Problems with my 99 Dodge Avenger 2.5l V6

[avenged1]

Currently I am having a consistent problem with my 99 Dodge Avenger 2.5l V6 automatic.

My car has 50,000 miles on it, with a recently changed fuel filter. My mods on the car are a AEM cold air intake and a magnaflow mirror finish muffler.

Here is what is going on with my car. The car starts and idles fine. When sitting still the rpms don't jump up or down. I am having problems on top end. When I accelerate the car shifts fine, but when the car shifts into 4th gear (overdrive) and the rpms reach around the 4,200 to 4,500 rpm range it feels like the car hits a brick wall. The rpms hit around that mark and drop down and it takes forever for the rpms to even go over 4,500 rpms. Even if I floor it, the car barely goes over 4,500rpms. The only way I can get it to go over that mark is to let off the gas and hit and pump on the pedal hard.
The car redlines at 6,500rpms. The shifts from 1st, 2nd,3rd all go to around 6,100rpms just fine. The problem is when I am accelerating or I give the car some gas and it downshifts fine but when it goes back into 4th gear.

My car didn't used to do this. I have taken my car to the Dodge Dealership and they weren't 2 helpful. The technician said that since I had an aftermarket air intake and exhaust, the car was getting in and out too much air. He also suggested I get bigger injectors. I kept my mouth shut and didn't say anything. I don't need bigger injectors unless I go forced induction or N20. My car worked fine for over a year with my mods and no problems until now.

I have had several people tell me that my problem is fuel related. My question is how do I know. I don't even think the tech checked my fuel pressure or scanned the car for codes.

What problems could this be. A faulty fuel pump that is shorting out, loss of fuel pressure, bad fuel pump relay? I am also going to change out the spark plugs and wires, distributor and rotor. What other things should I look for. I don't really hear any vacuum leaks.

Sorry for the lengthy post, but if anybody has any ideas, suggests, or comments I would greatly appreciate them.

Brian

I also have this post in the fwd section.

[rumblefish360]

avenged1 / Brian

Long posts may be harder to read, but it sure beats not getting enuff info. You did the right thing by posting a long one. (Smart)
Also posting in the other section was wise.

Just for kicks, puy the old box on and see if it works.
For a serious look, run the codes. This where I believe you'll solve your problem. Nor do I think it's the fuel pump. If it revs that hi in other gears it should run that hi in the last one. (Gear) Can you check the pressure?
I think it MIGHT be computer related.
I don't think you need bigger injectors ethier. The tune up is a good idea anyway.
The newer cars are hard this way for us ol'time iron junkys. There are a few shop owners/mech's here. Give it a few for them to chime in.

[dewme5]

what speed is that wall coming at? with camaros and some other cars, there is a speed limiter factory installed, unless you paid for the z rated tires from the factory. I don't know much about the avenger, but could something like that be the case?

[avenged1]

Well the speed where that wall comes in varies. Mostly around 80mph range. I have had this car up to 130mph with no problem. Now it seems so hard to get past 80mph. The speed limiter on the Avenger normally comes in around 125-135mph depending on vehicle. I also tried the speed limiter bypass mod and it still felt like I was hitting this wall. The car will go over 80mph. Not that I do 80mph or faster all the time. I do like to open my car up every once in awhile but I can't really do that now. There are so many sensors on the car. I have already tested the TPS and it was okay.

The car didn't use to do this. I have tried everything from taking off the battery terminal wires and re-setting the computer but with no luck. I kinda think it is a sensor or a computer problem. Maybe the computer is registering the rpms high and causing the car to lose power. I am going to the dealer or parts store to get an adaptor so I can tap in and check my fuel pressure.

Oh I forgot to mention that the tech at the dealership said that my car was running really lean under certain conditions. The car runs pretty rich at idle and I can smell it. Somebody said it could be the fuel pressure regulator that is causing me to run rich at idle and lean with a load.

Thanks again everybody for suggestions and comments.

[MoPaul]

Alas, the 50k mile wall hath claimed another victim!
Fear not, this is a creature often seen. I would say about 50% of the 2.5's on the road have had to face the horror. Try the Avenger/ Sebring Owner's Group, located at www.asog.net for the solution. I rarely go there anymore, but there is always this discussion. I didn't have to face it, but mine may just be a dogsled anyway. I have never tried to find out, 85-90 when not paying attention in Arizona was the highest mine has been.
I do have a little quesion about your post, though. The "getting past 80" thing just seems a little odd, since 3rd gear will get you over 115 @6000. Please keep in mind, I am feeble minded and easily confused. It just struck me as odd. Could you clarify, please. Good luck to you.

[avenged1]

I have been a member of ASOG for quite some time. I am also avenged1 on ASOG. I just signed up to this group recently after finding it doing using a search engine (www.google.com).

My car used to take 3rd gear all the way to around 100mph range. It doesn't do that anymore now. I have asked on asog and most people say I have a fuel problem. I am still trying to figure what is going wrong. I am going to take my car and have a different dealership look at it. I wonder if reflashing the computer will help?

I am just kinda stumped right now. I am going to try a tune up, and measure the fuel pressure.

Thanks again everybody for the replies.

Brian

[gsmopar]

Keep us posted. My fiance's Avenger will never see 130, but I'd like to be proactive when you find the solution.

Thanks,

Greg