93 V6 Rough Idle - Toyota 4Runner Forum

fjcruiserpd · 03-07-2014, 03:22 PM

93 V6 Automatic 167,000 miles. Second owner. Purchased in December 2013.

My truck has a bit of an intermittent shake when either in park or stopped at a light/stop sign almost as if it is going to stall but never does. And lately it has been hesitating a bit at acceleration from stop and just driving rougher than normal. Before all of this it was a smooth ride for most of the time.

I'm sure there a various things that could be going on, but I'm not much of a mechanic so if I could get an idea on where to start in terms of diagnosis that would be great. I'm good at fixing/replacing what is broken, just need to know how to find the problem.

77'911 · 03-07-2014, 03:36 PM

If it has never had the motor mounts done in 167k, you might consider replacing them. I would start there and then work your way to detonation quality(state of tune, fueling, etc..). Best of luck with it.
regards

giro · 03-07-2014, 06:15 PM

Have you been through a few tanks of gas while having this issue?

Does it happen when in Park, or only when stopped with the brake on? All the time, or just at night?

If the non-stopped issues aren't that bad, I'd probably just look at bumping up the idle a tiny bit. On some cars the brake lights are enough to cause a little roughness, or maybe that combined with the brakes trying to stop while the car is trying to go.

But roughness at other times might point somewhere else. If the air filter is good, you might consider replacing the fuel filter. I've never done it on my 4runner, but have had to occasionally on older non-toyota cars.

bills86e · 03-07-2014, 06:18 PM

Buy some CRC throttle body cleaner and clean it, the IAC, Modulator filter, MAF, and adjust the idle screw on throttle body to 750-850 rpms at idle.
If you pull the rubber hose off the EGR valve and it smooths out, you may have to look at the vacuum hose routeing diagram thats on driver side under the hood, to confirm each hose connection tube tubes are correct.

fjcruiserpd · 03-07-2014, 06:39 PM

Quote:

Originally Posted by giro

Have you been through a few tanks of gas while having this issue?

Does it happen when in Park, or only when stopped with the brake on? All the time, or just at night?

If the non-stopped issues aren't that bad, I'd probably just look at bumping up the idle a tiny bit. On some cars the brake lights are enough to cause a little roughness, or maybe that combined with the brakes trying to stop while the car is trying to go.

But roughness at other times might point somewhere else. If the air filter is good, you might consider replacing the fuel filter. I've never done it on my 4runner, but have had to occasionally on older non-toyota cars.

I believe this issue started with the current tank of gas.

It happens when it park as well no matter the time of day.

It already idles at around 850, should it be more?

What exactly constitutes a "good" air filter. I've checked it a few times and it never really looks dirty.

Also, to give some insight as to what I'm experiencing; when stopped at a light (or parked) the car will idle smooth for a few seconds and then give a little shake. It pretty much follows this pattern constantly.

fjcruiserpd · 03-07-2014, 07:47 PM

Quote:

Originally Posted by bills86e

Buy some CRC throttle body cleaner and clean it, the IAC, Modulator filter, MAF, and adjust the idle screw on throttle body to 750-850 rpms at idle.
If you pull the rubber hose off the EGR valve and it smooths out, you may have to look at the vacuum hose routeing diagram thats on driver side under the hood, to confirm each hose connection tube tubes are correct.

I cleaned the throttle body a few weeks ago just because. I'll look into the other things as well.

FWIW I just ran some Seafoam through it. I'll report back to see if anything changed.

541joseph · 03-07-2014, 09:51 PM

Quote:

Originally Posted by fjcruiserpd

I believe this issue started with the current tank of gas.

It happens when it park as well no matter the time of day.

It already idles at around 850, should it be more?

What exactly constitutes a "good" air filter. I've checked it a few times and it never really looks dirty.

Also, to give some insight as to what I'm experiencing; when stopped at a light (or parked) the car will idle smooth for a few seconds and then give a little shake. It pretty much follows this pattern constantly.

Drop the air filter on the ground dirty side down and if dirt falls off it needs replaced

fjcruiserpd · 03-08-2014, 12:34 AM

Well I drove it this evening and it drove terribly. Felt as though at any moment while I was on the highway that it would die on me. Then as soon as I pulled into my driveway the check engine light came on.

I lifted the hood and could hear what sort of sounded like air being pushed in (or out) but no place to go. Definitely not a sound I've heard before.

Hopefully whatever codes I can pull will give me some insight...

Jdrum1 · 03-08-2014, 11:01 AM

Vacuum line come loose?

fjcruiserpd · 03-08-2014, 11:26 AM

Quote:

Originally Posted by Jdrum1

Vacuum line come loose?

Just checked. Didn't see any lines that weren't connected to anything. And they all appeared to be routed to the corrected places.

Just a question: Would a bad or dead O2 sensor affect idle and drive quality? Not saying this is my diagnosed problem just wondering.

Orion_71115 · 03-08-2014, 11:34 AM

Yes it will.

bills86e · 03-08-2014, 12:22 PM

IAC or fuel pump, could be culpret.
Open the diagnostic port cover and look for T1 and E. jumper those then turn ignition to the ON position and watch for the DTC readings. Search the codes, fix what the code symptoms suggest is wrong.

541joseph · 03-08-2014, 12:45 PM

Quote:

Originally Posted by fjcruiserpd

Just checked. Didn't see any lines that weren't connected to anything. And they all appeared to be routed to the corrected places.

Just a question: Would a bad or dead O2 sensor affect idle and drive quality? Not saying this is my diagnosed problem just wondering.

Typically a bad o2 sensor won't cause this issue until after damage from running improperly is already caused

fjcruiserpd · 03-08-2014, 07:26 PM

Okay, so I'm going to check for codes either today or tomorrow. But I have questions.

I'm not a mechanic like I said, so I need some help getting the codes. I'm reading everywhere to use a jumper to find the codes. What is this jumper and where can I buy it? Is this the only way to pull codes? Is there a scanner like with newer OBDII enabled vehicles that will just show me the codes instead of me having to count engine light blinks?

Also, with these blinks - say the code is something like 85, does that mean I have to sit there and count 85 blinks? Or does it blink 8 times, pause and then blink 5 times?

541joseph · 03-08-2014, 09:08 PM

Quote:

Originally Posted by fjcruiserpd

Okay, so I'm going to check for codes either today or tomorrow. But I have questions.

I'm not a mechanic like I said, so I need some help getting the codes. I'm reading everywhere to use a jumper to find the codes. What is this jumper and where can I buy it? Is this the only way to pull codes? Is there a scanner like with newer OBDII enabled vehicles that will just show me the codes instead of me having to count engine light blinks?

Also, with these blinks - say the code is something like 85, does that mean I have to sit there and count 85 blinks? Or does it blink 8 times, pause and then blink 5 times?

Yes there are scanners that do it. Snap-on's modis scanners do it and simmilar high end ones will but we are talking thousands just take any wire laying around jump the ports. If its 85 it will blink 8 times then pause for a second and the do 5

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