99 silverado - got my codes - what next?

"Dru" <g22dru RemoveThis @gmail.com> wrote in news:1170173991.130133.98840
@s48g2000cws.googlegroups.com:

> 99 4.8L silverado 180Kmi
>
> Started late shifting into 2nd the other day. Not even a hard shift,
> just rpms go higher than usual and you almost have to wait on it or
> ease off the gas and it drops into 2nd. Drives fine otherwise. After
> reviewing this forum I decided to get my codes, expecting to see the
> infamous P1870 tanny slipping code. Got my codes from Autozone, they
> are as follows:
>
> P0102 - MAF sensor circuit, low input
> P0171 - Feul Trim system lean @ upstream o2 sensor (left cylinder
> bank)
> P0174 - Feul Trim system lean @ upstream o2 sensor (right cylinder
> bank)
> P0420 - Oxygen storage ability of catalyst (left cyinder bank) below
> calibrated threshold (4.8L, 5.3L or 6.0L V
>
> Okay, I somewhat understand what is going on here, but was hoping for
> more direct input from you guys.
>
> it seams I should first check MAF for cleanlyness? (I do have the K&N
> FIPK)
> How can I go about checking it for functionality?
> Make sure it's clean and what about voltage thru it?
>
> Are the "upstream" o2 sensors the pre-converters or post-converters?
>
> What should I do first/ next? At roughly 50 bucks each on th o2
> sensors, I'd kinda like to get it right the first time as to which to
> replace or if they need it at all.
>
> Could this just be a vacume issue or faulty gasket?
>
> Any help would me much appreciated.
> up stream means before convertor /as long as 02 signal is constantly
changing i wouldnt be throwing sensors in/could be a vac leak even tho
that eng design isnt pron to it, i squirt water out of shampoo bottle
aroung suspect areas to see and hear vac leaks/volts thru MAF is a tricky
measurement, again make sure its constantly changing/ i assume you have
done the first steps, fuel filter, check pres. at test port? reason to
ask = fuel trim lean both banks............how does it drive?
 >> Stay informed about: 99 silverado - got my codes - what next? 

> "Dru" <g22dru.RemoveThis@gmail.com> wrote in news:1170173991.130133.98840
> @s48g2000cws.googlegroups.com:
>
> > 99 4.8L silverado 180Kmi
> >
> > Started late shifting into 2nd the other day. Not even a hard shift,
> > just rpms go higher than usual and you almost have to wait on it or
> > ease off the gas and it drops into 2nd. Drives fine otherwise. After
> > reviewing this forum I decided to get my codes, expecting to see the
> > infamous P1870 tanny slipping code. Got my codes from Autozone, they
> > are as follows:
> >
> >
> > it seams I should first check MAF for cleanlyness? (I do have the K&N
> > FIPK)
> > How can I go about checking it for functionality?
> > Make sure it's clean and what about voltage thru it?
> >
Oil from the K&N filters will mess up the MAF sensor.

Whitelightning
 >> Stay informed about: 99 silverado - got my codes - what next? 

Sorry for the late reply, we were snowed in the last day or so, but
thank you for replying!

Ran a vacuum check the other night and seemed okay. Had a better OBD
reader at that shop (father in law's friend runs a big rig mech.
shop.). Same codes as above showed. We then ran up and down the road
with this OBD tester going and it showed 1 2 silenoid (sp?) shutting
off just before the shift into 2nd, even the 2 3 was shutting off at
this time, but both were "on" until the point of shift change. Seems
that this was causing the late shift? 1 2 shift time was reading from .
10 to .35 depending on how I ran the throttle. (I can let off the
accel just as it hits 3000rpms and it drops into 2nd easier than if I
keep a constant accel going.
I picked up a new voltmeter yesterday and ran some checks as
mentioned in my Chilton's book. MAF seemed fine, was tricky as you
mentioned, but appeared okay. Read I should check resistance @ fuel
injection electrical clips. Book says should be from 11.4 ohms to 12.6
ohms. All of mine read from 13.5 up to 14.5 or so. Averaging 14 ohms,
but were all roughly the same ohms. How would a high ohm reading
effect fuel injection, or would it? Didn't get a chance to test o2
sensors, will do that tonight.

Other than the late shift change, it still drives great. Even with the
late shift change it is a smooth one, not jerky or clunky.

Fuel filter was replace just about 2 months ago, but need to check
fuel pressure I guess. Gotta get that gauge from the shop. Is that a
tough check?

