So when accelerating mid load (maybe about 10mm/Hg), when the rpms pass about 1900rpm or so, the engine makes this very very subtle grunt. It probably lasts for about 20 rpms or so, meaning 1900-1920. Again, very subtle, but sounds exactly like a "grunt", and lasts as long as I'm under accel. and between about 1900-1920rpms. Otherwise great running engine...all upkeeps (except rod bearings, which should probably be replaced as it has been 160k or so...right?). Anyone know what the grunt noise is? It seems to be a natural strong vibration point for my car, so I didn't know if something might be loose and just vibrating at that rpm?

Next, when I'm not at WOT, I see ~14.2a/f ratio from full vacuum to 5psi. Then at 5psi it hops right down to about 12.4 and ends up at about 11.5 by high rpms. Obvious fix needed in the richness, but my question is: is 14.2a/f ratio acceptable for 0-5psi boost?

Next: got a flat tire on the highway (of all things!), pulled the car up on a flat bed by pulling from the control arms (is that as bad as it sounds?)...fixed the tire and rebalanced it. Now I get intermittent steering wheel shake at different speeds, BUT, it comes and goes. For example, shake at 60mph, speed up to 80 or slow down to 40, then return to 60mph, and half the time the shake is gone. Is this a simple balancing problem or something more serious? I ask because I find it curious that it's not consistantly shaking at set speeds (revolutions).

Please help with any or all.

In other news, I'm finalizing steps to install an electric cut-out in my exhaust, just after the downpipe. I can't wait to hear it, and more importantly post sound and video clips!

 

anyone?

 

First of all, the grunt could be from the exhaust system of your balance shaft belts are installed correctly. I have that same 'grunt' but between 2,00 and 2,250rpm. Sounds coming more from the rear muffler, could be a link there.

The a/f ratio should be 12.5:1 thoguhout all revs. You are getting rich at high revvs and lean at low revs. Should be the other way around maybe the chips have something to do with it. Too much fuel on high revs? that shouldn't happen with stock FPR and injectors.

The wheel vibs at different speeds is a balancing problem. If the control arm wa sdamaged, the it would shake at all times. Balancing the wheels on our cars are very VERY sensitive and delicate, try re-balancing that tire at a different place with more high-tech stuff.

 

I believe some tuners keep the lower RPM A/F ratios a bit lean for hotter exhaust gasses which facilitate a quicker spool-up

 

The chip programming will keep you in closed loop until 5psi or so before it drops into open loop.
So you will stay around 14:1. Ideally you should maintain 12.5:1 from there till redline so
you are a little fat at high RPMs.

 

From my last dyno run, I see that my A/F was 14:1 at 5 psi and becoming richer (to 12:1 at higher boost) beyond that point.

 

You sure it was a grunt and not a fart?

 

hahah thanks Danno :-)

yeah my chips are pig rich at higher rpm's....long story there
it probably is an exhaust grunt, as I know I have a very small leak in my crossover.

In other news, I swapped my pads front to rear (noticed they were much more worn in the front). Took about 35 pumps to get brakes back, and even at that point you had to push the brake pedal farther down than before to get the same braking....today (2 days later) it's almost back to normal...what is up with that?

 

Air in your brake system and/or check for bad lines

 

the shaking problem sounds like an out of balance tire. When tires are repaired sometimes places just make sure the tire is installed in the same place on the rim it was removed from by making chalk marks on the rim and tire, but if it has a patch or plug it is a slightly different weight than before so the old "balance" will not work.....or maybe they just didn't balance it right. Another problem could be the pulling it on the truck from the control arms. It may have changed the alignment settings such as the caster block setting or the camber settings, or both.

 

"and even at that point you had to push the brake pedal farther down than before to get the same braking....today (2 days later) it's almost back to normal...what is up with that?"

Seating of the pads. When switching the pads around the peaks of the pads are riding on the peaks of the discs, making the pads somewhat compressible (high peak stress). After they have seated the force is distributed over the full surface of the pads lowering the peak stress.