More Idle Issues...

[Supra-Man18]

I turned the car on today and it gave me a 550-600ish idle... I raise the idle to 900, wen finished i rev the car to about 4k and let it drop and the idle drops to 900 then gradually keeps going right back down to 650ish... And wen i turn my fogs, and or headlights on the idle drops another 150-200 rpm...I checked all vacuums, got a fresh Iacv and the positive wires for the alternator and battery are in tact.. can it be that i need a larger Positive cable from my battery to the front of the car ? or Will there be further issues if i disconnect the iacv and drive like that ?

[tlo86]

your car is just warming up right? what voltage are you running and does it actually seem like its struggling? the cable from the alt to the battery how is it connected? can always blame it on a poor connection if your voltage is too low.

[Supra-Man18]

yes.. well now i just drove it a couple miles and at start up the idle was at 900 while i drove the car it stayed around the same and wen it was at operating temp the idle dropped to low to mid 600's and it stayed there.

The battery cable is ran from the trunk behind the interior panels , thru a hole behind the kick panel to a Distributor block in the engine bay.. then on the opposing side of the distributor block the power runs directly to the alternator.. Would the thickness of the cable have anything to do with it ? Even tho the car drove perfect the past couple months apart from a vacuum leak...:1zhelp:

[tlo86]

yes.. well now i just drove it a couple miles and at start up the idle was at 900 while i drove the car it stayed around the same and wen it was at operating temp the idle dropped to low to mid 600's and it stayed there.

The battery cable is ran from the trunk behind the interior panels , thru a hole behind the kick panel to a Distributor block in the engine bay.. then on the opposing side of the distributor block the power runs directly to the alternator.. Would the thickness of the cable have anything to do with it ? Even tho the car drove perfect the past couple months apart from a vacuum leak...:1zhelp:

well if the voltage is dropping below normal operating levels it will - then its just a matter of figuring out what is causing it. i would dip around the 11v levels sometimes but i had a bad connection from my alt to the battery once it was fixed no troubles.

[Supra-Man18]

well if the voltage is dropping below normal operating levels it will - then its just a matter of figuring out what is causing it. i would dip around the 11v levels sometimes but i had a bad connection from my alt to the battery once it was fixed no troubles.

but did you have a similar idle problem or did it act in the same way? I cant check the voltage just yet but as soon as i do ill let you know...

[tlo86]

honestly sounds pretty normal to me, only i would have closer to 1k when i first started it and gradually went lower as it warmed up

[Supra-Man18]

honestly sounds pretty normal to me, only i would have closer to 1k when i first started it and gradually went lower as it warmed up

really ? my idles always been in the 800's steady... wen it goes that low to the 600's you feel vibration and the power steering is stiff but at 800 everything was smooth

[Supra-Man18]

Hey ! I was on the way home today and it was doing the same thing.. I got on the highway an went into boost 3rd gear to about 6500 rpm.... When i reached home the idle was at 850-900 PERFECT.. No Dropping wen i turn the lights or fogs on.. nor the hazards.. everything was how it was suppose to be.. So maybe the iacv had carbon deposits and needed positive pressure to clear it up a little i guess ???

[Guy Smiley]

Whats happening is when your battery is lower than it should be your alternator is taking up crank power and lowering your idle. After you drive around and get the battery back up to snuff there is no more load on the crank due to the alternator trying to recharge. If your battery is in your trunk you are also causing a bigger draw due to resistance of a really long battery cable. Most people run 4awg battery cable but that is not enough. You need 2awg or bigger depending on what total amp draw you will be having (stereo, lights electronics, etc.).

The safest bet would be to upgrade the gauge of wire and maybe order one of them fancy viper alternators from DM because those put out more amps than your Toyota one does. I would not upgrade the alt until you upgrade your cable though.


I know I am new here but I do have a lot of wiring/electrical exp. under my belt, as in, I did it for a living and not just a hobby where I hang out at radio shack too much. Not saying I'm a badass, but I can usually help, so if you have anymore questions let me know!

K6ESx

[Supra-Man18]

The safest bet would be to upgrade the gauge of wire and maybe order one of them fancy viper alternators from DM because those put out more amps than your Toyota one does. I would not upgrade the alt until you upgrade your cable though.

