2003 ss cuts out when putting pedal to the floor.
 

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.

http://i1087.photobucket.com/albums/...akebooster.jpg

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.

Just my input, many members have "seafoamed" their engines, I have yet to ever do that.
My experience with "injector" or "fuel system" cleaner is that it does not do anything (or at least at the point you think you need it). But I've heard rumor from a mechanic, when you think you need it, give the car about 3 bottles at once with a full tank of gas. It will not harm the engine (as it's mostly alcohol based which burns cleaner then gasoline, so I am told).

I still recommend following the items I outlined earlier. All easy to do and even if they don't fix the problem, they are low cost and worth while maintenance.

Among what everyone else mentioned about cleaning sensors, etc. and the possibility of needing new spark plugs or wires, you may have a bad ignition coil pack too. It's a relatively common issue on the 3800.

I've worked with those ignition coils for years (they are the same from the '94 3100 up to end of production 3800 Series III and 3400 engines). My experience, they rarely fail (I have worked with some that have failed, but it's VERY uncommon). And if the coil has an issue, most the time it's a "dirty" connection (take the plug wire off and the tip on the tower for the coil is rusty, try cleaning with a scotchbrite pad first before replacing).

I know cars running the factory original coils and pushing 200,000 miles or more. My Grand Am is excluded, I upgraded it a while ago to junk yard salvaged L67 coils. Prior to the L67 coil swap, it did have one factory original coil fail prior, replaced with a AutoZone what-ever-brand coil that failed about a year or so later (replaced with a spare factory coil and about a year later the L67s). I'm guessing the car was in the 130-150,000 mile range when it had a coil first fail.

All excellent advice. Thank you so much for all your input. I believe I need to remove the grey engine cover for me to be able to get to the MAF as I believe I have located it. Is that difficult? Also if there is rust on the top side of a spark plug, do you think that plugs could definitely be an issue? I am worried about having to try and get to the rear plugs they seem like a pain. Do you guys have any advice on how I should get to them and remove the grey engine cover that has like the 3800 v6 writing on it? Sorry if I seem a bit uneducated, I have not worked on a car since my 1992 nissan and this engine is quite a bit more advanced than that one and its been a while. Its a really nice car and I do not want to mess anything up, but I am pretty comfortable working on cars/boats and such. I just want to make sure I know any tricks/hints before i dig down into it.

- Remove the cover by twisting the oil cap, once it's loose and you can lift up, keep twisting to now twist the filler neck from the valve cover (might be a bit tight and take some wiggling).
- After that, gently lift the front of the cover and slide it back, should come off EASY!

As for the plugs and the "rust". If it bothers you, get a can of PB Blaster, with the engine cold spray them all and let the car SIT. If it helps build confidence, my wife got a '05 Impala (3400 v6) in December of 2010 with 150,000 on it and ORIGINAL plugs. All of them had a little rust on the nut. I don't even think I PB-ed them, I just went at it and I got lucky, they all broke free.

- When putting new plugs in, get a little Anti-Seize/Never-Seize (whatever they call it). Just a dab at the start of the threads. Helps ensure future plug changes go EASY.
- Make sure the new plug boots have some die electric grease, helps ensure the plug boots come off easier in the future AND helps protect connections from moisture.

- Back plugs. If you don't have a California emissions pump, and you can work by "touch", you should have NO reason to rock the engine forward (as some do). I've done it, no big deal.
- Worse part about ANY of the plugs is the metal heat shields on the boots. You can't get a good grip to twist and wiggle the boot itself. If you have trouble, get small vice grips or channel locks, grab what IS exposed of the boot and twist it good and pull back and it should come free.

Oh that is verrry helpful! thank you! I think I may have a fuel pump very close to going out. I did find a weird symptom today. When I parked facing down a hill for about 4 or 5 hours I went out and started my car and it was making a really funny noise kind of like a fan going bad or something like that. Then, when I started driving and leveled out, the noise quit. Can you hear your fuel pump like that? or would a bad fuel pump make a noticeable noise?

Fuel pumps by nature make a slight "hum". You might notice it slightly when you first start the car. BUT, if it's a loud hum, it can be a sign of it failing. OR, I had an instance where a disconnected vacuum line caused my fuel pump to run REAL loud (found the line quickly, so that was a plus).
If the fuel pump fails, GM does provide an access hatch on the 2000+ Monte in the trunk (between the seat and spare tire well).

Also remember, the way the pump is designed, it uses the fuel in the tank to "keep it cool"!! That's right, the fuel is the cooling agent for the pump. I've heard on older GMs with this design concept, people found pumps failing MORE when they tend to run the car until it's bone dry ALL the time. Now, I've never heard of that in a 90+ GM (heck, my '94 spent a couple of years with the fuel being at half a tank at most, no pre-mature fuel pump issues).

Actually, I started the car and noticed the noise. So, I lifted the hood and found out that when I tapped the radiator it quit. So, my radiator fans may be going bad and it is a completely separate issue from the one I have been asking about, I am going to get it diagnosed tomorrow because I dont have the tools to check the fuel pump and other issues.