Banks 1 and 2 Lean

[mranderson214]

Hey Everyone,

It's been a while since I was able to post on this forum, but I hope everyone is well. I know that this is a topic that has been discussed at length, and I've done a ton of research on the matter but have come up with nothing that worked in my case, thus far. Basically I have a lean condition and Check Engine light; and as I've done so much research and troubleshooting, this may be quite lengthy, my apologies in advance..

I have a 2002 Ford Explorer XLT, V6/4.0 L, with nearly 231,000 on the odometer (and still going strong). I have a small leak in the valve cover gasket, seen mostly on the drivers side, but my mechanic said that it could wait as the leak is small and I change the oil every 3,000 miles. After about a year and a half, I went in to have him change it one day but he mentioned that one of the bolts was stuck on/near the upper intake manifold. Ultimately he didn't change the valve cover gasket out of fear of breaking the plastic on the intake.

Shortly after that, I got a Check Engine light, P0171 and P0174. Checked all the hoses, cleared the light. It came back. Put a clamp around the air intake breather hose because it was loose where the hose met the intake.. same codes came back after about 10 miles after that. Cleared code, it came back again. I've driven it about 500 miles with the CEL and everything runs normal: no rough idle, no unusual fuel consumption.

I began working on it again, as my inspection is due by the end of July. Changed the air intake breather hose with a new one, cleaned the MAF, checked for loose hoses and worn hoses, took off the PCV valve hose and inspected it, changed the PCV valve, changed the fuel filter, checked hoses again, reset the code again. After about 15 miles, the code came back. One mechanic I had check it said it's probably a weak fuel pump, but I don't think so. I got the CEL done after the fuel filter, now I have a P0156 (Oxygen Sensor Circuit Malfunction (Bank 2 Sensor 2)), P0171 and P0174. I doubt that its a faulty O2 sensor considering both banks are "lean".

Reading the forums, I've come to the conclusion that it might be an intake gasket? I was planning to have a smoke test performed to check for vacuum leaks, but I was wondering if its possible to see an intake leak with a smoke test. Is there anything else you guys can think of that might've caused this?? Willing to take any advice anyone can provide.

Thanks in advance!

 

[Number4]

Seeing as hoe the mechanic attempted to remove the intake and your high mileage, you may have a crack or bad seal.

Might persue a new intake.

 

[mranderson214]

Thanks so much for your reply.

I finally had given in and had them so a smoke test today. Within a minute we saw smoke pouring out of the egr valve. After changing that and clearing the code, it hasn't come back on yet. It's been roughly 30 miles. I didn't expect that because I had it changed roughly 4 years ago. Didn't realize they could fail so quickly..

Time to hurry and do the state inspection before it decides to misbehave again.

 

[mranderson214]

I stand corrected.. The check engine light came back. Same lean codes, p0171 and p0174. Let the struggles continue..

 

[imp]

I stand corrected.. The check engine light came back. Same lean codes, p0171 and p0174. Let the struggles continue..

@mranderson214
A trick Iearned here has not been mentioned. A volatile, combustible spray, several kinds will work, like carburetor cleaner containing Toluene and Alcohol, is sprayed lightly around the intake manifold mounting area with the engine idling. If any change is detected in the idle quality or speed, air (and spray) are being drawn into the engine and burned, either via a leaking gasket, or cracked manifold. imp

 

[mranderson214]

Thanks for the tip! I forgot all about that. When I had initially started working on this Check Engine Light, I tried spraying carb cleaner and didnt notice any change in idle. I can definitely try again..

Since I started out with the P0171/P0174 combo, I ended up:
-Checking the hoses:

Only one hose looked questionable. It's one that goes from the driver-side top of the intake (near the "4.0 SOHC" engraving), right underneath the IAC valve. It's kind of a "two part" hose, and the smaller part that's attached to the IAC-area seems a little weak. Shouldn't the smoke test have picked this up if it were a problem?

I didnt take a picture of the hose this time, but I found one I took when I changed the IAC valve a few years ago.

http://imgur.com/a/3vUiV

-Checking the PCV Valve elbow, and changing the PCV valve itself.

