Project V8 RX-7: Goin' Legit

(Project RX-7 vs. the State of California) 

by Jeff Naeyaert

Now that it doesn't look like the world is gonna end we need to get our RX-7 smog legal and on the road!  Since the car has been down for surgery with the heart transplant the registration has long since expired. It's only a matter of time before we get busted by the fuzz for old tags and excessive hooning around.  A trip to the DMV and a smile got us a one day pass from the lady behind the counter with the date of issuance left blank so that if it took us more than a day to get our smoggin’ done we wouldn’t have to go back and wait in line again!

We did however have a couple check engine lights to clear before we could visit the referee.  The first diagnostic trouble code (DTC) was P1336 "Crankshaft Position System Variation Not Learned" which we expected actually.  This code got triggered when we exchanged our ECM calibrated for automatic transmission applications to one for a manual transmission (the only difference being the number of teeth on the reluctor wheel).  Apparently every ECM is calibrated to every engine at the factory and the computer cannot "self-relearn" this crankshaft position--you've got to take it to the dealer to have it relearned or find someone with a GM Tech II diagnostic tool.  We don't know anyone with a Tech II so it was off to Win Chevrolet in nearby Carson, California.

We dropped the car off with Win Chevrolet's service department and were able to escape 3 hours later for only $60 for the crankshaft relearn procedure.  All the other local stealers quoted us more than twice that amount for the service so we felt like we got a deal.  Bet it's not every day those GM techs get to work on a China car!

The second DTC, P0174 System Too Lean (Bank 2), came on while we were driving down the freeway.  Mildly alarmed we might be damaging our brand new engine we looked up possible causes.  The most frequent is a dirty MAF sensor, but our MAF is brand new so that's probably not it.  We were however worried we might have MAF turbulence from our air filter that was right smack in the middle of the opening in the bumper.

Got MAF turbulence?  We thought we might with our placement of the K&N filter in the air stream and the MAF sensor only 3" away from the filter. 

Digging a little deeper we found that some LS applications had airflow straighteners ahead of the MAF sensor from the factory to prevent MAF sensor turbulence and reduce ECM fuel trims.  Several companies sell honeycomb straighteners but we found the cheapest at saxonpc.com.  $10 for the size we needed and they even offer to trim them to fit for free!  

We ordered a 100mm honeycomb and asked for it to be custom cut to about 96.5mm to fit snug inside our 6" intake tube.  A week later it arrived but sadly it hadn't been trimmed.  


Not too worried we just flattened some of the holes around the edge till it fit into our tube just in front of the mounting boss for the MAF sensor.

We reinstalled our intake, cleared the DTC and have not seen the trouble code since!  We're finally ready to make our smog referee appointment!  

As one of our astute readers pointed out in the comments of our last article "Why do you need to go to a CARB Ref?  We thought the kit came with an EO sticker?" We thought the same thing, but just to be sure we called the CARB to see if the sticker was sufficient. Unfortunately, the nice lady on the other end of the line informed us that ALL engine changes have to be approved by a referee—EO sticker or not. BOO! It’s not the end of the world for us because we’re not trying to skirt the rules here anyway, it just would have been a lot more convenient if we could have hit up the smog shop down the street. Plan to schedule your appointment at a referee station in Los Angeles at least a week out from when you call because there aren’t that many of them and apparently they have a lot to do! Unfortunately our excitement to get the car legalized was gonna have to be put on hold…

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Monday, January 07, 2013 12:31 AM
About time! Thanks for the updates
Monday, January 07, 2013 5:54 AM
What a headache. But I guess all this bureaucratic nonsense must mean that California has zero smog right? You must have such clean air... ha.

Cool to see you actually weigh the swap, did you weigh it before as well?
Monday, January 07, 2013 6:06 AM
FYI EFILive can do crank relearns too, I don't even think you need a license to do it. I guess since this is one of very few GM vehicles in the MIQ stable that nobody had EFILive kicking around.
Dusty Duster
Dusty Dusterlink
Monday, January 07, 2013 8:47 AM
Yeah, because having a bend in your intake is clearly going to affect emissions.

