Idle speed drops and comes back in cycles
#1
Idle speed drops and comes back in cycles
Hi all,
I got a TL-S with about 95k miles and my Idle speed drops from 750 down to 500 or even lower then goes back up to normal. The cycle repeats every couple of seconds.
I noticed when RPM drops the dash board lights dim and motor shudders. After driving for about an hour the issue seem to go away until the car is cold again.
With a slight throttle or during normal driving I haven't noticed any RPM drop.
I searched the forums and I've seen similar problems but not exactly this one.
Do you have any ideas what to look for?
I got a TL-S with about 95k miles and my Idle speed drops from 750 down to 500 or even lower then goes back up to normal. The cycle repeats every couple of seconds.
I noticed when RPM drops the dash board lights dim and motor shudders. After driving for about an hour the issue seem to go away until the car is cold again.
With a slight throttle or during normal driving I haven't noticed any RPM drop.
I searched the forums and I've seen similar problems but not exactly this one.
Do you have any ideas what to look for?
#2
#4
Senior Moderator
Id start with cleaning the IAC valve
#5
Thanks for the pointers. But looks like I scared it. The idle is normal now. I wonder if I had bad gas/water or something. If rough idle comes back will try crack this baby open.
#6
Former Sponsor
iTrader: (3)
Idle Air Control Valve or Throttle Position Sensor. I've had the TPS sensor do this more that the IACV.
If you clean your IACV and it stops you're golden. If it doesn't stop unplug your TPS while the car is doing it's auto-rev thing. If it stops when you unplug it..... your TPS is dead.
If you clean your IACV and it stops you're golden. If it doesn't stop unplug your TPS while the car is doing it's auto-rev thing. If it stops when you unplug it..... your TPS is dead.
#7
This is the problem I'm having. When it's cold out and I'm in Drive and stopped at a light, the rpm's will drop a little bit and the car feels like it is pushing forward, and then the idle comes up again. After I've driven for 10-15 minutes, it's fine and there are no idle problems.
So far, I've cleaned the egr ports and cleaned the intake manifold. This weekend I cleaned the throttle body and the iac valve by taking everything off (I had to pull the airbox anyway to replace a bad driver's side wheel speed sensor) and using carb cleaner to get all the gunk out. The iac was definitely dirty so I thought cleaning it would take care of it. Nope. This morning (it's hot, too, at about 45 degrees) I'm still having the same problem. Normally it's well below freezing, maybe single digits.
Is there a way to check the tps or iac with an ohm meter or anything like that? The car doesn't show a CEL and autozone couldn't pull any codes. It's very frustrating.
So far, I've cleaned the egr ports and cleaned the intake manifold. This weekend I cleaned the throttle body and the iac valve by taking everything off (I had to pull the airbox anyway to replace a bad driver's side wheel speed sensor) and using carb cleaner to get all the gunk out. The iac was definitely dirty so I thought cleaning it would take care of it. Nope. This morning (it's hot, too, at about 45 degrees) I'm still having the same problem. Normally it's well below freezing, maybe single digits.
Is there a way to check the tps or iac with an ohm meter or anything like that? The car doesn't show a CEL and autozone couldn't pull any codes. It's very frustrating.
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#8
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I have the saem problem. Sometimes its BAD. Car almost stalls out. I just cleaned out the EGR port a little while ago but didn't think about the IAC. Generally speaking this should clear it up?
#9
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Oh yea I forgot to mention this happens only after I'm parked for a while and as soon as I give it a rev or 2 the problems fixed. Its not enought time for the engine to warm up so I don't know if it has anything to do with the engine being cold. Could this be a fuel pump problem or something like that?
#11
Senior Moderator
It may be a TPS sensor issue. I dont have my manual here to see what the testing procedure is, but if it is bad you cant replace it. You have to replace the whole TB.
What year is your car? Have you disconnected the battery lately? Mileage?
What year is your car? Have you disconnected the battery lately? Mileage?
#13
No He Can't
iTrader: (2)
Originally Posted by SRAcuraTL
Oh yea I forgot to mention this happens only after I'm parked for a while and as soon as I give it a rev or 2 the problems fixed. Its not enought time for the engine to warm up so I don't know if it has anything to do with the engine being cold. Could this be a fuel pump problem or something like that?
#14
Senior Moderator
Originally Posted by Montaigne
This is the problem I'm having. When it's cold out and I'm in Drive and stopped at a light, the rpm's will drop a little bit and the car feels like it is pushing forward, and then the idle comes up again. After I've driven for 10-15 minutes, it's fine and there are no idle problems.
#16
Foot's on the brake, but it feels like you have the emergency brake on and you're giving the car just the tiniest bit of throttle or that one foot is on the brake and the other on the gas. It lasts for probably just a second or two per push forward. It will keep doing that at a stop until the car heats up. Also, every so often and shortly after leaving a stop, I will push on the pedal to accelerate, but the car goes no where. The pedal is down and the engine doesn't rev or stumble.
It drove fine today. Though late tonight (while I'm hard wiring in the radar detector, which was a success), I let the car idle for a bit in park (no surges or noticeable fluctuations in rpm) and the CEL came on. I'll take it in to autozone tomorrow to get them to pull the code. Hopefully, my cleaning did enough damage to finish off a bad sensor and didn't kill a different one.
It drove fine today. Though late tonight (while I'm hard wiring in the radar detector, which was a success), I let the car idle for a bit in park (no surges or noticeable fluctuations in rpm) and the CEL came on. I'll take it in to autozone tomorrow to get them to pull the code. Hopefully, my cleaning did enough damage to finish off a bad sensor and didn't kill a different one.
#17
Registered Pimp
this problem seems to be happening alot lately, i think the people at acura just decided to hit the self destruct button on our iac's so that we all go in to replace them for a premium.....damn conspiracies
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