The PCV valve elbow has a small scrape on the back of it. I didnt think it would cause any issues because its literally like a part of the thick elbow had been scraped off. I'll be sure to spray that area with the carb cleaner too. I'm attempting to attach the image here:

http://imgur.com/a/0ZZuQ

-Cleaning the MAF sensor

-Changing the Fuel Filter

Within the past two years, I changed the IAC valve so I assumed that it was still good. Also because the symptoms I have now (none other than the light), don't match those I had before with a dirty IAC. Is it worth it to clean it/look at it even though its about 2 years old?

If it ends up leading me to the route of a weak fuel pump, or intake gaskets, I'll have to make a decision. I've owned the car for 8 years now, and put roughly 90,000 miles on it. Its now at 231,500 miles, and besides the stupid CEL, it runs extremely smooth so I would hate to get rid of the car now.

 

[mranderson214]

Something else noteworthy is that when I stuck my hand between the engine and firewall, I felt a hard plastic tube-type thing. It felt very loose, but I'm not sure what it was so i didnt want to keep tugging at it. I saw some pictures that look similar to how it felt

http://imgur.com/39pdt4i

Looking at RockAuto shows that its a "PCV Valve to Intake" hose. It feels like it's loose, connected on one end and disconnected elsewhere. Any ideas how to verify this considering I cant even see between the engine and firewall?

http://www.rockauto.com/en/moreinfo.php?pk=5937465&cc=1377660&jsn=9

 

[Drewmcg]

1) smoke test should have revealed all leaks. give us details on precisely how this was done, by whom, with what equipment. you might want to re-do smoke test after replacing the egr valve,
2) first pic is of the evap feed from purge valve (below fuse box driver side) to intake. leak there could result in unmetered air/lean condition. easy enough to replace that hose/clamp it with small band clamp, or temporarily block the opening and reset CEL light and see if it comes back,
3) if IAC gasket was not replaced and is not sealing, that might be the problem (seems unlikely),
4) my June 2002 XLS 4.0 SOHC does not have the pipe you link to @ Rockauto, which is an alternative to the pcv hose you posted a picture of (which looks fine, and is expensive to replace). You might want to replace the pcv valve if you have not done so already. But closely inspect the short crankcase breather hose, part no. 6853 at fordparts.com (type in your VIN), which have been known to fail/leak. Its on left of engine about a foot or so in from air filter box.

 

[mranderson214]

1. I did the smoke test at my mechanic in a shop. He basically brought out a smoke machine, hooked up one end to what I guess was a hose connected to the evap purge valve. It was a hose on the right side (drivers side), near the fuse box. Then he put power cables to my battery (to power the machine I'm guessing), and turned it on. After about 3 minutes, the smoke started shooting out from the EGR valve diaphragm. We waited another few minutes and didn't see smoke anywhere else. You're right, we should've smoked it again after the EGR valve and gasket were replaced.

2. I'll be sure to check that hose again. It didnt seem bad but it was definitely more worn than the others.

3. The IAC gasket was replaced at the time I did the valve replacement. It's been running fine since then so I don't know.

4. I looked up that part, and forgot to mention that I did change that little tube that's just past the MAF to the intake. I got it brand new and slipped it on. I made sure the connection was tight on both ends, to the intake and to the air-flow tube. Also, I did replace the PCV valve with a new one. Took off the hose, twisted out the old one, twisted in the new one, replaced the hose.

I'm still unsure what that hard tube-like thing is behind the engine. I felt it when I was initially looking for the pcv valve, and felt it again when I was changing the pcv valve. Whatever it is, I have a feeling that it shouldn't have that much play in it.

 

[Drewmcg]

The EVAP tube from the fuel tank/canister area to the EVAP purge valve/solenoid (which is located below the fuse box on driver side of engine compartment) runs through a metal tube behind the engine (from the passenger side to the drive side). It is held by a brace on the passenger side by one of the bellhousing bolts that connect the transmission to the back of the engine.

