Weak Engine

[phewop118]

My Intrigue seems to have lost the pep it once had. I only have 76k miles on it. When I push it for a downshift into 2nd at highway speeds, it revs fine, but it doesn't seem to pull like it should. When it shifts into 3rd and the revs drop, it then pulls a little better. Same goes for low speeds. I don't have very much power and probably can't spin tires in a straight line anymore. I do have an exhaust leak some where around the middle of the car. Not sure if it's the CAT or resonator. I'll check soon to see. I changed the fuel filter a few months back, so I know it isn't that. Perhaps the PCV? or an O2 sensor? Do we have EGRs on the 3.5's? I'm not getting an SES light, so whatever it is isn't too far out of spec. I haven't changed the plugs yet - I figured I'll go to the 100k mark for that. Any suggestions?

[GTP Dad]

At 75K miles changing the plugs would not be a bad idea. This will give you a good idea of what the combustion chambers look like and if they are burning correctly. Bad plugs can be an issue that will cause poor performance especially if they are burnt or damaged. Stick with a platinum plug but don't spend money on Bosch stay with AC, Autolites or Champion. Any of these are acceptable although the AC is OEM.

The other possibility is a partially blocked cat. Try the plugs first and if performance does not improve the cat will need to be looked at. Also the other thing to check is fuel pressure. If the fuel pump is not performing up to standard and not maintaining fuel pressure then reduced performance can occur. Go ahead and change the fuel filter again since it could be partially blocked, especially if the fuel pressure is low.

[panzer dragoon]

change that tranny fluid. I believe your fluid is roached (cooked) from all the hard driving.

[phewop118]

I changed my tranny fluid about 15,000 miles ago, along with all four rotors and pads and a coolant flush.

[Jimmy Olsen]

Originally Posted by phewop118

My Intrigue seems to have lost the pep it once had. I only have 76k miles on it. When I push it for a downshift into 2nd at highway speeds, it revs fine, but it doesn't seem to pull like it should. When it shifts into 3rd and the revs drop, it then pulls a little better. Same goes for low speeds. I don't have very much power and probably can't spin tires in a straight line anymore. I do have an exhaust leak some where around the middle of the car. Not sure if it's the CAT or resonator. I'll check soon to see. I changed the fuel filter a few months back, so I know it isn't that. Perhaps the PCV? or an O2 sensor? Do we have EGRs on the 3.5's? I'm not getting an SES light, so whatever it is isn't too far out of spec. I haven't changed the plugs yet - I figured I'll go to the 100k mark for that. Any suggestions?

My 2 cents is that you have serious deposits on your valves. What brand of gas are you using? Chevron is the best. Get some Techron additive and see if that makes any difference. Try some premium gas also from a tier 1 supplier. Could be that your gas has a low octane and the engine is being retarded to prevent pinging.

Also, I have found taking long road trips where I drive all day really improves the performance of the engine, especially if I use Chevron gas.

[LittleHoov]

A good thorough tuneup would be a good place to start. You might clean the throttle body and maybe run some SeaFoam through it to clean things up a bit.

[Solonys]

Careful with the SeaFoam, it will eat yer paint! Use a funnel if possible.

[prsoto21]

I agree with LittleHoove. I sprayed sea foam into my throttle body and the car ran great after words. Send me a PM if you want to know how I did it.

[Jimmy Olsen]

Techron is the best product on the market for removing deposits from valves and cylinders. Chevron spent a lot of money to develop it. The other products you see at Auto Zone or Wal-Mart are just re-formulations of chemicals that have been on the market since man invented the carburetor.

Getting back to gasolines, the cleaning additives that gasoline suppliers put in the gas makes a big difference over time in the performance of the engine. Shell puts 2X the minimum required by federal law in its regular and 5X in its premium gas. Many of the "cheapo" independent stations that sell gas for a few pennies less may not put any additive in since nobody is checking the gas, thereby actually making more in profit per gallon. (And leaving you with a engine that doesn't have good performance). Shell has a good additive for keeping the valves and injectors clean but not as good as Chevron.

Another thing I do to keep the fuel system clean is to add a gasoline stabilizer called Sta-Bil to my gas tank before adding gas, about 1 or 2 ounces per 10 gallons of gas. Helps keep the gas tank from getting gummed up and cleans the injectors also. Gas that has been sitting in the gas tank for a couple of months starts to form gum and collect water and doesn't provide the maximum level of combustion. Never put any other products (except alcohol water removers) in the gas tank.......just asking for problems down the road.

Also, I add a few ounces of "Marvel mystery oil" to the crankcase about 50 to 100 miles before changing the oil....helps to dissolve and get the sludge out of the engine.

[LittleHoov]

I actually meant running Seafoam through all of the various things that you can run SeaFoam through, like the gas,oil, and top-end...be careful with the oil though, I wouldnt run it through there very long. But cleaning the throttle body is usually a good idea, it can get gummed up in a hurry.

[phewop118]

As for gas, I usually use Amoco (from the local CoGo's). If I'm near a Shell station, I always get some gas from them, but there happens to be only one that I know of in the 50 mile radius of my home. I won't buy crappy gas, such as Kwik Fill or GetGo.

You guys saying I should get an injector cleaner that I add to my gasoline? OR should I get something to go into the oil? By the way, I run Mobile 1 synthetic extended performance and change my oil every 5-6k miles, usually before the light comes on.

Prsoto21 I'll pm you to find out how you cleaned your throttle body with Seafoam.

What about the MAF? should i clean it? When I get a tuneup, should I have them change the O2 sensors, too? By the way, I'm taking it in tomorrow. Hopefully I'll find out where the leak is in my exhaust and if that could be causing some power problems.

[LittleHoov]

Changing the o2 sensor in the exhaust manifold might not hurt, I was under the impression you were doing the work yourself. Having someone else do it and not really knowing what the problem is can get expensive in a hurry.