As the title says, my 1999 2.5 l while start to shake horribly after I I give it some revs or hard load. The truck will start and idle fine tho. If I drive easy and keep the rpms smooth the shaking never acures

Things I've done
checked compression, 150psi in all cylinders
New coils, plugs, and wires,
Checked for vacuum leaks. Non present.
new fuel filter.
checked codes and only thing I get is a cat code cause I currently have no cat. Standard obd2 scanner used.
new fuel filter.
tps was checked and works great, new maf, and air charge temp sensor
new fuel rail and injectors inspected, all in working order
I currently have the egr blocked off with a plate between the egr and the intake.
Fuel pressure was checked also, it jumps in between like 50 and 65 psi at idle. Jumps a lot on that note but never dips below 50psi.

Things I should do
Check the timing
Replace fuel,pump
other than those two things I have no clue why my truck runs like this . It almost feels like I drop a cylinder or 2 after hard revs and load. Any info or ideas are much appreciated. Ill try to,post a video when I get on my,laptop tomorrow.

 

Welcome to the forum

I would first check if all spark plugs are working

In 1995 to 2001 2.3l and 2.5l Lima engines you can unplug the 3 wire connector on one coil pack and engine will start and run on just the 4 spark plugs using other coil pack.
This tests if all 4 spark plugs are working on that coil pack, if you have a steady misfire then there is a problem
Then reverse test for other coil pack.

The Lima engines use 2 spark plugs for each cylinder because there was room in the head to do this, and it gives better performance, the 2.3l Lima engine was first used in 1974 and ran fine with 4 spark plugs until the second set was added in 1989


Also run a can of Seafoam in the gas tank, this cleans injector tips, you could have a couple of dirty tips that are causing the misfires under load

The jumping fuel pressure is a concern, it is regulated by the fuel filter, there is a 3rd hose on the filter that runs back to the gas tank, it has a valve to stabilize pressure in the system
Fuel filter should be changed every 5 years or so

If compression is OK, then that only leaves fuel and spark

You can check the spark timing but after 1994 there is no way to change it, it is fully controlled by the computer(PCM)

Throttle position sensor(TPS), should be checked with a Volt Meter, it could cause similar problems.
Use s sewing needle to pierce the center wire on the TPS
Key on, engine off
Ground the volt meter and test center wire
Throttle closed should read under 1 volt, .69-.99v is spec
Open throttle and voltage should go up, at WOT(wide open) voltage should be at 4.5-4.9volts
As you move the throttle, voltage should be stable, no jumping up or dropping down, its a variable resistor like a Light Dimmer or a Volume Control
Computer uses TPS so it can get a "heads up" on driver input, faulty TPS could cause delay in throttle response

 

Thanks for the info, ill try the spark plug trick and see what happens. Ive tested the tps with my voltmeter and everything is in spec. Also I'm currently running Lucas oil top end lubricant wich also has a injector cleaner in it also. Gonna pick up a new computer to test with from pick n pull this weekend and see if it has any difference.

Also, when I bought the truck the guy before me removed the primary coil pack and was only running the secondary. Had the same issue with the one coil. Since then I rewired the primary coil hoping that would fix my issue but it didn't.

Also, my fuel filter doenst have a third hose. But I do have a pressure regulator on the fuel rail that the standard vacum diaphragm. Also I noticed the truck has a high idle when in motion but will idle down once I come to a complete stop.

I'm still pretty stumped on the whole issue. Still feels like I'm losing a cylinder or 2 after the reving or hard driving load. It does clean up but gotta drive a min or 2. Gonna use a timing light and see if it's retarding the timeing or somethong after I rev it.
ill keep you posted.

 

I would like to thank you for the info again. I tried the pulling all the wires but one of the secondary coil and turns out the primary coil had no signal at all. One of the signal wires is grounded in the computer and the other one just has no signal output. I tested the signals connected to the computer and disconnected. When disconnected both signals wires test normal and not grounded but when you plug the computer back in the signal wire is grounded and the other has no signal. So the computer is hosed. It still runs with just the secondary if I take it easy so gonna keep driving it tell Saturday then gonna get a new computer from pick and and call it good.

 

Good work

The transistors that Ground and Unground the coils deal with ALOT of amps, so can fail, 1994 and earlier Rangers used separate Spark Control modules and not uncommon to have these fail over 10-15years, in 1995 these were moved inside the newer model computers, and they did NOT fail as often, so good upgrade, but..............anything can fail

Lucky you have a 1999 4cly Ranger, if it was a 1999 V6 you would have to deal with PATS(passive anti-theft system) so couldn't swap out computer without dealing with that system