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4 Wheel Drive/SUVs/Loss of acceleration / CEL on


I have a 2005 GMC Envoy SLT and recently my CEL has come on. It has loss of acceleration while driving. There is transmission fluid in the vehicle. What kind of mechanical problems may I be facing ?


The CEL light can come on for a multitude of reasons, usually a sensor related to smog control.  Not sure what you mean when you said that there is transmission fluid in the vehicle.  It sounds like you may have a broken transmission fluid line and, somehow it is squirting fluid.  I would check the fluid levels on the transmission, and the transfer case.  Also check under the vehicle for any leaks.
If you don't find any low fluids, or leaks, I would take it to a reputable shop, and have it scanned for error codes, to see what caused the CEL to come on.  The code scanner will give you an error code, or may tell you directly what caused the problem.
If your loss of acceleration is caused by a loss of power, it may be an engine problem.  If the engine is revving higher than normal, then the transmission is probably slipping, and may be the problem.
I wouldn't drive it any more than you have to, to prevent further damage.

I know that this is more of a general answer than you would like, but without actually checking out the vehicle, it is very hard to diagnose these problems.


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Carl Brandt


Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles, and I suggest that you obtain a repair manual for mechanical problems and do some research before asking your question. Most mechanical questions can't be answered completely without looking at, or listening to the vehicle in person.


40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Certified off-road instructor - Certificates in engineering/electronics

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