98 B2500 SOHC 155k. I have a high idle only while or after moving- between gear shifts, when coming to stops, and even just slowing down it will maintain speed until I brake to bog it down. Most of the time up to 3200 rpms and lasts for approximately 5 seconds.

I bought this vehicle new and have had this problem since about 50k miles. Multiple trips to dealer were unseccessful back in 2000 when this first started, changed dealers and service manager pulled wiring harness off TPS and drove it a few miles, plugged it back in and it worked fine for a few thousand miles. So that is what I've been doing over years. Now that "fix" only lasts a day or so.

I've cleaned the MAF sensor, changed PCV, cleaned throttle body. I found a TSB for a TPS wiring connection malfunction and think this may be my problem. I haven't changed the TPS yet. Should I change the TPS sensor before the electrical connection? Any other more likely possibilities? I would appreciate any advice. Thanks

 

change the tps.. pb blast the bolts before you remove the old one..
you might also clean the IAC valve.

oh and welcome!

 

Thanks for the advice 97ranger. I plan to change the TPS when I get time but I will clean the IAC valve first. What should I use to clean the IAC valve with? Thanks

 

There's also been issues with the TPS harness connector for your year and engine. Check out:

https://www.ford-trucks.com/forums/s...69&postcount=3

 

you can use carb cleaner... and compressed air to dry it.

 

Rockledge, yes I knew about the connector problem and my initial dilemma was changing the connector vs. the TPS. I'm going to clean the IAC first and see what happens then go from there. Thanks for the advice.

 

I was planning on cleaning the IAC valve today but got sidetracked- I decided to change plugs/wires and it took me longer than I thought. I must admit they had never been changed with 155k, but it ran fine, just a little down on power. Got the Autolite DP plugs and autolite wires, had to order intake valve cover/manifold gasket set, and went ahead and got a timing belt and fuel filter as well (no I've never changed them either).

So I removed the intake manifold and it was a little more difficult than I thought it would be. Lots of hidden lines connected underneath and I couldn't get a wrench to fit into the small space to disconnect the EGR line (which the haynes manual called for) so I finally just unbolted it and left the line connected. This made getting the very back bolt difficult to remove from the manifold but I finally got it with a universal joint on a ratchet extension. I got the plugs in and will get the gaskets tomorrow.

Anyway, I plan to remove the throttle body and give it a really good cleaning and will clean the IAC valve then also. I'm going to change the valve cover gasket while I'm at it.

Is there anything else I should do or change while I've got the intake manifold off? Do I need to coat the gaskets with anything before bolting them down? I don't think I have the skill to tackle the timing belt job so I'll likely have that done. Should I have the water pump changed at the same time? Thanks again!

 

I just bought a 99 b2500. Mine has a high idle, but then calms down after a bit. One thing I notice is when slowing down the idle stays high?? Saw a post that they are programmed to idle higher until less than 5mph, is that correct? Different area of the post, but where is that damn rattle in the right front of my engine coming from? Heat sheild??? Only happens between 2000-2800 rpm's..