YotaTech Forums  

Go Back   YotaTech Forums > Toyota SUV & Truck Tech > 86-95 Trucks & 4Runners
Sign in using an external account
Register Forgot Password?
Search


86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

Welcome to Yotatech!
Welcome to Yotatech,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
LinkBack Thread Tools Search this Thread
Old 06-03-2010, 12:04 PM   #1 (permalink)
Registered User
Personal Sales Rating: (0)
 
Join Date: Jun 2010
Posts: 3
Cool 94 4Runner V6 - Runs Rough on WARM Start

My 4Runner runs fine on cold start and continues to run well after it warms up. However, if you shut it down and try to restart it will run really rough.

At one point the check engine light came on and indicated a lean fuel ratio. My repair book suggested a bad O2 Sensor as a possible cause, which made sense because it runs fine when cold. (Doesn't explain running fine after warming up though?) I went ahead and changed the 02 Sensor, the check engine light went out, and it ran great for about three days then started having the same issues until now.

I don't think it's an electrical issue because the cap, rotor, plugs and wires are relatively new. I thought the fuel mixture ratio was preset and shouldn't be modified. I have considered trying to clean the MAF sensor to see if that helps.

Has anyone else experienced this type of problem? Any ideas or advice would be much appreciated.
This ad is not displayed to registered members.
Register your free account today and become a member on Yotatech!
ORoffroad is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-03-2010, 12:39 PM   #2 (permalink)
Registered User
Personal Sales Rating: (0)
 
thook's Avatar
 
Join Date: Sep 2005
Location: NW Ark on wooded ten acres...Ozarks at large!
Posts: 8,322
What brand of sensor did you install?

Just because all those new parts are on there does't mean it isn't electrically related. You have an air temp sensor in the airflow meter, a throttle position sensor, a coolant temp sensor for the EFI (not the temp sending unit), and so on.

Anyway......the first question, eh. ????
__________________
Matthew

Context is everything....
Quote:
Originally Posted by abecedarian View Post
freckles, shmeckles... that was your acne reflecting on my pearlescent skin.
My favorite method of troubleshooting..... :D
Quote:
Originally Posted by HighLux View Post
Oh...that was me thinking...then stopping mid sentence...then some more babbling and such. LOL
thook is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-03-2010, 12:49 PM   #3 (permalink)
Registered User
Personal Sales Rating: (0)
Threadstarter [OP]
 
Join Date: Jun 2010
Posts: 3
I put in a Bosch OE replacement sensor.
ORoffroad is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-03-2010, 03:04 PM   #4 (permalink)
Registered User
Personal Sales Rating: (0)
 
thook's Avatar
 
Join Date: Sep 2005
Location: NW Ark on wooded ten acres...Ozarks at large!
Posts: 8,322
Mmmmm.....first off I wll say more often than not, I talk to and read about people having issues using Bosch O2 sensors on their Yotas. I only know of one person that hasn't/doesn't/isn't. He's the anomoly I can't figure out. All I can say is if you read....run a search on the forum.....about the Bosch sensors you'll find displeasure and then improvement once a switch was made to an OEM Denso unit. This may not be your issue, though. I just wanted to point that out. You can try unplugging the sensor temporarily to see how it will affect running conditions. You will get a CEL, but not to worry. You're just testing. Try this and report back what happens.

Otherwise, it could be....say....the airflow meter, but I doubt it.
__________________
Matthew

Context is everything....
Quote:
Originally Posted by abecedarian View Post
freckles, shmeckles... that was your acne reflecting on my pearlescent skin.
My favorite method of troubleshooting..... :D
Quote:
Originally Posted by HighLux View Post
Oh...that was me thinking...then stopping mid sentence...then some more babbling and such. LOL
thook is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-11-2010, 11:48 AM   #5 (permalink)
Registered User
Personal Sales Rating: (0)
Threadstarter [OP]
 
Join Date: Jun 2010
Posts: 3
Tried unplugging the 02 Sensor when the engine was running rough. Check Engine light came on and the engine ran even worse than before. I could also smell gas.

I put my timing light on while it was running bad and it seemed to be off, however, the engine was idling slower than recommended (800rpm). I cranked up the idle to the 800RPM and that helped it run slightly better, but the timing still seemed off. I couldn't even see the timing mark on the pulley?