Any other advice? Again, I appreciate your time with this. I gotta get
this thing running a little better for the pregnant wife and 2 year
old. We only have the one vehicle for now.....thanks

Andru

> > up stream means before convertor /as long as 02 signal is constantly
> changing i wouldnt be throwing sensors in/could be a vac leak even tho
> that eng design isnt pron to it, i squirt water out of shampoo bottle
> aroung suspect areas to see and hear vac leaks/volts thru MAF is a tricky
> measurement, again make sure its constantly changing/ i assume you have
> done the first steps, fuel filter, check pres. at test port? reason to
> ask = fuel trim lean both banks............how does it drive?
 >> Stay informed about: 99 silverado - got my codes - what next? 

No offense, but K&N claim the'y've done extensive testing to clear
this myth.

http://www.knfilters.com/faq.htm#6

http://www.knfilters.com/MAF/massairfindings.htm


Like I said, I mean no offense. I actually would think the same.
Reguardless, I've checked cleanlyness and all seems fine, I never over
oil my filter and always follow instructions on this thing.


> Oil from the K&N filters will mess up the MAF sensor.
>
> Whitelightning
 >> Stay informed about: 99 silverado - got my codes - what next? 

Thanks for your help Steve.


Steve Barker wrote:
> BUT of course K$N would say that. It's not a myth. And their filters
> don't catch dirt either. No benefit to using them. In fact , they're a
> detriment.
>
> --
> Steve Barker
>
>
> "Dru" <g22dru DeleteThis @gmail.com> wrote in message
> news:1170436437.659478.307110@v45g2000cwv.googlegroups.com...
> > No offense, but K&N claim the'y've done extensive testing to clear
> > this myth.
> >
> > http://www.knfilters.com/faq.htm#6
> >
> > http://www.knfilters.com/MAF/massairfindings.htm
> >
> >
> > Like I said, I mean no offense. I actually would think the same.
> > Reguardless, I've checked cleanlyness and all seems fine, I never over
> > oil my filter and always follow instructions on this thing.
> >
> >
> >> Oil from the K&N filters will mess up the MAF sensor.
> >>
> >> Whitelightning
> >
 >> Stay informed about: 99 silverado - got my codes - what next? 

Any advice on where to go with this now? I've had the FIPK on the
truck for the last 85,000 miles or so. I'm not trying to be an arse,
just wanted to focus on issue at hand.


Steve Barker wrote:
> I just hate to see people burn needless dollars AND ruin their engines at
> the same time.
>
> So, you're welcome
> --
> Steve Barker
>
>
> "Dru" <g22dru.RemoveThis@gmail.com> wrote in message
> news:1170453224.294339.66230@k78g2000cwa.googlegroups.com...
> > Thanks for your help Steve.
> >
> >
 >> Stay informed about: 99 silverado - got my codes - what next? 

BUT of course K$N would say that. It's not a myth. And their filters
don't catch dirt either. No benefit to using them. In fact , they're a
detriment.

--
Steve Barker


"Dru" <g22dru RemoveThis @gmail.com> wrote in message
news:1170436437.659478.307110@v45g2000cwv.googlegroups.com...
> No offense, but K&N claim the'y've done extensive testing to clear
> this myth.
>
> http://www.knfilters.com/faq.htm#6
>
> http://www.knfilters.com/MAF/massairfindings.htm
>
>
> Like I said, I mean no offense. I actually would think the same.
> Reguardless, I've checked cleanlyness and all seems fine, I never over
> oil my filter and always follow instructions on this thing.
>
>
>> Oil from the K&N filters will mess up the MAF sensor.
>>
>> Whitelightning
>
 >> Stay informed about: 99 silverado - got my codes - what next? 

I just hate to see people burn needless dollars AND ruin their engines at
the same time.

So, you're welcome
--
Steve Barker


"Dru" <g22dru RemoveThis @gmail.com> wrote in message
news:1170453224.294339.66230@k78g2000cwa.googlegroups.com...
> Thanks for your help Steve.
>
>
 >> Stay informed about: 99 silverado - got my codes - what next? 

In article
<1170456207.244409.191080 RemoveThis @v45g2000cwv.googlegroups.com>,
"Dru" <g22dru RemoveThis @gmail.com> wrote:

> Any advice on where to go with this now? I've had the FIPK on the
> truck for the last 85,000 miles or so. I'm not trying to be an arse,
> just wanted to focus on issue at hand.

Have you actually tried cleaning the MAF sensor and test driving
after?
 >> Stay informed about: 99 silverado - got my codes - what next?