Running rough... I have no idea what it could be. Lot's of info, long read.

[#1]

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1997 Ranger 2.3 and a 5 speed manual.


I'll list some info, then watch the video...


It had this condition when I bought it a couple months ago. I start the engine and it will idle smooth. I rev the engine, then it will idle and run rough. After a while it will return to a smooth idle. For example, the engine will idle smooth, accelerate through first gear and shift then it will run rough in second, third, and so on.

After driving about 20 miles or so, the engine runs fairly good and this problem almost goes away.


I get a P1443 code every time I drive it.

I get a P0303 about every 800 to 1,000 miles.

It has new plugs, wires, coil packs, oxygen sensor, and IAC valve.

The MAF voltage was within specs according to autozone's website.

Sprayed MAF cleaner = no change.

The fuel pressure is at 30 psi smooth idle, 34 psi rough idle, and it will briefly jump to about 40 psi when I rev it.

The catalytic converter sounds like it has a crack in it and it leaks quite a bit.

I sprayed starting fluid everywhere and found no vacuum leaks.



All of the following are in "closed loop":

I can unplug the throttle position sensor and it will still run just the same. Should the engine still rev with this unplugged?

Unplug the IAC valve = no change

Unplug MAF sensor = engine will idle, but will stall when attempting to rev. Small "blip" in idle when connector unplugged.

unplug coolant temp sensor = no change

unplug air temp sensor = no change

I have a ScanGauge II that I use, and it shows -40 when unplugging the coolant temp sensor or the air temp sensor. Both sensors read normally when connected.

Unplugging all of these caused NO check engine light.



The following video has 3 parts in it. You can watch the throttle lever to see what kind of input the engine has. The engine was shaking quite a bit in most of the video, but for some reason it doesn't look or sound as bad on tape as it does live. It's worse than it appears.

The first part is the engine cold and running in open loop. The engine actually dies in this segment and is very difficult to restart. Then I shut the engine off. The next part is in closed loop. The final part is the exhaust.

 

[pops13]

have you checked compression? may have head gasket problem, this is only a guess.

 

[fastbluetruck]

try taking cat off and see if it still does it could be clogged

 

[TomTom3975]

Mine did something like that It was the MAF sensor it was fryed but I was scared of the price just to try it out I went to a Bone Yard and got it for 5 bucks I was very happy. Its just something to try if you can get it cheap. Thats my thought about it.Hope you get it fixed.

 

[Bryan22]

i'd start by changing the fuel filter, it's cheap and an easy job. especially since your fuel pressure is kind of inconsistent. did you try unplugging the Fuel pressure regulator while you were checking the pressure to see if it changed?

p0303 is misfire on cylinder 3.
p1443 - see here http://www.obdii.com/ubb/Forum1/HTML/002192.html

 

[#1]

I haven't checked compression. I'll check it this weekend and see what it is.

I'll talk to my exhaust guy about the cat, and the possible temporary removal of it for testing purposes.

I've suspected the MAF, but the price scared me also. I may watch for one at the pick-n-pull.

The fuel filter doesn't look very old... but looks can be deceiving. I've wanted to change it, but haven't had the time yet. I unplugged the vacuum from the regulator while it was running, but never with the gauge on it. It made no difference in the idle though.

P1443 - I tried a valve and sensor from the junkyard and new hoses, but still get the code. The junkyard part(s) could be defective also.

 

[Bryan22]

unplugging the FPR should make a difference. pull the line off the FPR when it's not running and check for raw fuel in the line. Still though you should change the filter, it only take a screw driver and 10 minutes.
and for refrence next time you have the guage...
key on engine off- 35-45 psi
idle FPR connected- 25-35
idle FPR disconnected- 35-45

Also for the MAF you should try to clean it and see if that makes any difference, there is a write up in the tech library on it.

 

[#1]

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Ok, I had some time to mess this thing...

When the engine is missing out, I can rev the engine a little and hear pinging from the engine.

I set the engine at TDC of the compression stroke and the timing marks lined up in each inspection hole in the timing cover.

I pulled the plugs from the passenger side - cylinder 1 smelled odd and had some brown/red specs on it. Cylinders 2 and 3 both smelled like unburnt gas. Cylinder 4 smelled normal. These plugs have only 1,500 miles on them.

The engine gets a P0303 (cylinder 3 misfire code) about every 800 miles, and only when the engine is cold.

I was going to do a compression test, but I can't find my adapter to screw the hose into the spark plug holes.


Pics... Cylinders 1 through 4, left to right, of the passenger side of the head.

 

[skyy_4life]

yea my first guess could be something with the MAF.

 

[#1]

MAF voltage was within specs.
Clean MAF with no change.
Swapped in a junk yard MAF with no change.

 

[4b316]

Did you try a O2 sensor yet?

 

[#1]

.

Here is everything that has been done, none of it changed anything...

New plugs

New wires

New coil packs

New oxygen sensor

Checked fuel pressure - 29 to 30 psi at idle. Will jump briefly to 45 psi when revving the engine

New IAC valve

Coolant temp sensor works fine

Air intake temp sensor works fine

Cleaned MAF

Swapped in junk yard MAF

Swapped in a different computer

Sprayed starting fluid to check for vacuum leaks

Checked and cleaned grounds

Checked timing belt - all marks line up

.

 

[#1]

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How do I check the cam position sensor and the crank position sensor?

And what does each of these do?

.

 

[4b316]

The crank sensor tells the ECM when to fire the plugs.About$30.the cam postion sensor does about the same thing.Try unhooking the cam sensor and see if it is any difeerent running.Check all your grounds?

 

[feellnfroggy]

The maf is fine, and so is the o2. Cyl 2 and 3 are running extremely rich almost like the injectors are not shutting down after a high rpm run. Also try new plugs in case whoever had the truck before you screwed with the gap. if 2 and 3 are gapped too much then it will kill you spark. Fuel pressure is also fine, My 2000 stang has a feature with the digital tach where you hold down the resest button while you turn it on and keep it held til the gauges jump and dashes show up across the board. Then you can punch the reset button and cycle through all the ecm self tests. it will give you codes and voltages and pressures and temps anything diagnostic. The fuel pressure on the stang always increases with RPM.

If the pressure was left constant and linear throughout the rpm range, then it would lean out at the higher rpms.

I am thinkin something is killing your spark in cyl 2 and 3 after high rpm. i would check the coil connections and maybe replace them(from a junkyard as well) Then I would troubleshoot the injectors. Also check your idle control screw make sure its not set too low. Just some other options. Hope it helps.