I have a 2004 Dodge Grand Caravan that has developed poor acceleration and shifting issues over a period of 2 month.
Before this, it ran like a champ. I first started to notice some subtle jerking or subtly wanting to stall when driving on the highway 60+ mph Then over time I started feeling it more. I would depress on the peddle while cruising steady at highway speed to gain more speed (80mph) to pass other cars or keep up with traffic and it would somewhat jerk so I would have to let up on the pedal. It got worse and worse until one day earlier this June I depressed the pedal going up on an incline on a hot day, the trans downshifted and engine revs went up but no power and then it just died down to 20MPH and I thought that was it for this car. I think it went into limp mode but can't tell for certain. But pulled off the highway immediately, let it cool down for some hours, started back up but would only accelerate very slowly up to speed of 35 mph. I would have to depress the pedal slowly and let the van slowly work up to speed. Sometimes I would have to lift up on the pedal to get it to shift from 2nd gear to 3rd gear. This is where I'm at today. I've done many things to begin the process of elimination. Changed air filter, cleaned residue around the butterfly intake manifold, new plugs, transmission filter change, engine oil and filter change but no luck. I've gotten the car to reach up to 55mph but only after driving without stopping. It seems that it will just not gain any speed if the pedal is depressed further than 2,500 rpm. In trying to troubleshoot this issue I finally determined it is heat related. I changed thermostat to dealer OEM thermostat, new radiator cap since I found rust bits under the cap. Added coolant since I saw the radiator was not filled to the top. Then, after a few days I thought the level of the coolant inside the reservoir should move up and down a little when car is hot and cools down and vice versa cool to hot. It was not moving at all. So I took the hose off that goes from radiator (next to the cap) and connects to reservoir. Behold, it was clogged with rust. Punched through the rust carefully with a wire coat hanger and pressure washed out the rest with water. Next I figured the reservoir must have rust in it so took it off, rinsed it, reinstalled and filled it back up with coolant. The car is running a little better but hasn't solved the problem. Finally took it to a mechanic, he drove it and he said to replace the catalytic converter because it could be clogged as he monitored the temperatures at determined this would be the problem. He found no codes whatsoever. Now, I heard many with the same problem I have and replaced the catalytic converter and many many parts with no luck. Now before I go put in a cat, there's another thing I'm currently chasing down. I noticed that some relays get extremely hot and that this is not normal. The relays that get the hottest to the touch are the fuel pump relay and especially the EATX safety transmission relay. Has anyone here ever experienced any repair work related to EATX or troubleshooting with this? I went as far as removing some "non-essential" relays (blower motor relays fr & bk), accessory relay, a/c clutch relay, fog light relay, front park light relay, tailgate fuse and others, wiper relays, sliding side door relays to try to isolate the problem and see if the car ran better and it does not. I still can't accelerate faster and have to watch revs to not go over 2,500rpm so the car can continue to gain speed over 35mph. Last year the car had a remanufactured starter, front blower motor and a new battery the year before.
I'm beginning to suspect the problem could be in and around the fuse box like the FCM part # 04748479AC that plugs right into the front of the fuse box. Has anyone ever replaced this part before that resolved issues. It gets just as hot, if not hotter than EATX transmission safety relay and the fuel pump relay. Someone please point me to what I could check or do next. Thanks.