Car Idle Problems

#1
Wondering if anyone has experience in what I'm going through. My car seems to not have a steady idle and dies sometimes when the idle is low. Many times when idle drops it makes a knocking sound. I would have to rev the engine on the road to get the idle good, I changed oil, cleaned and check the engine for leaks and such and couldn't find any. Still happens. Also my car is having problems shifting into 4th gear. What's going on.help!
 

Scott O'Kashan

Super Moderator
#2
What year Corolla, how many miles are on it and is it equipped with an automatic or manual transmission? Do the symptoms present themselves depending on if the engine ir hot, cold or both? How many miles has this been going on?
 
#3
2010 corolla le I got 62511 miles. It only happens after driving or during at stop lights. It also has problems shifting into 4th. I would have to manully go to 3rd gear then let the gas go and shift to D
 
#6
I want to say it is electrical related. Any add-ons done recently? Have you checked for frayed or torn grounds? How do the battery cables look?

Getting a check engine light?

Other things that can cause a poor idle:
Vacuum leak
Worn Upstream HO2S
Worn Spark Plugs
Plugged Air Filter
Bad Spark Plug Coils

However, those issues won't cause problems with 4th gear. That is why I'm leaning toward an electrical issue.
 
#7
Yeah I got a check engine light. I'm running a k n filter , exaust manifold, full muffler, no cat, unichip plug an play. Where would I check vacuum leaks.? My check engine light has always been on when I plug in the scan obd2 it shows just the 02 sensors are bad.
 

Scott O'Kashan

Super Moderator
#8
The scanner is probably saying the 02 sensors are bad because there is no catalytic converter, (illegal in the U.S. to remove a catalytic converter). The 02 sensors work in harmony with the catalytic converter and with it being removed, the 02 sensors are not going to read correctly.
 
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