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. :woot:


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.

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.

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.

Great find. I will try when I get home from work.

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?

Did ya ever do it?

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...

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.

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.

I am going to try this method tomorrow if I get a chance. Thanks for adding to the torubleshooting of SC400.

Quite the thread revival. Easy enough to try, I'll give it a shot tonight.

You notice OLT's post was from 7 years ago :D

But I'm glad it was bumped. I hadn't seen it and it's something I can always check.

So i'm assuming this is only for the SC400. Damn.... my 300 is having similar issues.

Wellp. the vvt-i dont appear to have this box. Unless its under the engine cover.

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.