Hey,

Here's my story... Please read it all before responding. Car is an 1990 S5 TII, lots of mods (see my signature for a list). Keep in mind that this is all taking place in Denver, 6000ft up, which is a pretty substantial difference as far as air goes.

A couple weeks back I went to the dyno with 4x 720cc injectors. All I have is an AFCII for any kind of fuel electronics. Anyway, so I dynoed it.. Made 300whp @ 9psi, but maxed my injectors out. Projected horespower at sea level was at ~370whp. At about 6000rpm it got really lean really fast, and putting it to +50% on the AFC did nothing (wouldn't get any richer).

So I pulled out 2 of the 720cc's (on sale now) and bought some 1600cc secondaries to get plenty of fuel, and dropped those in.

Back to today. I took it back to the dyno earlier and hooked it back up. Obviously the 1600's needed to be tuned. So we messed with it for about an hour and got it really smooth, a pretty damn straight line just around 11.8 all the way across the powerband.

Once we got the A/F curve flattened out, we decided we'd raise the boost (still at 9psi at this point, still at 300whp). I turned up the Profec B II to 30%, which is ~12psi. Once I did this we did another pull, and it basically fell on its face right around 6500rpm-- it got super super rich. So we figured what the heck? Lean it out some more. After a few more pulls we had it all the way down to -50% on the AFC and still, at 12psi, it gets super rich up top and will not accelerate further.

We then came to the conclusion the stock AFM had been maxed out, and would not allow further air to be drawn into the 60-1 compressor on my new turbo.

So.... I was wondering. Are there any AFM's that the FC will accept that allow more air flow? We looked at the Supra's (3'' inlet, compared to the 2.15 or w/e the FC's is) and wondered if that might work... I've heard that the FC will simply not take any other AFM's, but havnt really seen any definative answers or responses from people who have actually tried (yes, I searched).

Any help would be greatly appreciated. I'm pretty strapped for cash and really can't afford a standalone right now, so please dont tell me that's the only option unless you really know from personal experiance that it really is.

 

You can't slap on a hot-wire AFM from a later car, it just won't work. You need an interceptor to completely modify the signal so the stock ECU can use it, and although these supposedly exist I've yet to see a single FC owner do this successfully. You need to find a bigger flap or sliding-cone AFM, and the only one I know of is the sliding-cone AFM used on the JC Cosmo. Good luck getting hold of one...

I know you don't want to hear it, but you've reached a point were you really need to spend more money to proceed safely. If you can't afford a standalone than you probably also can't afford a rebuild. So why keep pushing it if you can't guarantee the engine's safety? Would you rather have a working 300rwhp engine or a dead one capable of 350?

BTW, when you "maxed out" those for 720's at 300rwhp, were you measuring duty cycle? They should be capable of far more than that.

 

At Corksport.com they sell the MAP ECU (third item from the bottom). I don't know anything about it, but it seems like a better method than the SAFC.

 

Jus wondering how you know that? Is that teh dyno correction factor or you got some math for that?

 

I was looking through your mods and see that you have a V mount set up. One way that i've heard of to make more power with the stock afm is to mount it in a "blow through" style in the intercooler piping. The turbo would have already compressed the air making it so that more air will go through the afm than if it was hooked up in the stock style. I've been very curious about trying this method but have picked up a megasquirt instead. You should consider megasquirt, cheap standalone.

 

That does not make any more power.

 

Mainly the dyno correction factor (you lose approximatly 16-18% HP just with the altitude).

I dont believe so, but everyone there agreed they were maxed out (3 very experianced A/F tuners).

Yeah, thats the point where i'm at now. My engine, with the 1600cc's, runs very smoothly and has the perfect amount of fuel all the way across the power band. Right now the only safe way to take it up to any higher HP (at this altitude) will have to be E6X. I'm the kind of guy who goes all or nothing.

Thanks for the advice to anyone who contributed. I'll be getting a Haltech, but won't be for a while.

-Andrew

 

the mx6/626 v6 from 93-02 have a larger afm, its cosmo sized, prolly not much of a hp gain

 

Thanks, I might look into that.

 

I want your car.

 

Thank you.

 

If you don't wanna go standalone I was gonna suggest the MAPECU we sell.

Ditch the AFM altogether.

 

Who is 'we' and how much does it cost? Is it difficult to install/program?

Thanks.

