Molly

Question about my AFRs...

My car is stock and freshly gone through, no vacuum leaks, no boost leaks, etc. The only mod I have is Autothority Stage 2 with banjo.

According to my AEM Uego, I'm seeing good AFRs at WOT, around 10.8-11.5 all the way to redline. It is rich but such is that old chipset. I'm also seeing a solid 15 lbs in 2nd and third at WOT on my Bosch boost gauge and an otherwise perfect boost & vacuum profile and idle and cruising AFRs. So everything seems pretty good. The thing straight up murders in 2nd and 3rd.

However when I get into boost in 2nd and 3rd for normal driving without WOT, so maybe about 3/4 throttle, and only up to about 4500 rpm, I'm seeing AFRs at about 12-13. This is at boost 7-10 lbs. If I go WOT it instantly jumps to the 11s or 10s as expected. Almost every component is new and or refreshed including my TPS which adjusted to perfection.

My question is is it dangerous to be at AFRs of 12-13 in part-throttle boost at mid RPMs. I would hate to break it just enjoying that thick *** mid-range but not even running it hard. I don't want to WOT just to get some boost.

Thanks

V2Rocket

10-11 sounds too rich even for WOT...but that's how the old chips did their magic and got some safeguard.

Depends how much boost you're getting when its running 12-13 afr, but part throttle cruise/accelerating is very different than WOT.

I bet you'd find a fair amount more power leaning it out to 12:1 at WOT, if the car will take it.

Molly

I guess with these chips there is no way to lean it out right? So I'll enjoy it until I upgrade. I only installed them because we had them laying around forever and never tried them... instead we used the car bone stock for the last 28 years. It's now just gotten its first freshening up and first mod, via these chips.

Rogue_Ant

High 10s, low/mid 11s under full boost is perfectly fine - nothing to worry about.

12-13.0 at 7-10psi is also perfectly fine, and again, nothing to worry about.


In-fact, the APE chips ran a little extra fuel in the peak-torque areas to try and provide a bit more margin against knock... I suggest leaving it exactly where it is at.

Molly

Thanks, I am going to leave it as I am more conservative with this car. I know well what makes it run rich as this thing was a pig before I fixed about 40 things and got it all refreshed. I guess I just don't have any options to make this one run leaner anyway, unless I start upgrading stuff.

The only other thing non-stock is a KN cone filter running in the hot air intake position. The cone is so filthy I was going to put the stock box back on but maybe I'll clean the cone for now and see what that does.
I would assume a would a caked filthy cone would cause richness?

fast951

The cone filter behind the radiator is not a good idea. The engine is sucking in "hot" air, which you do not want.

It's best to put the stock airbox back in place, with a clean filter.

Humboldtgrin

Regarding AFR lean best is 13:1 and rich best is 12:1. Between those two is where an engine will create the most power.

TheAllusionist

I find it very cool how Josh and John respond to post. That is why I plan on doing business with both of them sometime in the near future. In regards to Vitesse I bought on eBay a brand new Maf kit that I plan to pay for new software from John and do a stealth install. Thanks guys, find it very informative response as installing a wideband is first on my list before installing any mods and I hear all sorts of numbers and wasn't certain what to believe.

Molly

I agree... but even before their help here, I was fairly sure I would be buying stuff from them down the road anyway ; )

odonnell

+1 for Josh's stuff, NA-Tune transformed my '83. He even helped me out with an ignition table after I put a standalone in my car, which I didn't buy from him. That's stand up.