Lvangundy

(Thanks to Todd @ TM engineering and Tihn @ the auto store on artesia)

Hmm, I haven't officially given the car a good run yet (resetting ECU as I speak) but I took the car around the block with the stock filter on and it feels quite a bit different. Todd gave me the good suggestion if putting the stock air filter back on..so just today I did it.

Here's my input on why a K&N or another aftermarket filter isn't that great. --

First off, poor location. In my setup, the filter was left completely open to dirt, water etc. This allowed the filter to get dirty really quickly (and clog it).

Second, airflow (specifically cold) is lacking. After driving around for a few hours on a hot day and opening the hood. Heat is RAMPANT around the air filter area. Even when I had the stock air dam back in (sucks in from the grill) the are around there was oddly warm. Of course, any kind of mechanical machine runs worse when it's hot, but if the air outside is hot, there's not much you can do. So I gues in this regard, the stock filter doesn't present any good argument to cold air. (?)

Third and lastly, the first gen LS ECU!! According to Todd, the ECU (specifically MAF in this case) on these cars is ridiculously sensitive.

I confirmed this myself by first, unplugging the MAF sensor itself and starting the car. HILARIOUS! Trying to give the car gas just made the engine made loud sucking noise and come really close to stalling. Impossible to drive without this. Second, When everything back in place minus the air filter, barely putting my hand around the intake area made the car just plain stall. This car WANTS air! Maybe my throttle body needs a little cleaning also, but it's funny to make the car suffcoate with so little effort.

To end this, yes my K&N filter was completely gunked up with dirt and probably had the most to do with the rough idle and stalling/stuttering feeling (which I'm not sure is solved yet- tell you all in a sec) and cleaning it probably would have yielded better results, I'm going to stick with the stock filter for now and se how things are. Maybe time for one of those airbox mods JBrady made. ;-) ;-)

Ahanks again all - Will post drive test results soon! Still disappointed about the SC brakes! ;-(

GA400

Lvangundy,

Thanks for sharing your experience with the K&N. I had been debating getting one of those. Any other mods you have had good luck with (besides the Tokicos - I take it you are liking those)?

GA400

Lvangundy

RESULTS-

Dirty K&N's NOOO GOOD! Stock - Quiet and better performer.

Before after 3 runs (averaged) I was getting a 8.9 0-60 time. Now?

8.6 best out of 3! Avg - 8.7

So I dropped 2/10 of a second off my 0-60 by changing back to stock air filter. Last time I performed these tests was either with 1/4 gas in the tank or 3/4, I forgot , but this time it was 1/4.

The car came back to it's Lexus quiet sound and the performance on the highway and in 2nd gear is great! I really forgot how quiet the car was before the K&N. No doubt if you want loud growl, go for that K&N, but beware most likely you'll lose some time off your 0-60.

I'm still having that stutter off the line, which is pretty reduced, and a little stuttering on the highway when the T/C is doing something, but it's an improvement.

Does ANYONE have a shop where I can get some dyno runs in? I'd really like to compare stock setup vs jbrady's airbox mod, vs K&N.

This may only pertain to LS400's so please anyone don't take this as an anti K&N thing..

VicFerrari

here is my air box mod that i made from the stock air box after installing it back in, driving around far a long time the filter was cooler than without it, because it uses the original place lexus designed for air to come in

JBrady

Well, this information makes sense. Air flow to the MAF must be straight and free of turbulence. A MAF adapter and K&N can easily disturb that flow both reducing flow and confusing the ECU.

The factory air filter housing creates a smooth flow transition from the filter to the MAF. I would advise keeping that part. A drop in high-flow replacement filter could be worth a tiny amount of power but the main goal is to provide the air filter area with a larger supply of cold air. Think about a room with 2 doors on either end. One opens in, the other out. Crack the door opening in but leave almost shut. Rapidly open the other door and the 1st door is pulled open also. This is pressure drop and is what happens inside the filter housing when suddenly opening the throttle. Engines use air pressure to fill the cylinders and any drop in pressure reduces power. In fact this is exactly what a throttle does... it reduces the air pressure available and thereby controls engine speed vs. load.

VicFerrari, your mod is better than nothing as it uses a modified stock airbox as a heatshield but I would suggest there is more air flow through the stock air filter housing than a MAF adapter. You have opened the front up nicely. Try to get another stock filter and box to MAF and try it that way. I think you will like both the sound and have the max power available to your engine without a complete re-engineer of the system.

BTW, I haven't dyno'd my car but I did make multiple drag strip passes both with my modified box and a stock box. This is a real world dyno. Higher MPH = more HP. I calculated 5rwhp gain, 7bhp gain. Power difference on 1st gens is un-tested. JTJerry did his and likes the results. I would have opened the box up more to create maximum flow and guard against any turbulence. Still, he reports good things on his. Here are the links for 1st gens:

https://www.clublexus.com/forums/sho...threadid=56619
https://www.clublexus.com/forums/sho...threadid=55911

Here are the links for 2nd and 3rd gens:

https://www.clublexus.com/forums/sho...threadid=55111
https://www.clublexus.com/forums/sho...threadid=55640

Lvangundy

After a couple days ..

( 2nd gear is great! ) ;-) ;-)

Still getting the engine stutter. Can someone else here with a first gen try leaving the car in "L" (1st) gear and drive to about 20MPH and keep the pedal absolutely steady. The RPM's should keep still on the mark. What my car does at that point is lightly jerk and stutter, feels like if it continued the car would eventually stall. The jerking motion never gets any worse, it goes away eventually after the car speeds up a little. The RPM's move up and down in little bursts during the stutter.

Can anyone else try this and see what happens?

GA400

Lvangundy,

I will give this a try on my way home from work tonight with my 91 stock LS and see what happens.

GA400

JBrady

Taking an educated guess... It may be the speed of lockup for the torque converter. The lockup clutch may be worn/acting up and causing a more noticeable surge/jerk than otherwise.

Lvangundy

That was my guess from long ago also. I think the TC is worn, which explains why I can't peel out off the line, and why a 92 SC with 25K more miles than mine is so much more of a rocket...

when we race.... and i lose....

;-)

GA400

Lvangundy,

I tried it a couple of times on the way home. Kept car in low, accelerated to 20 mph and held it there. No shudder or vibration, just smooth acceleration and steady response. My LS has 206,000 miles on the stock tranny, t/c, and differential. I did change all the fluids out recently, but i was not having problems before, I just did it proactively.

Regards,

GA400

Leeladisky

So - is anyone running a K&N in an LS430??? I have been and have also noticed strange shifting behavior... In other words, the card just wants to get into 5th as fast as it can and there is a delay in downshifting....

Thoughts?

L

wolver1ne

Didn't your K&N filter come w/cleaner/recharge kit?

LS007

I have K&N in and don't notice any strange shifting. Only slightly quicker response from the engine when pushing the pedal down fast.

SCV8

Lvangundy,try popping the mixture adjustment screw cover out and moving the screw a screwdriver blade thickness in the clockwise direction.The cars are very sensitive to this adjustment,where most cars are to say,a quarter turn.
It may be that you've improved the efficiency of the intake to the point where the low speed needs an adjustment to compensate.
I did this on the old SC,and passed smog w/0000s,runs better too.
Just scratch a mark where you started,for reference.

Lvangundy

I'll try this right now ;-)

Wait I can't, all my seats are getting recushioned! ack