Hummer H3 has a misfire only at idle.
1,925

Asked by Jeff Jan 08, 2021 at 04:49 PM about the 2006 Hummer H3 4dr SUV 4WD

Question type: Maintenance & Repair

I have a Hummer H3. It has a misfire at idle. Code P0300. Misfire counter
tells me it is on cylinder 4. Checking PIDs it shows miss on cyl. 4 only at idle.
New plugs moved coils around and checked injector balance. I found loose
intake manifold bolts. Replaced intake manifold gasket, manifold surface was
flat. Cleaned throttle body. Misfire goes away at about 900 rpm. What am I
missing that could cause a misfire at idle? Has 160,000 miles on the
odometer.

3 Answers
1,925

Jeff answered 3 years ago

All cylinders have 170-180 compression. Battery is 5 months old and tests good grounds are clean and tight.

Mark helpful

Guru925J1H answered about a year ago

It's happened to me on my 07 H3 Hummer. I checked vacuum lines, did a smoke test and found one of my hoses on the evap canister in the back by the rear axle was bad, as well as a vacuum line was cracked. Replaced them and it disappeared.

Mark helpful

Your Answer:

Related Questions

  • Hummer H3 has a misfire only at idle. 3 Answers

    I have a Hummer H3. It has a misfire at idle. Code P0300. Misfire counter tells me it is on cylinder 4. Checking PIDs it shows miss on cyl. 4 only at idle. New plugs moved coils around and checked i...

    2006 Hummer H3 4dr SUV 4WD

    -

    Maintenance & Repair

  • Hummer H3 5 Answers

    My hummer h3 gets stuck when I turn the steering wheel almost all the way like when I need to back up and turn to pull out or to just take a sharp turn to drive in to a parking it slowly comes to...

    2006 Hummer H3 4dr SUV 4WD

    -

    Maintenance & Repair

  • do 2006 hummer h3 require a rear wheel alignment 3 Answers

    Do 2006 Hummer H3 require or even allow a rear wheel alignment.

    2006 Hummer H3 4dr SUV 4WD

    -

    Maintenance & Repair

  • Scan tool for H3 Hummer 3 Answers

    I am looking for a scan tool that will read H3 Hummer error codes on the ABS, Traction control and Stabilitrack. I have been told that the Equus 3130 scan tool will work ok on the H3 Hummer.

    2007 Hummer H3 4 Dr Base

    -

    Maintenance & Repair

  • 2007 Hummer h3 2 Answers

    I have a 2007 Hummer h3. I have had a miss and replaced the coils plugs and injectors. And check engine light went off. After three days the light came back on saying fuel cap or running lean. Wh...

    2007 Hummer H3

    -

    Maintenance & Repair

H3

Looking for a Used H3 in your area?

CarGurus has 8 nationwide H3 listings starting at $7,995.

Postal Code:

Shortcuts

Search Hummer H3 Questions

CarGurus Experts

  • #1
    cocod
    Reputation
    2,050
  • #2
    HummerGirl
    Reputation
    1,590
  • #3
    PatriciaDoss
    Reputation
    1,390
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Hummer H2
29 listings starting at $17,500
Used Jeep Wrangler
133 Great Deals out of 5,956 listings starting at $8,990
Used Hummer H2 SUT
5 listings
Used Jeep Grand Cherokee
126 Great Deals out of 3,682 listings starting at $5,555
Used Chevrolet Tahoe
13 Great Deals out of 815 listings starting at $9,980
Used Chevrolet Silverado 1500
201 Great Deals out of 7,977 listings starting at $3,000
Used Dodge Charger
31 Great Deals out of 910 listings starting at $5,995
Used Hummer H1
3 listings
Used Ford F-150
310 Great Deals out of 13,812 listings starting at $3,800
Used Dodge RAM 1500
91 listings starting at $2,500
Used Chevrolet Corvette
28 Great Deals out of 756 listings starting at $10,989
Used Ford Mustang
41 Great Deals out of 1,627 listings starting at $5,977
Used Ford Explorer
58 Great Deals out of 2,040 listings starting at $6,990

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. Content will be removed if CarGurus becomes aware that it violates our policies.