I am at the end of my rope trying to figure this thing out. It wouldnt start out of nowhere one day, let it sit for about 10 minutes, and fired right up. Ran like a dream all day after that. Best ive ever had it running. The next day, same issue, but it just wouldnt start. That afternoon I finally got it to start and idle just fine for about 5 minutes or so, but after that the idle becomes absolutely horrible, after it starts doing that it will only run under a really odd condition, and that is by disconnecting the vacuum line to brake booster, which is why i replaced the idle air control thinking it wasnt getting any air. Plug that line back in and the truck dies. Ive read so many forums saying to check this and that and still nothing. So heres what i have done so far. Replaced crank and cam sensor (long story, lots of other forums recommended this. Did not fix) and idle air control valve. Ive cleaned my maf and map sensor really well, and the throttle body. I know its a bad idea in general to throw parts at it. But im honestly out of things to throw at it that i think could be the issue. Im lost at this point and its been 3 days of trying everything i can think of. Plugs and wires are new, within 2k miles give or take. Coil pack is fairly new. Fuel filter was replaced recently as well, and i know im building pressure in the rail. I dont know how much, i dont have a tester, but it seems that fuel delivery isnt the cause. Anyone have any advice?

 

Welcome to the forum

You should include the Year of Ranger along with engine size
2001 I think???

IAC Valve needs to be Ford brand, other brands don't work, just FYI
Put original one back on, if new one is not Ford brand(motorcraft)

First do the 50/50 test
Pull off the air tube from the intake, you can leave it off
Try to start engine
If its a No Start, spray fuel, gasoline or Quick Start(ether) into the intake, open throttle manually and spray fuel in
Try to start
If it starts and dies then Spark is OK but fuel delivery is not
If it doesn't start/fire, then Spark is the problem
50/50 INSTANT results on where to look next

This has been the GO TO TEST for over 100 years of gasoline engine repair, lol
Testing spark and fuel pressure is something you can do AFTER 50/50 test has told you whats missing


Cold gasoline engines need to be choked, this means computer needs to give engine RICH fuel mix and high idle just after startup
When it does start is the idle high, and does it get lower and lower as engine warms up, it should

2001 Ranger uses 60psi fuel pressure
Its common for fuel pressure to drop to 0psi after vehicle sits awhile, not correct, it should stay above 30psi for MONTHS, but it is a common issue
When you turn key on the fuel pump only runs for 2 seconds(adds 10psi), its a safety thing, it won't run again no matter how long you crank the engine over
To build up pressure from 0psi cycle key off and on at least 3 times and THEN try to start
After engine RPMs are above 400 computer will turn on fuel pump full time, cranking speed is 200rpm, just FYI

Report back on 50/50 test results

 

Thank you ronD. Yes it is a 2001. Ive seen your name in several other posts, and have actually given me a lot of good results with previous issues. The iac i replaced isnt the original, and has no ford markings. But its been on the truck for a few years now and no issues until now. Ill swap it back on and start with the 50/50 test and go from there. Thank you for the quick reply.

Update: truck started for a second then died. Will Only crank now. Ether didnt help. cycling the key didnt work either.

 

Response is confusing

So it will NOT start when fuel is added?

So its a spark issue

Look at the dash lights
The CEL(check engine light) should come on with key on, means computer is on, and it should go OFF as soon as engine is cranking, that means computer is seeing a timing signal

THEFT light should also come on and then go OFF, no flashing

 

Exactly. CEL came on and went off during cranking. Theft light came on then went away as well.

Update: somehow she decided to start? I havent changed anything. idles good for a minute, then stuttered and almost died, but pulled itself back up. Its done that 3 times now since ive gotten it to start, but seems to be idling perfectly as of now.
Update: Well right as i post that the rpms increased to 2k and then promply died. My scanner also lost the reading for engine temp when it did that. Ive got it started again and its having trouble idling. Not too terrible but its definitely not okay. Temp is reading normal again, but climbing extremely slowly. Ive just recently replaced the thermostat, and both temp sensors (cht and coolant sensor) for that exact reason.
idle is changing between from about 900 rpm and kinda shaky for a minute, to about 500 and extremely rough for a few seconds, back and forth. Sounds like it has a definite misfire. Checking plugs now. #3 and #4 had no change on idle when i pulled the wire from the coil. So im not getting spark to those 2 cylinders. But why would it run perfectly for so long and all of a sudden just stop sending spark to those 2 cylinders??

