91 Exlporer High Idle And Tranny Issue

[91_XLT]

Hi, I have a 91 Explorer that has around 235,000 KMS on it. I replaced the alternator about a month ago (used one) and everything seemed to be ok. I was on the highway today and was cruising at 100kms/hr when I noticed the tranny seemed like it was slipping, rpm's going up and then would come down again. Before this the engine was idling a little bit rough but not more that usual. I thought it was the cruise control at first, then I shut off the cruise control and pressed the gas manually and still the same thing. When I got off the highway I noticed the engines RPM's were about 200 higher and it was idling around 1000. When I got home and put it in park the rpm's just went even higher to 3000 and stayed there. I turned the motor off and when I went to start it again it cranked over for awhile until the battery died, which maybe took about 15 seconds. I know the battery is not in great shape and the alternator is charging properly because I put a volt meter on it.

Any suggestions ?

Thanx in advance.

 

[Howard]

At a complete guess I would say to check the vacuum modulator. The vacuum leak could be causing the rev increase. Check the pipes for atf ingress.

 

[slag]

after checking your vacuum modulator, take the tps off and test it.

I bet your TPS is going bad. It affects your torque conver lockup, tranny shifting, and idle rpm

 

[91_XLT]

I'll Have a Look

I'll check out the modulator and TPS sensor. I noticed when the truck is hot and I go start it up again that the starter keeps draining my battery. I have tried another battery and the same thing. I have removed the starter and will get it replaced as well. I have not noticed any vacuum leaks anywhere. I went to start it up again this morhing and it was idling fine again.
Could the starter be drawing from the battery and causing all these issues ?

Hmmm, I will see what happens when I replace the starter.

Thanx for the info guys !!

 

[Ozonkiller]

I know it's been a long time since your post but I found a post by JrGaylor with the same symptoms that you described. I'm having the same issues and I'm going to replace my TPS in the morning as he discovered was the solution to his problem. I hope this helps.