Hi, all.

I am having issues with what I believe is fuel delivery in my '05 X-Type 3.0 Sportwagon with 162k. See attached video:

The car will intermittently refuse to rev past 3k. Doesn't matter if I floor it or use partial throttle; this happens when accelerating, though not always present. As seen in the video, I can floor the gas later on without issue—though the problem is becoming more frequent. This issue started a few days ago.

Additionally, I've noticed it hesitates on cold starts. When warm it will suddenly but briefly idle low for just a second. The RPM's also slightly fluctuate.

My original fear was that the transmission was having issues. These last few days tt seemed to hunt a bit and started randomly clunking into gear every now and then. Now that the (supposed) fuel delivery issue has reared its head I believe the funky transmission shifting is related.

I have the following codes:

P0171
P0174
P0420
P0430

The "system too lean" codes are new. The cat codes have been present for the last two years and haven't been a source of any real concern (I know, I know...).

​​​​Any help would be much appreciated.

* The common issues with the breather hose, IMT o-rings, fuel filter, and brake booster hose have been replaced and are not the issue. *

 

I chased these "leak related" 171/174 codes for quite awhile ensuring there was no possible leak from the "big 3", O2 sensor failures nor engine gaskets. Finally changed the MAF (no aftermarket) and gone for several years now.

 

Bennett, well, you have replaced the normal "easy things". So, this is leading you to the more difficult things to replace. From what you are describing with the P0171 and P0174 codes, you have a significant air leak. Because you have replaced the big 3, this leaves a few options still. I would say to start with seeing if you can do a smoke test of the intake. If you don't have the stuff for that, then I would say to grab a cigar (or a friend that will smoke one for you) and what you do is with the motor cold, start the engine and then gently blow the smoke into the engine bay. You are looking for the smoke to be moving through the engine bay and then make a sudden turn towards the engine. That will be your vacuum leak. You can also try using some starter fluid and spraying every joint (I would focus on the intake joints under the intake) and if you spray the starter fluid near the leak point, you will hear the engine RPMs rise. Spray every joint you can think of that may see vacuum and see what you find. The final way is to get yourself a piece of tubing and you put one end near your ear (DO NOT!!!!! make a seal to your ear) and then you run the other end near all the joints. When you get near the vacuum leak, you will hear a sucking sound in the tube. Run the tube over the entire engine and see what you find.

Odds are, you are going to find that either your upper and/or your lower intake seals are leaking. I would say that if you are going in to replace the uppers, based on the age of the car, I would would spend the little extra money and time and do the lowers too. You can pick up both seal kits at your local auto parts store for around $25 a kit. If they say that they don't have the kits, ask them for the kit for a "Lincoln LS 3.0L" of the same year. Same parts. Yes, this will probably take you 3 hours to do, but it will be time well spent.

From there, I would look under the intake for a green and orange tube. These can become brittle and if you crack them, they will cause a vacuum leak that will come and go like you are seeing. But, I think you will find your leak using one of the methods I put in the first paragraph.

 

Automotive stethoscopes are available dirt cheap through Harbor Freight for like $4.99 (or mail order). Great for tracking down vacuum leaks and engine noises.

 

Thank you all for the detailed responses and suggestions.

It may be worth taking to a shop to have the smoke test done to rule out a vacuum leak. Could a bad fuel pump cause this? Thermo, if you can recall, I wrote in a couple of months ago asking about a strange no start issue where it sounded like the car was starved of fuel. This miraculously cured itself; could these issues be related?

Additionally, after more research, it seems clogged cats are a relatively common cause of my symptoms. Is this correct? I have had the cat codes for a while... Is it really time to change them? Considering the monstrous cost it is something I'd have to do myself.

