Emmsions problem and more

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Slygh93

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Hey guys a have a 96 ford bronco with a 351 v8. Any way I can't get my truck through inspection due to the fact that the motor is running lean. I have codes for lean bank 1 and 2 and I also have a code for p0401(can't remember what that one stands for) my truck has an extreme loss in power and sometimes has a hard time starting, it will idle really tough and I can feather the gas to keep it running but If I give it to much it just cuts out all together. Any help at all would be nice, I'd really love I get my truck running right again and through inspection. Thanks guys!

 

NaturalRampage

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Hey guys a have a 96 ford bronco with a 351 v8. Any way I can't get my truck through inspection due to the fact that the motor is running lean. I have codes for lean bank 1 and 2 and I also have a code for p0401(can't remember what that one stands for) my truck has an extreme loss in power and sometimes has a hard time starting, it will idle really tough and I can feather the gas to keep it running but If I give it to much it just cuts out all together. Any help at all would be nice, I'd really love I get my truck running right again and through inspection. Thanks guys!
Sounds to me like you're misfiring real bad. I'd check out alot of things, starting with your Ignition system, I prefer to start backwards meaning from the Spark plugs. Check their gap and wether or not they're firing (via Spark light). Check your coils and if you have a distributor system, check out your cap and rotor for excessive damage to the contact points. Back to your Spark plugs, if they're new, are they OEM? Because different spark plugs can cause major issues if the threads are completely different from the original.

Also make sure your Fuel system is getting the right amount of pressure at the fuel injectors, Clogged injectors could be another factor to this.

Question for you: Was this recent? Are you overheating at all? And did you use a different type of fuel (Regular, Premium, Plus) recently to fuel up with?

Start off with what I've explained and update us on your situation! Good luck!

 
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Slygh93

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Spark plugs and wires are actually almost brand new, maybe 2 months old and they are oem.

 
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Slygh93

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And no to over heating and still using the same fuel as always

 

Rons beast

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Hey Sly,

Welcome,

First scan for all codes KOEO and KOER engine warmed up. Let us know if you have any others.

P0401= low EGR flow. First check the hose to the EGR sensor is intact. A common problem with these engines is carbon buildup in the throttle body. Specifically the EGR passage. Seafoam makes a spray that has a small hose that can be slipped in the air hose duct before the T-body. Run the engine warmed up and at about 1500 to 2K rpm...then add the spray. it will help clean the T-body.

From your symptoms it sounds like you may have a vacuume leak as well. look for any broken or cracked vacuum lines. The pvc line is often colapsed from oil and heat often behind the intake manifold where it isn't seen.

If you would have an ignition miss the EMS would flag a rich condition from unburned fuel.

You say you are lean....look for vacuum leaks and EGR issues.

Good Luck

 

miesk5

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I had DTC PO401 too; went through the diagnostics and checked possible causes shown below; when I pulled REF hose off, fine particles fell out of DPFE

DPFE Location pic in a 96 5.8

p1010104.jpg

Source: by bergs

P0401 - EGR Flow Insufficient Detected The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPFE sensor indicates that EGR flow is less than the desired minimum. Vacuum supply

EGR valve stuck closed

EGR valve leaks vacuum

EGR flow path restricted

EGRVR circuit shorted to PWR

VREF open to DPFE sensor

DPFE sensor downstream hose off or plugged

EGRVR circuit open to PCM

VPWR open to EGRVR solenoid

DPFE sensor hoses both off

DPFE sensor hoses reversed

Damaged EGR orifice tube

Damaged EGRVR solenoid

Damaged PCM

Perform KOER self-test and look for DTC P1408 as an indication of a hard fault. If P1408 is not present, look for contamination, restrictions, leaks, and intermittents.

