1998 Ford Windstar 3.8 Lean Bank 1 and 2, and misfire

keith

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#1
Van has a pretty hard misfire at times on cylinder #4. Had a code P304 before but this code has not reset, however the car is still missing. Van has had tune up, plugs, wires and filters . This is the main problem with the van engine is shaking and missing. I checked ohms of injectors and for vacuum leaks, checked all cylinders for spark. The codes I get are lean bank 1 and 2. I also replaced the fuel pump because the pressure is only at 10-20 psi when running. However, I still have low fuel pressure with the new pump. If I clamp the returm line the pressure jumps to 60psi but still misses. The fuel pressure seem low to me and may be causing the lean code but I still have the missfire. I will probably replace the fuel pressure regulator tomorrow becuase the fuel pressure is still only at 20psi, however the regulator is on leaking gas into the vacuum line.

I was wondering if the runners which open and close the air passage ways will cause a lean code and a misfire? I really do not know anything about the runners I just was learning about these a couple weeks ago on here so I am not completly sure how they work, I do see the vacuum motors moving in and out when you open the throttle. Or is there a way I could get a lean codes for both banks and a misfire on only one cylinder? For example I could have a bad fuel pressure regualtor causing the lean code and a plugged injector causing the miss on #4, or am and missing anything that would cause both problems. Even and intake vacuum leak on #4 which was causing a miss would not cause a lean on bank 2 would it? Does anyone else have any ideas?
 
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#2
please post all the the codes you get - ie p0171- sometimes there is confusion.

are you capable of readng P1xxx codes- sometimes called manufacturer specific? as the manifold controls are likely to set these codes.

the low fuel pressure is first issue I would tackle- regulator- leaking injector- any evidence of a fuel wet plug, excess fuel smell in oil? something unique to this egine is a pressure reliefe valve??...let me look at it and add

what is psi with reg vac line removed and capped?
 

nickb2

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#3
To bad lots of info got lost in the site crash, I posted a while back a really long post about intake manifold runner controls, I think Kev was referring to those, look for broken tabs at manifold runner control, you will see the rod for the runners just hanging and the tabs missing or lying on the manifold in pieces. These will set lean codes for both banks and not set a specific manifold runner control code as the actuator is working but tabs are busted, I did see a few times the gear in the runner control motor slip out of its notch but this set control code. I believe on the 98 windstar the runners are vacuum controled, so check to see if you have proper vacuum to these runners. If those runners have been in-operative for a long time, you may have to remove the manifold and work those runners by hand and loosen them up. However reading your post, the runners could be another problem, the low fuel pressure is a biggie and needs to be addressed. Fuel spec for this engine is 28psi regulated. I would like to see anew fuel filter in there, I would like to know vacuum readings if you have a gauge. Should have 17-20Hg at pressure regulator. Do you see any gas leaking from injector at #4 cyl, could be losing pressure there. Any hissing sound such as a vacuum leak? I know you checked for vacuum leaks, how and what was the verdict in numbers? If you have ford specific codes appearing as kev2 stated, you could have p1131 and p1151. I would also check for leaks past the MAF sensor, will cause lean codes for both banks as well.
 

keith

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#4
Thanks for the help. Acctually the long post you made before was also due to a question raised about someone elses post (a lean code on a Ford Ranger I believe). Then I was just curious, now I wish I would have saved the post. Here is the lates info. Codes are P171 and 174. The fuel filter is new. I just checked the fuel pressure and it was reading 25 psi on my guage, I did replace the regulator by the way. The engine has strong vacuum and the fuel pressure goes up a few 3-5 psi when I pull the vacuum line off the regualtor. I am thinking the fuel pressure is now not a problem, if I am getting 25 my guage could be off a few psi and it is a little hard to read ( the guage is small). I did look at the motors that open the runners they are electric and move when you rev up the engine. I pulled the upper intake and saw the two air passage ways when I was doing the tune up. By the way I do not hear a vacuum leak nor can I find one. I next plan to pull the upper intake them move the runner and see if they are moving. I am not exactly sure what to be looking for though. Shoud it look like butterfly throttles opening and closing? I believe you called them tabs. If a tab is broken what is the methed for repair? Would a broken tab cause a misfire and P171 and 174? Thanks for the help.
 

