Assuming you've already checked for vacuum leaks and there aren't some problems, the throttle plate stop screw should be adjusted for 675-725 RPM idle, all accessories off, all sensors and actuators connected and functional, in park or neutral. The center pin of the tps reads about 1.3V on mine. If I reach my finger in the throttle body and plug the iac air passage, the idle drops to the point it almost quits running. If your air temp sensor is dirty, any solvent cleaner can be used to hose it off, the variable temp resistor is coated with epoxy and very robust. These 2.9's always did have an unstable idle, key is to make it livable and thus someone has probably messed with the butterfly stop screw. Another thing to look out for is the ecm power relays can get flakey, you can see the dirty power using an oscilloscope, when this happens.
I know this is an old ass video but you don't even need that intake air temp sensor it does nothing important I have an 88 2.9l and changed it and nothing happens
It's the fuel pressure regulator easiest way to find out is pull the vacuumed line facing you next to the regulator and if there's gas boom issue solved what happens is fuel bypasses the vacuumed seal and goes into the manifold
My 89 B2 is currently doing this, got worse after replacing the idle air controller. trying to find a new MAF sensor currently and going to clean the throttle body and intake manifold
Somebody has turned the butterfly stop screw, they always do this because the 2.9 idle tends to hunt a bit, all you can do is minimize it. Readjust butterfly stop screw to 700+/-25rpm in neutral or park no accessories, everything connected and functioning. Center wire of my tps is 1.3V when set this way.
Assuming you've already checked for vacuum leaks and there aren't some problems, the throttle plate stop screw should be adjusted for 675-725 RPM idle, all accessories off, all sensors and actuators connected and functional, in park or neutral.
The center pin of the tps reads about 1.3V on mine.
If I reach my finger in the throttle body and plug the iac air passage, the idle drops to the point it almost quits running.
If your air temp sensor is dirty, any solvent cleaner can be used to hose it off, the variable temp resistor is coated with epoxy and very robust.
These 2.9's always did have an unstable idle, key is to make it livable and thus someone has probably messed with the butterfly stop screw.
Another thing to look out for is the ecm power relays can get flakey, you can see the dirty power using an oscilloscope, when this happens.
I know this is an old ass video but you don't even need that intake air temp sensor it does nothing important I have an 88 2.9l and changed it and nothing happens
It's the fuel pressure regulator easiest way to find out is pull the vacuumed line facing you next to the regulator and if there's gas boom issue solved what happens is fuel bypasses the vacuumed seal and goes into the manifold
Ever get it rite? Just purchased 89 B2 and does the same thing.
My 89 B2 is currently doing this, got worse after replacing the idle air controller. trying to find a new MAF sensor currently and going to clean the throttle body and intake manifold
Somebody has turned the butterfly stop screw, they always do this because the 2.9 idle tends to hunt a bit, all you can do is minimize it.
Readjust butterfly stop screw to 700+/-25rpm in neutral or park no accessories, everything connected and functioning.
Center wire of my tps is 1.3V when set this way.
I had the same problem, check for vacuum leak s or map sensor on the firewall,clean idle sensor with carb cleaner.
My 87 2.9 is doing the same exact thing your truck is doing. My IAC is only about a year old and I took it off it’s clean can’t find no vacume leaks
89 Ranger does this too mine also dies too sometimes when I tried it reverse or put it in drive.
Double check, everything, remove idle valve, and clean, with carb cleaner.
Check map sensor on the firewall!,or you have a vacuum leak.
Do they all have the tick/knock ish sound to them mine has it and idk if i should be worried about it
Has it blown up yet?
I have same issue on my 86 ranger someone help me please
Did you ever figure out mine has same problem
I'm in the same boat as you were with this - did you figure out what the issue was? I've replaced nearly every sensor this thing has lol
You ever figure out I’m in the same sinking boat and I love this truck
@@sawzallmechanic9383well now I’m in the same situation did you ever figure it out?