Performance & Maintenance Engine, forced induction, intakes, exhausts, torque converters, transmissions, etc.

Hesitation? Stalling? Poor cold start? Stumble? Low RPM? Sluggish? *LOOK HERE*

Thread Tools
 
Search this Thread
 
Old 03-02-06, 11:22 AM
  #1  
O. L. T.
Keeper of the light
Thread Starter
iTrader: (17)
 
O. L. T.'s Avatar
 
Join Date: Feb 2003
Location: My little world
Posts: 34,097
Received 335 Likes on 221 Posts
Default Hesitation? Stalling? Poor cold start? Stumble? Low RPM? Sluggish? *LOOK HERE*

I've battled an issue with my car having a stumble when cold. Hesitation, low RPM. I did the Seafoam thing a while back and it helped a TON, but I've noticed there was still something going on.

Today I was checking the fluids and such looking around with the motor running. I happened to lean against the box that is under the intake and my RPM went up by 800 RPM! I knew instantly I found my issue.

The box that is under the intake is part of a two piece system for the intake, some of you know this. What I have NOT seen mentioned is the fact that the box does not square up to the intake tube very well and that causes an air leak!


I tie strapped the box to the intake and took a drive and ALL my issues went away.


Go outside and start your car. Grab the box under the intake and force it upwards snug to the intake tube. If your RPM changes, you have a leak and your car could be suffering from it.


Use tie straps on both the front and the back to seal both end of the box to the tube. (silicone it before hand if you really want a heck of a seal).

Remember to reset your computer after you do this before you take a test drive. Otherwise your new found proper air circulation will not change performance much since your computer is feeding it old and bad info from your MAF.
Attached Thumbnails Hesitation? Stalling? Poor cold start? Stumble? Low RPM?  Sluggish? *LOOK HERE*-air-medium-.jpg  
Old 03-02-06, 11:30 AM
  #2  
JspecSC3
Lexus Champion
iTrader: (4)
 
JspecSC3's Avatar
 
Join Date: Jan 2005
Location: N/A
Posts: 4,908
Likes: 0
Received 0 Likes on 0 Posts
Default

I am currently having those symptoms. I have been meaning to take that square thing out. I'll check it out and see if it is that problem. Another thing I recently noticed was that when I downshift hard my intake makes a quick whistling sound. It probably is a leak.
Old 03-02-06, 11:33 AM
  #3  
O. L. T.
Keeper of the light
Thread Starter
iTrader: (17)
 
O. L. T.'s Avatar
 
Join Date: Feb 2003
Location: My little world
Posts: 34,097
Received 335 Likes on 221 Posts
Default

Do this after you test it: https://www.clublexus.com/forums/sho...49&postcount=5

Just grab that box and push it up. if your RPM changes, you found your leak. Also, try and pull it down too so you'll know if it is loose and needs some attention. It looks like this is something that will easily come loose under the high heat.

Lemme know how it works for you.
Old 03-02-06, 11:47 AM
  #4  
weekenduse
Rookie
 
weekenduse's Avatar
 
Join Date: Mar 2005
Location: T-DOT
Posts: 86
Likes: 0
Received 0 Likes on 0 Posts
Default

Great find. I will try when I get home from work.
Old 03-02-06, 05:38 PM
  #5  
SCV8
Instructor
 
SCV8's Avatar
 
Join Date: Jun 2001
Location: Seattle
Posts: 1,135
Likes: 0
Received 1 Like on 1 Post
Default

That and the rubber hose to the MAF upstream can crack underneath, making for another difficult-to-find leak.
The ECU will learn the new settings after a couple days of driving, no real need for a reset, unless you happen to be in th fuse box already I suppose.
I wonder how long it was like that?
Old 03-04-06, 07:12 AM
  #6  
O. L. T.
Keeper of the light
Thread Starter
iTrader: (17)
 
O. L. T.'s Avatar
 
Join Date: Feb 2003
Location: My little world
Posts: 34,097
Received 335 Likes on 221 Posts
Default

Originally Posted by JspecSC3
I am currently having those symptoms. I have been meaning to take that square thing out. I'll check it out and see if it is that problem. Another thing I recently noticed was that when I downshift hard my intake makes a quick whistling sound. It probably is a leak.
Did ya ever do it?
Old 01-03-13, 11:43 PM
  #7  
ninjasc400
Driver School Candidate
 
ninjasc400's Avatar
 
Join Date: Jun 2008
Location: Sacramento, CA
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default

This MIGHT be the fix I was looking for.

