1999 2.5l, issues need help
 

Hello, today i got a 1999 ford ranger with a 2.5l. Just replaced the computer, icv, coils, plugs, wires. I've tested the tps and it works in spec. ALso, replaced the fuel filter.
I've tested the compression and all cylinders are 150psi plus or minus like 3 psi. Issues i had before i replaced the computer was the engine would stumble and studder really bad after reving or accelerating with more than 1/4 throttle. Also, the primary coil had no signal at all so it wouldn't spark.

Replaced the computer and now the main coil has spark. WOOHOO fixed that issue. But the engine still stumbles : worse then before: with both coils running. I've used my timing light to check timing advance and it shows -4 to 10 at ideal just kinda goes between those marks. WHen checking timing at ideal with my ob2 scanner it holds a pretty constant -4 to 2 degrees. is that normal timing?. Also, when i unplug three wires from the secondary coil and run on the primary coil the whole engine just runs pretty bad. Like what's up with that. Kinda feels like the primary coil isn't firing 100% with this new computer. I'm gonna check the timing belt and see if all he marks are on point and probably replace the crank postion sensor and just see what happens.

Any info would help a ton. I could post a video tomorrow to show exactly what i mean if that would help you guys out.

With compression above 150psi the timing belt is OK

The 1995 and up 2.3l or 2.5l Lima engines run dual spark plugs and coil packs for better performance
The engine should run or idle fine on just one coil pack, there is no "main" coil pack, both are equal and get signal to spark at the same time, they are labelled primary and secondary but that's just for description purposes, they could be labelled 1 and 2 or front and back

There are only 2 coils in each coil pack, but 4 spark plugs are connected................
The spark plugs on each coil pack are fired in PAIRS, 1 and 4 fire at the same time, 2 and 3 fire at the same time
So 1 and 4 share one coil in that coil pack, 2 and 3 share the other coil

Make sure they are wired that way,
[1/4]
[2/3]
or
[4/1]
[3/2]

If unplugging one coil pack causes rough running then you will need to make sure coil pack wiring is correct and then check each spark plug
Since you have a timing light check each spark plug wire on that coil pack to make sure it is sparking every 1 RPM

Engine should idle smooth on either coil pack

8-10deg BTDC should be what computer shows at warm idle.

So you bought this truck knowing engine wasn't running correctly?

Does engine running any different after it warms up?
Better, worse or no change

Is there any smell of fuel like Rich running?
Or any Pinging/knocking, like Lean running?

I understand how the coils are paired in two. I've doubled checked my wiring and plug wire postion and everything is where it should be. But i have a old timing light and its kinda poopy. But when i use it on the front coil it works just fine, but when i use it on the coil closest to the fire wall it really hard to pick up the signal from the plug wire like it's a weak spark or something. Can't remember if every wire does it on that coil but i can confirm number 1 wire does it for sure. Also, i confirmed plugs 1 and 4 where paired correctly as the both showed the timing mark with the timing light.

I do have suspicion or rich or lean. i only notice a gas smell when running it cold backing out of m drive way, sometimes its really strong but i almost always smell it in the morning. Also, yes i bought the truck with this issue cause it will run fine if you drive it easy, but when you need the power it's really annoying to release the throttle knowing the engine is going to hickup and stutter really bad. Can't complain for 300 bucks also on a low income budget haha. It pretty much runs the same when it warms up. smooth if you drive it easy but runs rough after hard acceleration. ALso, both cold and warm it has a hanging ideal and always ideals pretty high with the clutch in when moving. But i understand from research these trucks ideal high untell you go below 5mph for fuel economy. other than this stupid issue the truck runs great, pulls really strong and good but once you come back to ideal its just the engine falls flat somewhere and just takes awhile to catch back up with its self. The worst part is there is no engine codes popping up at all.

Could the head be cracked with 150PSI. I have a leaky gauge so once i get a better tester i'll redo the compression test and see if the cylinders have leak off.

Today i will be replacing the crank postion sensor to if that makes an difference and checking the timing belt to set my mind at ease about it.

Thanks for the reply, hope we can figure this guy out.

So does the engine run rough if either front or rear coil pack is unplugged?

Or just one is misfiring when the other one is unplugged?

You can pull the spark plug wires off the one misfiring coil pack and put them on the other if you have one that's working OK, that would tell you it its a spark plug issue or coil pack/computer issue

Crank sensor works or it doesn't, and if it doesn't then you get a No Start, not rough running, and you would get a code and CEL(check engine light) if Cam sensor was pulsing but Crank sensor was not
Crank sensor reads a tone wheel on the back of the crank pulley, picture here: https://www.partsgeek.com/assets/dim...ll/1406937.jpg
That tone wheel has one missing tooth, seen at about 1:00 in the picture, thats what tells the computer when #1(and #4) are at TDC
That tone wheel is a press fit onto the crank pulley, not Keyed, only seen it happen once, but it did shift, that would cause rough and barely running condition, but at any RPM, no power at all

Cam sensor can cause rough running, computer uses this sensor to fine tune the timing of the fuel injectors and spark
But computer would set a code if cam sensor was not matching up with crank sensor
Cam sensor reads the AUX(oil pump) timing gear, on drivers side about 1/2 way down timing cover on the back side.
Cam and AUX gear are the same size, so also long as they are timed correctly then reading AUX gear is the same as reading Cam gear

Well seems i'm in a pickle haha. The rear coil pack witch is the exhaust side is brand new and is the one i'm concerned about. with the front coil unplugged and only running on the ear coil is feels like one cylinder isn't running at all but all cylinders have spark. But when running on the front col that's on the intake side it ideals just fine and runs smooth but still has the stutter issue after revving or after hard acceleration.

I'll tinker with it today and see if i can find anything new.

Intake side spark plugs and coil pack all work
So swap those 4 wires over to the Exhaust side coil pack, if it still misses then new coil is the issue

Swap the exhaust side spark plug wires to the intake coil pack, if you still have misfire then one of the exhaust side spark plugs is bad, yes new spark plugs can be bad, have run into that myself

Did you check the gap on the plugs or just put them in from the auto store?

Ive found that the "pregapped" plugs auto stores offer sometimes are WAY out of spec....

might we worth pulling number 1 and having a look.