 

Got it fired up again. Swapped plugs 1 and 4 to test spark. Ran like a dream for a while, then again with the rough idle. Pulling the wires for 3 and 4 off the coil didnt change a thing, however they are getting spark for sure, but seems like too much fuel. It smooths out if i disconnect the vacuum line to the brake booster, as it has been doing. Unplugging the tps was hit or miss. No change the first time. Then it changed when unplugging, and again when plugged back in. Third time again, and no change. Im so confused, however The tps doesnt seem to be the cause of issue. Not entirely anyways. Could it be injectors? How would i know? I dont have a set of noid lights.

 

When was PCV valve last changed, Ford says every year, but every 2 years is usually fine

It's a PITA on the 2.3l Duratec in Rangers but it is a controlled vacuum leak so might be the problem

 

It hasnt ever been to my knowledge. How can i test if thats bad? We have been chasing vacuum because of our findings involving the brake booster. I guess that could make sense. Ill see if i cant find where its located and take a look at it.

 

If you haven't changed it in 2 years its bad

 

Ill replace that and see what she does. Thank you!
Update: had to remove the oil separator to get the pcv valve off, but i got it. I know these things have a small bearing in them and a lot.of times they sieze up. This one still seems like its working fine? I dont know if thats good news or bad news. Unfortunately cant replace it until tomorrow anyways so i might try to clean this one up if i can. The oil separator was filthy. I know thats not necessarily a good sign.

 

Some pictures here in this How-To: https://www.ranger-forums.com/engine...-valve-116900/

Ford wants you to do this every YEAR, lol

There are also a few videos

As said PCV Valve IS a vacuum device, and from your description changing the vacuum level in the intake, opening power brake booster line, allowed engine to stay running

 

Unfortunately i wont have the part to replace it until tuesday morning. Is there anything else it could be? The engine runs with that line in place, just very poorly. Taking the line off smoothes it out, and placing it back on will kill the engine, unless done very carefully. That valve is a couple bucks, so i have no problem replacing it. Is there anything i can check in the mean time while waiting for the new one? Id like to check compression but i dont have a tester.

 

Just to be clear

Engine runs fine above idle, no loss of power at speed or under load

This is JUST an idle issue?

 

Thats how it started, but after a while it affected how the engine ran at all times. I tried to test how it handled under driving just up my driveway, but it still only ran on cylinder 1 and 2. I just cleaned the pcv valve to see if maybe cleaning it out a bit would change anything, and with it attached to the hose, but not installed into the separator, it idled pretty damn good, but after deciding the valve was good enough to test it further i put it into the separator, and idles damn near perfectly. Even drove it up the way a bit just now. Definitely not entirely fixed but i think you hit spot on with the pcv valve. Unfortunately the one i ordered wont be in until tomorrow morning. You would think oreillys would carry at least a couple since it seems most cars generally use the same one. so i wont know for sure until tomorrow. Still has a bit of an issue when it gets up to temp, but i checked spark again how i have been and it actually turned out to be firing on all 4, which is definitely better than just the two! I do have a code for a rich condition though, Ill see if that goes away with the new one as well, but that could be from the last few days of cranking it and trying to get it to run while dumping fuel into the engine and it not completely burning. Ill do more updates as i figure anything else out, but i really am hopeful that just that 3 dollar part will solve this, i dont even want to talk about the money ive spent before hand trying to solve this haha.

 

Its been a few days now, got the new valve in. The truck runs like it used to. CEL is on for a rich condition. Im going to monitor it over the next few days and see if it isnt something that may correct itself. I dont know if the 02 sensors wouldve gone bad with me trying for days to get it to run and just dumping fuel into the cylinders and not burning. Any suggestions? It seems to have been fixed except for that part. I really appreciate your help man! Solid advice. Thank you.

