What's wrong with my car?

August 30, 2007 1:07 PM

2004 Chevy Blazer 4x4 4dr - Sometimes, not always, for the last couple of months when I accelerate my RPMs go up (the engine gets pretty loud but I do not redline) but my car seems to not accelerate very much – Which really sucks on a right on red. It eventually will get up to speed.

Also sometimes I might be trying to accelerate and a second or two later I’ll feel the car jerk like my pressing down didn’t “catch” until then. What’s wrong with my car and is it expensive?

posted by doorsfan to sports, hobbies, & recreation (15 comments total)

Automatic transmission?

Check the transmission fluid.
posted by C17H19NO3 at 1:12 PM on August 30, 2007

It sounds like your transmission is slipping. My first recommendation would be to have the transmission fluid changed. Almost any lube shop can do this. It's not expensive at all, and it will probably fix the issue.

If that doesn't fix it... things get a little worse. But dirty fluid tends to cause exactly the problem you describe. And in a 3 year old car, it's likely not been replaced unless it has been maintained regularly.
posted by ninjew at 1:14 PM on August 30, 2007

Standard transmission? Could be the clutch slipping. If so, it'll have to be replaced. (But that doesn't seem likely for a 3 year old car, unless you've really been abusing the clutch.)
posted by Steven C. Den Beste at 1:14 PM on August 30, 2007

Assuming it's an automatic, check the fluid level in the transmission. My guess is that it's low, and bringing it up to the mark is all that you need. DO NOT OVERFILL. Check the level with the car well warmed up, on a level surface. Use the correct fluid to refill.

If that's not it, I'd go to a shop. There are inexpensive adjustments that a transmission shop can make which may help.
posted by anadem at 1:14 PM on August 30, 2007

Awesome - I love this place! Thanks for the direction.
posted by doorsfan at 1:18 PM on August 30, 2007

There are inexpensive adjustments that a transmission shop can make which may help.

And there's horrifically expensive issues that can cause the same thing, so if anyone tries to sell you a new transmission make sure you get a second opinion before you commit - no reason to spend $4000 unnecessarily because your first mechanic was lazy/stupid.
posted by phearlez at 1:37 PM on August 30, 2007

I hate to make a silly suggestion, but that behavior is almost exactly what happens when I run the air conditioner in my very under-powered car. "Last couple of months"=summer, you know. Do you have the same problem when the AC is off?
posted by MrMoonPie at 1:41 PM on August 30, 2007

Intersesting MrMoonPie...
I can't say that it has happened with the air not on but here in Texas I do not know when I might be able to test that theory. Next time I feel it i'll quickly cut the air. Would that be a battery or alternator issue then?
posted by doorsfan at 1:47 PM on August 30, 2007

With my car, it's a horsepower issue--my little 100 hp engine just can't accelerate and run the AC at the same time, at least, not very effectively. I wouldn't really expect a Blazer to have the same issue, but I thought I'd throw it out there as a possibility.
posted by MrMoonPie at 2:09 PM on August 30, 2007

Doorsfan, air conditioning has its own compressor run from the engine, usually on the same belt as the alternator. When air conditioning is running, it's using mechanical energy from the belt which loads the engine and leaves less power for the wheels.

Conservation of energy, you know? Energy used for air conditioning can't be used for anything else.
posted by Steven C. Den Beste at 2:24 PM on August 30, 2007

Transmission fluid, check that first. Secondly if you notice engine lugging at a stop or transmission shudder at lights, that may also be the torque converter portion of your transmission going.
posted by clanger at 2:52 PM on August 30, 2007

Do you mean Trailblazer?

If so: My 2002 had the exact same problem, especially in colder weather. RPMs up for about 10 minutes, engine roaring, hard acceleration. The fan clutch was faulty (which explained the cold-weather trigger) and cost ~$600 to fix. As far as I know it's a known issue with the car, but no recalls have been issued. I complained to Chevy corporate anyway and was able to get about 2/3 of my bill refunded.
posted by phatkitten at 3:31 PM on August 30, 2007

"With my car, it's a horsepower issue--my little 100 hp engine just can't accelerate and run the AC at the same time, at least, not very effectively. I wouldn't really expect a Blazer to have the same issue, but I thought I'd throw it out there as a possibility."
posted by MrMoonPie at 5:09 PM on August 30 [+] [!]

Since about 1962, all automotive air conditioners have been equipped with a throttle position or vacuum sensor, which acts to cut power to the electrically operated air conditioner compressor clutch, to stop the air conditioner from sucking power during hard acceleration, or passing demands. On a 2004 Blazer, that function is going to be done by the Throttle Position Sensor, and some logic in the engine control module. The TPS has to work for the vehicle to run. The likelihood that the air conditioner clutch bypass isn't working is very small, but not zero. If you know what to listen for, you can hear the AC compressor running, punch the throttle, and hear it cut out immediately, and then cut back on when you ease off the throttle. If it's doing that, as it should, you're not losing power to AC, and your hesitation is probably transmission related.

If you have an automatic, you probably not only need the fluid changed, but you need the transmission filter changed, too. Dirty fluid plugs the filter pretty fast, and the result is low internal pump pressure, which will cause slippage on the internal clutches, and failure of the torque converter to "lock up" into gas saving mode at highway speed. Usually done as part of a proper fluid change, where they drop the transmission pan, change the filter and pan gasket, and change the fluid. Paying a little extra for a machine assisted fluid change, which will extract the quart of fluid in the torque converter usually missed by a simple gravity drain of the fluid makes sense, too.
posted by paulsc at 3:40 PM on August 30, 2007

Replace your spark plugs while you're at it. It's a cheap way to revive some power to your engine.
posted by idiotfactory at 4:34 PM on August 30, 2007

Just in case anyone comes back...
It was the fanbelt. It actually broke on me last night. I have to replace the belt (I only have 1) and the pully (original belt melted ruining existing) AND may have to get a battery.
So I am getting out for what looks to be $300 but at least I am able to correct the real problem once rather than paying for 1 try after another.

Thanks though for everyone's help!!!
posted by doorsfan at 9:52 AM on September 7, 2007