RPM jumping 1-2 RPM during idle?
09-06-2008, 08:25 PM
#1
1999 Accord 4 cyl
Thread Starter
Join Date: Oct 2003
Posts: 893
Likes: 0
Received 0 Likes
on
0 Posts
RPM jumping 1-2 RPM during idle?
I just encountered this problem. The night before it idle fine. Today I start the car (cold) and the idle was kept bouncing between 1000-2000 rpms in a continuous cycle. I drove around for 30 mins (warm)... still bouncing.
Possible culprits?
BTW: No check engine lights. The night before it happened I was driving in unusually heavy rain.
Possible culprits?
BTW: No check engine lights. The night before it happened I was driving in unusually heavy rain.
Last edited by mxl36o; 09-06-2008 at 08:41 PM.
09-06-2008, 08:49 PM
#2
v-card member alpha
Join Date: Oct 2006
Location: Assplosion, NE
Posts: 4,010
Likes: 0
Received 0 Likes
on
0 Posts
Sounds like either a vacuum leak or the IACV is acting up (assuming it's in reference to your '99).
It drives and seems normal in every other aspect I assume?
It drives and seems normal in every other aspect I assume?
09-06-2008, 09:11 PM
#3
1999 Accord 4 cyl
Thread Starter
Join Date: Oct 2003
Posts: 893
Likes: 0
Received 0 Likes
on
0 Posts
It's a 5 speed. If i'm accelerating in gear it drives normal. But lets say I"m in 1st gear below 2k rpm and release the gas... it feels different, jerking harder than normal.
09-06-2008, 09:29 PM
#4
v-card member alpha
Join Date: Oct 2006
Location: Assplosion, NE
Posts: 4,010
Likes: 0
Received 0 Likes
on
0 Posts
On that car, it doesn't have a Fast Idle Thermo Valve (unless I'm very mistaken), which would normally be my guess. Your car just has an Idle Air Control Valve, which does the job of both the FITV and the EACV (E for electronic)on older cars.
If you disconnect the electrical connector on the IACV (located on intake manifold) it's going to make the surging go away, but not necessarily b/c the IACV itself is the problem. Could also be a vacuum leak, one way to check for those is to spray starting fluid around the vacuum lines and manifold w/ the engine running to see if the idle surges b/c the starting fluid is making it's way into the manifold through a leak somewhere. You might have to disconnect the IACV first in order to get a stable idle, so you can tell if, and where, spraying the fluid has an effect.
Also could just be that the IACV needs cleaned :shrug:, but I've never removed or worked on an actual IACV, just it's older counterparts.
If you disconnect the electrical connector on the IACV (located on intake manifold) it's going to make the surging go away, but not necessarily b/c the IACV itself is the problem. Could also be a vacuum leak, one way to check for those is to spray starting fluid around the vacuum lines and manifold w/ the engine running to see if the idle surges b/c the starting fluid is making it's way into the manifold through a leak somewhere. You might have to disconnect the IACV first in order to get a stable idle, so you can tell if, and where, spraying the fluid has an effect.
Also could just be that the IACV needs cleaned :shrug:, but I've never removed or worked on an actual IACV, just it's older counterparts.
Last edited by A-series; 09-06-2008 at 09:34 PM.
09-07-2008, 12:28 PM
#6
1999 Accord 4 cyl
Thread Starter
Join Date: Oct 2003
Posts: 893
Likes: 0
Received 0 Likes
on
0 Posts
I just started it back up this morning. It had a steady high rev (1.8k rpm) for about 5 minutes. Then rpm started jumping again. I parked it went to store to buy carb cleaner, came back out and it steady at 600 rpm to eventually idling back to normal around 770 rpm. So far it's good again.
