Ben951S

Hi All,

I am still having my 'running rich all the time'.

No vacuum leaks (smoke tested), AFM replaced with known good, vacuum lines routed correctly, and has street cam.

Bottom line, my vacuum at cold idle is 7-9psi, warm vacuum is 12-14psi.

In gear while coasting at speed, I can pull 22psi vacuum.

None-the-less, I am still running rich. I still get down to less than 11 on WOT, and idle at 14.7.

I am running a 2.5bar instead of a 3.0bar FPR (3.0 is required by A-Tune).

I am thinking of getting an adjustable leaning out even more.

I get 20.5mpg no matter how I drive. I don't want to try and get 25+mpg only to lean out and blow up my motor. Temps are great, tempted to just leave it as is.

If I am running too lean, would be able to see on the WBO2, but would I still idle at 14.7? I know I am not lean now, just asking.

So, in short...

Does low vacuum mean running lean? With a cam, is there anyway to get the vacuum back up? Is this even related?

Thank you!

TurboTommy

With a more agressive cam, your vacuum numbers are normal; lower vacuum at idle, and that's just the way it is.
Generally, a cam (and differences in vacuum) will not affect the air/fuel ratios.
Running lean will not cause low vacuum, unless at idle it's running so lean that your idle RPM is significantly lower.

Ben951S

I thought the FPR would be affected by the overall vacuum of the system.

If my vacuum numbers are not affecting how rich I run, then I still have my darn 'Running Rich' problem! Argh!

Known good AFM
DME Temp Switch replaced
A-Tune
No Vacuum leaks, resealed throttle body, good Wideband#s (rich at WOT, idle at 14.7). Argh!

lart951

who told you 11 a/f ratio is too rich?

Ben951S

I dip below 11 at WOT... I got this from searching...

"Idle 14.7 - 14.9
part throttle 13.2-15.1
interstate cruise 14.8-15.3
boost 11.7 - 12.4


Idle - 14.7
Low Load (Highway) - 16.0/17.0
1/4 Throttle - 14.0/15.5
1/2 Throtte - 13.5/14.5
3/4 Throttle - 13.0/13.5
Full Throttle - 12.0/12.8


"

So it seems most say 11.5 or so at WOT. I dip under 11 depending on gear.

Also, my rear bumper (white) turns black (spotted) because of running rich. My poor cat!

lart951

I gonna tell you something 10:9 -11:1 at wot isn't that bad, I always have a saying if you see that black smoke coming out of your car, that means is happy. I wouldn't worry about and I don't think cylinder's wall washing would occur at 11 a/f . Anything above 11:7 isn't too safe unless you are running race fuel, I have seen a lot of vendors suggesting 12:1-12:5 , that is BS. I am one of those old school 951 guys who tuned my car at 11:1-11:5 at wot ran 21-23psi daily for 4 years until my car was rear ended and had to parted out, sold my engine to the infamous ST and he made that claimed 602rwhp with my block, by the way my block was scoreless even after 4 years of rich mix and high boost

Ben951S

I am okay with 11.-11.5 for WOT.

But I mean, 20.5mpg, mostly highway... =\ and the rear-bumper coloring/speckling... It just seems a little excessive.

But in the interest of lazy, I'd rather not lean it out and lose the motor either...

Hey Lart, did you see my PM? I want some parts if you have em!

TurboTommy

[QUOTE=Ben951S;9411681]I thought the FPR would be affected by the overall vacuum of the system.

QUOTE]

The vacuum/pressure line that's connected to the FPR keeps the pressure differential always the same across the injectors; precisely so that intake manifold pressure or vacuum WILL NOT affect the air/fuel ratios.

An even 11:1 is a little rich, especially if you said you had to down from the prescribed 3.0 bar FPR to a 2.5 bar.

What's your wideband say when at part throttle/lower boost acceleration?

lart951

I am going through my pm's now lol

Ben951S

[quote=TurboTommy;9411697]
Part throttle it only goes down a little bit, I really need to hit 50% throttle to get it down in 13's or lower. It seems to need WOT to dive into 12s or 11s, and needs to be boosting too, if I'm in 4th at 40 and go 'WOT' I don't get a lower AFR until boost spools up, and it seems right.

And yes, it does get under 11 under some conditions.

Oh. It runs at 10 (off the gauge) on start-up. Maybe due to O2 not being warmed up/open loop mode, but I believe even that I was told, is low It takes warming up to get to 14.7

I did use the 'generic' Engine Temp sensor, but it is the compatible part/spec (Walker I think? Doorman?)... That's the only thing I can think of maybe... Injectors do not leak, Fuel pressure gauge seems reasonable. I think I should log fuel pressure with WBO2...

SummitP

Meant to post in different thread.....
#struggling with the internet.

SummitP

meant to post in other thread. forum challenges for me. Please delete post...

Black51

Just FYI, vacuum is not measured in psi. It's measured in in/hg, or "inches of mercury".

Have you checked the FQS setting on the DME?

F18Rep

Yea and I wonder what a restrictive cat (since you mentioned it) does to AF....Bruce