2000 3.0L Flex Fuel Vin V - Rough idle, Misfire codes, P0174 P0171 lean codes. Cannot figure out the problem

[wyatthansen]

Hello,

So I've been lurking in the shadows of many of these and similar forums gathering information and trying to solve my problem for a couple months now... here's the issue

2000 Ford ranger 4x4 3.0l Flex fuel Vin V(8th digit) about 154,000 mi on it

-Engine reads Misfire codes on cylinders 1 and 3
-P0174 and P0171 lean codes
-Rough as heck idle
-low top end power (lucky to top out at 70-75 on the freeway after gunning it for 2 minutes to get there)

More recently:
-Even rougher idle especially at startup and when cold
-will die randomly after <10 min of city driving (dies as engine comes to idle)
-strong smell of fuel
-worse fuel mileage

So, reading through all the forums I have done/checked the following...

-Replaced the coil pack
-Checked all spark plug wires
-Checked spark at all plugs
-Felt for injectors to pop with a screwdriver at the base of each (and they did)
-Tested ECM signal to injectors
-Resistance tested each injector (they were all within spec, cant recall the number but either 14 or 18 ohms I think)
-Tested fuel rail pressure ( a solid and healthy 53 psi with no leaks)
-Ran a couple of fuel system and injector cleaners through it
-Thoroughly checked for vacuum/intake leaks with starting fluid

Then I took it to a local mechanic who tested some other things for me...
-Read codes ( all same except for a faulty coolant temp sensor which I replaced when he told me that)
-Checked backpressure on cats (those were fine)
-Then he did some compression tests and this is where things get interesting
- Compression in the cylinders was around 230 psi for most all cylinders, one or two was closer to 190-200ish psi (obviously too high)

When I bought the truck in august, the owner had or had someone do the timing chain before the sale, so that dynamite compression had me and the mechanic convinced there had to be something wrong there. And I'm no fool to pay someone $1200 to see if that's my problem so I decided to tackle the job myself. I just got done with the job(of removal and getting to the timing chain) and I found that everything seems to be in good alignment as far as the chain and gears but there was about 1/2" to 5/8" slack in the old timing chain. I slapped my new one on there and same amount of slack. The brand I used was made in USA (Cloyes) so I'm not thinking its just a bad part. There's no play in the cam or crankshaft so the slack is completely from the gears and chain. I'm not a professional but it seems to me there shouldn't be that much play. I looked at a professionally rebuilt 3.0 last week and the timing chain was pretty snug.

Long story short, I'm stumped and so is the mechanic with 25+ years under his belt. At this point I'm about to throw a long block a it but I fear that it may not solve my problem. I'm going to put this engine back together in the next couple days so I can continue to try solving my problem. Has anyone had a similar or the same experience? Where should I go next?

Thanks in advance, your help keeps me from going more insane than I already am!

P.S. A little background on myself... I'm 21 and I been wrenching longer than I been walking. I've fixed alot of vehicles for myself, my friends, and even as a side gig. I also dabble in diesels. I'm definitely not a genius but I know a couple things, I'm always looking for more knowledge so I'm all ears for anyone who's got it!

 

[stmitch]

Since you've got misfires for specific cylinders, I think it's worth swapping fuel injectors from those cylinders to other cylinders to see if the misfires follow the injectors or if they stay on the same cylinders. That would at least tell you if there's an issue with the injectors or not. Might as well check fuel pressure at the rail too (although it's probably fine if you're running rich).

Really, having FCs for lean conditions while running rich (fuel smell and reduced fuel economy) seems more like a sensor issue to me than a mechanical one. The sensors that have the largest input on fueling are the O2s and the MAF. These sensors are also involved when the engine switches from "open loop" to "closed loop" once the engine heats up. "Open loop" mostly ignores sensor input and the engine runs based on known fueling tables. It switches to "closed loop" once coolant temp gets warm enough, and at that point the PCM alters fuel based on input from the MAF and O2s.

It sounds like the engine is now randomly shutting off when it gets to operating temp, which is likely when it switches from open loop to closed loop. I think Id unplug the MAF at idle and see if your problem changes at all. If the problems get better with the MAF unplugged, that's a good indication that the MAF is bad.

I'm sure you don't want to just throw money at this, but at 20 years old and 150k miles it can't hurt a thing to replace the O2 sensors and at least eliminate them as a possible contributor.

If you think it's a timing issue, I'd check the alignment of the cam synchro too. They're known to fail around 120-180k miles if original. Maybe yours has jumped a tooth as its worn. Maybe the previous owner replaced it and didn't properly align the new one. If you do replace your cam synchro, don't bother with anything but a Motorcraft part.

 

[wyatthansen]

Since you've got misfires for specific cylinders, I think it's worth swapping fuel injectors from those cylinders to other cylinders to see if the misfires follow the injectors or if they stay on the same cylinders. That would at least tell you if there's an issue with the injectors or not. Might as well check fuel pressure at the rail too (although it's probably fine if you're running rich).

