2.3L ('83-'97) 91 5spd Won't rev past 2.5k

[91KateTheRanger]

Hey all!
Got a little ranger few days ago, and have chased down a few problems.
But now I am chasing why my tach won't go past 2.5k. Any help? I honestly don't know where to start for this one. No CEL(yes cel works) No codes when jumped. She runs good, she was having starting issues, but it was the pcm relay, and those are gone now.
Any help is appreciated!

 

[alwaysFlOoReD]

I believe there is a rpm limiter if the truck isnt moving.

 

[scotts90ranger]

The rev limiter is up at 6000rpm, does it rev up past that and the tach just stops or does it stop revving at that?

The tach is driven off of the ignition module and specifically related to the drivers side coil output... if you have the drivers side coil unplugged the tach won't work... so that said it's either the drivers side coil or the DIS module (easy to spot, says DIS right on it on the front of the intake manifold on the drivers side...)

My '90 the tach is strange at times... on a cold start it reads about ~110% of actual engine speed then once it's up to temp it reads normal for whatever reason, unless the tach is right and the speedo is what's lazy? That would probably make more sense, the drum (or whatever you wanna call it, I tried to figure it out back in the day, I think it's some type of Bernoulli flow deal or something...) in the speedo is probably corroded... didn't think of that possibility until a couple minutes ago... I think I had the GPS on at one point though, 60mph in 5th gear should be 3000rpm but it'll show 3300rpm or so...

 

[91KateTheRanger]

The rev limiter is up at 6000rpm, does it rev up past that and the tach just stops or does it stop revving at that?

The tach is driven off of the ignition module and specifically related to the drivers side coil output... if you have the drivers side coil unplugged the tach won't work... so that said it's either the drivers side coil or the DIS module (easy to spot, says DIS right on it on the front of the intake manifold on the drivers side...)

My '90 the tach is strange at times... on a cold start it reads about ~110% of actual engine speed then once it's up to temp it reads normal for whatever reason, unless the tach is right and the speedo is what's lazy? That would probably make more sense, the drum (or whatever you wanna call it, I tried to figure it out back in the day, I think it's some type of Bernoulli flow deal or something...) in the speedo is probably corroded... didn't think of that possibility until a couple minutes ago... I think I had the GPS on at one point though, 60mph in 5th gear should be 3000rpm but it'll show 3300rpm or so...

It physically won't go past 2.5k on the tach. When I drive it, it sounds like it may, but maybe it's not going past 2.5k. Interesting so if my drivers side coils unplugged the tach won't work?

 

[91KateTheRanger]

I believe there is a rpm limiter if the truck isnt moving.

It only goes to 2.5k even down the road, though.

 

[bobbywalter]

Should be 42 to 4600 on the limiter.


The tach could have bad signal or resistor blown or loose ....if the engine is still revving normally

 

[scotts90ranger]

on a 2.3L it's 6000rpm, believe me, I've checked , a 4.0L yeah, they're down low...

The drivers side coil is "secondary" and doesn't get used during cranking so they put the tach output on that side of the module for whatever reason...

Ok, so it's revving up there but just stops? taking the tach out of the picture, does it "sound" like it's only turning 2500rpm or does it sound faster? 2500rpm isn't that fast... if it is in fact going slow the rev limiter and anything that would limit rpm is doing so by limiting spark so it's either the crank sensor or ignition module although in all my years here I've never heard of either causing this...