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As the title says, my Honda Accord has a terribly rough idle, but only with a/c on. The idle isn’t perfect with it off, but when I turn the a/c on it get horrible. I’ve replaced all motor mounts except for two under the transmission, but I took those out and they look fine. I replaced the pcv a while ago and I have no check engine light. However, there was a CEL a while ago about a vacuum leak, but that went out and hasn’t come back for a while. The coolant shouldn’t have any air in it. I’m stumped. Please, any help would be great. Thank you.
Pickles
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How rough an idle are we talking? What size engine? Did you service the A/C using one of those do it yourself canisters (which have sloppy gauges at best)?
On a 4 cylinder engine, the idle is usually not that great anyways but if yours seems worse than the norm, might want to get that straightened out because the A/C puts a pretty good strain on the engine and if it struggles as it is, the added challenge of A/C is gonna bog the hell out of it.
This is a wild guess but it seems a lot of times with rough idle, if the IACV is not at fault and all the other usual crap checks out (good fuel pressure, spark on all 4 cylinders, air filter doesn’t look like a cigarette smoker’s lungs, etc) then one place to suspect are the intake gaskets.
Maybe pick up a vacuum gauge and see how that acts. They are not real expensive.
[quote=”99Nightmare” post=112964]How rough an idle are we talking? What size engine? Did you service the A/C using one of those do it yourself canisters (which have sloppy gauges at best)?
On a 4 cylinder engine, the idle is usually not that great anyways but if yours seems worse than the norm, might want to get that straightened out because the A/C puts a pretty good strain on the engine and if it struggles as it is, the added challenge of A/C is gonna bog the hell out of it.
This is a wild guess but it seems a lot of times with rough idle, if the IACV is not at fault and all the other usual crap checks out (good fuel pressure, spark on all 4 cylinders, air filter doesn’t look like a cigarette smoker’s lungs, etc) then one place to suspect are the intake gaskets.
Maybe pick up a vacuum gauge and see how that acts. They are not real expensive.[/quote]
It is a 2.4L. I have not used one of those “pro a/c” things, but when I bought the car used, the air didn’t work. So, I found a guy that could recharge it. He did and it works fine now. I just have no idea if he knew what he was doing. Is it possible that there is air in the a/c system? I don’t recall him vacuuming it before recharging it, but my memory may be off.
With the a/c on, the idle is terrible. Way worse than it should be. Enough to rattle the things in my glove box. With the a/c off, its actually okay. Also, it is at its worst in drive or reverse. Anything else it isn’t that bad. So, in drive with a/c on = the worst. Drive/reverse, no a/c = not too bad. Any other gear with a/c = okay, but not great. Any gear other than D/R without a/c = fantastic. I don’t know if that helps but I hope it does.
I’ll be checking out the IACV tomorrow afternoon. I’ll be sure to post results. And about the intake gaskets, doesn’t that usually cause coolant leakage? I haven’t had any of that. I could be wrong though. Is there any easy way to check intake gaskets?
Thank you for the reply by the way.
[quote=”barneyb” post=112966]At what rpm does the engine idle at with the A/C off and on?[/quote]
In park without a/c is about 1500. with a/c in park it hardly drops at all. In drive without a/c it idles a bit below 1000. with a/c in drive it gets slightly lower. So, 600-700ish?
1500 is high for an idle. Is this on a cold start? First thing I would do is pull the belt off and see if the compressor is starting to lock up. Check the clutch and the pulley.
Something’s going on here. 1500 is to high. I would suspect maybe something going on like a duff sensor (coolant temp sensor comes to mind…just as a possible one….)
Can you get a scan tool for the system and monitor the readings for a short while? I’m interested in seeing if the engine temp is doing it’s thing correctly.
As a rule, you turn on the A/C at idle. The system will automatically bump your idle up so not to stall or bog the engine down. I think there’s a couple of things in play here. What year are we talking about?
S-
After another check when the vehicle was warm. At Park with no a/c it is at about 900. With a/c in Park it doesn’t move too much. Then in drive with no a/c it’s about 700. Then with I turn on the a/c it drops to about 500 then goes up to 800. Sorry about the confusion. I should have thought about a cold start. And it is a 2004
I’m guessing that someone has attempted to adjust the idle with the screw on the throttle body. This is wrong. The engine will not be able to maintain the correct idle if this screw is misadjusted. I recommend you start by addressing the idle to see if you can make that better first and then turn your attention to the AC. Who knows, it could get solved just by fixing the idle issue. I’ve written extensively on Honda idle issues here. I suggest you read through it and see if that can help you with your idle issue.
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
Keep us posted.
[quote=”EricTheCarGuy” post=113021]I’m guessing that someone has attempted to adjust the idle with the screw on the throttle body. This is wrong. The engine will not be able to maintain the correct idle if this screw is misadjusted. I recommend you start by addressing the idle to see if you can make that better first and then turn your attention to the AC. Who knows, it could get solved just by fixing the idle issue. I’ve written extensively on Honda idle issues here. I suggest you read through it and see if that can help you with your idle issue.
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
Keep us posted.[/quote]
Oh, I had no idea that was even a thing. I’ll check it out. Thank you. And I will certainly keep you posted. Does it help to say the vibrations stop when I go above 1000 rpms? Almost instantly actually.
EDIT: So, I just looked into it, and my accord doesn’t have an adjustment screw on the throttle body. Maybe I’m missing it and all my sources are just wrong? I’m not sure. But I don’t see it and neither does anyone else.
New update. Been going through etcg’s diagnostics on idle. Fuel pressure sensor, bleeding air out of the coolant system, stuff like that. I was driving it this morning and the check engine light came on. It’s now hesitating. Haven’t checked the code, but last time it did this it was something about a vacuum leak. I’m thinking egr valve, but I never looked into before because the cel went off. Will check the code tomorrow and post results. I don’t know if the egr valve could cause my issues….? Anyway, thanks for all the help!
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