Really, having FCs for lean conditions while running rich (fuel smell and reduced fuel economy) seems more like a sensor issue to me than a mechanical one. The sensors that have the largest input on fueling are the O2s and the MAF. These sensors are also involved when the engine switches from "open loop" to "closed loop" once the engine heats up. "Open loop" mostly ignores sensor input and the engine runs based on known fueling tables. It switches to "closed loop" once coolant temp gets warm enough, and at that point the PCM alters fuel based on input from the MAF and O2s.

It sounds like the engine is now randomly shutting off when it gets to operating temp, which is likely when it switches from open loop to closed loop. I think Id unplug the MAF at idle and see if your problem changes at all. If the problems get better with the MAF unplugged, that's a good indication that the MAF is bad.

I'm sure you don't want to just throw money at this, but at 20 years old and 150k miles it can't hurt a thing to replace the O2 sensors and at least eliminate them as a possible contributor.

If you think it's a timing issue, I'd check the alignment of the cam synchro too. They're known to fail around 120-180k miles if original. Maybe yours has jumped a tooth as its worn. Maybe the previous owner replaced it and didn't properly align the new one. If you do replace your cam synchro, don't bother with anything but a Motorcraft part.

Yeah I been through the MAF and O2s before but I guess it cant hurt since the smell has gotten worse since then. Ill have to swap the injectors around too when I get it put back together in the next couple days. As for the cam synchro I'll have to see if it looks like he messed with it, I wouldn't be surprised if it was installed wrong with as many bolts the guy who did the timing chain last forgot to replace. I'll make sure to give everyone an update when I do these things. Thanks!

 

[pjtoledo]

check the output of the flex fuel sensor, what the PCM says the alcohol content is.
if is mis-reads the alcohol it adds more fuel.

 

[pjtoledo]

pull the cam sync and look at the drive gear, those can wear a lot, and they drive the oil pump.

 

[RonD]

You don't mention that the engine is pinging/knocking like crazy on Regular gas(87 octane) and it should with compression north of 180psi

3.0l Vulcan runs 9.3:1 compression ratio(CR)
Rule of thumb is 18 X CR = expected PSI
18 X 9.3 = 167.4psi
That's for cold engine test, which I prefer, you can add 5-10psi for warm engine test

200psi / 18 = 11:1 CR, any CR over about 9.5:1 requires 89octane, 11:1 93 octane or pinging and knocking like crazy

I don't think you could get 200psi compression from a stock 3.0l by cam timing, so not surprised about the cam/crank timing being OK, yes the slack is normal for the 3.0l, and it doesn't use a tensioner
You might be able to get close to 200psi with Carbon coating on piston tops and cylinder chambers, but that's not happening or you would be having pinging/knocking
So I would get another gauge and retest compression

It's possible valve guide seals are leaking ALOT, causing WET compression test every time, lol, but you would also be blowing SMOKE out the tail pipe and burning lots of oil, which you don't mention


The 3.0l Vulcan used either an EGR Valve or a Knock sensor to control pinging on regular gas, but usually not both
Which does your 2000 3.0l have?

EGR is easy to spot, lol
Knock Sensor is on passenger side of block down low, near the motor mount. just behind it
If you have a Knock sensor then that could explain the sluggish engine, it would advance spark timing to the point of very low power, if there was pinging detected and you wouldn't hear the pinging


As for the codes
The LEAN codes are the result of the Misfires NOT the cause, if you ONLY had Lean codes and no running issues then vacuum leak possibly or low fuel pressure
O2 sensors can only see Oxygen not fuel
So while WE think of Lean and Rich being fuel related that's not what lean and rich codes mean
Lean is high oxygen in exhaust, like when a cylinder Misfires and no Oxygen is burned up and its dumped into the exhaust, so O2s see High Oxygen and lean codes are set, so Lean codes are the result of misfires not the cause

Misfire codes are generated by the Cam sensor(along with Crank sensor), and exact numbers are suspect
Rotational speed is how the Cam sensor detects a misfire
At any RPM it should take the cam(or crank) a specific millisecond TIME to move from point A to point B
If a cylinder misfires then the TIME it takes is longer, as no power was added to the spin of cam or crank, this can be a total misfire(no power added) or a partial misfire(less power added)
And the misfire must be repeated many times for a code to be set, and for the Cam to ID which cylinder is misfiring in the firing order, and it can be off 1 cylinder either way, lol, so not "the word of God" just a best guess by the cam/computer

The P0301-306 codes are usually spark plug or exhaust valve(compression) issues
Spark(coil) and injector issue can generate these codes but they have other codes as well

Look here: https://www.therangerstation.com/tech_library/OBD-II_codes.shtml
In the 260's and 300's, separate codes for coil and injector issues

The result of computer "seeing" lean codes, is that it adds more fuel to all the cylinders and that causes sluggish engine performance, more fuel doesn't mean more power, it means flooded engine in this case

What did the old spark plug tips tell you about each cylinders condition?
Good cylinder should show


If you have a computer issue then swapping engine won't help
So I would re-test compression
Look at spark plug tips
See which anti-ping unit you use, EGR or Knock Sensor

 

[wyatthansen]

RonD,

I got the truck all back together yesterday and ran it a little last night. I got a code for the coolant temperature sensor again so I'm planning on replacing that today. As well as run some sea foam spray through the intake before the throttle body to see what that does.