nickb2

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#5
Ok so on yours it is electric control not vacuum, so you will see two metal rods that connect to the runners that do effectively look like butterfly throttle valve. You can't see then without the intake removed. You can check to see if they move freely by disconnecting them from runner control motor and see if they are sticky. The white plastic clips resemble clips that hold door handle rods in a door such as lock mechanisms and key cylinder and such. Here is a link of a vacuum control picture, you can still see the clip that holds the rod to runner, this one is black, but same.http://rides.webshots.com/photo/2818039750011220610NJerWA
Also do you have access to o2 sensor info and what they are reading?
If you remove the runner clip and rod from actuator you can move those runners like I said.
 

billr

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#6
I may be way off base here, but the fuel pressure readings kind of caught my eye. Is this a port-injection system? If so, I don't recall ever seeing injector specs (any make or model) for pressure as low as 25 psi; more like 40 or so and up. Also, if the engine has "good vacuum" I'm thinking that is about 20" Hg; and pulling vacuum off the FPR should raise fuel pressure more like 10 psi.
 

nickb2

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#7
Well Billr, from what I saw in my research on this 3.8l the fuel pressure spec is 28psi. If I could get that damn 75gig mitchel download I spent 4weeks downloading to work I could post a for sure spec, but that damn application is to complicated for my grease monkey brain to install. Floppy disk? I thought those went out years ago. Now I need a VFD, ok got one, now what? But that is a whole other post. So spec should be 28psi if my research was on the ball. Good vacuum on a used engine should be 17-20Hg so that was on the ball Bill.
 

billr

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#8
Nickb2,

OK, I accept that pressure is supposed to be 28 psi; I assume that means at full MAP, or vacuum off of FPR. Then with the (17-20") of vacuum on the pressure should have dropped down 8-10 psi to 20-18 psi. That's my point now, 3-5 psi change with/without vacuum on the FPR doesn't seem enough...

However, I have read through the thread again and think I will butt-out now; I think you and kev2 can give more correct advice. My last advice to the poster is to answer your specific questions as they are asked, even if he thinks they have already been covered.
 

