Rough idle?

[ZombieHunter]

Had my 01 Job 2 Trac for about a year, and the forum has been great! Anyway, I've got some rough idle issues. Started off with the Lean Banks 1 & 2 codes, found the threads on the cracked vacuum elbow, and replaced that. It was cracked of course. Cleaned and tested the MAF. Cleaned the IAC. Changed the fuel filter. Changed the plugs with Motorcraft OEM replacements. My mileage has gone down to 13-15 MPG. I'm not throwing anymore codes, and just finished up a 1500 mile trip. I've got a K&N FIPK on there, but the trouble didn't start until 5000 miles after installation. SOMETIMES, I can hear a burbling sound in the K&N intake tube, almost like a backfire but not loud. Idle in neutral is about 700 RPM. I'm at a loss here. Any ideas? :scratch:

 

[dinks07]

Im having kinda the same issues any ideas

 

[ZombieHunter]

Any ideas? I'm thinking the popping/burbling in the air tube is a mis-fire. Since I'm not throwing any codes, I have no idea for sure. I had the whole fuel system cleaned at Express Lube about a year ago. I'm going to SeaFoam the engine anyway. Where should I look next? Other vacuum leaks? Bad coil packs or wires? PCV valve or O2 sensor? Fuel pressure? Just looking for some ideas on where to start.

 

[Clusterpup]

You changed the plugs but how about the wires?

 

[ZombieHunter]

Checked them for resistance Pup, they were all in spec. That's a good idea though, nothing to be lost be changing plug wires.

 

[Clusterpup]

Another vacuum leak? Could be. You could change the PCV.

 

[ERUSH97XLT]

Hello,

Seems like you've covered all the "check this first" laundry list items to cure your lean codes.

Since you're having both banks run lean, it has to be something that effects the engine as a whole, not just one set of cylinders. This should rule out individual spark plugs/wires, bank-specific oxygen sensors, and cylinder-specific fuel injectors. Consider diagnosing items like another vacuum leak, coil pack, FPR, fuel pump, and other components which affect the engine as a whole. You really won't know what sensor data the engine is using to compute its enrichment without hooking it up to a scanner.

Check out some of my posts regarding this same issue, both with myself and others.

Tell us more about this burbling/popping you hear. Are you sure it's from your intake and not a cylinder head?

Lean codes are very difficult to cure, so bring your patience along with any advice you receive.

Regards,

ERUSH

 

[ZombieHunter]

Well, I haven't thrown another code sine I replaced the vacuum elbow 2000 miles ago. That's what is confusing me. The Lean on both banks codes went away. I'm going to do the sparkplug wires, PCV and any other routine maintenance tasks you guys think may need to be done anyway. I'll squirt some more carb cleaner around the intake manifold and see if I can find any leaks. I'm just surprised I have no codes.

The burbling/popping noise echos clearly in the intake tube. I'm not sure where it originates, but it seems like a mis-fire/backfire type of situation. So I'm thinking ignition or timing related?

 

[ERUSH97XLT]

Well, I haven't thrown another code sine I replaced the vacuum elbow 2000 miles ago.

There may be some pending codes that haven't tripped the CEL yet.

it seems like a mis-fire/backfire type of situation

If you suspect a backfire, it's most likely a fuel problem. Do you have access to a fuel pressure gauge? I would check your fuel pressure at the rail.

 

[ZombieHunter]

There may be some pending codes that haven't tripped the CEL yet.


If you suspect a backfire, it's most likely a fuel problem. Do you have access to a fuel pressure gauge? I would check your fuel pressure at the rail.

Is there a time frame or mileage interval that usually has to occur before they trip the CEL?

Just ordered a gauge yesterday actually. I really appreciate all the feedback. I'll keep you guys posted on what I find. Once again, the community here is awesome!

 

[ERUSH97XLT]

Is there a time frame or mileage interval that usually has to occur before they trip the CEL?

The OBD-II system typically doesn't track malfunctions by mileage nor time interval, but rather repeated system failures or on-average-out-of-spec sensory data. If I recall, the lean codes are tripped when the fuel adjustment trims exceed +20%. I'm not sure if this is an instantaneous occurrence (i.e., the moment the trims exceed +20%), or an average of +20% over the course of a drive cycle. If I recall, again, the OBD-II "drive cycle" tries to account for all types of driving, including short trip, long trip, and daily driving. I forget the exact conditions needed for the OBD-II system completes a drive cycle. I've sometimes completed them in a few days and sometimes over an oil change interval; it depends on your driving habits.

Moral of the story, I think the lean codes need to trip twice in order for your CEL to illuminate. You may have tripped them once, causing a pending code, or you may be approaching the +20% enrichment without throwing a code (i.e., +16% to +19%). Regardless, you need to have your truck scanned if your fuel pressure test passes or is inconclusive.

 

[ZombieHunter]

Anybody ever used this scan tool? Think it will give me the info I need to tell what my engine is doing?

http://www.amazon.com/ElmScan-Compact-OBD-II-Diagnostic-Software/dp/B002PYBZJO/ref=sr_1_6?s=automotive&ie=UTF8&qid=1313449986&sr=1-6

 

[ERUSH97XLT]

Anybody ever used this scan tool? Think it will give me the info I need to tell what my engine is doing?

I have not used an ElmScan, but I HIGHLY recommend a scanner from the following link:

http://obd-2.com/

I personally own the TRICAN option and it is definitely worth its salt: I have run diagnostics on each of my Explorers ('97 through '03), plus my sister's '06 Buick Lucerne and '96 Oldsmobile Eighty Eight. Many CELs and computer misbehaviors have been studied and corrected with the use of this scanner. If you choose this one, do not order the USB cable; it's junk. Get a good one from your preferred electronics store. This scanner has paid for itself dozens of times.

If I recall correctly, you will need separate software to read Ford's enhanced parameters with the ElmScan (ElmScan owners: correct me if I'm wrong). I think the product only reads the universal parameters common to most manufacturers. The product mentioned above has Ford's enhanced parameters, along with about a dozen others manufacturers' parameters, included in the software.

 

[ZombieHunter]

I just wanted to close this out. I replaced my plug wires. To give credit where credit is due, my wife told me I should have done this when I changed the plugs. I knew this, but I was being a cheapskate I guess. I checked them for resistance, and let it go. The Number 3 wire was actually worn right through the insulation on the AC Condenser. My wife, who has never spun a wrench in her life, looked kinda smug when I told her she was right.

In any event, that cured most of the problems. I still have a little bit of a rough idle, but I'll track it down. Most of my major issues were solved by:

Replacing the infamous vacuum hose elbow.
New plugs, my old ones had HUGE gaps.
New Plug Wires (see above)
Cleaned the MAF
Cleaned the IAC

GTG for now. Thanks all.

 

[Jay02sports trac]

Fixed my rough idle problem for 2 bucks!

Before going through all the trouble of replacing plugs, wires, and everything else . I listen to my truck. Yes that's right! I heard the whistling and sucking noise which had to be a Vac leak! All of my rubber Vac hoses were stiff and rigid ( just like they should be) except for one. This hose was lose and spongie to the touch. It was the 90 degree 6 inch heater hose just to the left of the throttle body. It cost 2 bucks at advance to replace. Have patience and listen to your vehicle! I now have a 99% happy sports trac.