I ran it a little last night and to my surprise it was actually running better than before, but it was still a little shaky on the idle.

On the Camshaft synchro and positioning sensor... Everything was lined up correctly, the sensor looked in good shape (newer like someone replaced it before) and I messed with the flag on the synchro and it had negligible play. Both the little bolts holding the Cam sensor (black puck on top) were a little loose so I made sure to tighten them down better when I reinstalled everything. I didn't take the synchro out because I didn't feel any play in there.

Turns out someone swapped the "new" timing chain set into my box at the store so I went and got a replacement an the slack went from 5/8" to about 1/4"... which makes me feel a little better haha.

The spark plugs on cylinders 1 and 3 had carbon deposits an were rather dark but the rest looked normal, so that lines up with the story the codes are telling me. I also got a P0300 code for random misfires along with my P0301 and P0303 codes if that helps.

Yeah I don't hear any pinging or knocking really when its running either, I know the shop I went to was having troubles with their machine so maybe I just got some bad data out of it or something. I don't have the stuff for compression checking gas engines so I might just have to go out and get a harbor freight set or something (probly cheaper than having someone else do it for me). There's no smoke or anything but there was a strong smell of gas.

And yes my 3.0 has an EGR. Is it worth replacing in my case?

So what I'll be doing next...
Replace Coolant temp sensor
Sea foam the top end (hopefully clear up some carbon that's in 1 and 3)
Check the Flex Fuel sensor output (thanks for mentioning that pjtoledo)
Drive it around and see if I can get some codes back
Swap injectors around if I get the codes back
clear codes and see if misfire moves

If it wont break the bank I'll get some compression testing stuff too

 

[laser3kw]

pull the cam sync and look at the drive gear, those can wear a lot, and they drive the oil pump.

That is what killed my 99 at only 86k miles. Dealer would not warranty it?

 

[stmitch]

Your local parts store probably rents compression testing equipment

 

[pjtoledo]

FYI, the compression tester I have needs an adapter. the smallish tunnel before the threads did not allow the hose to get close enough to catch threads.
it's set up for both the 18mm plug threads and the older bigger plugs. the big threads is what doesn't fit in the tunnel.

 

[wyatthansen]

Something interesting happened...

Replaced the coolant temp sensor and used that Sea Foam Spray and I definitely noticed a difference in how she ran. Much smoother. Unfortunately it seems I have a leak towards the rear of the oil pan through the oil pan gasket so I get to have the fun of doing that job again. Noticeably more power than before. I noticed the misfire comes on when I decelerate and if I let the engine drop to an idle, then it goes away(drove it about 30 miles and took it on the interstate, noticeable improvement overall). Also, there was a crack in the intake tube coming from the filter housing so I decided to tape it up with elec tape(wish I did this sooner) and I cleared the two misfire codes I had (same as before on cylinders 1 and 3) and I ran it for a while in park and it started idling nasty and gave me 6 codes... P0176 Fuel Comp sensor circuit, P1451 Evap Emission Control System Vent control Circuit, P0135 O2 sensor heater circuit bank 1 sensor 1, P0141 O2 sensor heater circuit bank 1 sensor 2, P0155 o2 sensor heater circuit bank 2 sensor 1, and P1409 EGR Vacuum Regulator Solenoid Circuit. I cleared these codes and disconnected the ground on the battery then started it up twice and those same 6 codes came back up.

Looking further into it my reader said these things...
Heater control for O2S11 Fault - Yes Fault
Heater control for o2S21 Fault - Yes Fault
Heater control for O2S12 Fault - Yes Fault
Exhaust Gas Recirculation Vacuum Regulator Fault - Open Circuit
Evaporative Emission Canister Purge Valve - Yes Fault

Also, checked on the flex fuel sensor and it was reading 5600Hz with no fault codes until I got these 6 codes and now it says 0Hz with a "Yes Fault" status.

 

[pjtoledo]

those all get power from the same point. fuse 13 in the battery junction box. except the evap canister purge valve.
it gets power from the same circuit before the fuse. either way, circuit 361 supplies power to all those thru S121.
it also powers the fuel pump relay and the injectors, and the PCM. it's the red wire(s).

 

[wyatthansen]

Yep... wish I saw your post sooner, just found that one out looking at a similar diagram. It was indeed fuse 13, replaced it and everything is working fine. Must have shorted when I was disconnecting some plugs to check them and clean them out... I feel dumb for that one haha.

On the other hand still the same as far as a noticeable improvement, just the misfire when coming down to an idle but after it sets for 3-6 seconds its smooths out and the misfire is gone, does that sound like anything in particular to you? I'm going to check around and see if there's anything like that in another forum too.

 

[laser3kw]

Unfortunately it seems I have a leak towards the rear of the oil pan through the oil pan gasket so I get to have the fun of doing that job again

Ha ha! I too had an oil pan start leaking. Mine push the timing cover seal seal out first. Then a short time later the pan started to rust(!) and ooze oil. Still got the old pan - for sentimental reasons