2.5L ('98-'01) 99 2.5 running rough, previous owner removed EVERYTHING

[ZMan]

I bought a 99 Ranger recently with the 2.5 and a 5 speed.

All the emissions equipment has been removed.

The idle is all over the place, sometimes it will idle smooth, then it will almost die, rev up, and run rough. It has a high idle between shifts, but runs down the road good. Just looking for a little advice before we dive into it.

The codes it has are:
P1409 Electronic vacuum regulator control circuit
P1401 DPFE Sensor Circuit high voltage
P1451 Evap emissions system vent control valve circuit malfunction
P0443 Evap emission system purge control valve circuit

All of these systems have been removed. The truck has a fuel cell which explains the purge and vent codes. The one that is a little perplexing to me is that it does not have a P0420 code even though the cat has been removed, I don't believe it has a defouler installed on the rear 02.

We plan to get it on my buddies scanner to read live data, all I have is a code reader.

The previous owner(s) told me it was running rough, and they removed everything thinking that would fix it. They do claim it runs better, but obviously it doesn't run good.

Should I start with putting the DPFE and EGR back on? I'll have to go and buy them since they didn't come with the truck, the plugs are still there on the harness. I sprayed everything down and I don't think it has any vacuum leaks.

 

[Josh B]

I would recommend a wrecking yard over a parts store, simply my way of thinking, believing an old Ford part is better than anything out of china
You can also get a warranted price most times and get a second or third shot maybe

 

[scotts90ranger]

By "vacuum control valve" does that mean IAC? I would investigate that first on a rough/inconsistent idle... It's 2 wires that should just go to the ECM I believe, there could be something going on with one of them... I don't remember if '99 had a body module that interpreted the signal from the rear axle to get the vehicle speed but in that era the idle circuit in the computer took input from vehicle speed to smoothly transition to idle on decel if I understand correctly.

I've never once had a random symptom and just said "well, I don't know what I'm doing but we'll just remove everything, see if that helps" but hey, what do I know , I do understand though, the body drop process isn't likely simple...

 

[ZMan]

I would recommend a wrecking yard over a parts store, simply my way of thinking, believing an old Ford part is better than anything out of china
You can also get a warranted price most times and get a second or third shot maybe

Yeah i would get the parts from pullapart as long as i can find good ones

By "vacuum control valve" does that mean IAC? I would investigate that first on a rough/inconsistent idle... It's 2 wires that should just go to the ECM I believe, there could be something going on with one of them... I don't remember if '99 had a body module that interpreted the signal from the rear axle to get the vehicle speed but in that era the idle circuit in the computer took input from vehicle speed to smoothly transition to idle on decel if I understand correctly.

I've never once had a random symptom and just said "well, I don't know what I'm doing but we'll just remove everything, see if that helps" but hey, what do I know , I do understand though, the body drop process isn't likely simple...

It does have a new IAC on it. I will check it and the wiring. I was told about the only thing they haven't "checked" is the under dash wiring. When the truck was body dropped some 15ish years ago they shoved the under hood fuse box under the dash somewhere, so that should be fun.

2 owners ago daily drove the truck 100 miles a day for 2 years before things went south. He ended up putting another engine in it, i guess the original one had a cracked head. But this new engine has never ran perfect. Everything was deleted when this new engine was installed I guess, or shortly after.

 

[ZMan]

@scotts90ranger I did a quick search and the p1409 is this part:

 

[scotts90ranger]

Oh, the EGR vacuum valve... I guess ignore that then...

 

[ZMan]

Finally dug a little deeper on the engine issues today. I seem to have found a vacuum leak under the intake manifold, so I'm going to pop it off and replace all the lines. With the live data, fuel trims were super high, MAF voltage was high (1.2v), and when i sprayed brake cleaner around the vacuum lines everything evened out.
There's also an IAC code. It has a newer iac on it that the previous owner installed. We will have to do more diag to determine if it's the IAC, wiring, or PCM.
It also has about 88psi on the fuel pressure, which is very concerning. It also leaked down to about 43 and held there when shut off. I swapped in a junkyard FPR, still high pressure but it leaks to zero pretty quickly. I'll put the old FPR back in and test again after I fix the vacuum leak.

 

[-Nate]

Subscribed to find out what the problem was .

I have a 2.5L / 5 speed 2001 and the IAC valve was sticking , I removed and cleaned it and the engine runs better & smoother than ever before but it still stalls out occasionally when I come to a stop .

At hot idle the idle speed 'hunts' a bit before it stalls out .

 

[ZMan]

Subscribed to find out what the problem was .

I have a 2.5L / 5 speed 2001 and the IAC valve was sticking , I removed and cleaned it and the engine runs better & smoother than ever before but it still stalls out occasionally when I come to a stop .

At hot idle the idle speed 'hunts' a bit before it stalls out .

that certainly sounds like a vacuum leak.

 

[-Nate]

Thanx, my hearing is shot so I no longer hear the vacuum leak whistles .

 

[Josh B]

It's a wonder I have any hearing left after all the noisy jobs I had, most specially the mine. I worked on one blast we were loading in 12 hour shifts around the clock for three days.

The third day we all got in the cars to go back to the shaft and back to the surface but we weren't moving.
I realized why when the guy behind me said "you'd better cover your ears"
I got home after a bit and they said "man, did you hear about that blast they had today?? It busted the water main and set off the bank alarm" and we had been over half a mile down

 

[-Nate]

Wow .

I ride Motocycles too and didn't grasp the importance of ear plugs until far too late .

As well as being a Journeyman Mechanic so loud sounds were a daily thing .

I'm pondering how to test for vacuum leaks, maybe a spray bottle of water as there's myriad hoses and what not under the intake manifold .

 

[Josh B]

I think ether works too, altho it may be more prone to flare if used wrecklessly