Ok so I put the fuel return line back at fuel filler neck and fuel pressure is back at 35 psi. one problem solved, but she still has a issue with bucking when u hit gas hard, wether ur just sitting or moving, she will pop at intake if I hit it hard enough. seems like a vacuum leak. exhaust leaks at back of cats which id like to fix by taking factory cats off and running straight pipes for now. probable put aftermarket ones on soon. the factory ones are hitting cross member because too tight a fit. new muffler are a bit heavier and pulling them down just enough to hit. always something to fix, right

 

Check TPS(throttle position sensor), that's the "accelerator pump" for fuel injection.
Key on, engine off
Use a sewing needle to pierce upper wire on TPS, should show 5volts
Move needle to center wire, should show .69 to .99volts, under 1 volt
Slowly open throttle and watch voltage, should react instantly and be steady, no jumps or drops.
At WOT it should be at or above 4.5volts

 

Hey ty, good place to check...its a new one but u never know

 

ok the tps seems ok....on to other things that might be the culprit

 

Well "new" used to mean "tested and works"
"New" now means "you test it and we will warranty it".
So I never trust "new" anymore.

After engine is fully warmed up and idling, unplug the IAC Valve
It will close all the way and idle will drop to 500rpm or engine may even stall, either is GOOD, it means no vacuum leaks
If idle stays higher then there is a leak, leave IAC Valve unplugged and start looking for it.

TPS is really the only "quick" reaction sensor for acceleration, MAF will have a delay, but can cause bogging just after you push down on the gas pedal.

Are you running distributor or distributorless spark system?
Slow to react spark advance can cause similar issue

 

Ok good idea on iac, been awhile since I spent lots of time on her. I'm running distributorless spark system, the way she was in mountaineer is how she is now except for cold air intake which I got a mustang gt setup cheap and made it work. I took time to tighten up exhaust with some brackets and hangers to get cats away from the transfer case skid plate. ok, iac is working and idle dropped. shouldn't be any vac leaks. I like how u said new used to mean we tested it and its good, now it means u buy it and hope it works...I was talking to guy at parts store telling him I thought cats might be plugging up and not allowing it to get to higher rpm fast. he asked his boss who has a pa insp and emiss license if I can take second cats off since I have pre cats. the guy said it has to pass visual so maybe not. I said I wanted to take bigger ones of since they leak in rear. put straight pipes on to see what that does, then get new aftermarket cats later. my neighbor thinks cats aren't the problem. when she cools down id like to check pvc valve just to be safe.....thanks for your help.

 

I almost forgot to mention, last night I cleared the codes. the only codes were for both banks running rich which I felt was a result of fuel pressure issue. I checked today, 1 pending code...bank 1 running rich.

 

You can test exhaust and ALOT more with a $20 Vacuum gauge

With vacuum gauge attached and say showing 18" at idle, if you open throttle plate quickly and let is snap closed you should see vacuum drop to close to 0" then pop back up to 18" quickly
If exhaust is partially blocked it will be slow to return to 18" because of back pressure build up

All gas engines are just self powered air pumps so you can tell alot about it by watching it's pressure.
No matter what "they" add to the outside, computer, spark or fuel, sensors and controls, it is still just an air pump.



Rich code means computer is closing injectors on that bank sooner than expected.
So if computer has calculated that each injector on that bank should be open 100ms(milli-seconds) at say 2,000RPMs and O2 sensor on that bank shows too little Oxygen(rich) then computer will start to close injectors sooner, 99ms, then 98ms, then 97ms and so on, until O2 sensor reports correct Oxygen level
If there is a 15% difference between computer calculation and O2 sensors correct level then computer will set a code, Rich(less open time) or Lean(longer open time), to notify driver of the problem with the calculation

I would run it that way for a week or so and then pull all 4 spark plugs on that bank, see if one has darker tip than the others, so showing Rich running, could be injector had issue with the 65psi pressure, shouldn't but....................
Just takes one injector on effected bank to cause that

If you get Rich or Lean codes on both banks then you can look at MAF or other devices that effect BOTH sides of an engine.
With just one bank effected then injector or O2 sensor is suspect, if Lean code then lower intake vacuum leak is possible

 

Gotcha, I will be getting a vacuum tester 2moro. I did have both banks running rich b4. I thought maybe it was the fuel pressure issue causing it. most of this stuff started 2 weeks ago when I got back from a trip. found 2 cracked vac hoses, fixed them. but then it started with the hesitating bad when I hit it quick. I drove it on parkway, I simply babied it and it did 60 mph. first day I had issues but the found pcv breather hose torn. today I started it to test drive after tightening exhaust hangers. it idled ok, put it in reverse and it stalled. so I put it in neutral to drift onto street, put it in drive and tapped gas and she went. as long as I baby it she will go. hit it hard and it buckles

 

So last night I was thinking about how she is running, bucking when I hit gas hard and I was thinking what different stuff might do this and I remembered when the egr stuck open it did the same but all the time. I wondered if maybe the egr might be staying open a lil too long but not all the time, which I know it has perameters . doesn't open til certain temp, closes at wot...so this morning I unhooked it and drove it to get my morning coffee. she ran better, however, at gas station I started her up, put it in reverse backed up and she stalled. started it up, stalled...felt like something holding it back? started her up she tried to stall, then idle went high some like she was fighting it. I hit gas and she took off. I drove up the street where she would not go good if I hit pedal harder and she responded. so time to check the exhaust

 

Ok, she runs at 12 in of vacuum which I'm pretty sure is low. she drops to zero when I rev her up and goes right back to 12

 

Was looking at vacuum gauge readings online and what different ones might mean, the one said that a steady low reading between 8 and 14 is normally valve timing off? I cant see her doing 60 on road if the valve timing is that bad or am I wrong. other videos said a low reading can be a restriction in exhaust.

 

Low vacuum could be clogged exhaust but............it would get worse as RPMs and exhaust flow increased so that would prevent the 60MPH

Have you done a compression test lately?
with 9.0:1 ratio I would expect above 150psi, lower would indicate incorrect valve timing and the reason for low vacuum

Yes, vacuum is too low, expected is 17"-21"
Test vacuum gauge on another vehicle if you can, just to take gauge issue off the table.

Vacuum is not related to engine size or model, it is the pressure created from a cylinder pulling in a "limited" amount of air because throttle plate is closed.
As throttle plate opens vacuum goes down because more air flow is available
So any other opening in the intake will also cause vacuum to go down, i.e. a vacuum leak

What was the "rebound" vacuum pressure?
When you open throttle to say 2,000rpms and then let it snap closed, you should see above 20" of vacuum before it returns to 12"

Aggressive cams will also cause less vacuum at idle, valve timing changed, although for performance at higher RPMs it is a good thing, lol

Now as RPMs increase with 1/2 opened throttle plate vacuum will come back up, because it is back to "limited" air flow for the increased RPMs

At WOT and max speed vacuum should be under 2", 1"-1.5" is optimal and shows that there are no air restrictions in the system for the displacement of that engine.

 

could this be as simple as possibly a bad ground screwing with things?if i remember correctly to make the 98 ranger wiring mesh with a 96-97 ecu you had to cut one wire and ground it....have yet to do a swap but have been reading about it so double check me i could be wrong but grounds will cause strange things to happen