TOPIC: Grooved a 2001 Nissan Altima

Any thoughts guys?
I just grooved a 2001 Nissan Altima GXE, auto, 2.4L.
I got an 11.5% increase in mpg, from 28.51 up to 31.80.
Here's what I did, I grooved only half of the TB on the manifold butterfly side, I rounded the butterfly a little on the air intake side (not the engine manifold side), I regapped the plugs from .043" to .049" which is a 14% increase, I also set the timing up 3 degrees more.
I forgot to do the ECU recalibration procedure but I did disconnect the battery for a little over 5 mins.

Any ideas of how I can get more mpg out of her??

Thanks,
Ron

Hi Ron,

You may want to see how they routed the PCV connection for that engine.

If it goes to the manifold side you will want to move it to the intake side and cap the manifold connection. Doing that you should see a difference.

The manifold vacuum is an important part ofthe groove. 18-20 inches are some numbers that I have seen.

You might want to check some of the other posts, I believe that Ron (Hatton) had mentioned doing that but on the manifold side of the plate after the groove was done.
(Something to check, the change there might be minimal)

Changing the timing is something that all vehicles with ecu's have an option on so your experience with that will have its own story.

At some point when everything has settled down and you have more numbers you might want to change the timing back just to confirm that it had an effect positive or otherwise.

Welcome to the team

Karl Fortner
Tacoma, Wa.

Hi Ron this it Tracy in Reno NV. I'm a newbie too. Did you re-direct the PCV hose that goes from the PCV Valve to manifold vacuum? That is important to do. Others on here have spoken at length of this. Find your PCV Valve. Trace the hose from the PCV to where it connects to manifold or "active" vacuum-this will be somewhere downstrean between the throttle plate and the intake valves. Pull the hose off of the nipple, and cap this nipple/port off .Now this end of the hose you took off needs to be directed into the air intake system Upstream Before the throttle plate. Many folks here say it's easiest to just find the other PCV hose (sometimes called the Breather hose) and just tee the first hose from the PCV into this second one. This lets the engine breathe and keeps blowby gases still directed into the engine to be burned. Reason for this is to improve manifold vacuum levels. You probably already understand, the Groove works by greatly accenting manifold vacuum during intake stroke of piston, higher vac. increases fuel vaporization a LOT! From this standpoint the PCV system in stock form is a huge vacuum leak. Ron Hatton says to rigorously inspect and test w/ a hand vacuum pump (Mityvac) any vacuum hose connected to the intake manifold to verify the hose itself or whatever its hooked to does not leak vacuum. Also Ron also says its usually best to Retard timing, the fuel is burning more completely and faster- so you might try going opposite way on timing. Sorry such a long answer, just tried to describe what I've learned. Let us know how it goes w/ your Altima! TracyG

Another thought as well, was reminded by another post.

If your throttlebody has an IAC or Idle Air Control valve, check the in and out flow of that IAC as well as the size of the opening.

Either way, the opening to the manifold size sure be about 1/8", If the opening is on the groove side of the throttleplate shaft, you will want to reroute it so that it is opening at or above (preferably) the shaft.

Pic's would help

Karl Fortner
Tacoma, Wa.