Accord idles rougher when I turn on the heater on high

[quickster]

Is that normal? The car drives fine, it idles a little rough. Where should I start?

The heater doesn't blow very hot either. Its luke warm at best, when its freezing outside it doesn;t even blow warm at all really. Where do I start?

I have a 91 accord LX 130k miles on it. Just bought it about a month ago, put new tires and given it an oil filter and oil change since I bought it. I've had the alternator and battery tested. Both were fine. My clock light dims when I turn on my brights as well. Is that normal? I know I owned another car that did that, problem isn't really major to me, but the heater not blowing proper heat is kind of an issue right now since my windows get foggy if I don't drive with my windows cracked.

[Mister Jew]

well usually when a heater doesnt work its because you have air in the cooling system.
as for why it runs rough when you turn up the blower motor thats something else.
flush and do a cooling system service and you should get heat that way.

[slomofo]

Three possibilities for heater being lukewarm:

1. Bad thermostat.
2. Low coolant
3. Clogged heater core.

I'd start out by checking anti-freeze level first, if it's low, add some, if it's not low, change your thermostat. While your thermostat is out, you can take off both your heater hoses, put an air blower in one hose and blow the crap out of the other. Hondas rarely have clogged heater cores though.

Rough idle:

Are your battery terminals dirty?

[quickster]

I've only had the car for like 3 weeks and did notice that I need to do a coolant flush since it looks like there is mainly just water in the coolant system. I wasn't aware that this would cause heater problems though. I ran water in my last honda (it was a civic) and didn't have heater issues. Good to know though, so I'll defiantly start there. I was planning on taking it to a shop and having them rod out the radiator. I'm sure that the water hasnt treated it very good, so it probably needs a good cleaning. I'll try the thermostat afterwerds if that doesnt fix the issue. And yes, my terminal are a little dirty. I bought some vasoline and new terminals, just waiting for the rain to stop.

[JGAccorn]

Flush out the cooling system and fill it with 50/50. Then you MUST bleed the system properly. If you have an air bubble, even a small one, it will cause idle issues. Most of the time it's just a wandering idle. Go ahead and get a t-stat and a new cap, just do it right since you don't know the car's history. Just cheap insurance buddy!

[quickster]

UPDATE:

I noticed a small tear in my pcv valve hose so i replaced that and the pcv valve. Little to no improvement...

I've replaced the spark plugs, spark plug wires, did a coolant flush. Little to no improvement.

I changed the distibutor last weekend because my car just died on me and wouldnt start. It started after I switched that out....bad coil but i had the money and it was easier just to replace the whole distributor. The roter was corroded a bit too so I swapped that out.

Now when I drive my car and it warms up, my check engine light comes on. I trolled around every parts store on the strip and all the places i could think of that might do it for free to check my check engine code. i need an OBD1 code reader to know why its lighting up. The only thing that I notice is that my car idles at about 1500 rpms when its cold at start up, and idles about 500-300 rpms right after I slow down from a drive and put it into nuetral at a stop light.

Today I took off the EACV, and sprayed some carb cleaner into it. there was those weird triangle drive screws that I didnt have the drivers for so i couldnt get all the way inside though. So I put it back on and the hoses, , new clamps. bled the coolant system bleeder valve from any air bubbles. Tried to adjust what I think is the idle adjustment screw, but I might of stripped it, does it take LONG flathead driver? Pictures would be greatly appreciated.

anyway, my car's idle is getting worse, also I didnt do the timing after I switched out the distributor, mostly because the manual says that "the timing is controlled by the computer and shouldnt need adjusting after maitenance"

Please help, I'm a smart kid, but I'm just a noob and alone with my tools and a chiltons/hanes manual. Thanks.

[quickster]

Originally Posted by slomofo

Rough idle:

Are your battery terminals dirty?

No, it probably wouldnt hurt to buy new ones, but I clean them regularly. I clean them about once a month, or whenever I see that it needs it.

[19Accord97]

I suppose you use Bosch spark plugs? Hondas HATE any spark plug other than NGK or Denso and can cause coils to go bad if you use other brands.

