Hi guys,

 

I just down to my local Autobacs (in Japan) to buy an Apex'i Power Intake Filter. The guy I spoke to looked it up in the catalogue and said that it was strongly recommended that it be installed with the Apex'i Air/Fuel computer S-AFC-II. I had a look at the catalogue myself and he was indeed right.

 

I asked him about it but he didn't know much so I got him to call Apex'i and ask. They said that without the fuel computer you risk having rough idle and running slightly too lean risking engine damage. Something to do with the "dual funnel" design of this filter resulting in too smooth airflow for the air meter to measure accurately. Not sure though, my Japanese was failing me at this point. But I did understand that it would only be very slightly lean, not enough to cause noticable detonation, but enough to potentially cause engine damage over a longer period of time.

 

He then tried to sell me a HKS filter which apparently comes with no such recommendation / warning. I really want the Apex'i though since it's best for both flow rate and quality of filtration.

 

I know that many people have this Apex'i filter installed and I believe they do so without having the fuel computer in. Also, I kind of find it hard to believe that if this is really a problem then it will only affect the Apex'i filters.

 

I really don't want to cause any engine damage just for the sake of a few extra horsepower and I don't really want to have to pay for an Fuel / Air computer just yet since my car isn't yet modified anywhere near enough to really justify it (all I have is a cat-back exhaust).

 

Does anyone have any knowledge of this? What do the people say who are using this filter? Anyone caused any damage this way? I'm really looking for people who have fitted A/F meters and can comment on the effect this mod really has becauseI don't think it would necessarily be noticable without accurate guages.

 

I'll be back in the UK in about a month now but would like to have this fitted here before leaving because it only costs 30 quid here. Of course, that's not including the S-AFC-II !!!

 

As always, thanks for your help. :bow:

I have 2 Apexi filters on mine and have no problems. I've also been to Thor since to get it mapped etc (yes I have an AFC too) as I was rich most of the time as aftermarket ECU's tend to overfuel for safety anyway.

One of the reasons I started this thread is that in the back of my mind I remembered seeing a webpage of a performance tuner who had recently 'done' a 300ZX. I remember them finding this running lean problem after installing the A'pexi.

 

I thought I'd lost the link to the page but I've just found it again. If you're sceptical please have a look:

 

http://www.importtuner.com/tech/0403it_300zx/

 

 

Also, whilst trying to find it again I also stumbled across this link that does a very good test of quality of filtration and power increase for the following filters:

 

A'pexi

HKS

Blitz

K&N

 

It's very interesting!

 

Anyway, thank you everyone for your help and advice with this post.

Hi. Sorry for the delay getting back. As always, Im very happy to answer any questions about Japan, just please start a new thread otherwise everything gets too confusing for everyone involved.

 

Cheers!

 

Rory

I bought the filter this morning and had a look at the instruction manual. I scanned the page that gives details of the recommended settings for the AFC. Here's the link:

 

http://www.streetneeds.com/uploads/misc/Apexi6-AFCPage.gif

 

At 4000 rpm, full throttle it requires a 14 percent fuelling increase :eek: That's more than just slightly lean without it.

 

 

 

 

Here's the complete manual if anyone's interested:

 

Apexi1-Frontpage.gif

Apexi2-Parts.gif

Apexi3-Airboxremoval.gif

Apexi4-Install.gif

Apexi5-replacementfilters.gif

Apexi6-AFCPage.gif

Apexi7-Contactdetails.gif

Hi Rory!

 

Initially I thought this thread was put up as a "scare" story but having followed it's progress for a while I'm glad to see it has true technical merrit.

 

I am a reseller of A'PEXi products in the UK and the induction kits are by far the most popular and best selling item. As you have indicated, by posting the link to the comparison tests, the A'PEXi filters come out on top in every aspect from filtration quality to flow-through rate. Simply put, you can't find a better performing aftermarket filter than the A'PEXi's.

 

The recommendation for the addition of an Air/Fuel Controller is really only applicable to those vehicles who are running higher boost and aftermarket ECU chips in pursuit of big BHP gains. It is always a good recommendation to have an air/fuel controller when tuning a car and our resident tuners - THOR Racing - will certainly concur. When an aftermarket filter is installed the ECU must be reset and the "self-learn" values cleared to allow it to adjust to the new amount of air that is available throughout the rev range. Even the standard Nissan chip has maps build in to compensate for increased airflow, etc. Once the new values have been "learned" the ECU will be able to cope with most situations thus minimising the risk of letting the engine run too lean or rich thereby causing internal damage.

 

So, in daily use there is an insignificant risk of causing engine problems if you add a filter without also installing an air/fuel controller. This risk obviously increases as you make further performance changes.

 

As you have said, the recommendation by A'PEXi to add an AFC is only on the Japanese site which leads me to believe that in their other markets A'PEXi realises that the risk is too insignificant to mention.

 

As a general note to everyone who has an A'PEXi filter fitted or is looking to fit one I have the following to say. I have sold well over a hundred A'PEXi airfilter over the past two years and not once has an engine problem been the result of these filters. I fully recommend these airfilters and in my opinion there is no risk whatsoever if fitted properly. Of course there are certain rules which need to be followed when you're tuning your car for big BHP but the addition of this airfilter is, in my opinion, completely safe.

 

Rory - thanks for bringing this subject matter to our collective attention.

 

If anyone has any further questions regarding A'PEXi products or want to order an airfilter (currently only 2 left in stock) then please (1) post them in the DTA-Motorsport section of the Traders Forum or (2) give me a call on 07044016586.

 

Regards,

Hi.

 

Thanks for your input.

 

I fitted the filter to my car last night and can report back that the installation is easy and the supplied support brackets hold everything firmly in place.

 

I disconnected the battery during installation to reset the ECU. After re-starting the car instantly settled to a normal, smooth idle, so I have no concerns there.

 

As for the running lean, I'm still not convinced that there is really no issue. But, I'd now agree with you that the risk is relatively low and one that is acceptable for most people with everyday usage patterns.

 

If anyone ever gets the chance to experiment a bit on a rolling road, maybe with different makes of filter, and with positioning tape on the cone to adjust how the air flows over the MAF then I'd be very interested to see the results.

 

It'd also be interesting to see how the A/F ratio changes once the ECU has been given a week or two to fine tune itself. I appreciate the fact that in the link I posted the car's tuners fitted the filter and then took the A/F readings without giving the car any time to find its feet (wheels).

 

Anway, enough, this thread's gone on long enough so I'll shut up now. :x:

 

Thanks a lot to everyone who's contributed or followed.