RPMs Bouncing up and down. - Engine Troubleshooting


	Auto Repair Home	SEARCH POSTS	WHO'S ONLINE	LOG IN

Automotive Repair

Car Troubleshooting Topics
  Car Troubleshooting
  Engine Troubleshooting
  Engine Fault Codes
  Electrical and Wiring
  Transmission Problems

Car Repair Topics
  Car Making Noises
  Car Stereo Repair
  Heating or AC Issues
  Motorcycles and ATVs
  Tricks of the Trade
  Truck Repair Advice

Site Options:
  Login
  Sign up here!

Latest Forum Post

1989 toyota pickup 3.0 crank no start

I have a 1989 toyota pickup 3.0 crank no...

Strut spring orientation and strut mount tension nut

2017 Nissan rogue awd 2.5 L Put in Monro...

Transmission stuck in part, I have tried everything

So I'm working on my elderly fathers 201...

2017 dodge journey LED headlights on/off randomly

Year of vehicle 2017 Make of vehicle dod...

Kia Soul starter replacement issues!

Okay so my car is a 2010 Kia soul 2.0 en...

Please Help - Knock sound & engine fail

Hi all, Hoping to get some insight and ...

multiple warning lights

2013 GMC Terrain 130,000 miles 4 cylinde...

03 alero no low speed blower

Good day everyone, I have a 2003 Olds a...

04 Chevy 2500hd tail light issues

Help!!! I have changed my combo switch...

1999 Grand Caravan Sport not starting.

Hi. I'm new here. I hope someone can hel...

RPMs Bouncing up and down.

Sign up here!

Search for (search options)

Auto Repair Home>> Automotive Repair>> Engine Troubleshooting

Patches33001
Novice

Nov 6, 2017, 9:27 AM

Post #1 of 4 (2493 views)

RPMs Bouncing up and down.	Sign In

Hi, so i have a 1998 Pontiac Sunfire, and last winter i had trouble with the RPM bouncing up and down after driving it for awhile. Then it stopped for awhile once i replaced all the O2 sensors (which at the time was triggering an engine code) and this summer i replaced the EGR valve. But it snowed this weekend, and last night when i got home from walmart it started doing it again. With the dashlights on they kind of dim and brighten repeatedly with the engine sounds. I tested the battery and alternator and both were fine. There isn't an engine code, so what else would be the problem? Thanks![:)]
-Patches

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 6, 2017, 9:33 AM

Post #2 of 4 (2491 views)

Re: RPMs Bouncing up and down.	Sign In

First eliminate all vacuum or air leaks in the system (very important)

. You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Patches33001
Novice

Nov 6, 2017, 9:44 AM

Post #3 of 4 (2483 views)

Re: RPMs Bouncing up and down.	Sign In

Okay, thanks, last time i took off the intake the throttle body looked fine, but ill check the backside just in case.
-Patches

Patches33001
Novice

Nov 9, 2017, 10:45 AM

Post #4 of 4 (2439 views)

Re: RPMs Bouncing up and down.	Sign In

Just cleaned the entire thing today, seemed fine. But we'll see how it helps! I found the IACV so if i do have to replace it in the future i know where it is. Thanks for the help!

-Patches

Search for (options) Privacy Sitemap