassis. I have seen where a ground was run to the chassis and then to the engine. The end result was the engine would not function properly. Hope this helps with your issue. If not, make sure to get a scan tool and diagnose the problem properly. To many times people end up spending more money on parts that are good rather than spend a couple hundred bucks and maybe there was a loose wire.
Sorry it got so long.
Good Luck,
Mark
On a side note, you should always run a single ground from your battery to your engine, and one from your battery to your chassis. I have seen where a ground was run to the chassis and then to the engine. The end result was the engine would not function properly. Hope this helps with your issue. If not, make sure to get a scan tool and diagnose the problem properly. To many times people end up spending more money on parts that are good rather than spend a couple hundred bucks and maybe there was a loose wire.
Sorry it got so long.
Good Luck,
Mark
thanks for the replys and i have a matco pathfinder scanner. once i hook up my obd2 port i'll run it and see whats up code wise and sensor wise.
as far as running the engine. i only let it run for llike 20 seconds (the radiator is not hooked up yet) and i wont idle on its on but once i had oil presure on the gauge i cracked it up to about 4 grand it sounded great it just wouldnt idle w/ out some throttle?
now that i read this i remember disconnecting the grounds on the back of the head from the donor car, but i dont recall hooking them up. i'll have to check that.
as far as running the engine. i only let it run for llike 20 seconds (the radiator is not hooked up yet) and i wont idle on its on but once i had oil presure on the gauge i cracked it up to about 4 grand it sounded great it just wouldnt idle w/ out some throttle?
now that i read this i remember disconnecting the grounds on the back of the head from the donor car, but i dont recall hooking them up. i'll have to check that.
Leon, go to the Help! section at your LAP, and get a few braided ground wires. Connect your block to your frame, your frame to your body, and your core-support to your frame. If you can, run a ground wire to the block from the batt (Big one) and a smaller one to the fender rail or core support. This will ground the vehicle. The computer itself has a lot of grounds that should all go to the engine block.
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
Don`t worry about the engine not wanting to idle right now. It just has to re-learn the idle. My engine did that the first time and still does it if I have the battery disconnected long enough. Just give it enough throttle to keep it running, and slowly back down till it will idle. It may take 30-45 seconds of slowly backing out of it for it to re-learn the idle.
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Grounds VERY Very Very important! in older cars ive seen speedometer cables that melted because that was the only ground from the block to the chassis , now add all the current day electronics (compared to the old cars) and it gets very sensitive . my wifes suburban almost went up in flames -how i got so lucky ill never know!the braided fuel hose was rubbing on the body-between the bellhousing and it arced thru the braided cover to cause a massive fuel leak- how it never ignited ill never know, so i replaced the fuel line and added a seperate ground from the block to the chassis- live and learn 
i dont think you can have too many good grounds!
i dont think you can have too many good grounds!
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i doublr checked and they are connected on the driver side head.
i wonder if not having one of the o2 sensors hooked up would cause it not to idle? but i thought it would be in open loop till it warmed up so the 02 wouldnt even matter?
my buddy was over the other day and he thinks i have a vacuum leak, but i thought that would make it idle high?
its been too cold to work on it (even with my turbo heater) so by this weekend i will have the radiator and serp belt on it so i can let it run longer and figure somw stuff out.
i wonder if not having one of the o2 sensors hooked up would cause it not to idle? but i thought it would be in open loop till it warmed up so the 02 wouldnt even matter?
my buddy was over the other day and he thinks i have a vacuum leak, but i thought that would make it idle high?
its been too cold to work on it (even with my turbo heater) so by this weekend i will have the radiator and serp belt on it so i can let it run longer and figure somw stuff out.