nickb2

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#9
nay but out bill, your knowledge is good to have and you have us on our toes for good advice, I posted least psi the spec ford gives is 28-45psi engine running. Spec has been elusive to track down. They seem to say most run at 35-40psi. I asked about cracks in duct work after maf. Were there any? Ford windstar had a tbs out for maf. here it is:
Vehicle Level Powertrain Management Computers and Control Systems Air Flow Meter/Sensor
Technical Service Bulletins All Technical Service Bulletins Engine - Lean Driveability Symptoms
Engine - Lean Driveability Symptoms
Notes
Article No.
98-23-10
11/23/98
MASS AIR FLOW (MAF) - SENSOR
CONTAMINATION - SERVICE TIP
FORD:
1990-97 THUNDERBIRD
1990-99 MUSTANG, TAURUS SHO
1991-99 CROWN VICTORIA, ESCORT, TAURUS
1992-94 TEMPO
1993-97 PROBE
1995-99 CONTOUR
LINCOLN-MERCURY:
1990-97 COUGAR
1991-99 CONTINENTAL, GRAND MARQUIS, SABLE, TOWN CAR, TRACER
1992-94 TOPAZ
1993-98 MARK VIII
1995-99 MYSTIQUE
LIGHT TRUCK:
1990 BRONCO II
1990-97 AEROSTAR
1990-99 RANGER
1991-99 EXPLORER
1994-96 BRONCO
1994-97 F SUPER DUTY, F-250 HD
1994-99 ECONOLINE, F-150, F-250 LD, F-350
1995-99 WINDSTAR
1997-99 EXPEDITION, MOUNTAINEER
1998-99 NAVIGATOR
1999 F-250 HD, SUPER DUTY F SERIES
ISSUE
This TSB article is a diagnostic procedure to address vehicles that exhibit lean
driveability symptoms and may or may not have any Diagnostic Trouble Codes
(DTCs) stored in memory.
ACTION
Follow the diagnostic procedures described in the following Service Tip. The
revised diagnostic procedure is a more accurate means of diagnosing the
symptoms.
SERVICE TIP
MASS AIR FLOW (MAF) DISCUSSION
MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon,
spider webs, potting compound from the sensor itself, etc. When a MAF sensor
gets contaminated, it skews the transfer function such that the sensor overestimates
air flow at idle (causes the fuel system to go rich) and under-estimates
air flow at high air flows (causes fuel system to go lean). This means Long Term
Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive)
corrections at higher air flows.
If vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system
normally goes open loop rich to provide maximum power. If the MAF sensor is
contaminated, the fuel system will actually be lean because of under-estimated air
flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim
corrections that have been learned during closed loop operation. These
corrections are often lean corrections learned at lower air flows. This combination
of under-estimated air flow and lean fuel trim corrections can result in spark
knock/detonation and lack of power concerns at WOT and high loads.
One of the indicators for diagnosing this condition is barometric pressure.
Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM)
software at part throttle and WOT (there is no actual BARO sensor on MAFequipped
vehicles, except for the 3.8L Supercharged engine). At high air flows, a
contaminated MAF sensor will under-estimate air flow coming into the engine,
hence the PCM infers that the vehicle is operating at a higher altitude. The BARO
reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators
are Long Term Fuel Trim and MAF voltage at idle.
NOTE THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE
VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCS.
Symptoms
^ Lack of Power
^ Spark Knock/Detonation
^ Buck/Jerk
^ Hesitation/Surge on Acceleration
OBDII DTCs
OBDI DTCs
NOTE :DO NOT DISCONNECT THE BATTERY. IT WILL ERASE KEEP ALIVE
MEMORY AND RESET LONG TERM FUEL TRIM AND BARO TO THEIR
STARTING/BASE VALUES. THE BARO PARAMETER IDENTIFICATION
DISPLAY (PID) IS USED FOR THIS DIAGNOSTIC PROCEDURE. ALL OBDII
APPLICATIONS HAVE THIS PID AVAILABLE. THERE ARE SOME OBDI
VEHICLES THAT DO NOT HAVE THE BARO PID, FOR THESE VEHICLES
OMIT THE BARO CHECK AND REFER ONLY TO STEPS 2, 3, AND 4 IN THE
DIAGNOSTIC PROCEDURE.
^ Malfunction Indicator Lamp (MIL) Illuminated -
DTCs P0171, P0172, P0174, P0175 may be stored in memory
^ P0171, P0174 (Fuel system lean, Bank 1 or 2)
^ P0172, P0175, (Fuel system rich, Bank 1 or 2)
