Jerky Movement

Tiny
DAVEHINDS
  • MEMBER
  • 2003 GMC ENVOY
  • 120,000 MILES
When I am driving my GMC Envoy SLE, I notice that from time to time, there is a sudden slight*****. It is most noticeable whenever I am approaching an incline.
Friday, October 7th, 2011 AT 2:31 PM

2 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Sounds like a spark plug or coil breaking down under load. Could also be something with the transmission like the converter going in and out.

You need a shop to at least road test it for you to verify and get a bid.

Roy
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Friday, October 7th, 2011 AT 2:40 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
Went thru same deal w/ '03 Ford Escape

Repetitive, fast hesitation, lasting 1-2 seconds, more evident climbing a incline, while slowly administering gas. Random or none on level ground.

---No codes --- cleaned 1st, and/ or replaced the following

New Plugs. Then "genuine plugs". Bah-Hum-bug, nothing WAS wrong with the other new ones, I just installed!

Boots and springs

air filter

MAF

EGR

A new IAC (JUST for Giggles!)

Mega Vacuum leak search several times.

Fought with wife many times over situation, 2+ months!

I really hated taking off the "Plenum" so many times to access the other 3 cylinders

Each part seem to fix it for a day or two.I did not mind replacing the suggested parts, as I am all for "PM" and she's got 100,000 miles on her rig.

The final cure was #3 misfiring (lucked into the correct cylinder) I was gonna swap a new coil pack down the line, till it stopped HESITATING. THEN I CAUGHT A BREAK!

#3 was the ticket!

I had tried to get the Technical school to ride me with their portable machine---things did not work out, with their schedule.

I went to a salvage yard to get a used pack ($10) to swap around, TO SEE IF THINGS CHANGED, then I was gonna buy a new one if solved the problem.

So happened, the salvage yard guy had a machine, in a stored code, it said #3 had misfired. My little scanner could not tell me that!

Runs perfect now, with the New $79 Coil Pack!

THE OTHER PARTS I PUT ON, I SORTA CONSIDER PREVENTATIVE MAINTENANCE, (I NOW HAVE SOME SPARES FOR FUTURE TESTING. HER RIG DOES HAVE OVER 100,000 MILES.

I WILL DO ANYTHING TO AVOID THE DEALER OR A BIG SHOP, I FEEL NOT ONLY DO I HAVE IF FIXED, EVEN WITH THE UN-NEEDED PARTS (NOW INSTALLED).I'M SURE I CAME OUT TO THE "GOOD", COMPARED TO, IF THE DEALER REPAIRED THE COIL ISSUE ALONE!

The Medic
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Friday, October 7th, 2011 AT 8:58 PM

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