I know I am new here but I do have a lot of wiring/electrical exp. under my belt, as in, I did it for a living and not just a hobby where I hang out at radio shack too much. Not saying I'm a badass, but I can usually help, so if you have anymore questions let me know!


Makes Sense... But Do i upgrade the cable Before Or after the the distributor block ? i believe i have a 4 gauge cable from the battery to the block and after that i believe an 8 gauge...

[tlo86]

how large of a wire is from your alternator?

if i remember right the 4 gauge might be too small

[Supra-Man18]

how large of a wire is from your alternator?

if i remember right the 4 gauge might be too small

Yea I just double checked earlier, I have a 4 gauge from the battery to the distributor block BUT after the distributor block is Even smaller :aigo: SHIIT !!!

[tlo86]

what ground are you using? and ground points?

[Supra-Man18]

I have a couple grounds off the battery str8 down to the chassis.. because my trunk has no carpet.. and i also have my intake manifold grounded to the chassis with 8 gauge cable... Where do i start testing for voltage drops ? Can the alternator itself be too weak? Or should i start from the cables ?

[tlo86]

so you have no ground from the battery to the block? might be a good idea to get the right size cable to it (iirc 0 gauge? 1? something like that)

there really are guides written all over the net though do a little searching i would for ya but short on time usually when im on heh.. usually for the length of the wires you are going to run and what the minimum gauge should be. and this really is to keep the car from potentially going into flames...

[Supra-Man18]

So give me the basics of what to go and do.. So i can jus go thru everything and get it right.. im tired of this Dying idle.. : /

[Guy Smiley]

2 gauge all the way back to your battery, 6 gauge to the alternator. Make sure your engine is grounded well to the frame, and from the same spot on the frame, run a 4 gauge back to ground your battery and run maybe an 8 gauge to some bolt in the trunk area itself to help with grounding.










THEN go get a better alternator.


Good luck buddy

[Supra-Man18]

Alright Im gonna have to do this next weekend when i get paid.. The performance store by me sells 20 ft of insulated 2gauge Battery cable for $92 :aigo: then Ill jus use my current power cable as a ground back to the battery..


Ill let u guys kno how this goes.. Thanks all for your help

[Guy Smiley]

No problem man. Everything should be Awesome. You may also eventually want to get a second battery to run your accessories. You can have them isolated from each other but charge at the same time. It's cool stuff. You can then wire in a switch to jump start your car using your own batteries. Electrical is a lot of fun once your not scared of it. That part took me a while!

[tlo86]

No problem man. Everything should be Awesome. You may also eventually want to get a second battery to run your accessories. You can have them isolated from each other but charge at the same time. It's cool stuff. You can then wire in a switch to jump start your car using your own batteries. Electrical is a lot of fun once your not scared of it. That part took me a while!

why would you install a second battery? ive never found any reason to do so ive even heard it is pointless.

[Supra-Man18]

No problem man. Everything should be Awesome. You may also eventually want to get a second battery to run your accessories. You can have them isolated from each other but charge at the same time. It's cool stuff. You can then wire in a switch to jump start your car using your own batteries. Electrical is a lot of fun once your not scared of it. That part took me a while!

Well im still scared shitless of electricals.. But this is simple enough.. haha

[Supra-Man18]

It was not my voltage guys -__- !!!!! Its dumping fuel for sum odd reason... Just bought a new o2 and Lucas fuel injector cleaner : / If those dont clear it up then im going to try a diff ECU. Ill keep you guys posted.

[tlo86]

so its running too rich? maybe not getting enough air?

[Supra-Man18]

I dont think so cauz at start-up its fine.. after about 3-5 minutes of driving.. it goes shitfaced and idles 450-500 dumping fuel...drove it yesterday and it did the same thing for a while but then stopped. My voltage is a constant 13.6 to 13.9 while driving or idle

[Supra-Man18]

Lets say it wasnt getting enough air.. what would i check..? Intake? Map Sensor ?

[Supra-Man18]

IDLE ISSUE FIXED !!! The car got so bad to a point it shut off and the engine locked, and fuel was coming out of my exhaust :( ... Wen we noticed this and went over erverything under the hood, we turned to the ecu.. It had 3 Leaky capacitors !!! Got it fixed the same day and Voila ! Idles and drives perfect !! I have way too much gas in my oil tho so i have to change that asap :) My mileage should increase like crazy too :D