DTC PO401; Most of the time, because of hot exh gases flowing thru the DPFE, it is a failed DPFE sensor; Before you buy a new one; ck the two high temperature silicone hoses that go fromthe EGT Tube's 2 small diameter tubes to the DPFE sensor. They are available at your local Ford Dealer. The dealer sells this special silicone hose by the foot ( I paid $10.00 for each hose & you trim it to exact length. PNs 1L3Z-9P761-AA - 1/4" for REF - Downstream hose (INTAKE) & 1L3Z-9P761-BA - 5/16" for Upstream hose (EXHAUST);

For DPFE Sensor, The new DPFE sensor will be plastic as your original is still probably die cast metal; dealers in area want $150.00 for the DPFE Sensor and will not discount; so I bought the MOTORCRAFT DPFE15 thru Amazon w/free S&H for $60.00 and no tax;

Also read the DPFE Testing & Vacuum/Voltage Parameters & pics on both older Aluminum & Newer Plastic Version

@ http://www.tomco-inc.com/Tech_Tips/ttt36.pdf

backprobe connector using long straight pin (I use my better-half's sewing kit pins with large plastic balls on end and clip one meter's lead to it)

backprobingterminal.jpg

Select Volts DC on your Multimeter

Connect the BLACK lead of the Multimeter to a good ground point on the engine or to the Battery Negative Terminal.

for the tests req. a hand held vacuum pump

Vacuum pump and gauge tester includes 24 in. tube.jpg

go to local parts store and use their Loan-A-Tool Program

 

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Slygh93

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One other problem I forgot to mention in the power loss department, say I'm cruising at 50 and I wanted to pull out and pass somebody of I pushed the pedal any more than 3/4 of the way down my rpms would jump like normal to say 3000-3500 bit the truck goes no faster at all, it can't pick up any speed when u get on it, not sure what would cause that

 

Rons beast

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Hey Sly

Again what codes do you have. Still sounds like the engine is running too lean. (Lean= low power...no molecules to rapidly expand) What was the result of your checks of vacuum lines and M5's checks? You may need to spray some carb cleaner around the base of the manifold to search for a vacuum leak as well.

If all looks good and well, a strong possibility is the MAF sensor. ( M5 should have the process for checking that.) I chased codes on the Beast for almost a year. Lean bank 1..Lean bank 2...Egr flow....Changed the MAF.....codes and problems gone.

Good Luck

 

Krafty

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also have you checked for fuel pressure, a highly restrictive fuel filter or bad fuel pressure regulator could also be the culprit.

 

miesk5

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For the downshift issues; does the Bronco have any over-sized tires (such as over 33) or engine and transmission mods?

Is the transmission control indicator lamp (OD on/off switch with LED @ end of shifer stalk) Flashing?

Fluid Level and Condition ok? last time fluid was flushed & filled?

This is by Ford for the 96;

Downshifts (Automatic)

Possible Component Reference/Action

229 ELECTRICAL ROUTINE

Powertrain Control System

Electrical inputs/outputs, vehicle wiring harnesses, powertrain control module

Run On-Board Diagnostics. This is a Scan for Diagnostic Trouble Codes (DTCs) that can be done for Free @ local Parts Store; get it done with Key On and Engine Off and while at engine normal operating temperature (greater than 180° F) for the Key On Engine Running (KOER) test.

329 � HYDRAULIC/MECHANICAL ROUTINE

Main Controls (Valve Body)

Bolts not tightened to specification

Retighten bolts to specification.

Gaskets damaged, misaligned

Inspect for damage and replace.

CB7 check ball missing, wrong

Inspect for damage. Service as required.

Valve body separator plate damaged

Inspect for damage. Service as required.

Improper parts used in rebuild

Verify that correct parts were used.

-------

 
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Slygh93

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Codes are p0171 p0174 and what ever the other cod I mentioned was and the fuel filter is brand new

 

miesk5

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P0171- System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:

Fuel system

Excessive fuel pressure.

Leaking/contaminated fuel injectors.

Leaking fuel pressure regulator.

Low fuel pressure or running out of fuel.

Vapor recovery system.

Induction system:

•The MAF (Mass Air Flow) Sensor is dirty or faulty

Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.

Air leaks after the MAF.

Vacuum Leaks.

•Possible cracked vacuum or PCV line/connection

•Faulty or stuck open PCV valve

.

Improperly seated engine oil dipstick.

EGR system:

Leaking gasket.

Stuck EGR valve.

Leaking diaphragm or EVR.

Base Engine:

Oil overfill.

Cam timing.

Cylinder compression.

