2.5L ('98-'01) 2.5 manual Rpm takes ages to drop when shifing in 1st and 2nd

[MadLadDon_23]

I have a 1999 ranger with the 2.5l 8 spark plug motor paired to a 2WD 5 speed manual and ive been having this issue since I bought it about 5 months ago where when I am taking off in 1st gear I usually let the rpm get to about 3500, 4000, and I have to wait a solid 4 seconds for the rpm to go down enough for a smooth sift point. Is this because of a bad IAC or something else. I have verified there are no vacuume leaks as I have resealed the whole topend of the motor. I will also mention that someone before me removed both front wheel speed sensors for the abs system and I haven't put them back yet.

 

[franklin2]

Wheel speed sensors may help it, not sure how it's programmed. I will say all newer vehicles do this somewhat, revving the engine up and then having the throttle slam shut creates a lot of emissions. They bring it down slowly, but probably not as slowly as you are describing.

 

[scotts90ranger]

They can do that somewhat with speed sensor issues but I'm only familiar with the ones with a transmission mounted speed sensor... not sure if that moved to the rear axle sensor or the front sensors after that point... I know the speedo is driven off the rear speed sensor.

 

[RobWigglezz]

Its not necessarily a bad IAC. It could be very dirty causing the valve to be slow. I would try cleaning it first. And after you clean it or replace it, give it a few drive cycles with different kinds of driving. Every time I disconnect my battery, my IAC hangs the revs for a couple days then drives perfectly.

 

[MadLadDon_23]

Cleaned it twice now and still have issues with it, I used FordScan to actuate it manually and it is not operating properly, I have ordered a Delphi unit and I hope that helps.
I also found some coil pack wires that were bare and redid the wires as it caused a no start issue for a day before I found the problem.

 

[RobWigglezz]

If the revs climb on the first start with the new IAC, turn it off and start it unplugged. If it will stay running, plug it back in. That's what I had to do on a previous ranger I had when I replaced the IAC

 

[MadLadDon_23]

If the revs climb on the first start with the new IAC, turn it off and start it unplugged. If it will stay running, plug it back in. That's what I had to do on a previous ranger I had when I replaced the IAC

Thanks for the advice, the new unit should be here in the next few days.