Ok, I have a new alternator and battery in there. But when I’m driving at night and I come to a stop, I hit the brakes, and my car starts to idle lower like around 4-500rpms and sounds like it’s about to die. In the morning, I tested the idle again my just turning on my headlights and see what happens with the idle, it goes down a bit. Then when I turn off my headlights, it goes back up again and idles fine. Why is it when I have my accessories on or when I hit the brakes the idle goes down? I just put in a new alternator so I hope that’s not it again. What do you guys think? TIA for your replies.
Do you have a manual or auto? When you say the idle is fine when the lights are off, where is it at?
It’s a 5spd. When the car idles fine it’s between 8-1K rpms.
It sounds to me like the alternator or battery…but if you say you just replaced both…hmmm…Is the alternator a remanufactured one or a new one? How do other things work, if you have power windows, are they rolling up super slow or abnormal? I’d start by checking elec. connections, etc. Easy way to check alt. though is to turn off engine with lights running and they should dim down, if not then its not putting out. HTH.
Also, the reason it would idle low like that w/your brakes on is b/c you have power brakes, and then take engine vacuum to operate the brake booster…this is not norm. though, I’d just start by checking the above things…did you put the alt. in yourself?
sometimes it can be something as simple as too small of a ground for the car. My idle used to drop a small amount whenever i’d be driving with the lights on and hit the brakes (like at stop signs). Also, the lights would dim when i’d hit the brakes at idle.
when i did my swap a few weeks back i upgraded my grounds. I put an 8ga to the valve cover and 4ga from the batt to the chassis to the tranny. Since then i haven’t had any dimming of the lights or idle drop when i hit the brakes.
This might not be your remedy, but its something to look into.
Good idea as well…RX-7’s have a big problem with grounds…very frusterating. Good luck getting it solved though.
You might wanna check the IACV valve. These symptoms are mentioned in the Helms, and they point to a faulty IACV.
Thanks for the replies fellas.
The alternator was changed out by the dealer. It is a remanufactured Honda unit. Just to also note, my master cylinder needs to be changed out for sure since sometimes I have to pump my brakes to get any bite. I have new pads and resurfaced rotors on there. I’ll try a larger ground wire to the valve cover and swapping out the IACV since I have a spare one. We’ll see what happens. Thanks.
Leo,
There are many things you can do to get rid of the problem. but I would start with the booster/master cylinder. This is a relatively easy fix and if you are already having brake trouble, it will make you a lot safer Trust me on this one, because you never know when the time will come that you need immediate braking power and you won’t have it because of your master cylinder problem. Not trying to sound like a grandpa or anything, just warning you.
Steve
well the reason why your stuff would dim etc is your alternator being weak. however it should not idel like that despite the fact itis not getting enough power. it sounds like your IAC might be messed up and needs to be readjusted. or you could try this method which might fix it. on your throttle body there is a flat screw that you will be able to see if you look at from the left side. turn counterlcokwise about a full turn and then see how that works. it might make your car a little louder but it probably will fix the problem
hey buddy., all of the replies are good but they won’t solve the problem. IACV, Alternator, Brake Master Clylinder, are all wrong. i have the same problem and i had those things replaced and still my idle fluctuates. Just to save you money bro. those 4 i mentioned. they are fine and don’ t need to be replaced.
Originally posted by 93B18
[B]Thanks for the replies fellas.
The alternator was changed out by the dealer. It is a remanufactured Honda unit. Just to also note, my master cylinder needs to be changed out for sure since sometimes I have to pump my brakes to get any bite. I have new pads and resurfaced rotors on there. I’ll try a larger ground wire to the valve cover and swapping out the IACV since I have a spare one. We’ll see what happens. Thanks. [/B]
leo, i’d upgrade the ground to the chassis/tranny first. In my situation it was the one that made the real difference.
Why is it when I have my accessories on or when I hit the brakes the idle goes down? I just put in a new alternator so I hope that’s not it again. What do you guys think? TIA for your replies.
For what it’s worth, my car has done this since rolling off the dealer lot 11 years and 194000 miles ago. It is fairly normal for the idle to drop a bit in these conditions. Typically my warm idle drops from about 750 rpm to about 600 rpm. Yours is going lower than that, I guess. It could be a lot of stuff. Your input that you know you need a new master cylinder tells me that you should try that first. A bad master cylinder means the brake booster will not build up enough pressure. I had this problem and it caused my idle to drop.
Each load that you put on the engine will cause the idle to drop. P/S pump, charging system, AC, brake booster. If one of them is giving you more trouble than the rest, the drop might be enough for you to notice. Your IACV is in charge of making sure your throttle gets enough air to idle. If that is going, then you will have some problems. Your TPS tells the ECU where you have the throttle. If that is going or gone, then the ECU might send the wrong signal to the EFI and you get bad idle. If one of your vacuum hoses has a leak, then the IACV won’t have enough air to control the idle. If you have low coolant, then the IACV won’t work correctly. etc. etc. etc. There is a ton of info on bad idle if you do a search. If you have a Helm manual there is a diagnostic checklist in the EFI section. Check each possible cause and diagnose that system. I would go easiest to hardest, obviously. Make sure you reset your ECU after each change, too.
But like I said, if your brakes feel like they are fading, then fix the master cylinder. It costs $120 or so and could be the difference between a squealing tire and your teg being in the graveyard, nevermind you. :uhoh:
Steve
adjust the screw and u’ll be ok.
sorry fellas, but adjusting the screw is just temporay fix. The idle will still fluctuate. FYI
Originally posted by n17
sorry fellas, but adjusting the screw is just temporay fix. The idle will still fluctuate. FYI
agreed.
LODOSS, you should stop giving out info like its the solve all end all. Problems like this could be caused by any number of different things…since you’re not driving his car and you’re not testing it all yourself you don’t know what the problem is. I noticed you were doing this in a post about hesitation as well.
adjusting a simple screw is not like spending 100 bucks on replacing soemthing. he can test it out and if he does not work he can switch it back and he lsot no money. it is the first thing i would do since it is easiest and it is free. it is very possible his car is just not getting enough air at idle. adjusting the screw will fix the problem just like that. i’ve messed around with it a lot and i know exactly what it does. and i can tell you even at wot it makes a difference.
woops
sorry, some more. when i put the 403 cams in my car the car would almost stall but when i gave it more air by adjusting the idle it got a lot better.
do a test adjust it so it is clockwise all the way and go out and drive and hear and feel the engine and then turn it back all the way and go out and drive it i am pretty sure you’ll feel a difference. the car is notiecably louder and the rpm stays higher at speeds that is same as when the screw is clockwised all the way.