Low Idle after wiring upgrade

[ryan s]

now its narrowed down to bad connections and/or bad battery terminals. pics of the ring terminals and battery terminals would help, as would pics of the ground locations themselves.

first step is to set the meter to ohms, and most are marked with a setting called "10" or something similar...set it to that. measure from the negative battery terminal to the chassis ground...battery terminal to the transmission ground...battery ground cable end-to-end...and so forth. cheap meters from harbor freight or menards will only go down to about .5 ohms or so, which is ok. thats close enough to 0 as long as we know that it can't actually display 0.

next is to switch the meter to DC voltage or some are marked just DCV, again to the "tens" position. might as well measure across the battery terminals to start, making sure we have 12.8v or higher with the car off, and it should show 13+ with it idling. once that's done, start probing the grounds with the black lead while holding the red lead on the positive battery terminal. if you see a spot with low voltage, there's your problem. alternately, use the resistance setting and do the same.

 

[Jayson]

These are the terminals I'm using. I'm not exactly sure what to do with the multimeter, where do I put the red/black contacts and what numbers are considered "normal"?

I am doing this upgrade because I had been running my sound system on the stock wiring. I have a 400 watt 4 channel Alpine amp that's only using the 2 front channels right now, but I plan to get the rear speakers and a separate mono amp for a 10" sub when I have the money laying around. I'm not sure if the Big 3 is necessary yet but since it's relatively cheap and I like working on my car I decided to start doing it now.

I'd like to mention that last night I drove out to downtown Sacramento to meet some friends which is like 30 miles from where I live, so it was a good little test. It seemed to run well, the idle looked solid. It fluctuated a little bit which might be normal, nothing like before with noticeable dips or jumps when I shift. I have to start it today to see if it's still doing alright.

 

[ryan s]

ok, the ring terminals are the normal, flat ones. those conform to curves and such.

which battery terminals, then?

for measurements, you want impedance/resistance to be low...under 1. voltage/DCV should be over 12 for the static battery, and well over 13 when running.

i have the "dipping" idle issue, as well, when shifting or slowing down for a stoplight. it's corrected when there's a load sensed by the ELD system...in other words, using the headlights, turning the A/C on...there's a variety of factors that the computer sees and adjusts the voltage to suit. a stereo is not something which the ELD adjusts for. so, i've narrowed it down to the alternator, possibly its internal regulator. i'd bet mine is OEM from 1998 with 154k on it, so not real surprising. the last almost 6 years with a stereo setup of some kind installed...

speaking of, i'm running 80w to each front speaker (two mids, two tweeters, though the tweeters see a lot less power) and 300w to the sub. i have a stock electrical system aside from the 4ga power/ground wires which go to my distribution block. there's a hint of headlight dimming if i play rap (ugh...) at full tilt and look really closely at the lights in the garage or whatever.

doing the big 3 is largely unnecessary unless you're upgrading to a high output alternator, adding batteries, all that...OR if your stock wiring is degraded beyond its useful life.

 

[Jayson]

Terminals

Battery (+)

Battery (-) to chassis

Block to chassis

Thank you for all the suggestions ryan_s and everyone, I'm gonna measure the resistance when I have a chance to see if it looks alright. The car still seems to be running good today.

 

[Jayson]

Well I think I found the problem for the idle issues, my engine grounds were poorly sanded. You called it ryan_s.

since it only started after messing with the ground and the terminals, well, there's your problem in there somewhere. bad connection, bad wire, bad termination, inadequate bare metal at the ground point, poor plating on any terminal/ring terminal, loose connections, etc...

I used 220 grit sandpaper (which is all I had around) and did it by hand, I couldn't really tell if I was seeing bare metal or not. I busted out a wire brush drill bit and power drill and took off the paint that way, and now I know that I definitely wasn't grounded to bare metal before. Now the idle has been pretty solid for the past few days.

So yea, don't skimp on the sanding part when grounding like I did. Thanks again everyone for the help.