...when the autometer air/fuel gauge says rich? I know those gauges are crap, but during slight or even full throttle, all the green lights say rich. Is there any possibility that I'm running on the lean side? In other words, is the gauge "lying" to me?

 

"lean" is a relative term. While you may be on the rich side of stoic, you can still be relatively "lean" in that you aren't rich enough. Rotaries like to run rich, like 11:1 to 12:1 for maximum safety. 12:1 is still way into the Rich area on an A/F ratio meter, but it is at the lean end of the scale for safely running a rotary under boost. And you are right, those A/F meters that use the stock sensor are not very accurate in the first place, and could be way off.

-Max

 

Maxcooper is right. My friend in his turbo II had Autometer guages in his car. When he overboosted a little and cracked or warped one of his Apex seals, I believe his A/F guage never read lean. The guage ran off of the stock sensor, and probably could not react fast enough to a spike of boost from 13 to 16 psi. I would invest in a PowerFC, and head to a tuning shop and have them (or yourself) tune your car with a wideband O2 sensor. Then you will know what ratios your car is running at all times. I plan on doing this as soon as I get enough money to buy a Power FC. A higher quality guage or controller such as the A'PEXi S-AFC would be a great replacement for that Autometer guage, and would allow adjustimg your ratios, but the PowerFC has MANY more capabilities and costs barely more than twice as much as the S-AFC.

 

thanks for the replies guys. anyone else have opinions?

 

^

 

I would never trust those cheap Autometer A/F gauges, if you want a good A/F gauge you have to get one that comes with it's own wideband O2 sensor.. I think Greddy makes one. There are two problems, the first of which is that it runs on the stock O2 sensor, which usually sends out a reading between 0-1V if I am not mistaken.. it just simply does not have the 'density' in terms of reading that a wide band does. The second problem is with the gauge, I mean.. if I am three green lights into the rich what the hell does that mean? 11:1? 12:1? And most of the time 1/3 of the lights are lit, each one progressively dimmer out from the center most LED that is lit up.. talk about vague. They work ok on other conventional (piston) motors because they can operate as an 'oh sh*t' gauge because they can handle light detonation, if you see red even for a split second you can let off and be safe most of the time. Not the case with a rotary. I would bank on an EGT before an A/F gauge anyday.

Matt
93 touring

 

aren't wideband 02 sensors like a couple grand??!!

 

Yeah, they're insane.. the Greddy was around $400 or so if I remember correctly, but they didn't last nearly as long. Wide band sensors have a lifetime measured in hours.

Matt

 

I have a Tri-point one and believe that it works well. If you're not boosting over 12 with a regular ecu you're fine.
If you are boosting between 12 to 14.5. Then you better have at least a upgraded ecu.

Heed all warnings if your air-fuel runs normal or lean at WOT. I blew a engine from not taking the warnings. It will tell you also if your 02 is starting to die. The O2 died and the ECU did not know what fuel the engine needed. This is what caused my blown engine.

As long as you are at full rich at WOT and not boosting over the amounts above with the proper ECU. You should be fine.

Make sure you run with good GAS 92 or higher and maybe even some
NOS Octane boost.

my regards... jc.

 

Thanks for the reply. The reason I'm asking is because I"m thinking of putting on a hi-flow cat. Right now all I have is an HKS DP and everything else stock.

 

now, would mixing race gas with 91 octane (thats all we have in CA) help prevent detonation? Or would it just be bad for the motor?

 

I've been running a Bonez Hiflow cat, Trust Catback, RB intake duct, K&N filter, boost control pill to 10.5 psi, stock ECU, and original O2 sensor for 5 years with absolutely no problems (93,000 miles original motor and turbos). I run Sunoco 94 octane regularly, and Elf 114 or Sunoco 104 unleaded at the track for safety's sake.

BTW, I have no A/F gauge or water temp gauge, but I do have an Autometer boost gauge!

You'll be cool. The stock ECU can handle it. If you intend to go with a larger IC, and better intake, THEN, you'll need an ECU upgrade FOR SURE!

 

Thanks for the info. SleepR1...actually your mods sounded like the mods I used to have before I started returning it back to mostly stock. So is it safe to mix 101 with 91 to get a higher octane? And will this help with my situation?