 

He is from Corksport... It is $649. The install seem easy 5 wires to hook up.

 

As Dom_C mentioned above, have you looked into a Megasquirt n' Spark? It takes a little bit of DIY work, but its a full standalone that only costs ~$250. Pre-made kits can be purchased for around $350, which cuts down on some of the fab work. Sounds like it might be a good solution for you...

 

For under $200 you can get a Megasquirt ECU that will control fuel and ignition. Your mods really are begging for a standalone. The support and user base is really starting to grow on this forum.

Either way you're still stuck with tuning--unless you are going to trust their base map with your engine.

I think you really need to consider a standalone (I hate to say that cause there was a time I also said--don't tell me about standalones).

My 2cts.

Scott

 

It's so hard to convince people how great the MAPECU is without actually showing them. Too bad. Why should you bother rewiring all your stuff and installing a new ECU when you can just plug this into your stock ECU, retain all of the OEM functionality, and get much more tuning capability?

If you decide you want a real, in a box product, and not a megasquirt, let me know and I'll hook you up.

 

I'll definatly keep you in mind, and talk to some of my buddies about it.

I'll let you know. Thanks again.

 

So this megasquirt works with any engine and all you need is the wiring harness for the engine? Basically you wouldn't need the stock ECU at all?

The MAP ECU sounds cool too unless you don't want to keep your stock ECU.

 

Most people use the stock connecters with a new custom made harness.

You usually need to make a new one (For Megasquirt).

 

Actually to just control fuel that's about all you need for Megasquirt: tach,O2, tps, MAT, CLT, primaries, secondaries, power and ground. I'm running MS right now in a piggy back mode and still in the tuning phase--very impressive capabilities--basically full control over fuel. Later on I'll hook up the ignition. I can change fuel cut, change O2 setpoint, run to a mapped AFR or open loop, change secondary transition conditions, cranking pulse w/temp, after start enrichment, accel enrichment, use a WB02, scale for bigger injectors, log anything, you name it--and I haven't even gotten started. Guess I'm trying to say it is definitely worth checking out. But yes you do need to be alot smarter than "out of the box". Building the MS was really not hard, but I could see where wiring up to the ECU might be difficult for some.

The MAPECU is still just a piggyback air fuel controllerand very overpriced for that. I like that you can remove the AFM, but for $650 you're very close to the price of a Microtech (if you want out of the box). Don't get me wrong this could be very good for some people, but his application is really begging for a standalone ECU.

Scott

p.s. I'm real glad you guys at Corksport are supporting the RX-7 community--I love my DP.

 

Does anyone have any experiance with the HKS VPC? I've been reading about it. The whole use for it is to eliminate the stock AFM. It basically puts in a couple tiny sensors and takes the signal and converts it so the stock ECU thinks it still has an AFM. Sounds like its exactly what I need.

I think I might try it out. Not that expensive either (especially compared to standalone).

http://www.hksusa.com/categories/?id=1921

-Andrew

 

Seriously. MEGASQUIRT 'N SPARK!!

Jason+Ken (Tofuball+Muythaibxr on the forum) sell them for like $350 pre-made kits. All you'd have to do is build you're engine harness, OR, you can buy one from Jason and Ken also..

Either way, a complete MSnS and new harness from them, will run you less than anything else you can buy as far as standalones go.

And it is infinitely tunable!! My T2 is getting one, and my GTU is currently awaiting one in my garage too.

 

Don't spend another cent on the stock ECU! Once you have purchased all the piggybacks you need to get fuel and timing control, you could have bought a Haltech/Microtech or several Megasquirts ('n Sparks).

While things like the VPC and MAPECU may give you fuel control, they are STILL limited by the capabilities of the stock ECU. Remember, fuel is not everything. When you start getting into upgraded turbos and the power levels you want, timing is important as well.

Another plus about a full standalone is that you can ditch that 20 year old wiring harness. Lose all those cracked, broken and brittle connectors for nice modern replacements, and end up with a car that is MUCH more reliable over stock.

You're still going to have to tune all those piggybacks, so why not tune a standalone instead? The result wil be much improved over anything run by the stock ECU.

 

i got a MS setup, all wired and uses a modified stock ECU with it...
all you have to do is give me 300 and ill ship it with sensors, and it is a direct plug and play....
megasquirt does fuel, stock ecu does timing.