Misfire p300, p171, p174

30

Asked by Jan 28, 2017 at 10:33 PM about the 2001 Chevrolet Silverado 2500HD LT Extended Cab 4WD

Question type: Maintenance & Repair

Have a 2001 Chevy 2500hd 6.0 Liter 4x4. Truck is running
rough throwing codes p300, p171, p174 which I know is
misfire all cyclinder, and lean code on pre cat oxygen
sensors. Have already replaced plugs with suggested
NGK iridium tip gapped at .40 wires replaced also. Still
nothing. Been to two different shops one in which was a
Chevy dealer. Was told needed two injectors, they
replaced ran ok for a week and back to what it was doing.
Then told needed to just replace the remaining 6 injectors.
Bought a match set of remanfactured ones with warranty
etc. they installed and said runs worse now. Fuel pressure
is good, have great spark in all cyclinders. Intake gasket
no leaks, throttle body cleaned. No vacuum leaks of any
kind. Parts already replaced before everything, fuel pump,
filter, pressure regulator. Since then been to a total of 4
shops and no answers what is going on.

5 Answers

69,325

A dirty or bad MAF (Mass Air Flow) sensor can cause the P0171 & P0174 codes together. The P0300 code should be ignored. It's most likely being triggered by the two lean condition codes. If you have one of those aftermarket cold air intake system air filter set ups the MAF is highly suspect. The oil used on the air filter contaminates the MAF! Another cause for the two lean codes could be a stuck open PCV valve. HTH. -Jim

30

Ok will have that checked. Don't have a after market cold air intake. It might still be the mass air flow

1 of 1 people found this helpful.
30

AskTrannyMan, yes it was the Chevy dealer that said it ran worse with the other injectors in. Also, for got to add to the write up, truck has 102,000 miles.

1 of 1 people found this helpful.
69,325

With both codes together the MAF is definitely suspect since you don't have a vacuum leak. If you don't know when the PCV valve was last changed, replace it. They're very cheap. HTH. -Jim

30

Pcv valve and mass air flow sensor both checked and not the problem. Still miss fire and lean codes

1 of 1 people found this helpful.

Your Answer

Silverado 2500HD

Looking for a Used Silverado 2500HD in your area?

CarGurus has 831 nationwide Silverado 2500HD listings starting at $899.

Postal Code:

Chevrolet Silverado 2500HD Experts

  • #1
    Steven Loeffler
    Reputation
    480
  • #2
    piocon
    Reputation
    280
  • #2
    Tom Demyan
    Reputation
    280
View All

Related Models For Sale

Used GMC Sierra 2500HD
27 Great Deals out of 983 listings starting at $6,500
Used Ford F-250 Super Duty
20 Great Deals out of 797 listings starting at $6,000
Used Chevrolet Silverado 1500
158 Great Deals out of 10,560 listings starting at $100
Used Dodge Ram 2500
9 Great Deals out of 91 listings starting at $1,995
Used Ford F-150
434 Great Deals out of 9,102 listings starting at $922
Used Ford F-350 Super Duty
28 Great Deals out of 1,120 listings starting at $8,000
Used GMC Sierra 1500
231 Great Deals out of 10,278 listings starting at $2,995
Used Chevrolet Silverado 2500
5 listings starting at $10,000
Used Chevrolet Silverado 1500HD
4 listings starting at $9,995
Used Toyota Tundra
18 Great Deals out of 783 listings starting at $4,499
Used Chevrolet Silverado 3500
11 listings starting at $10,844
Used Dodge Ram 3500
3 Great Deals out of 69 listings starting at $12,450

Used Cars For Sale

2017 Chevrolet Silverado 2500HD For Sale
490 listings starting at $899
2016 Chevrolet Silverado 2500HD For Sale
39 listings starting at $39,980
2015 Chevrolet Silverado 2500HD For Sale
74 listings starting at $31,995
2014 Chevrolet Silverado 2500HD For Sale
12 listings starting at $34,998
2013 Chevrolet Silverado 2500HD For Sale
15 listings starting at $22,995

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.