Intermittent rough idle no codes

[squidmotion]

Hi friends!

I've read a lot of posts about this issue, but need some advice.

A month or so ago, I started having this idle issue, while idling in drive. It idles ok but there is this rough idle for a few seconds then it goes away. Sometimes it hesitates a bit while pulling away. No other issues after that. I'm confounded that it doesn't throw a CEL or a code (I've checked it with my reader). It starts as it always has.

So far, I've replaced the fuel filter, air filter, and cleaned the MAF twice.

Here are my next steps:

• Throttle body cleaning
• PCV valve and grommet (on the way)
• Spark plugs
• Coils (If I find any that are cracked, etc.)
• Fuel Pump?

Am I diving into this in the proper sequence? Are there any other items I'm overlooking, or sensors to be cleaned?

 

[Bleu62]

Hi friends!

I've read a lot of posts about this issue, but need some advice.

A month or so ago, I started having this idle issue, while idling in drive. It idles ok but there is this rough idle for a few seconds then it goes away. Sometimes it hesitates a bit while pulling away. No other issues after that. I'm confounded that it doesn't throw a CEL or a code (I've checked it with my reader). It starts as it always has.

So far, I've replaced the fuel filter, air filter, and cleaned the MAF twice.

Here are my next steps:

• Throttle body cleaning
• PCV valve and grommet (on the way)
• Spark plugs
• Coils (If I find any that are cracked, etc.)
• Fuel Pump?

Am I diving into this in the proper sequence? Are there any other items I'm overlooking, or sensors to be cleaned?

Does it sound/ feel more like the engine is missing on a cylinder or is it your ac pump turning off and on?

 

[2001LC]

Likely misfire. 9 out of 10 times, it's a weak coil. Crack in coils, means, subject to excessive heat. Which is not great for coils, but crack doesn't mean the coil is bad. We do have factory coils go bad. But if any after market, or purchases from third party parts. They're highly suspect.
I buy coils, directly from Toyota or Denso distributor. Some have had good luck, buying from Rock Auto.

 

[squidmotion]

Thanks, guys. I did a thorough throttle body cleaning. It seemed to make a difference, but then back to the same. I'll keep at it, and report back.

Does it sound/ feel more like the engine is missing on a cylinder or is it your ac pump turning off and on?

When it kicks into high idle for the AC compressor kicking on, it goes away... it's when it's idling in gear, around 600rpms when it happens.

Likely misfire. 9 out of 10 times, it's a weak coil. Crack in coils, means, subject to excessive heat. Which is not great for coils, but crack doesn't mean the coil is bad. We do have factory coils go bad. But if any after market, or purchases from third parts. They're highly suspect.
I buy coil directly from Toyota or Denso distributor. Some have had good luck, buying from Rock Auto.

I think pulling the coils and plugs is next on my list.

 

[2001LC]

Thanks, guys. I did a thorough throttle body cleaning. It seemed to make a difference, but then back to the same. I'll keep at it, and report back.


When it kicks into high idle for the AC compressor kicking on, it goes away... it's when it's idling in gear, around 600rpms when it happens.


I think pulling the coils and plugs is next on my list.

Pulling coils & plugs and replace all $550+. Scan for misfires $40.

 

[squidmotion]

Pulling coils & plugs and replace all $550+. Scan for misfires $40.

Been using my quality scan tool.. . no miss fires. That is confounding. I've never wished for a code, but I sure wish it would give me one.

 

[2001LC]

You'll not see misfire, with a scan. You must be watching for it in "Tech Stream", engine data screen. They're most times very hard to catch live. You must recreate condition i. e. idle, in gear & foot on brake. Often times, it only appears for a moment. See one say at cylinder #1. Replace or swap that coil. See if returns or not at #1, or moves to swap.

Watch video.