[quickster]

I did use Bosch! Did not know that they were bad for honda coils. I did not mention that one of my spark plug wires popped off while driving though, I was assuming that was the reason for the coil fowling. I'm going to swap those out for NGKs today then if you arae being serious, can anybody else confirm that? Probably not gonna fix the main concern though, the idle problem. Thanks for the info.

[joc1394]

Originally Posted by quickster

I did use Bosch! ... can anybody else confirm that? Probably not gonna fix the main concern though, the idle problem. Thanks for the info.

I've been running Bosch Platinum Plus plugs in my '92 Accord EX for the last 40k miles or so with no problem, so I can't confirm that.

As for the idle, I had a similar issue with a the rough idle under electrical load (headlights, blower motor on high, gauges dimming with brakes at idle, etc.) and even though the battery would pass the Auto Parts' store test every time, the battery was actually a dud (and cooked 2 alternators in the process due to below spec CCA). If you can afford it, buy a new battery with more than 550CCA (I went straight for 1000CCA) and hope that helps.

If it's really idling less than 500 RPMs, I'm not really sure what to tell you. Mine did that once when I cranked the FITV (Fast Idle Thermo Valve) nut down too far.

To the CEL (Check Engine Light), you can check that by shorting out the little blue connector behind the Pass. Side front kick-panel. Here's the link on how to check the CEL: http://honda-tech.com/showthread.php?t=1901557 and I see you've already found this in the thread that discusses how to adjust the FITV and IAC.

Hopefully this helps!

[quickster]

thanks, yea the loss of power doesnt happen so much anymore since i cleaned the positive terminal. im almost positive it is my base idle that is off, or i need to actually take apart my EACV and/or TB and clean them out with carb cleaner. I should at least be able to figure out where to start after i do the check engine like bridge trick to get the trouble code.

PS. this site rocks! theres so many things that a person wouldnt know the first time just reading through a manual, its nice to have experianced people here to let me know what their experiances have been.

[quickster]

where is the FITV adjuster nut? and where is the base idle control screw on a 91 accord lx? anybody have pictures or diagrams. im having a feeling that the one i stripped was the fast idle. its the one just to the left of those 2 tubes coming out of the TB.

[fleetw00d]

Originally Posted by quickster

UPDATE:

I changed the distibutor last weekend because my car just died on me and wouldnt start. It started after I switched that out....bad coil but i had the money and it was easier just to replace the whole distributor. The roter was corroded a bit too so I swapped that out.

anyway, my car's idle is getting worse, also I didnt do the timing after I switched out the distributor, mostly because the manual says that "the timing is controlled by the computer and shouldnt need adjusting after maitenance"

You do need to adjust the base timing, this is the "maintenance" the manual is talking about. With the same blue connector mentioned earlier shorted, engine at temperature and idling, the timing should be set to 15 BTDC. Also, if I'm not mistaken, the tachometer starts at 500 rpm (so you can't read 300).

[quickster]

I adjusted with the nuts and the harness for the hose on the gas pedal tensioner cable and got the idle up to 700, no more CEL , no more dropping lower after putting it in nuetral, then i drove to the store, then drove back and went back down on the drive back and the CEL came back on. (I guess that was a shorter quick fix than what I thought lol) So the CEL definatly has something to do with the idle being too low. I'll get a reading on the CEL today and its probably going to confirm what most people have told me. My base timing is off.

[stockracer]

It shouldnt matter what brand of spark plug you use. The gap is the main thing you should worry about.

[quickster]

Bosch's come pregapped guaranteed. I did the paperclip trick to get my trouble codes and I got EGR and IAV. So I took out the IAV again and filled it with carb cleaner and let it sit for about 20mins. If its not clean now I dont know what is lol. EGR was most likely in there because I forgot to plug it back in to the plug by the distributor after i changed it. SO thats probably where all the problems were right there. I broke my PCV when working on it lastnight so I still havent driven it, I'll know by mid day today if its fixed or not.

[quickster]

k I popped on a new PCV, started it up. Still a bad idle, it even stalled and died once. I drove it back, and bled the coolant system of any air with my heater on full blast. Drove it again, and problem solved, the car idles like normal again, no dipping, it actually slows down around 1000 rpms when it drops from a load and then slowly drops to 800-750 like its supposed to.