 

Bennett, clogged cats would not cause what you are seeing. As for a bad fuel pump, this is where I am thinking you may need to check the fuel pressure regulator as it has a line from the intake to maintain a proper differential pressure across the fuel injectors.. You start getting the wrong presssures and now your engine is not getting fueled correctly. But ,this would tend to give more of a rich condition if anything. If the fuel pump is failing, it would not give the intake vacuum leak error codes. So, I am not thinking it is related.

 

If it was parked, there's likely a rev limit at 3000 (to protect things such as trans).

 

That's relatively good news. The fuel pump and cats are two things I'm not looking forward to replacing if/when they go.

Cleaning the MAF did not help.

The car actually ran fine this morning without hiccuping. So strange that it comes and goes like this...

I will check the fuel sender/hose when I get home this evening.

Could this be a bad/failing fuel injector?

No Rev limit in park. The car was accelerating when I experienced the issue.

 

Bennett, if it was a fuel injector, you should be getting a lean/rich code on 1 or 2 cylinders. You don't mention any codes that are specific to a cylinder or two. This is where we are again looking back at some sort of vacuum leak.

 

I took the car to my local shop to have a smoke test done to identify the vacuum leak. The mechanic experienced the issue and diagnosed it as an electrical problem; he suggested I take it elsewhere. I'm disappointed with this conclusion and disagree with them. Could this really be an electrical issue or were they just not interested in working on it as I suspect?

 

I have the same car (05 Wagon) with virtually the same mileage and had the same symptoms late last year when I bought the car. Sometimes it would rev, but other times not but it got worse / happened more often.

In the end it was the lower intake manifold gaskets. If you are reasonably (but no need to be professionally) handy this can be tackled yourself and by doing it yourself you will know it was done and done correctly.. Note that this is probably the most invasive/difficult of the dozen or so things that are most likely to be wrong to cause this issue.

Before I got to that point of changing those I also checked both small hoses that go into the intake from the top. Both O-rings were bad, one a few months ago when I initially checked them, and one just last week when the check engine light came back on with the same codes, but I was able to fix it in under two minutes start to finish this time.

Anyway, check the two little O-rings, you have to very carefully with a pick or small screwdriver pull them out, they look fine installed but may well crumble or be cracked.
Check the Brake Booster line diaphragm, mine looked great, I think it was recently replaced by previous owner
Check the big O-rings in the actuator at the back of the engine bay. I replaced mine just to be safe. The O-ring can stretch over the assembly, no need to completely remove it beyond the two screws.
Check the MAF (cleaned and then also swapped mine with a different junkyard one, no difference)
Check the MAP (cleaned and also swapped, no difference)
Check the ribbed hose on top of the engine from the PCV (I changed mine with a different good one, no difference)
Check the PCV valve, it was cheap so I just got and installed a new one, no difference, but astounded how much oil gets into the intake.
Make sure the throttle body boot is tight, this one is free. Also make sure there are no tears in it, so remove it to check. (the short but thick ribbed piece)
I swapped the fuel filter due to the car coming to me with a spare new one, no change.
I then bought spark plugs, plug boots, and upper as well as lower intake manifold gaskets as a hail mary. While changing the whole kit and kaboodle (besides the boots as mine in the car looked different than the ones I bought), the lower intake manifold gaskets in the car looked far worse (original?) than anything else I had examined to date. Swapped them and still had the same issue on the first test drive only. Huge bummer.. But on the second test drive the 3000rpm cutout went away (YAY!) and after five drives the check engine light went off (Ice cream for everybody!)

No issues since (except for the O-ting last week), but as I said that was easy to diagnose and fix since I knew everything else was in good shape, but amazing how one single crack/break in the tiny O-ring can light the check engine light.

You can do the entire list in an easy afternoon and the gasket swap in another easy, afternoon at a very relaxed pace. An extra pair of hands helps, but it can be completely unskilled labor (honey, just hold this up and out of the way while I scrub this, thanks!).

Good luck!