Screw California's government.
Monday, January 07, 2013 9:06 AM
Dusty Duster, having a bend in your intake can significantly affect the perceived mass air flow. this legitimately can affect emissions.

in fact, that's why they had the issue with needing the flow straightener mentioned on page one of this article.
Jeff Naeyaert
Jeff Naeyaertlink
Monday, January 07, 2013 9:37 AM
@bc: no we didn't weigh the car before.. the car hasn't had a rotary in it since 2005 :)

@supercharged: yeah, at the time we didn't have a handheld.. but we do now :) (more to come on that)

@Dusty & Marc: It is true a bend or that squash in the K&N intake would effect the metering if the sensor were placed there... that's why they specify it being in the middle of a straight 4" diameter tube 6" long. But how it is now is fine.
Monday, January 07, 2013 10:47 AM
The idea that any of this CA smog insanity has a significant effect on pollution went out the window when the catalitic converter became a mandatory peice of equipment. OBD 0, 1, and 2 help but in very small quantities compared to the cat. These days, manufacturers are being extremely efficient on their own because higher efficiency means better gas milage, reliability and hp.

To argue that a bend in the intake tube has a major effect on emissions is like claiming that spitting in a public pool will significantly alter its chemical balance.

Besides, by the numbers it obviously passed.
Jeff Naeyaert
Jeff Naeyaertlink
Monday, January 07, 2013 11:23 AM
Actually we looked at the short term fuel trims after that DTC for the lean condition came on (presumably from MAF turbulence) and it was maxing out at like 25%. So technically it could effect it to some degree although the computer probably corrected a good part of that. Not a specious argument on the government's part but keep in mind that intake IS a CARB legal intake for another LS3 application--that's why I thought it was lame.
Monday, January 07, 2013 12:38 PM
Sweet! So all said and done, the Ref gave you no sticker and the EO sticker was all that's needed for a smog at a station.

Questions: Since there's no sticker from the ref and the "ALL swaps need to go to a ref" statement...any wondering of how a officer of the law will see it? I mean if you get pulled over, EO sticker/number on hand....and you're still directed to a ref who won't look at the car because of the EO sticker/number, then what?
Monday, January 07, 2013 1:12 PM
Proto, a car can pull down better fuel economy at 16.XX:1 than 14.7, 14.7 is purely for emissions. I will say that as OEMs continue to use more advanced engine management, the engine consistently runs more and more cleanly under all conditions. The insides of most new tailpipes seem to stay clean instead of turning black, very impressive IMO.

Jeff FWIW in the C5 Corvette world, the C5 Z06 was the only car to get a screenless MAF. As luck would have it, some aftermarket CAI kits will set a CEL as the incoming air becomes more turbulent. Happened to me before I got the lid installed. Not an issue with stock airboxes, and some say the only reason the Vette even got a screen in the first place is because they used a truck MAF and the trucks have a big 90 degree bend in the intake tract. Halltech sells an add on MAF screen that bolts into the GM MAF housing, but wouldn't do much good in a straight pipe like this. Now that you're legit, do you have plans to stick a regular MAF in there? How snug is that screen? Seems like friction is all that holds it in with no ridges or anything along the way.
Jeff Naeyaert
Jeff Naeyaertlink
Monday, January 07, 2013 1:58 PM
That screen is pretty tight in there--I only clearanced it enough to squeeze in there and the pressure of the sprung honeycombs holds it in there good. It's not going anywhere if that's what you were worried about.

What do you mean by "regular" MAF? If I do anything I'll probably ditch it altogether and just run the speed density. Then I'll have more flexibility on the intake setup and tuning.

