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.

 

[squidmotion]

I thought I should do a follow up on this post. It’s fixed!

Cleaned the throttle body again. Also installed a new pcv valve and grommet. Did a much more comprehensive search for a vacuum leak. No love.

While I was changing the plugs, I inspected the coils, and they all looked fine. However, among all of the factory coils, there was an imposter, a non OEM coil.. gray in color. It looked ok, but I put it on my list to get another Denso coil on the way. I moved that one to the number one spot, so it would be easy to change when the new coil arrived.

Cold idle got worse and worse, so I decided to plug in the code reader. Still no CEL but now I was getting an intermittent P0301 code. VICTORY.

Installed the new coil, and it now runs beautifully.

Never trust non-OEM parts!!!

 

[2001LC]

Good Job!

For those that come to this thread in the future:

Thread 'When to replace Ignition coils.'

Jan 30, 2016

As our 100 series fleet ages we're seeing more ignition coil failures. Is there a certain mileage or age where our 100 series with the 2UZ-FE engine are seeing the need to replace one or more ignition coils?

If you’ve replaced any coils please post any performance differences before & after, along with your millage, years in service and anything that contributing to the reason why you replaced them. Such as age, climate condition, bad spark plugs or improper gap, spark plug tube gasket oil leak, under or over voltage or anything you consider could be a contributing factor...

• 2001LC
• Replies: 327
• Forum: 100-Series Cruisers

• 

 

[squidmotion]

Good Job!

For those that come to this thread in the future:

Thread 'When to replace Ignition coils.'

Jan 30, 2016

As our 100 series fleet ages we're seeing more ignition coil failures. Is there a certain mileage or age where our 100 series with the 2UZ-FE engine are seeing the need to replace one or more ignition coils?

If you’ve replaced any coils please post any performance differences before & after, along with your millage, years in service and anything that contributing to the reason why you replaced them. Such as age, climate condition, bad spark plugs or improper gap, spark plug tube gasket oil leak, under or over voltage or anything you consider could be a contributing factor...

• 2001LC
• Replies: 327
• Forum: 100-Series Cruisers

• 

Brother, you are a boon of information. I tend to follow your word on these things. You said early on it was a coil or misfire. Thanks to everyone on this forum. This is why we have the internet, as far as I’m concerned.


BTW, the surf in Texas last Saturday morning was incredible.