That metal tube is not braced on the driver side of the rear of the engine, where it eventually transitions back to a rubber hose as it approaches the purge valve. So you might perceive it as "floppy." Moreover, if you've had a transmission changed or a rear timing chain replaced, the mechanic who bolted the transmission back to the rear of the block might not have located that brace through one of the bolts, making it even "floppier." Nothing to worry about, and not related to your issue.

 

[mranderson214]

The EVAP tube from the fuel tank/canister area to the EVAP purge valve/solenoid (which is located below the fuse box on driver side of engine compartment) runs through a metal tube behind the engine (from the passenger side to the drive side). It is held by a brace on the passenger side by one of the bellhousing bolts that connect the transmission to the back of the engine.

That metal tube is not braced on the driver side of the rear of the engine, where it eventually transitions back to a rubber hose as it approaches the purge valve. So you might perceive it as "floppy." Moreover, if you've had a transmission changed or a rear timing chain replaced, the mechanic who bolted the transmission back to the rear of the block might not have located that brace through one of the bolts, making it even "floppier." Nothing to worry about, and not related to your issue.

Thanks for the response. I did have some transmission work done about two years ago, so maybe that's why I feel that much play. I haven't gotten a chance to get back into looking at the p0171/p0174 problems yet.

I'll have to try the carb cleaner to check the hoses again seeing as how my mechanic is out of town. Hopefully this points me in the right direction. Once he's back, we'll do another smoke test.

Also, If there was an intake gasket leak, would the smoke test also show that.. or does it just show vacuum line leaks?

 

[imp]

Thanks for the response. I did have some transmission work done about two years ago, so maybe that's why I feel that much play. I haven't gotten a chance to get back into looking at the p0171/p0174 problems yet.

I'll have to try the carb cleaner to check the hoses again seeing as how my mechanic is out of town. Hopefully this points me in the right direction. Once he's back, we'll do another smoke test.

Also, If there was an intake gasket leak, would the smoke test also show that.. or does it just show vacuum line leaks?

The intake gasket, depending on engine design, will always pose possible vacuum leakage, but also coolant as well as exhaust.

imp

 

[Drewmcg]

not sure about the gen 2's, but I'm not aware that an intake gasket leak on a gen 3 would cause a coolant leak. someone please correct me if I'm wrong. rather, the intake gaskets on the one-piece gen 3 intake seem only to stop unmetered air film entering the cylinders.

 

[mranderson214]

Well I think I figured out the problem.

Today I brought out the carb cleaner and started spraying to listen for changes in idle. I sprayed the hoses and didnt notice any changes in idle. small changes, but nothing significant. However, when I got to the EGR area, there was a dramatic change in idle. I tried spraying again, and the same thing happened. Just to be sure, I sprayed a third time, and the engine completely stalled. It seems like there's some problem with the EGR. Either the replacement valve was also bad, but I think more likely the gasket/seal between the EGR and the intake isnt strong enough.

This is the general area that I sprayed when I noticed the dramatic idle difference, and stalling engine.

http://imgur.com/a/au0qd

 

[Drewmcg]

What brand EGR valve did you put in there when you replaced it, out of curiosity?

 

[mranderson214]

What brand EGR valve did you put in there when you replaced it, out of curiosity?

I'm not sure the brand that my mechanic put in. I think I saw it come out of a red and blue box though.

I remember the original egr valve when I got the car was black. When he changed it about 5 years ago, it was silver. Then he changed it again recently and its silver again.

 

[lincolnshibuya]

if you have forscan you can easily figure out if it's an egr valve or solenoid issue. You can change the duty cycle of the solenoid until it stall out, if changing the duty cycle doesn't do anything then the solenoid is bad (or it could be open in your case)

 

[mranderson214]

well, he redid the smoke test today and confirmed its something around where the EGR connects to the Intake Manifold. He put a new EGR gasket on and some type of gasket seal paste around the joint where the EGR connects to the intake. Resmoked, cleared the light, now it's been 10 miles since.. No Check Engine Light yet, hopefully it doesnt come back.

 

[mranderson214]

It came back after 300 miles.

I guess the paste that he put on may have worn out? I sprayed the carb cleaner at the area again and got the same results as last time, just not as dramatic. I wonder if there's another gasket in the same area that may have gotten worn out; other than the EGR to Intake gasket.