outlander
NAXJA Forum User
- Location
- Columbus,Ohio
I've read alot of posts on this and alot of people say that the tps is causing this or that the iac is bad.I have the dreaded 2000rpm idle surge at start up on my 89 xj and have developed a theory that needs a little validation.
I'm thinking that the problem has something to do with the latch circuit on these older 4.0's.The latch circuit is responsible for positioning the iac properly for the next start up.So if the latch circuit is not functioning properly the iac is too far out of the tb resulting in the high idle at start up so many of us suffer from.
While working on the rig today I was looking into my high idle problem.Started it up and idle surged to 2000rpm then settled right back down to a normal steady idle.I unplugged the iac while it was in the right position with the jeep running.Turned of the engine started it again and no more high idle at start up!
My tps is not the problem...it tests out fine and the iac is functioning properly so I'm looking into the latch circuit as the problem.
Just thought I would start a thread on this while I'm working on the problem.More to come as I dig deeper into the latch circuit.
I'm thinking that the problem has something to do with the latch circuit on these older 4.0's.The latch circuit is responsible for positioning the iac properly for the next start up.So if the latch circuit is not functioning properly the iac is too far out of the tb resulting in the high idle at start up so many of us suffer from.
While working on the rig today I was looking into my high idle problem.Started it up and idle surged to 2000rpm then settled right back down to a normal steady idle.I unplugged the iac while it was in the right position with the jeep running.Turned of the engine started it again and no more high idle at start up!
My tps is not the problem...it tests out fine and the iac is functioning properly so I'm looking into the latch circuit as the problem.
Just thought I would start a thread on this while I'm working on the problem.More to come as I dig deeper into the latch circuit.