@M: If that situation does happen and the cop isn't satisfied with the EO sticker for whatever reason it would just be a matter of showing the ref the ticket and the sticker i suppose. I'd probably get grief about the intake again.. But in THAT case I'd probably just do what the ref wants to see--a tube straight off the intake like the picture and I'd roll in without the hood on. That's what i had to do to get my certification with the LS1 years ago with an enormous stock camaro intake box. You don't need a hood to pass smog!
Monday, January 07, 2013 3:30 PM
I figured you'd get less roadside grief with a regular old LS style MAF in there instead of the tube that screams aftermarket to the uninitiated. MAF-less FTW though, on my truck and Vette it's as simple as unplugging the MAF and flashing it so it doesn't throw a MAF related CEL. I'm kind of surprised they didn't just include a regular old MAF anyway, unless the intent of the tube is that it forces every knuckle dragger who thinks they can pull off a legit motor swap to have a 6" straight section.
Jeff Naeyaert
Jeff Naeyaertlink
Monday, January 07, 2013 3:53 PM
Well everyone's application is different and the MAF is the same as is in the current applications--where it just screws into a boss.. so I don't have a problem with it. I've only had one cop on a bike pull up next to me once at a light and say "that's not the motor that came in that thing!!" I said, "it's all legal though" which he countered with "I don't care!" smiled and road off! Cops like V8's!
Monday, January 07, 2013 5:53 PM
Yea, when ricing was at its peak in Palmdale every fart can civic on the road was being pulled over whether it was legal or not, yet a few open pipe harleys or mustangs can roar by and hardly even garner a look.

This is still so awesome though. If that E-Rod would come down in price in the future (I cant imagine markup cost that CARB legality added to the engine) or if the EO sticker is transferable the "350" might be the mother of all engine swaps forever to come.

Buying an e36, rx-7, supra, 240, or 510 with a blown motor now seems all the more feasible...
Mike Kojima
Mike Kojimalink
Monday, January 07, 2013 6:59 PM
The latest smog law for new STAR smog. Any car with a profile for failing, like I suppose any performance car gets sent to a super stringent STAR station for a though inspection and smog check.

The criteria for being selected for STAR is:
Your car has previously failed
Your car is a model which has a history of failing, like I am sure every performance car does
Your car falls into a certain percentage that is randomly selected

I am not sure why another layer is needed, Test Only stations were supposed to fill the role of this. I think STAR stations are allowed to do repairs on smog systems while test only stations cannot.
Scott Helmer
Scott Helmerlink
Tuesday, January 08, 2013 4:02 AM
I'm so very, very glad I live in a smog-less emissions state (at least I've never heard of any need of a CARB sticker or anything like that. Just an OBDII port, or a tailpipe test if the car wasn't originally supplied with one. Hell, if the car's 25 years old or older, or lives in certain counties, no emissions at all! That, and the ability to drive in, on, around, and through just about every terrain and elevation you can throw at a motorized vehicle (among a few other cool reasons I suppose) is why I enjoy living in Washington State. Makes my 2.5RS coupe that much more fun!

Now if only I had money to start buying, prepping, installing, and fabricating parts (where I can/need to, obviously), so it wasn't dead stock aside from the STI carbon fiber front strut tower bar I bought and the "custom exhaust" the kid I bought it from supposedly had made at an exhaust shop for it... I'd kill for an apprenticeship at a tuning shop or something XD
Tuesday, January 08, 2013 6:21 AM
From wiki: FD RX7 curb weight 2830 lbs. Not sure what level trim it is (MT or AT), but goes to show you it is around the same weight. Not sure what kind of interior changes you guys had though, if any.
Jeff Naeyaert
Jeff Naeyaertlink
Tuesday, January 08, 2013 9:04 AM
stock interior all there in R1 trim.. battery relocated behind passenger seat.
Tuesday, January 08, 2013 9:08 AM
Rotaries are cool, but this is definitely the right motor in the right car. CA should pay you for making the car cleaner than it was stock. I'd really like to run into one of these at the track, but no such luck yet.
Tuesday, January 08, 2013 9:22 AM
@ Proto: All 510s and 240Z/260Zs are exempt from CARB shenanigans anyway, as you only need to smog 1976 and newer vehicles.

This does open the door for the later S30 chassis vehicles (280Z, not the 280ZX abomination) though, as well as the 3 non-destroyed stock S13/S14 chassis cars left in CA...