Exhaust leaks before or near the HO2Ss

•Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling

•Inspect all vacuum and PCV hoses, replace/repair as required

•Inspect all hoses and connections in the air intake system

•Inspect and/or test the intake manifold gaskets for leakage

•Check for a dirty fuel filter and proper fuel pressure

•Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool

•If you have access, you may want to run a smoke test

DTC P0171 & P0174 Lean Troubleshooting; "...These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel). Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor (MAF) that is not reading airflow accurately, an EGR valve is not closing (DPFE) and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow). If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors

I can try and get the Ford Pin-Point test if you want; you will need patience to read it and test. Or have the $ to have a shop do it for you.

 

Rons beast

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Hey Sly,

Here's the deal on what you need to do. Starting with the stuff that's free first:

#1- Check your base timing. ( remember to remove the spout connector). Adjust if necessary.

#2- Check engine vacuum....less that about 18 at idle, look for a big vacuum leak. 18 to 22? ok go to #3

#3- check for vacuum leaks...lines...manifold,etc. It's common for the hard plactic line to the Vac solenoid for the recirculating blend door to leak close to the solenoid. ( this is the one at the top of the heater core box at the corner of the right fender and firewall) Check the Vac line to the brake booster and the booster itself. ( with the engine running, trans in park, parking brake applied get under the dash, press the brake pedal slightly and listen for hissing....hear hissing? booster has a leak.

If you find leaks fix them, and clear codes, Test drive. If you find none go to #4

#4- Remove and clean the EGR valve. Check that it is not sticking. Inspect the line to the DPFE sensor (EGR sensor)

Clean the throttle body as described in a post above. Do the DPFE test as M5 outlined.

Repair any problems found, clear codes, Test Drive. No problems found go to #5

#5-Clean MAF sensor with approved cleaner. Clear any codes, Test Drive. Problem solved have beer. If not go to #6

#6- Test fuel preasure at fuel rail. ( this is where it may require you to open wallet and buy a fuel preasure testor...you may find a part store that will check for free, or a friend with a testor, or you may get creative and have a friend or friends go together and split the cost of the testor.......and the beer.)

Fuel preasure low? pull line off regulator. Still low replace regulator. Still low replace fuel pump. (you said the filter was new.) Clear codes, Test Drive. Problem solved Have beer If not go to #7

#7- If you have dilligently checked everything and find no vacuum leakes, stuck EGR valves, bad fuel preasure regulators or pumps, Done the checks that M5 suggested and gotten no where, you need to have a beer and realize that you are working on a vehicle that is 16 or 17 years old. You will have to replace items that have been in service for that long even if they may appear to be ok. This I am saying from personal experiance. I had the exact same codes that would reappear after checking and clearing. Sometimes in a day....sometimes a week...sometimes longer. I replaced the DPFE sensor, and that corrected the P0401 code. The P0171 and P0174 codes took a little more time. Replaced the EGR valve with 170,000 miles on it. ( let's admit it deserved to be retired.) Codes went away for a few months....then came back. Finaly replaced the MAF sensor at 173000 miles and the codes went away,( didn't return after being cleared.)The Beast had more power and got better gas mileage. Now have 180000 miles and still no codes, and runs better than new. If you don't want to go this route, you can go to #8

#8-Sell the truck.... Drink beer.......don't drive.

Good Luck

 
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Slygh93

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Replaced the mass air flow today, and since I'm on a limited budget it's the only thing getting done until pay day next week but I noticed no real difference. And I've started to notice recently the truck has a real hard time starting back up after long drives. It'll crank md turn over and stumble around 300-400 rpms then stall. After doing that a few times it eventually not turn over at all until it has sat for a while

 
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Slygh93

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And when you say remove and clean the egr valve is there a specific cleaner? Or no?

 

Rons beast

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Hey Sly,

No specific cleaner for the EGR. I use carb cleaner and sometimes some Seafoam.

Did you bother to go through any checks? Timing , Fuel preasure, Vacuum leaks?

Clear codes and see what resets?

 
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Slygh93

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Haven't gotten to fuel pressure and no idea how to check timing. And so far I haven't found any vacuum leaks so far

 

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