 

How long did it take for CEL to come on after the repair?
If it was a few days then something else may be wrong
If it was right away then drive a bit longer to see if it clears, or there are actual symptoms of Rich running, i.e. smoke out the tail pipe and MPG in the toilet

No, short term issue shouldn't effect O2

 

Here i am again, with what i feel like is a related issue to the original problem. After we talked last, the truck had been running amazingly. Check engine light cleared itself the day after. Perfect temps since i replaced the CHT (nothing over 230°F, these 2.3 duratec engines love to run hot, from what ive read this is perfectly normal) but, it got cold as hell here where live this winter, and its beginning to act like it had before. My ultra gauge reads perfect temp, but seems to randomly show negative temps and the rpms spike to about 2k. This happened last time too, and progressively got worse until the truck just wouldnt run. Im afraid its happening again. This morning when it happend, the truck died, and had hell starting for a minute, but eventually did once my gauge started reading the temp correctly again, this time there is no CEL when it acts up with the gauge showing negative temp. Last time took me 2 months to find the correct cht sensor, as its the long version, all parts stores only have the short ones. Last time i tried the short one just for gigs, it didnt seem to work at all. Any advice for trying to solve this situation?

 

You said this was a 2001.5 Ranger, correct? The 2.3 in the 2001-2003 Ranger used a special intake manifold that is known to cause issues. There is a small cap that plugs the IMRC shaft on the #1 cylinder intake runner. If this cap falls out, it will cause all kinds of idle and driveability issues. I would at least check in that area and make sure the intake manifold is in good condition. They replaced this with a non IMRC intake in 04 for costs and simplicity.

I tried buying the Cylinder Head Temp Sensor from an aftermarket source, but the dealer is honestly the only acceptable option for this engine, as far as sensors are concerned. The new one I purchased was aluminum, and had about half the reach of the stock OEM brass unit I removed. But it works like a dream. I spent about 60 with tax on mine.

The CHT does NOT display its temp reading on the cluster, that sensor is in the water neck on the back of the block. The CHT will cause the dash gauge to peg MAX HOT and cause your "Check Gauges" light to come on when there is an issue with the cooling system.

FWIW, the intake coolant temp you are seeing is before the coolant passes through the engine. The 2001-2003 thermostats are rated for 210 degrees, and have a "20 degree" resistor in them to artificially raise the thermostat temp from 190 to 210 to open it. They removed this for a more simple standard 190 degree T-Stat in 2004. If you need to replace the T-Stat, please replace it with a FoMoCo part only, whether its the heated T-Stat or the 04+ mechanical only unit. I swapped to the 04 unit and just plugged my old T-Stat in to keep the CEL from triggering.

 

I have a 2.3L DOHC Duratec engine in my 2002 Ranger. It recently started idling very rough and threw a P0171 code and Check Engine. I looked for vacuum leaks, couldn't locate any and replaced the IAC valve, the MAF sensor and the PCV valve (what a pain that was!). Turns out the plug that seals the hole through which the rod on which is mounted the butterfly vales for IMRC (intake manifold runner control) had come out. It's on the front end of the manifold, very close to the head. Spray carb cleaner in that area (just behind the steering pump) to see if revs change. If they do, there's a leak. The hole can be sealed up using a metal disc and 2-part epoxy adhesive. It's necessary to pull the steering pump away, leaving the hose connected, to access the hole. There's a bolt (10 mm head) directly in front of the hose that runs to the rack and it helps to use a ratchet wrench. Leave this one until last as it will stay with the pump.

Disc shown glued to the hole in manifold

 

I read that somewhere else, and was the first thing i checked the first time this happened. My intake is only a couple years old now (id replaced it when the imrc system broke entirely) this time it was the actual sensor again. I was able to replace it with a part directly from ford themselves. The long version of the cht is obsolete. I was luck to get the one i got last time, but as of now they dont exist brand new anymore. They gave me a new aluminum body sensor without the long portion past the threads. The short ones hadnt worked before, but I trusted fords word that the new one was a direct replacement, and regardless of it being short, its working beautifully. My temps are perfect, ive regained fuel mileage (a considerable amount) and with the other one sometimes it would feel somewhat hesitant, thats gone as well with this new one. It may have been the aftermarket sensor i went with last time i tried the short version just didnt work for these, but the direct ford replacement is doing very well. If your cht goes out, and your truck uses the ling version, go straight to ford and get the actual replacement sensor. Thats the only solution i have found so far, and it seems to be working like a charm! I appreciate all of your help, and i hope this gives yall a good amount of helpful advice for your troubleshooting as well.

 

I've probably had about every mechanical issue you could come up with on my 2.3NS ranger, so if you ever have a problem with it, reach out and I will try to help as best as I can.