The truck works fine when cold and even after warmed up as long as the engine stays running. The big question is what changes in engine logic take place when restarting with a warm engine. If someone knows that, I think we may be able to narrow down the problem.

Thanks for all your advice.
ORoffroad is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-11-2010, 01:34 PM   #6 (permalink)
Registered User
Personal Sales Rating: (0)
 
thook's Avatar
 
Join Date: Sep 2005
Location: NW Ark on wooded ten acres...Ozarks at large!
Posts: 8,322
I think what you're dealing is called starting problems after hot soak. Now, I remember reading some things about that specific here recently, but don't remember the exact possible cause/s. I'll have to find the info again and get back with you.

Later......
__________________
Matthew

Context is everything....
Quote:
Originally Posted by abecedarian View Post
freckles, shmeckles... that was your acne reflecting on my pearlescent skin.
My favorite method of troubleshooting..... :D
Quote:
Originally Posted by HighLux View Post
Oh...that was me thinking...then stopping mid sentence...then some more babbling and such. LOL
thook is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-13-2010, 09:49 PM   #7 (permalink)
Registered User
Personal Sales Rating: (0)
 
thook's Avatar
 
Join Date: Sep 2005
Location: NW Ark on wooded ten acres...Ozarks at large!
Posts: 8,322
Okay.....I found the info I was looking for. There a vacuum switching valve referred to as the fuel pressure up valve connected in line with your fuel pressure regulator. It's suppose allow atomospheric air into the fuel pressure regulator and increase fuel pressure under hot soak conditions upon starting. If that's not working....allowing air in...it can create this problem.

Any questions??? You still around, bubba?
__________________
Matthew

Context is everything....
Quote:
Originally Posted by abecedarian View Post
freckles, shmeckles... that was your acne reflecting on my pearlescent skin.
My favorite method of troubleshooting..... :D
Quote:
Originally Posted by HighLux View Post
Oh...that was me thinking...then stopping mid sentence...then some more babbling and such. LOL
thook is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-13-2010, 11:05 PM   #8 (permalink)
Registered User
Personal Sales Rating: (0)
 
Join Date: May 2009
Location: BC Man!
Posts: 70
Ive had this exact some issue for years and never figured it out!!!

3 mechanics couldnt figure it out and I was sick of replacing parts on their ideas so I told them if they cant garuntee that it will fix it then I dont want it. They couldnt garuntee it so I just deal with it. One also mentioned a fuel/air mix error came up on one of their "tests" but that lead him to replacing some intake hose that was cracked that didnt make a difference (but cost me 200 bucks)

Over time ive looked at/been told to replace Fuel pressure reg, EGR valve, and the Oxygen sensor.

Does yours also sometimes run a little hesitant/jerky in the winter? Its fine when it warms up but if you only let it idle for a minute or so before driving it seems to struggle/hesitate pretty bad in the cold.
__________________
94 4runner, 3vze 5spd, with too many miles
Fishaa is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-18-2010, 05:30 AM   #9 (permalink)
Registered User
Personal Sales Rating: (0)
 
Reedr125's Avatar
 
Join Date: Dec 2009
Location: Ohio
Posts: 53
Send a message via Yahoo to Reedr125
I have had 2 diffrent vehicles do this to me. In both cases it turned out i had a pin hole in my gas line. I think they call it vapor locking, the pressure slowly goes down and fills the line with air. Creating a pocket of air in the line. Try turning it on and letting the pump primes itsself for a minute. I never seen a leak on my truck, but then the line blew out, after fixing it, the truck ran perfect all the time. Gives ya something easy to look for though.
Reedr125 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-28-2011, 04:57 AM   #10 (permalink)
Registered User
Personal Sales Rating: (0)
 
Join Date: Jun 2011
Posts: 1
Hello
I just joined to follow this problem. This exactly what my well tuned 185xxx miles 4 run is doing.
Please keep us posted on how to fix the rough hot run/start.
Lou
lou94v6 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 06-28-2011, 04:57 AM
Yotatech
4WD Truck




Paid Advertisement
Reply

Tags
1995, 4runner, 94, cel, fuel, hot, idles, pressure, rough, running, runns, runs, toyota, up, valve, warms

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -8. The time now is 04:45 AM.


2010 InternetBrands, Inc.

Search Engine Friendly URLs by vBSEO 3.5.2