Hello everyone. I have been lurking these forums for some time now. I would like to post an issue that has been bothering me lately and killing my gas mileage.

I have a 1999 Dodge Avenger ES with the V6. It has 135,000 miles.

First off, I had a multiple misfire problem. I replaced the spark plugs and the cap and rotor. That eliminated the misfire code I was receiving when running an engine code scanner. The front three on the distributor cap had white powder stuck in the contacts.

However, in the last week, I have had a serious decrease in power. My car also stalls at every stop. This stalling slightly improved after I replaced the spark plugs and cap and rotor, but then quickly returned. I also have a very rough idle, which I also had before I replaced the spark plugs and cap and rotor. For the last two or three years, I have heard a whistling sound when accelerating. I used carb spray all around the vacuum lines while the car was running. My idle didn't increase when using the carb spray in any area.

I'm thinking maybe the catalytic converter has been going out for awhile, but now it is really bad? I have found two holes in my intake manifold. One near the EGR tube and one near the bottom of the intake manifold on the front. I know that a bad catalytic converter can send tons of heat back up to the intake manifold, which could be the reason for these holes. Any other ideas?

I also have codes that say I have high voltage on my air temperature sensor and my throttle position sensor, as well as a code stating that manifold pressure hasn't changed from start to run.

Things I have tried:

Replaced spark plugs
Replaced cap and rotor
Cleaned IAC and blocked off EGR valve
Cleaned all electrical connectors that connect to the intake manifold with connector cleaner
Ran seafoam through the brake booster line, placed in the crankcase (oil changed a day later to Royal Purple), and also ran in the gas tank.
Replaced PCV

Thanks in advance.

 

sounds like a vacumn leak on the gasket between upper and lower intake as well as a voltage issue

 

Thanks for the feedback.

You believe that a bad gasket would cause holes in the intake manifold? You didn't address the holes in the intake manifold in your reply...

The car has been running rich, which would cause unburned fuel to enter the catalytic converter. That is horrible for a catalytic converter.

Anyone ever ran a vacuum test where it pretty much indicated that it was the catalytic converter, but then after the catalytic converter was replaced, you experienced the same issues?

I guess I could just vacuum test the brake booster to diagnose the issue. I don't really want to drill another hole through the firewall...

 

Gasket since you replaced spark plugs you removed the plenum and might not got it sealed back up 100% a leak there could be the whisteling sound ...
You COULD have a bad IAC as well just cause you cleaned it doesn't mean its working properly ...

 

I stated that I have had the whistling noise for two to three years now, with very little horsepower loss. Now, after having the holes in my intake manifold, I have had a severe horsepower loss. Obviously, something is creating enough heat to cause holes in it.

I didn't remove the intake manifold until this last month. The holes in my intake manifold are within the last month or so.

 

Guess I'm not following holes in the manifold

 

http://www.taurusclub.com/forum/82-m...-manifold.html

Here is one example. Learn something new and fun every day .

 

I can see the composite melting in the taurus but not the metal on the venge

 

This is a follow-up to the original issue. My horsepower loss was from my spark plug wires being bad. After replacing them, all my power came back. It also appears most of my gas mileage has, as well. After repairs, the only code that appeared other than transmission related codes at the auto parts store was no change in map from start to run. That code still hasn't gone away. My car also still stalls ALL the time. I have sprayed carb spray everywhere and cannot find a leak. The seal between lower and upper intake is great. Any ideas?

I find it odd that I had a bad o2 sensor code for 3 or 4 years that went away only after replacing the spark plug wires. Well, according to Autozone's code scanner, at least.

Any ideas?

 

the car stalling can be a bad EGR or dirty/ bad IAC
block off the EGR and see if the car ifles better