Re: P0171/P0174 Help! *update*

aarcuda69062 wrote:
>
> In article <wEdfk.16479$89.6181@nlpi069.nbdc.sbc.com>,
> "Pete C." <[email protected]> wrote:
>
> > > Don't need to. Test drive it like you stole it, set the Snap-On scanner
> > > in 'movie' mode, floor it in first gear and when it shifts to second,
> >
> > Woa there, "when it shifts to second"??? What do you think I am, some
> > kinda wuss? I only drive trucks with real transmissions :) (NP4500 in
> > this case). Heck, one of the reason I keep getting bigger trucks is my
> > hatred of automatics.
>
> Okay, when YOU shift to second.
>
> > > hit the trigger on the scanner, review the movie near frame "0" forward
> > > and backwards frame by frame until you find the max RPM, then scroll to
> > > the MAF sensor and read the grams per second. With RPM, engine size and
> > > a few other ambient details, I can calculate whether the theoretical
> > > volumetric efficiency matches what the PCM PID are reporting.
> > > I'm leaning towards three things; either the MAF sensor isn't reading
> > > correctly or you have plugged injectors or your fuel pump can't keep up.
> >
> > Well, it's on the third or is it fourth fuel pump. Since the problem has
> > existed over at least two pumps I'm inclined to think it's probably not
> > the pump.
>
> Doesn't mean it's not fuel pump related.
> These things are well known for overheated harnesses in the tank and
> where the FP module plugs in.

The last replacement, I replaced the hanger assembly as well.

>
> > The fuel injectors were replaced some 130k ago or so, at the same time
> > the cats were replaced under warranty (also replaced all four HO2S). The
> > facts that I always get both 171 and 174, all the recently pulled plugs
> > were consistent, and the tank and FPR screens were all spotless leans me
> > away from a fuel injector problem.
>
> Still doesn't lean me away from an injector problem.
> The PCM is still able to compensate for the lean condition, that's what
> the fuel trim numbers indicate, so it's not unusual that the plug color
> looks okay.

You think it would be that consistent to always be both banks? I guess I
could try the injector balance test if I get my friend over with the
real scanner.

>
> > The MAF, well, that's original, now with 199,500+ miles of use on it. I
> > did clean it with CRC MAF cleaner, though there was no sign of any
> > visible dirt on it.
>
> Two ways to tell if it's functioning properly, take the measurements and
> do the calculations or replace it with a new (not different) one.

Ok, sounds like I need the real scanner again.

>
> > >
> > > 44-45 percent fuel correction is HUGE, there is a real problem there and
> > > you'd best fix it before there's collateral damage.
> >
> > I've certainly been trying to locate and fix it.
> >
> > >
> > > > I also don't have a "real"
> > > > scan tool to read parameters in real time. All I have is the "good"
> > > > Harbor Freight CAN / OBD2 scanner that displays / clears codes and
> > > > displays associated freeze data. I do have a friend with a real scanner
> > > > (Snap-On I believe), so perhaps I can get a test plan together and visit
> > > > him.
> > >
> > > That's not a scan tool. In my business, that's an invitation to
> > > frustration.
> >
> > It's a step above a basic code reader at least. I may need to invest in
> > something better, perhaps PC based, got any suggestions for something
> > good, but less $$$ than pro stuff?
>
> Autoenginuity.
> http://www.autoenginuity.com/
> You can get into the enhanced GM package for about $400
>
> The interface sucks but isn't as bad as some, It graphs, does mode 6
> conversion without any hexdecimal conversions, does cam offset relearn,
> has bi-directional control, it is as close to a Tech 2 as you can get
> without spending $6K. On a laptop platform, it's not as easy to
> manipulate while driving as a dedicated scan tool.
> Or, buy a Snap-On scanner off of e-bay, they're pretty low on resale.
> http://motors.shop.ebay.com/_Automotive-Tools__W0QQToolType5b20e8c2ZDiagn
> osticToolsEquipmentc18aef6QQ_catZ43989QQ_flnZ1QQ_pcatsZ34998Q2c6028Q2c600
> 0QQ_ssovZ1?_rkw=mt%202500

Ok, thanks.