Re: P0171/P0174 Help! *update*

Technical aspects of automobiles, et. al., post #21,701
Author:
Date:
Subject:
 mr158912
 2008-07-19 17:20:31
 Re: P0171/P0174 Help! *update*
there is a company on ebay selling a pc based scantool program and it's by browser
electronics it seems to be worth the 400.00 for the whole thing from what i am seeing

"Pete C." wrote:

> aarcuda69062 wrote:
> >
> > In article <xDcfk.29661$co7.17199@nlpi066.nbdc.sbc.com>,
> > "Pete C." <[email protected]> wrote:
> >
> > > aarcuda69062 wrote:
> > > >
> > > > In article <dYafk.32612$ZE5.7110@nlpi061.nbdc.sbc.com>,
> > > > "Pete C." <[email protected]> wrote:
> > > >
> > > > > "Pete C." wrote:
> > > > > >
> > > > > > '97 Chev K3500 7.4L
> > > > > >
> > > > > > Been chasing after the source of intermittent P0171/P0174 (always both
> > > > > > set) for some time without success. I'm running out of ideas on what to
> > > > > > check now, I don't have a full feature scan tool so I can't perform all
> > > > > > the possible checks. Some of the possible items seem to not be
> > > > > > applicable due to it always setting both codes, i.e. exhaust or HO2S
> > > > > > issues not likely since it's dual exhaust with dual cats.
> > > > > >
> > > > > > I've replaced the fuel pump recently and the tank interior was spotless,
> > > > > > so clogging / contamination is not likely. I just replaced the FPR and
> > > > > > it's filter screen was clean as well. The FPR did fix pressure leak down
> > > > > > on pump shutoff, but that seems to not have been a significant issue.
> > > > > >
> > > > > > I did plugs/wires/cap/rotor while I was at it this last service
> > > > > > Saturday, and the removed plugs all had moderate tan deposits that seem
> > > > > > consistent with the 130k or so on them. I also cleaned the IM passages
> > > > > > and ports while things were apart.
> > > > > >
> > > > > > I do have freeze frame data from the trouble codes as noted below:
> > > > > >
> > > > > > Closed loop / closed loop
> > > > > > Calc. load 19.2%
> > > > > > Coolant temp 167F
> > > > > > ST1 0.7%
> > > > > > LT1 24.9%
> > > > > > ST2 1.5%
> > > > > > LT2 24.9%
> > > > > > MAP 17.4 in/hg
> > > > > > RPM 2521
> > > > > > MPH 65
> > > > > > MAF 7.152 lb/min
> > > > > > TPS 20.7%
> > > > > >
> > > > > > No trouble codes other than the P0171/P0174 have ever been set.
> > > > > >
> > > > > > Any ideas where else to look?
> > > > > >
> > > > > > Thanks!
> > > > >
> > > > > After erasing the previous codes and logging another 140 miles or so, I
> > > > > have yet another set of P0171/P0174 set and another pending set. New
> > > > > freeze data is as follows:
> > > > >
> > > > > Closed loop / closed loop
> > > > > Calc. load 10.1%
> > > > > Coolant temp 172F
> > > > > ST1 17.9%
> > > > > LT1 24.9%
> > > > > ST2 21.0%
> > > > > LT2 24.9%
> > > > > MAP 17.1 in/hg
> > > > > RPM 1489
> > > > > MPH 28
> > > > > MAF 3.875 lb/min
> > > > > TPS 12.9%
> > > >
> > > > What is the fuel pressure during these conditions (simulate the freeze
> > > > frame)?
> > > >
> > > > Can you get the MAF reading at whatever is the safest maximum RPM for
> > > > that engine at WOT?
> > > >
> > > > Does your scan tool support graphing?
> > >
> > > Not sure I have a way to simulate a load.
> >
> > 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.
>
> > 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.
>
> 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.
>
> 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.
>
> >
> > 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?
Author:
Date:
Subject:
 Mike Romain
 2008-07-15 20:54:58
 Re: P0171/P0174 Help! *update*
Pete C. wrote:
> "Pete C." wrote:
>> '97 Chev K3500 7.4L
>>
>> Been chasing after the source of intermittent P0171/P0174 (always both
>> set) for some time without success. I'm running out of ideas on what to
>> check now, I don't have a full feature scan tool so I can't perform all
>> the possible checks. Some of the possible items seem to not be
>> applicable due to it always setting both codes, i.e. exhaust or HO2S
>> issues not likely since it's dual exhaust with dual cats.
>>
>> I've replaced the fuel pump recently and the tank interior was spotless,
>> so clogging / contamination is not likely. I just replaced the FPR and
>> it's filter screen was clean as well. The FPR did fix pressure leak down
>> on pump shutoff, but that seems to not have been a significant issue.
>>
>> I did plugs/wires/cap/rotor while I was at it this last service
>> Saturday, and the removed plugs all had moderate tan deposits that seem
>> consistent with the 130k or so on them. I also cleaned the IM passages
>> and ports while things were apart.
>>
>> I do have freeze frame data from the trouble codes as noted below:
>>
>> Closed loop / closed loop
>> Calc. load 19.2%
>> Coolant temp 167F
>> ST1 0.7%
>> LT1 24.9%
>> ST2 1.5%
>> LT2 24.9%
>> MAP 17.4 in/hg
>> RPM 2521
>> MPH 65
>> MAF 7.152 lb/min
>> TPS 20.7%
>>
>> No trouble codes other than the P0171/P0174 have ever been set.
>>
>> Any ideas where else to look?
>>
>> Thanks!
>
> After erasing the previous codes and logging another 140 miles or so, I
> have yet another set of P0171/P0174 set and another pending set. New
> freeze data is as follows:
>
> Closed loop / closed loop
> Calc. load 10.1%
> Coolant temp 172F
> ST1 17.9%
> LT1 24.9%
> ST2 21.0%
> LT2 24.9%
> MAP 17.1 in/hg
> RPM 1489
> MPH 28
> MAF 3.875 lb/min
> TPS 12.9%

In my opinion, the folks that sold you the scanner are laughing all the
way to the bank along with the mechanics that live in your area.

I think those things are sucker tools.....

Does the vehicle run OK or not?

I mean it's over ten years old and the mini pins on all the sensors only
pass computer signals which means tons of intermittent failures 'show'
on these foolish tools without meaning squat as far as running goes.

A good spray with an electronic contact cleaner on all the plugs and
sockets for the sensors on an old vehicle can do wonders for them.

They 'really' are a 'sucker tool' you know....

Just my $0.02,

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com