When I tried lifting that box upwards, although it barely moved, I did notice that the engine didn't sound like it was about to stall. As soon as I let go, it would sputter here and there. I did this numerous times just to make sure I wasn't going crazy.

Didn't have any zipties on hand this late at night but I'm going to give it a shot first thing in the morning and return with updates.

The problems I'm having are that the engine stalls when idling and while coming to a stop while driving. Unplugging the MAF made the car run fine but with a CEL and it would run rich and smell gassy. Plugging in a replacement MAF and resetting the ECU caused the same problems even though the CEL went away.

Went back to the old MAF, reset the ECU again and this time I was pulling on the box. The engine didn't cut off once in the 30 minutes the car was running.

Let's see what happens when I buy some zipties tomorrow morning...
Old 01-04-13, 04:07 PM
  #8  
SOLID300
Pole Position
iTrader: (7)
 
SOLID300's Avatar
 
Join Date: Apr 2010
Location: Florida
Posts: 230
Likes: 0
Received 0 Likes on 0 Posts
Default

interesting. This may be the problem a buddy of mine is having with his car. I dont understand why the issue only occurs when the engine is cold though. Good find.
Old 01-05-13, 04:26 PM
  #9  
Casper9604
Rookie
iTrader: (1)
 
Casper9604's Avatar
 
Join Date: Sep 2012
Location: Portland, OR
Posts: 72
Likes: 0
Received 0 Likes on 0 Posts
Default

Is this on both the 300 and 400? I removed my intake in order to fix a coolant issue a while back and i've been experiencing a ridiculously low idle and it's shaky.
Old 01-05-13, 06:38 PM
  #10  
1JZPWRD
1JZ Single SC400
iTrader: (59)
 
1JZPWRD's Avatar
 
Join Date: Jan 2009
Location: Alabama, Roll Tide!
Posts: 8,518
Likes: 0
Received 15 Likes on 12 Posts
Default

I am going to try this method tomorrow if I get a chance. Thanks for adding to the torubleshooting of SC400.
Old 01-05-13, 08:17 PM
  #11  
scENFORCER
Lexus Champion
 
scENFORCER's Avatar
 
Join Date: Oct 2006
Location: BC
Posts: 3,114
Likes: 0
Received 2 Likes on 2 Posts
Default

Quite the thread revival. Easy enough to try, I'll give it a shot tonight.
Old 01-05-13, 08:19 PM
  #12  
MooJohn
Lead Lap
 
MooJohn's Avatar
 
Join Date: May 2011
Location: GA
Posts: 485
Likes: 0
Received 2 Likes on 2 Posts
Default

You notice OLT's post was from 7 years ago

But I'm glad it was bumped. I hadn't seen it and it's something I can always check.
Old 01-05-13, 08:26 PM
  #13  
Casper9604
Rookie
iTrader: (1)
 
Casper9604's Avatar
 
Join Date: Sep 2012
Location: Portland, OR
Posts: 72
Likes: 0
Received 0 Likes on 0 Posts
Default

So i'm assuming this is only for the SC400. Damn.... my 300 is having similar issues.
Old 01-07-13, 08:53 AM
  #14  
scENFORCER
Lexus Champion
 
scENFORCER's Avatar
 
Join Date: Oct 2006
Location: BC
Posts: 3,114
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by scENFORCER
Quite the thread revival. Easy enough to try, I'll give it a shot tonight.
Wellp. the vvt-i dont appear to have this box. Unless its under the engine cover.
Old 01-07-13, 10:19 AM
  #15  
Candela
Lead Lap
iTrader: (1)
 
Candela's Avatar
 
Join Date: Oct 2010
Location: NY
Posts: 650
Likes: 0
Received 1 Like on 1 Post
Default

If someone starts a new thread its a problem and they get told to search, but if an old thread is updated apparently its a problem too. Come on guys, lets stick to our word here.


Quick Reply: Hesitation? Stalling? Poor cold start? Stumble? Low RPM? Sluggish? *LOOK HERE*



All times are GMT -7. The time now is 09:53 AM.