 

This is great insight. Thank you for helping me to feel better about this issue. I had my suspicions of the lower intake manifold gaskets but the Carfax said the spark plugs were replaced a few years ago. I suppose I talked myself into believing the gaskets were replaced at that time, too. Wishful thinking! Everything else is indeed in good shape. I'll go ahead and replace the lower gaskets myself.

I love these cars—that's why I have two! This one has proven reliable as this is my first "major" issue. This car has been great in further developing my shade tree mechanic abilities. Everyone likes to tell me it's a Ford—until I ask them to repair it. Lame! It's amazing what a mechanic will say just to avoid working on it.

 

My carfax actually said the intake manifold gaskets had been replaced a couple of years ago, if so it was just the uppers when I compare the condition of those to what I pulled out below. The lowers don't get accessed for spark plugs, but it's an extra fifteen minute while you're in there kind of step and at this age/mileage if it isn't actually your problem (but I'll bet it is), will be eventually anyway..

When you take the upper manifold off you'll see the fuel rail and a black block that the fuel stuff is bolted to. The injectors etc can stay where they are, the black block is held on by I believe it was four bolts. Some say there is another bolt at the right edge, I don't recall that. Take those four out and it likely still won't move though, I spent twenty minutes revisiting everything online to make sure I had it all. In the end I had to use a screwdriver (gently) as a bit of a pry bar from the side to "pop" that assembly loose. Then you see the crud built up from the last 17 years around the edges which should be removed and cleaned up after you put something down the intake to stop the crud from falling in. A shop vac helps too. The black block and fuel stuff can just sort of "fold" up and out of the way, this is where the extra set of hands is handy to keep it out of the way without putting strain on anything.while you clean and replace the lower gaskets.

There are a couple of good threads with pictures or at least excellent descriptions showing exactly how to get in there. Just keep lots of baggies handy, place everything down in a long row in order of assembly and take lots of pictures. The hidden bolt in back by the firewall is the hardest part but even with my big meathooks was doable. Oh and mark which intake bolt goes with which hole, there are different length bolts for different holes.

Good luck!

 

Unfortunately, my issue persists. See the above posts and the video for reference.

I have most recently replaced:
- both upper and lower intake manifold gaskets
- IMT o-rings
- PCV and PCV hose
- brake booster vacuum hose
- the vacuum hose that runs under the intake and connects to the rear
- the golden pieces the brake booster lines connect to in the manifold

A mechanic has verified with a smoke test there are no vacuum leaks; I am still getting the P0171 and P0172 and the car usually won't rev past 3k rpm. Sort of at a loss now... could oxygen sensors have anything to do with it now? I noticed oil in the intake tube and by the throttle body... could a bad throttle body cause my intermittent 3k rpm rev issue?

 

Odd to have both P0171 & P0172 as they are polar opposites!

 

They are booth lean codes, bank one and bank two.

 

If you are running lean and have no air leaks, could it be a fuel line pressure issue?
Clogged fuel filter, bad pressure sensor or a bad pump?
See if you can get a pressure reading and see if rail pressure drops away when you lift RPM.

 

P0172 is the bank 1 upstream sensor showing too rich. P0171 is bank 1 downstream showing too lean. As JagV8 said, this is diametrically opposite readings. Too rich going in to CAT and too lean coming out of CAT.

P0171 =






P0172 =



So in answer to your question, could the O2 sensors have anything to do with it, the answer is yes.
BUT... as mentioned in the beginning of this thread I had the ubiquitous P0171 and P0174 (NOT 172) codes that researching air leaks (most common) did not have. I too cleaned my MAF with no corrective results, then changed to a NEW OEM MAF which cured my codes

 

Incorrect!

 

My mistake! You are correct, I have P0171 and P0174. I also now have P0430 and P0420.

I just reseated the intake manifold to rule out any leaks from replacing the gaskets there, changed both upstream sensors, and replaced spark plugs just as a "while I'm in there" item. Still have the issue, running lean and often won't rev past 3k rpm. What could possibly be my issue??? Feeling very defeated. Nothing I've done has made any improvement.