famous loping idle problem in 3100, 3400

[IanSzgatti]

has anyone actually found out why so many of these motors end up with a loping idle? I dont need a list of why a loping idle can happen, but rather real experiance with find and eliminating the problem....

assume that the LIM and UIM have both been repaired... and no MIL present

[Superdave]

clogged or worn out injectors are the largest cause of this.

my '04 GAGT does it once in a while, i usually have to smack the injectors around a little with a screwdriver and then it stops.

[IanSzgatti]

brute force and ignorance... i like... alright... next time it's idleing like that i'll beat the shit out of them... thanks

[Superdave]

brute force and ignorance... i like... alright... next time it's idleing like that i'll beat the shit out of them... thanks

my wife took it in to the GM dealership for service when it acted up like that a few years ago, the service tech told her to smack the injectors around a little with a screwdriver the next time it happens. I guess the little ball in the end of the injector sticks if you use low grade gas. (Iowa gas isn't the best out there).

[IanSzgatti]

my wife took it in to the GM dealership for service when it acted up like that a few years ago, the service tech told her to smack the injectors around a little with a screwdriver the next time it happens. I guess the little ball in the end of the injector sticks if you use low grade gas. (Iowa gas isn't the best out there).

no kidding eh... you'd think the detergents in the gas out my way would take care of that... but i dont discount it.. i will be trying it

[PCGUY112887]

Aftermarket camshafts tend to do this as well

[RedBird]

mine does that a little....... but they have a tendency to sound way meaner on good 'ole batch-fire MPFI no 24x crank pulley ring to use to smooth the idle out.....

[Andromeda451]

Loping idle possible fix

All,

My 1999 Lumina LS 3100 had a slight lope when first purchased. The unit had 115K miles (or so) on it, I suspected a carbon lope problem. Purchased GM Top engine cleaner from the friendly local GM dealer and treated the intake to a canful. Lope cleaned up a little bit (still aggravating). Purchased Ventil Sauber valve decarbonizer and fuel system cleaner from local BAP and after a tankful of gasoline , I am one happy camper, lope was gone. Ventil Sauber is a product by Lubro-moly. I've used their products in VWs for years. At around $6.00 for a treatment it's not a killer if it doesn't work.

Rgds,
Andromeda451

[IanSzgatti]

so exactly how long have you been working for Lubro-Moly?

[Andromeda451]

Lubro-Moly shameless plug

I wish! just seems their stuff works when other miracle shytte doesn't

regards,
Andromeda451

[Juglenaut]

spark to cold, or inadequate fuel burn on 1 or 2 cylinders, weak or leaking coil. inadequate compression on 1 or 2 cylinders typically opposite in fire order, bad o2, typically more pronounced on heated applications. I have experienced several different issues related to boggy or lopy idle.

Most injectors have a sediment trap screen this can corrode or get contaminated.

[acacia052]

If you have disconnected the battery, it will reset the info in the ECM for the idle and has to reprogram the Idle control sensor. At a dealership, they do this by putting it in park, drive, reverse, over and over while setting on the brake. That and a little time in driving conditions usually fixes it. Or if you havent taken off the batt. It might be the sensor itself. You can pull it, and clean the pintle with solvent to remove any deposits, then making sure its dry so you dont fry anything, replace it and see if the idle gets better.

[lilnbody]

well i was gonna make a long post asking about this, alas i don't need to.... but am curious, does the car stall on anyone else? does it' "correct" itself after revving the car?...

[Turbo Diesel]

clogged or worn out injectors are the largest cause of this.

my '04 GAGT does it once in a while, i usually have to smack the injectors around a little with a screwdriver and then it stops.

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I'm thinking your momma smacked you around a little too much as a child perhaps.
Fuel injectors dirty/worn? Sorry, but that sounds pretty unlikely (and ridiculous) to me!

How is it that the idle loping issue can just come on all of a sudden... and vary a lot in it's occurances. It sometimes can be so severe that the car idles from about 450 to 1,200 RPM's consistantly. Other times, the damned thing can sit there and idle just fine. Additionally, the engine eventually just dies out all together at times.

I can make it go away on my 1998 3.1L V-6 just by pulling the PCV valve from the valve cover and let it hang by its tube out in the "atmosphere". Sounds like an idle air control or mass air flow problem to me. It's certainly NOT a fuel injector problem.

[LX9Power]

************************************************** **************

I'm thinking your momma smacked you around a little too much as a child perhaps.
Fuel injectors dirty/worn? Sorry, but that sounds pretty unlikely (and ridiculous) to me!

How is it that the idle loping issue can just come on all of a sudden... and vary a lot in it's occurances. It sometimes can be so severe that the car idles from about 450 to 1,200 RPM's consistantly. Other times, the damned thing can sit there and idle just fine. Additionally, the engine eventually just dies out all together at times.

I can make it go away on my 1998 3.1L V-6 just by pulling the PCV valve from the valve cover and let it hang by its tube out in the "atmosphere". Sounds like an idle air control or mass air flow problem to me. It's certainly NOT a fuel injector problem.

You do understand that this post is over 5 years old? If someone got smacked when when he was a child, that must be you.