Hello,
I have a 2003 monte carlo SS and have been having an odd issue. When I am in park if i put the pedal down to about 4000 RPMS it starts missing really bad cutting in and out. Also, when I am driving if I go from a stop and put it to the floor it revs really high and will start making a clicking noise at about 4000 rpms. When I am going about 60 and give it a bit of gas it will do it as well. Basically if I drive it like a grandma and dont put the pedal down at all it drives fine, but its like when I get the rpms past a certain point it seems to be really missing. Even if I start off slowly accelerating if i step on it even a bit it seems like its missing it will like accelerate fast and then slow down then speed up. I just changed the fuel filter hoping that was it, it only has 82,000 miles on it and the plug wires "seem" fine however, i did see a little bit of rust on the top of one of the plugs and was thinking maybe that could be it. Does anybody have any ideas? I have heard the throttle position sensor is prone to going bad on these. It is consistent in the fact that =>4000 rpms it starts missing up until then it accelerates and performs just fine.

 

How's the fuel filter? Possibly not getting enough fuel?

 

I just replaced it yesterday so should be good

 

In park you have a 4k rev limiter. It could be a clogged cat, bad TPS, maybe even a dirty EGR.

 

That sounds like it could be why it cuts out in park because i was wondering if 4k rpms was the limiter anyway. Do you know if it could be the MAF , IAC or plugs and Wires? The wires look good but I did see a tad bit of rust on the top side of one of the plugs on the outside without pulling the boot off. Also, do you know if I just pull the boot off or is there any wrenching that is needed? I dont want to break my boots/sleaves by trying to pull too hard on the plugs. Also do you know of any good websites/reference material to find out how to check out all these things? I know the cat will be pretty tough to do myself but everything else seems possible. Thanks alot for the help.

 

Interesting, I know I replied to this thread last night. Well, here I try again....
You may simply need new plugs. The plugs in the car from the factory are supposed to last roughly 100,000 miles (but it's not a 100% exact number, but most people find they can go beyond that).
Before doing so, here's a few guesses (and each one is good maintenance, listed in order of what I think is the cause and I think oddly by price):
- Change the fuel filter (you've done that, so disregard)
- Change the air filter
- Clean the MAF (use the special MAF cleaner from the parts store)
- Clean the IAC
- Change the plugs and the wires (do NOT get BOSCH plugs, they are junk, stick to AC Delco or NGK platinum or irridium plugs, but BOSCH wires are OK)

If none of these items do the trick, I would explore diagnosing the fuel pump for failure (I'd suspect you're not getting enough fuel pressure at the higher RPM).

It could be a clogged cat, but excluding the I think '00-'01 cars GM extended a warranty on the cats, I rarely see the cat going bad. And if it were the cat, I think you would see bigger issues. Typically if a cat has gone bad, you can look under the car after you took it for a ride and a clogged cat will look cherry red (as the exhaust gases are heating it up).

Hope this helps!

 

Is your CEL on or does it flash when this happens? Any stored codes? At 82,000 miles I'd start with giving the vehicle a tune up (plugs/wires/air filter/pcv valve/clean MAF) and run a bottle of injector cleaner (like Chevron Techron) through the fuel system. If that doesn't help then I'd run a fuel pressure test at the schrader valve underhood. If that reading is low I'd run a second pressure test at the inlet of the fuel filter to determine if the pump or regulator is defective.

 

Well I know the cat's not completely clogged because the car would be dying just about anytime you try to climb a hill or give it a little punch. Like Maniac said, you can also clean everything in the path of the air intake (replace the filter, clean your throttle body and clean your MAF).

When cleaning the TB, REMOVE IT FIRST and then clean it outside the car, or you'll be spraying cleaner through your MAF that isn't MAF cleaner and you'll destroy it. Then clean the MAF.

I still think some carb cleaner to the EGR valve couldn't hurt, I forgot what year tended to dirty up a lot and have issues from it (I think 05)

Take it to an AutoZone to scan for stored codes (the computer can still throw a code without throwing a light on the dash).

You can also try seafoaming the car. Get a bottle of Seafoam and pour in half the can through the brake booster line and put a bottle of Chevron Techron in the fuel tank.

 

Okay that is some good advice. So just buy some fuel Checron Techron and pour it in the gas tank? I have not ever done that before. Also, where can I find the MAF and TB? I have not worked on this engine before and its a bit new to me. Thanks for all the advice.

 

The thing circled in red is your Brake Booster vacuum line where you'd pour in your Seafoam, if you choose to do that. You know where your idle is, right? Just after the air intake snorkel - that's your TB there. Just disconnect the air intake snorkel and remove it, clean it with some Carb cleaner.