For me, I think an E30 or E36 with E-ROD would be cool.
Jeff Naeyaert
Jeff Naeyaertlink
Tuesday, January 08, 2013 10:26 AM
Samberg makes a kit for the E36 too! SAMBERG E36 LS SUBFRAME KIT
Sunday, January 13, 2013 11:17 AM
Awesome tread,I'm probably go the same direction on my RX7. Do you have a tread about the preparing of the RX7 for the V8? I would have some info about moving it as far to the back as possible.
Thx again.
Jeff Naeyaert
Jeff Naeyaertlink
Sunday, January 13, 2013 1:52 PM
I don't have a thread on that... but the mount kit positions everything for you--there isn't any adjustment in it or anything. the only prep I did to the chassis was ripping everything out of the engine bay and painting it that grey color.
Sunday, January 13, 2013 3:59 PM
I see, I thought you moved the engine so far back you had to rebuild the firewall like this guy.


My plan was to have it as far back and down as possible. I would have to go for a dry sump as well.

Jeff Naeyaert
Jeff Naeyaertlink
Sunday, January 13, 2013 4:07 PM
oh wow, no! I don't know why you'd want to do that unless you were going to put a big turbo up front or something and needed more room.. as you can see the weight distribution is fine with the kit as it is and it's super simple. My first smog legal LS swap was done in exactly 3 months with only hand tools in my home garage.
Sunday, January 13, 2013 4:18 PM
I have spoken to the gov who will be legalize it and they claimed the weight distribution would be wrong, and i can't go for more hp then the 315hp LS1. So some bad bits for a car build as ours here in Sweden.
Did you weight the car before and after at each wheel or do you know where to find such data? Maybe i can use it against them...
Sunday, January 13, 2013 4:22 PM
After reading this post i don't know what my gov talking about. Maybe they thought I would be using a iron block?!

Thx for the help man. This will help me alot!
Sunday, January 13, 2013 4:23 PM
Jeff Naeyaert
Jeff Naeyaertlink
Sunday, January 13, 2013 4:36 PM
Interesting.. so you have a horsepower limit for a car to be "street legal" in sweden? Don't worry, the LS1 is still no slouch, and those engine were underrated anyway--you'll probably make almost that power you mentioned to the wheels. The older LT1's were iron blocks, maybe that's what they're thinking.
Sunday, January 13, 2013 4:50 PM
In short terms we have two options if we want a legal engine swap. Either build a car with almost no limits but then you need to change the whole base construction like Koenigsegg ;) Or my option, 20%hp increase from stock with a original engine from whatever you want but still a safe and at least as good as the car would be stock.

So the only thing with the LS1 is that it have to look like a stock LS1. I wonder if I can go for a LS2 and make it look like a LS1, they don't do a dyno run.
Jeff Naeyaert
Jeff Naeyaertlink
Sunday, January 13, 2013 5:03 PM
you could probably do a LS7 and they wouldn't know it wasn't an LS1! A cam, exhaust and tune will go a long way to start.
Friday, May 10, 2013 10:10 PM
I've just joined MotoIQ, because I am so impressed with your FD3 project. After three blown engines I am seriously considering this mod. But I am curious to know how much MotoIQ ended up spending on the whole project.
Tuesday, April 29, 2014 12:16 PM
Jeff, as 2002TruBlu asked, "I am curious to know how much MotoIQ ended up spending on the whole project." Thanks,
Jeff Naeyaert
Jeff Naeyaertlink
Tuesday, April 29, 2014 12:39 PM
hmmm, if you to itemize everything brand new i would guess somewhere between $15-18k.
Tuesday, July 08, 2014 9:09 AM
Jeff - Awesome build, man! I've been looking into getting one for quite some time now. Went through a number of cars throughout the years, but my heart always had a soft spot for an FD. I'm relatively new to SoCal (orig. from Bay Area) and don't know any shops or have connections down here. It would be great if I can get in contact with you for some help on a similar build. It'll be my DD. Pls msg me at mntran85@gmail.com or drop me your contact info. Thanks!
Monday, August 04, 2014 7:49 PM
Very exciting build. I have a 93 RX7 and an very interested in the LS 3 swap-build. Need help as I am an amateur enthusiast.
Monday, August 04, 2014 8:13 PM
Jeff, could you send me in the right direction as I don't know anyone who could assist me in doing a smog legal build like yours. I live in SoCal I'd love to come by your shop/show room . Any advise would be greatly appreciated!
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