I have a 90 honda civic si. When I'm on a stop light it tends to feel like it wants to die. That happen only on hot days only. Some time the car well sit under 500 RPM or it well idle. Whats wrong?

 

try adjusting (tightening) your throttle cable to lift your idle a bit, maybe even the idle screw on the intake manifold.

 

try replacing your main relay

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by I CRX I &raquo;</TD></TR><TR><TD CLASS="quote">try adjusting (tightening) your throttle cable to lift your idle a bit, maybe even the idle screw on the intake manifold.</TD></TR></TABLE>The idle screw is adjusted properly from the factory. If it is idling too low, there is something else affecting it. Adjusting the idle screw is a last resort.

Look at the idle air control valve. Should be mounted on the firewall closer to the passenger side. Pull the vacuum lines that run to it and see if anything changes. Unplug it, and see if anything changes. Pull off the intake tube and put your finger over the holes on the inside of the throttle body. Any suction? Did the idle change? Did the engine die?

 

I did all that. I even spray carburetor to see if there was air leak and there isn't any air leak anywhere. Now the rpm needle sit at 300-500 rpm any help?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.Meowsome &raquo;</TD></TR><TR><TD CLASS="quote">try replacing your main relay</TD></TR></TABLE>i agree - replace the main relay - common problem

 

My main relay only ever effected starting the car in hot weather?

 

I replace that main relay about one year ago from honda dealer could that still cause the problem? Today I drove the car about 2 mile down and when I put it into neutral my rpm drop to 100 rpm and stayed there till I turn off the car. The car didn't die which it amaze me. When I restarted the car and it went back to 500 rpm. I'm so frustrating over this problem. Thank to all who answer my question.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.Meowsome &raquo;</TD></TR><TR><TD CLASS="quote">try replacing your main relay</TD></TR></TABLE> yeah that sounds like it might be the problem (since you only have this happen on hotter days)

 

the solder connections can crack with the extreme heat and make a poor connection and kill the car. if you are feeling brave, you can resolder the connections

 

Tried cleaning your IACV & FITV?

 

Yesterday I changed the Main relay so see how it run today and I'll keep you guys updated. Thankx

 

Everything went good but one thing it still sit at 400 rpm whats the deal? The car feel like its about to die which it don't. I have no air leak my needle on the throttle body don't affect my rpm which I don't know why. I can have that taking out and it still don't idle it sit at 1,000 rpm which where I like it to be at. Any suggestion let me know. thx

 

The main relay affects startup. Once it's running, it shouldn't affect the car at all since that circuit is bypassed (according to my memory). Have you changed spark plugs or wires? Possibly an electrical problem.

 

Yes I change the whole spark plug and wire. I also got new distributor.

 

Check the IACV as mentioned above, when my IACV acts up I have problems with my idle being super low like the car is going to stall out, sometimes it does. You may need to clean the "screen", it may be bad, it may have bad wiring or a lose connection. Mine only seems to act up when it's hot as well, so I would check it out.

Start the car and let it idle until it gets to the "low idle" then open the hood and tap on the wire that goes to the IACV, if you idle changes then you got a bad connection or a short in the wire somewhere. If that doesn't do anything then take the IACV off the Intake Manifold and clean the little screen out, I think I used brake cleaner to clean mine out and then I used qtips to clean out all the "gunk" - Remember not to get the electrical part wet, make sure you let it dry properly, and be aware that you may need a new "gasket" or some sort of gasket sealant if your seal is bad when reinstalling the IACV - DO NOT REMOVE THE SCREWS ON THE BOTTOM OF THE IACV where the coolant lines run to, there is nothing in there to clean and it brakes a seal which needs to be resealed with a bond like Hondabond.

See if that makes any difference, mine was CLOGGED, if anything it should help make the car idle better even if it's not the problem. BTW my car is a '90 CRX Si with a B16A2 swap running OBD1, so some of this may be different if your running something else, but the idea should be the same. Hope this helps


Modified by g2tegsown at 2:33 PM 6/13/2008

 

thx I well do that. I have a B18A1 swap.

 

Do I have to take off my manifold to take off the IACV?

 

no, 2 bolts hold it onto the back of the manifold.

 

Well I just got done cleaning the IACV and no change. First when I put it back together it idle like 100 rpm to 2000 rpm than it died. So I had to put some gas for about 10 sec than it didn't die but the engin was shaking. Now its kinda back to how it was . Well I also talk to the last owner of this car and he said he did everything but didn't know the problem. When he sold it to me he thought he fix it and I called him about it and he said, it well act up in the summer time. I had this car since october of last year and it was running great till summer time came around. Any suggestion let me know thx.

 

Would the tps gotta do anything with it?

 

From what I know about the TPS (Which is not much) is that you calibrate when you install it, as long as it still functions it's not likely that the settings would have changed since it's screwed in, unless someone messed with it. So if this problem started around a time messing with the TPS then maybe you need to recalibrate it. You will need a multimeter to do it, and it's kinda a pain, easy but a pain.

However I don't know if it would be causing your idle problem, maybe try running without it (Although I don't know if the car will), that at least will tell you if it's working or not. (BTW by "without it" I mean just simply unplugging it)

Also I re-read the original post, and my car does the same thing in the summer, once she is warmed up she will idle like 100-500 most of the time. Somedays she won't, usually the hotter it is, the more likely it is to occur.


Modified by g2tegsown at 4:41 PM 6/15/2008

 

How did you fix that problem with the idle 100-500 rpm. I was thinking since I done about almost everything should I replace the throttle body and manifold?

 

Have you checked to see if your ECU is blinking any codes?

 

You know I am not sure how to fix it, until this thread I just assumed it was my IACV since I have to fix my wiring to it. I think it has something to do with a sensor not telling the ECU to raise the idle, which I think is the job of the IACV. My CEL is always on since I don't run with a O2 sensor, but even when I did I never got a check engine light when it would idle that low.

Anyone know what other sensors adjust the idle?