I have reviewed a few posts/dynos with the a/f running lean. But most if not all NA mods won't make the engine run lean during closed loop operation. There is a chance that heavy na mods might make the engine go lean during OPEN LOOP operation. ie.. WOT where pre-determined a/f ratios are used only. Since dynos are run WOT, people assume na mods will make your car run lean ALL the time.

 

what I've been told is that the sniffer test isn't really correct since u're suppose to measure right before your catback and not at the end since it'll always be a lil bit leaner from the tail pipe.

JEVERYDAY - Running lean mean the Air to Fuel Ration is high, more air and less fuel, will cause detonation in the long run if not corrected. Running Rich is the opposite.

 

Yes they DO. As evidenced by looking at an A/F ratio after installing them and posted by an early tester.

(You need to follow your own advice).

 

It might well have a problem depending on how lean you were to start with. The stock ECU will NOT adjust. It has pre-determined maps (with one specifically for WOT) and it switches between them.

If you have an aftermarket ECU like the E-manage or UTEC or you get a custom reflash then you can fix the A/F ratio.

 

Bad info.

The MREV2 improves airflow to the front two inlets as well as some of the rear through reshaping of aluminum. It will work in a very complementary fashion to the spacer IF you can get more fuel into the mix to keep the A/F ratio on target. Otherwise adding one to the other will not incrementally increase HP but will increase your risk for detonation/knock/pinging etc.

The only reason I would select the spacer is because it's cheaper for similar gains (I think it is at this point at least).

 

This is what you should do if you do not have the capability to tune or don't want to spend the $$$ to get the capability to tune.

Getting both on a non rev up is wasted money otherwise...

 

On authority from an upper level diagnostics engineer at Nissan, the ECU wil adjust to changes that you make to the engine to a point where it thinks are the optimum engine operation settings. That's why is isn't necessary to reset the ECU when installing simple engine mods. Granted, if you go FI, an aftermarket unit is necessary.

Thanks for correcting me. I said I don't know much about the MREV. I have two pre-Rev Up motors and I haven't studied the MREV. I do know that I received a noticable benefit from the spacer.

 

I'm not sure if people understand open loop and closed loop here.

The ecu and the injectors can adjust up to the point where the injectors are firing almost all the time in order to attempt to keep the a/f in an accepable range. ie.. 14:1 crusing, 13-1 part throttle etc. etc. etc.

It's very difficult if not close to impossible to get the injectors to run "static" with normal na mods. Unless the VQ35 injectors are almost at their limit stock. Which I really don't believe.

Now WOT is another ballgame. The ecu uses preset a/f ratios no matter what. Ie.. it ignores the MAF readings and 02 sensor to calc injector pulse. So if you add enough mods, it IS possible to make the engine run lean during WOT. But this is not because you are running the injectors close/over their size capacity. It's because the fuel maps are present for the equipment that came stock. Make mods that throw more air into the engine and it's no longer calibrated for those mods.

I'm wondering if a slight bump in fuel pressure at WOT would fix this vs a reflash or DIY piggy ecu.

 

So unless I do an ECU reflash, it will run lean at WOT no matter what w/ those 2 mods running together on non-REVUP engine? And how can you change the fuel pressure?

EDIT: and running lean ONLY at WOT but not lean anywhere else, is that still bad enough to need fixing?

 

I am afraid that there is more to it (at WOT) then just a preset A/F - see my chart below.

I wonder the same about fuel pressure and hopefully one day (before installing piggy-back ECU and/or FI) might be able to try it.

 

How can we change the fuel pressure? I might consider tryin that out if it's not to expensive/to hard...

 

I didn't mean preset a/f, I meant preset fuel maps that are calibrated to a certain a/f with known mods. (ie.. stock stuff)

But if you know more on this, please elaborate. Thanks for the excellent data log!

Regarding the fuel pressure. I'm not sure how up it in a controlled manner with our returnless. But there is some type of fuel regulator so.......

 

A spacer is going to add air to the combustion... the MREV2 however (from my understanding) only smoothes the airflow... the spacer can (and in my case did) lean out the a/f ratio... the lower collector (MREV2) doesn’t necessarily... the reason I say this is there simply isn’t any/enough data to support the theory that it might.

I thought it could, I asked Tony - as have others, and apparently it won't unless you were already lean. Tony is VERY knowledgeable and if there were a leaning out concern I'm certain he would have made it very clear by now.

I only wish we could see some results from all that keep saying they have the MREV2 and "plan to dyno"....

 

Ok bottom line
Get A SPACER?
or GET A MREV2
for a AT 2004.5 coupe?????????????????????

 

exactly