Hi, I have a 99 Honda Accord V6 automatic 4DR sedan with ~78K miles. I have 2 issues with my car:

1) Weird Idle
About a year and half ago, I turned on my car and it went into this strange idle mode where it continuously revved up and down between ~1200 and 2K rpm on its own. During this idling, I revved the engine up to about 3K rpms to see if that stopped it but it didn't. I even tried stopping the engine and then restarting but it just resumed the weird idle. I then let it continue idling up and down for about 5 minutes, then it just went into normal idle ~1K rpm. It didn't happen again until just a while ago (1 and 1/2 years) later. I didn't wait the 5 minutes this time and it'll probably continue if I go back out there. The only similarity in the two situations is that it happened after not driving the car for a couple of days. The first time was about 4 days and this time it was 7 days. However, in between episodes the car has sat for more than 7 days on a number of occasions? What could be the problem here?

UPDATE: I just went back out there and it's still doing it. I let it run for about 3-4 mins but no change. I don't want to leave it going long because the cyclical load can't be good for the mounts.


2) Possible Transmission Problem
About 30K miles ago, I noticed a slight hesitation accelerating at lower speeds (between 25-40 mph). About 3 or 4 months ago it started getting worse where i appears car struggles to get out of the lower gear and kicks into the next gears (between 25-40 mph). It also feels like the car has lost power. It seems it could be a transmission issue but I'm not sure. The effect is less when the car is warm (driving for about 20 minutes). Could it be that my 78K transmission has gone bad and I need a new one? Could it be something else?

Could any of these be warning signs of the timing belt going?



Thanks in advance!

Maybe you have a vacuum leak and it also affects the transmission?

foreign,

i thought that at first too, but it's so inconsistent that i personally would look elsewhere.... :)

Your timing belt is not due by mileage but over by Honda's specified time interval of 7 years.
If the belt were loose enough to cause your running problems it would have jumped time a long time ago.

Your surging idle is more than likely a sticky IAC valve, it's easy to clean if you have access to compressed air of at least 90 psi. You need to remove the intake ductwork to the throttle body, spray some carb cleaner into the hole on the side of the opening (not the plate itself), I'd spray for 2 to 3 seconds. Then wait no longer than 10 seconds, take compressed air and blow into that opening and purge the valve of the gunk and cleaner.

The car will be hard to start after this, but should idle normally again.


If your transmission was or is flaring at low speeds, revving without moving then slamming into a gear, it's on it's way out.
You can try to have the fluid changed repeatedly with Z1 and see if it helps.

Has the check engine light come on?

2) Possible Transmission Problem
About 30K miles ago, I noticed a slight hesitation accelerating at lower speeds (between 25-40 mph). About 3 or 4 months ago it started getting worse where i appears car struggles to get out of the lower gear and kicks into the next gears (between 25-40 mph). It also feels like the car has lost power.

Thanks in advance!

problem 1 sounds like a vacuum leak.

so about 3-4 months ago you started loosing power, is that the same time you started using your AC again? because when i use my AC my car has allot less power, and shifts different, it dose not like to downshift, i think. but i don't really use AC anyway

just my $0.02:dunno:

Your timing belt is not due by mileage but over by Honda's specified time interval of 7 years.
If the belt were loose enough to cause your running problems it would have jumped time a long time ago.

Your surging idle is more than likely a sticky IAC valve, it's easy to clean if you have access to compressed air of at least 90 psi. You need to remove the intake ductwork to the throttle body, spray some carb cleaner into the hole on the side of the opening (not the plate itself), I'd spray for 2 to 3 seconds. Then wait no longer than 10 seconds, take compressed air and blow into that opening and purge the valve of the gunk and cleaner.

The car will be hard to start after this, but should idle normally again.


If your transmission was or is flaring at low speeds, revving without moving then slamming into a gear, it's on it's way out.
You can try to have the fluid changed repeatedly with Z1 and see if it helps.

Has the check engine light come on?
Fredsvt,

Thanks for the response. I don't have a compressor so is it worth it to get one or to just take it to a garage. Also, I haven't tried putting into gear (just doesn't seem like a good idea). Is there an even more lo-tech solution to at least be able to move the car to a garage or to a hardware store?

Thank you all for your responses. I don't have the tools, the location, or the expertise to do any real work on my car. So, if I'm looking at getting a garage to:
1) fix the vacuum leak (if this is the case)
2) replace or rebuild transmission
3) sticky IAC

what should I expect to pay or at least labor hours/part?

Thanks again.

BTW, I live just outside DC in Virginia

I can tell you from experience with these cars that the IAC is sticking.
I've made it happen myself when doing a 105k service, I always clean out the egr ports and the throttle body.
On several, when the car restarted, the idle did exactly what yours is doing, running from lower than normal idle to about 1500, cycling back and forth.

Performing the cleaning I mentioned has fixed all of them.

There are very few vacuum leaks, shy of the brake booster hose that would cause such a huge variation in idle speed.

The plunger in the IAC valve gets crud on it, the PCM tries to open the valve slightly to do the normal idle raising when starting or to compensate for A/C or putting into gear. The valve gets stuck in its bore, then the PCM commands more current to the valve which causes it to pop open (high idle) then the PCM slams it shut again to try and get the engine speed under control again.

This will happen over and over until either the crud liquifies enough that the thing doesn't require over current to open or it gives up entirely and the thing sets a check engine light and you get a code for idle control system.

BTW, I just thought of one other thing that can cause this, at least on much older Hondas, a failing TPS, it sends a wrong signal to the PCM, which causes severe idle instability, and can cause the odd transmission operation (definitely on a newer one) you are experiencing.

You can put it in gear, while it's doing this, it won't hurt it, it will actually settle down to a steady engine speed with load placed on the engine.

Once you've gotten the idle situation rectified, have the transmission diagnosed by a Honda specific shop (dealer OR independent) so they can tell you what's wrong. You may get a good-will from Honda if the trans is bad.

The weird idle stopped the next morning but I will attempt to do the clean Fredsvt described this weekend. I'll also take the car into a Honda dealership to check out the tranny. Hopefully I get a good-will because I'm not too happy dealing with transmission problems @ 78K on a HONDA of all cars.

You guys are awesome. Thanks for all the advice.