Please help! is this really “lean”?
- Thread starter 1995 5.0 vert
- Start date
-
Sponsors (?)
If you are boosted, AFR will be closer to 12.0. If you were boosted though, it would have definitely blown sky high.
You definitely have a serious vacuum leak somewhere.
You definitely have a serious vacuum leak somewhere.
If you run it in the dark with the hood open, I bet your headers start glowing within a few minutes. LoL
No... I would [not] run that car until this issue is resolved.
I don't know. Are they mechanics?
My advice would be that if you're not prepared to diagnose and fix this issue on your own that you should enlist the help of a qualified mechanic and let him/her tell you when it's ready to go to the dyno.
jozsefsz
15 Year Member
The above suggestions are directionally accurate, and you are lean, though reasonable AFR's are driven by load as well as RPM. That's why, as Noobz mentions, commanded AFR would be even richer if you had forced induction (i.e. higher load). In the tune it looks something like the below, at lower loads an AFR of about 14.3:1 is ok. At higher load, 12.1 is reasonable (if you were using FI that would be even lower, 10.5-11:1). So how bad your AFR actually is, is a function of how much load the dyno is applying.
There are actually two types of dynos - inertia and load-bearing. The "inertia" version is just designed to tune at WOT for the most part, that's where the 'peak numbers' that most people are interest in bragging about come in. The "load-bearing" version varies load at stable RPM allowing the entire map to be evaluated and tuned. That's what you want when you're interested in street-driveability across the RPM and load range and not just drag-strip performance. It's not clear to me which one the Dynapack dyno is, though its literature says it's not inertial.
This is perhaps a bit over-scientific, and at the end of the day, either way, you're running quite a bit lean whichever type of dyno session those numbers came from. On the brighter side, as your map is nice and straight and consistently lean, you could bump the injector size (from 19-24lb for example) or your fuel pressure setting (using an adjustable fuel-pressure-regulator) to make it more driveable until it could be fully tuned.
I'd also install a wideband to see what you're actually getting as that printout is of questionable value without context (i.e. what type of testing was being done). If it's anything much leaner than 14:1 at mid-throttle throughout the RPM range, increase fuel pressure even more until it is reasonable. Then you'll have it safe enough to drive around until tuned. If you don't do any of this, I wouldn't drive it like it is.
There are actually two types of dynos - inertia and load-bearing. The "inertia" version is just designed to tune at WOT for the most part, that's where the 'peak numbers' that most people are interest in bragging about come in. The "load-bearing" version varies load at stable RPM allowing the entire map to be evaluated and tuned. That's what you want when you're interested in street-driveability across the RPM and load range and not just drag-strip performance. It's not clear to me which one the Dynapack dyno is, though its literature says it's not inertial.
This is perhaps a bit over-scientific, and at the end of the day, either way, you're running quite a bit lean whichever type of dyno session those numbers came from. On the brighter side, as your map is nice and straight and consistently lean, you could bump the injector size (from 19-24lb for example) or your fuel pressure setting (using an adjustable fuel-pressure-regulator) to make it more driveable until it could be fully tuned.
I'd also install a wideband to see what you're actually getting as that printout is of questionable value without context (i.e. what type of testing was being done). If it's anything much leaner than 14:1 at mid-throttle throughout the RPM range, increase fuel pressure even more until it is reasonable. Then you'll have it safe enough to drive around until tuned. If you don't do any of this, I wouldn't drive it like it is.
I’m honestly shocked the dyno operator ran it north of 2000 rpm where it was obviously very lean. I like to see around 12.5-12.8 on a n/a wot pull.
Can you confirm fuel pressure is at 40psi and not dropping upon acceleration?
Can you confirm fuel pressure is at 40psi and not dropping upon acceleration?