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Ok.. So I drove my car to work today without a problem. But when I left work after a massive rain storm, the engine made a weird sound (it sounded like the intake wasn't on the throttle body and the engine is lacking horsepower, not much.. but noticeable).

I pulled over a mile down the road in someone's driveway and checked the engine.. It didn't have any leaks, the air filter wasn't wet and the piping was still connected without any gaps/air leaks.

It sounded like there was no filter on the car during any acceleration. It has been doing it ever since I left work at 3pm and I’ve drove it a good amount after with no change in noise. Even my friends could tell it was lacking power and sounded different.

Sorry my description is very limited. I think I’m going to take a better look at it tomorrow and see if I can get a better description on the problem.

IMO = It sounds like an intake problem from what I see. I wonder if the air/fuel ratio is off. Almost like its running way to lean (now that I think about it)

any idea's/suggestions will be great!

Thanks
-Chris

I would suggest checking your Plugs, your oil, and make sure you don't have a loose ground. How long has it been since your 02 sensor has been replaced? Check all of these items, if everything seems normal and you are still having the problem then take it to a professional. It's better to spend the 80 for a diagnostic to find out the problem than to replace a bunch of parts that don't need to be replaced. IMHO Good Luck

Yeah ill have to check all that.

I just replaced the spark plugs and did the oil about 500miles ago.

Could be an 02 sensor, ill have to look into that.

Thanks
-Chris

Also check the cat converter. If it decided to suddenly fail, you will have no power, and the engine will bog, making the intake sound louder. Don't laugh, I have had the honey comb in the cat flip sideways on another car I had. It went from fine, to max speed of 60 mph @WOT in a matter of seconds.

Possibly something crawled up your tail pipe to escape the rain?

I know that one is wide open.... But it could happen.

If you pull the o2 sensor and leave it connected/tied out of the way and drive it, and power improves, it is exhaust related. You would be amazed how much difference that little hole makes.
If it makes a difference on a 350 chevy truck, a 4 cyl should do better.

Yeah, ill have to look into that.

Right now its still driveable.. So im going to drive it. But once i get some more money in the pocket. Ill be looking into checking the 02 sensor and the cat converter.

thanks guys
-chris

Maybe water got on your exhaust? If you have an aftermarket exhaust, and it gets wet, it could distort and sound super weird. Mine will from time to time.

is that possible that some amount of water is sucked into the engine and the engine is still running?

esfan wrote:is that possible that some amount of water is sucked into the engine and the engine is still running?

It'll usually evaporate during combustion, unless it fills up the combustion chamber. Then, refer to my avatar.

Im pretty sure i have a clogged cat..

When i come to a stop, the RPM's drop slowly almost as if the exhaust is having a hard time leaving the engine.

I know water didn't get up in my exhaust and if a good amount of water got into the engine and is still there.. im pretty sure i would have a picture in this post just like ZC's avatar..

Thanks everyone!
-Chris

Chris definitely let us know how this turns out for you. I am interested to figure out what it is myself.

Yeah no prob. I just need to get some money saved up for a new cat and time to install it. Ill let you all know.

I'm leaning towards the cat being bad as well. Easy test? Drop the cat and hang it out of the way and drive it. It will be loud as hell, but you'll know soon enough if that is the problem

Wasn't there a way to run it at night, and if it heats up cherry red its a good indicator that its bad?

Haganracing wrote:Im pretty sure i have a clogged cat..
When i come to a stop, the RPM's drop slowly almost as if the exhaust is having a hard time leaving the engine. -Chris

But see, that part just doesn't make sense. If the exhaust was clogged, the rpm's would drop fast. You would have a good engine brake with a clogged exhaust.

IDK if the IAC would try to compensate for that kind of load.
A sticking open/slow to close IAC would make the throttle response a little quicker, not slower, so that is out too.

either the cat or the o2 sensor and do as DANTENEON said easy way to tell

occasional demons wrote:

Haganracing wrote:Im pretty sure i have a clogged cat..
When i come to a stop, the RPM's drop slowly almost as if the exhaust is having a hard time leaving the engine. -Chris

But see, that part just doesn't make sense. If the exhaust was clogged, the rpm's would drop fast. You would have a good engine brake with a clogged exhaust.

IDK if the IAC would try to compensate for that kind of load.
A sticking open/slow to close IAC would make the throttle response a little quicker, not slower, so that is out too.

Wait.. if the exhaust is clogged, the rpm's would drop fast?? In first gear?? I would think the restricted flow would make rpm's drop slow because it takes it longer to get out of the piping.

Ive had a rough few days... IAC??

Edit: would the check engine light come on if the o2 sensor was bad?

V.95srt wrote:either the cat or the o2 sensor and do as DANTENEON said easy way to tell

Now thats thinkin with your dipstick, jimmy.

Haganracing wrote:

occasional demons wrote:

Haganracing wrote:Im pretty sure i have a clogged cat..
When i come to a stop, the RPM's drop slowly almost as if the exhaust is having a hard time leaving the engine. -Chris

But see, that part just doesn't make sense. If the exhaust was clogged, the rpm's would drop fast. You would have a good engine brake with a clogged exhaust.

IDK if the IAC would try to compensate for that kind of load.
A sticking open/slow to close IAC would make the throttle response a little quicker, not slower, so that is out too.

Wait.. if the exhaust is clogged, the rpm's would drop fast?? In first gear?? I would think the restricted flow would make rpm's drop slow because it takes it longer to get out of the piping.

Ive had a rough few days... IAC??

Edit: would the check engine light come on if the o2 sensor was bad?

Typically your check engine light will come on. But there have been occasions when I have had O2 sensor die without a check engine light. The RPMs will drop fast due to the inability to push out all of that exhaust creating more back pressure than the motor needs. So unless you continue giving it throttle, it will try to choke and die. Think of it the same way if your intake was clogged and not getting any air, it would rev slow and want to choke and die. So when your on the throttle continuously pushing air through the exhaust the circulation remains current, but when you let off the circulation become restricted and harder to push out. So it slows your motor down faster. It's practically bogging you down. Thats my little theory in a nut shell. Enjoy.

Ok.. the engine went back to sounding "normal" without doing anything

But it also came with valve rattle when i turn off the car...

*palmface*

Haganracing wrote:Ok.. the engine went back to sounding "normal" without doing anything

But it also came with valve rattle when i turn off the car...

*palmface*

That's FacePalm!

I suspect a lot of carbon build up. Possibly the exhaust ports were so clogged with carbon, it was not able to breathe well enough.

I had to do a valve job on mine due to carbon weighing the exhaust valves down, causing the guides to wear out of spec. The exhaust ports were clogged to less than half their size.

But it ran fine.

My troubles were more after I got it reassembled. with the Mag cam, and open exhaust ports, it took the PCM 700 miles to finally make some power.

Get 2 cans Mopar Combustion Cleaner and run one through the TB after warm up. Pull the plugs, and spray the other into the sparkplug holes. Turn the engine by hand, (front crank bolt)to push some out into the port area. Let sit about 4 hours/more.

Now with the plugs still out, crank with the starter. You may want to put a towel with something to hold it in place over the holes.

Once it has expelled the excess goo from the cylinders, reinstall the sparkplugs. If they are pricey ones, get a cheap set. Start up the engine, and enjoy the smoke cloud.

Run until clear. Change oil/filter.

This should cure the spark knock after shutdown. Will it run any better? Maybe.

This will cost about $8 per can, plus plugs, oil, and filter.