Acceleration, hard shifting, low RPM issues

[DanKoloff]

Hello,
I have a 2002 Windstar . It had an issue with low RPM while idling so I've decided to clean the IAC valve and the throttle using a crc throttle body cleaner. I accidentally opened the TPS that clicked. I put it back together and since then I have slow acceleration (I literally press the pedal to the floor and nothing), hard shifting between 1 2 and 3, and it still has low RPM while idling (not as much compared to before tho).

I tried several positions of the TPS because I honestly thought that was the issue but it did not have any effect. At this point I am not sure what to do. I read some person online suggest that it could be a clogged EGR valve but i wanted to confirm first with you.

I would appreciate any asap ideas because it's my only car and I need t for work.

thank you

[tomj76]

If you think its the EGR, then it is probably stuck open (for those symptoms). Test the manifold vacuum with a gauge. At idle it should be about 20-24 inches of vacuum. Also check if you can make the situation change by manually activating the EGR through the vacuum control port.

This link describes how to diagnose EGR issues:

http://easyautodiagnostics.com/ford/4.6L-5.4L/how-to-test-the-egr-system-1

"Rough idling, hesitation, poor performance, weak vacuum and backfiring all seem to indicated that the EGR valve is at least partially stuck open. Additionally, you can hear what sounds to be exhaust notes coming from the open throttle. Lastly, applying vacuum to the EGR valve has no effect on it."

Also I found this"

"When I accelerate my engine struggles to get up to speed or slows down near idle when im trying to go but its not the transmission so what should I consider now to resolve my issue?"

"It was a faulty fuel flow sensor thing nothing more than needing to be cleaned and the issue with the idling was fixed thanks for the help Shes happy now so i assume its good"

[DanKoloff]

Thank you Tomj. I bought an OBD 2 scanner to narrow my assumptions down, and it turned out to be the TPS sensor It was a P0122 code Windstar. A post online suggester that it could be a burned fuse or the sensor itself got fried. I checked the fuses and they were all right. (I found the car's manual and found out the purpose of each fuse). I believe it was fuse 19 or fuse 20 from the higher voltage fuses under the hood, besides the battery (that box was very difficult to open. I had to remove the + from the battery and half of the air intake pipe and pushed the plastic edge with a thin screwdriver. But the thing is, that these two fuses are responsible for other things too, so if the rest of the things are working fine initially, there is no point to try to open that fuse box.

So, I went to the store to ask for a new TPS sensor and I was told that it costs $70. So I decided, instead, to get it for $15 from the local junkyard. If other people read this post, I'd recommend to be careful from what car you are picking up the sensor. If it had transmission issues, you may be transferring a part of that transmission causing issue to your car. Just be mindful. Since I changed it, it is working a lot better. The acceleration came back, transmission's hard shifting is almost non-existent, and the RPM is way better. Before you change the TPS sensor, make sure to unplug the battery first. Put the new sensor and attach the cable for it. Then re-attach the battery.Sorry for being so anal, but if someone else has similar issues, this post might help them.

[tomj76]

A scan tool is indispensable for modern auto repair. I have one that reads live data which is also great help. I only wish that I could read the manufacturer's custom PIDs to get even more information.... maybe soon.

The TPS is a resistor network, so if you have an ohm meter you should be able to diagnose a faulty one and/or check a used one. I once disconnected it on a a different vehicle (it has drive by wire throttle control as well as the TPS) while it was running, which caused all kinds of crazy behaviour until I shut it down. It still acted up when I restarted the engine until I turned off the engine and removed the key. Then the computer recalibrated the TPS and it worked OK.

There is also a TRS (Transmission Range Sensor) that sometimes fails (also a resistor network) and causes the PCM to control the transmission in erratic ways.

Glad you found the real problem without throwing parts at it.