^ P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1)
^ P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2)
^ 181, 189 (Fuel system lean, Bank 1 or 2)
^ 179, 188 (Fuel system rich, Bank 1 or 2)
^ 171, 172, 173 (HO2S11 lack of switching, Bank 1)
^ 175, 176, 177 (HO2S21 lack of switching, Bank 2)
^ 184, 185 (MAF higher/lower than expected)
^ 186, 187 (Injector pulse width higher/lower than expected)
NOTE REMEMBER THAT MOST WEATHER SERVICES REPORT A LOCAL
BAROMETRIC PRESSURE THAT HAS BEEN CORRECTED TO SEA LEVEL.
THE BARO PID, ON THE OTHER HAND, REPORTS THE ACTUAL
BAROMETRIC PRESSURE FOR THE ALTITUDE THE VEHICLE IS BEING
OPERATED IN. LOCAL WEATHER CONDITIONS (HIGH AND LOW PRESSURE
AREAS) WILL CHANGE THE LOCAL BAROMETRIC PRESSURE BY SEVERAL
INCHES OF MERCURY (+/- 3 Hz, +/- 1 in. Hg.).
NOTE BARO IS UPDATED ONLY WHEN THE VEHICLE IS AT HIGH THROTTLE
OPENINGS. THEREFORE, A VEHICLE WHICH IS DRIVEN DOWN FROM A
HIGHER ALTITUDE MAY NOT HAVE HAD AN OPPORTUNITY TO UPDATE
THE BARO VALUE IN KAM. IF YOU ARE NOT CONFIDENT THAT BARO HAS
BEEN UPDATED, PERFORM THREE OR FOUR HEAVY, SUSTAINED
ACCELERATIONS AT GREATER THAN HALF-THROTTLE TO ALLOW BARO
TO UPDATE.
NOTE DUE TO INCREASINGLY STRINGENT EMISSION/OBDII
1. Look at the BARO PID. Refer to the Barometric Pressure Reference Chart in
this article. At sea level, BARO should read about 159 Hz (29.91 in. Hg). As a
reference, Denver, Colorado at 1524 meters (5000 ft.) altitude should be about
144 Hz (24.88 in.Hg). Normal learned BARO variability is up to +/- 6 Hz (+/- 2
in. Hg.). If BARO indicates a higher altitude than you are not at (7 or more Hz
lower than expected), you may have MAF contamination. If available, Service
Bay Diagnostic System (SBDS) has a Manifold Absolute Pressure (MAP)
sensor that can be used as a barometric pressure reference. Use
"MAP/BARO" test under "Powertrain," "Testers and Meters." Ignore the hookup
screen. Connect GP2 to the reference MAP on the following screen.
2. On a fully warmed up engine, look at Long Term Fuel Trim at idle, in Neutral,
A/C off, (LONGFT1 and/or LONGFT2 PIDs). If it is more negative than -12%,
the fuel system has learned lean corrections which may be due to the MAF
sensor over-estimating air flow at idle. Note that both Banks 1 and 2 will exhibit
negative corrections for 2-bank system. If only one bank of a 2-bank system
has negative corrections, the MAF sensor is probably not contaminated.
3. On a fully warmed up engine, look at MAF voltage at idle, in Neutral, A/C off
(MAF V PID). If it's 30% greater than the nominal MAF V voltage listed in the
Powertrain Control/Emissions Diagnosis (PC/ED) Diagnostic Value Reference
Charts for your vehicle, or greater than 1.1 volts as a rough guide, the MAF
sensor is over-estimating air flow at idle.
4. If at least tow of the previous three steps are true, proceed to disconnect the
MAF sensor connector. This puts the vehicle into Failure Mode and Effects
Management (FMEM). In FMEM mode, air flow is inferred by using rpm and
throttle position instead of reading the MAF sensor. (In addition, the BARO
value is reset to a base/unlearned value.) If the lean driveability symptoms go
away, the MAF sensor is probably contaminated and should be replaced. If the
lean driveability symptoms do not go away, go to the PC/ED Service Manual
for the appropriate diagnostics.
REQUIREMENTS, IT IS POSSIBLE FOR SOME VEHICLES WITH MAF SENSOR
CONTAMINATION TO SET FUEL SYSTEM DTCs AND ILLUMINATE THE MIL
WITH NO DRIVEABILITY CONCERNS. DISCONNECTING THE MAF ON THESE
VEHICLES WILL, THEREFORE, PRODUCE NO IMPROVEMENTS IN
DRIVEABILITY. IN THESE CASES, IF THE BARO, LONGFT1, LONGFT2, AND
MAF V PIDs INDICATE THAT THE MAF IS CONTAMINATED, PROCEED TO
REPLACE THE MAF SENSOR.
After replacing the MAF sensor, disconnect the vehicle battery (5 minutes,
minimum to reset KAM, or on newer vehicles, use the "KAM Reset" feature on the
New Generation Star (NGS) Tester and verify that the lean driveability symptoms
are gone.
OTHER APPLICABLE ARTICLES:: NONE
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 206000, 610000, 610500, 610600, 610700, 611000, 611500,
612000, 612500, 614000, 614500, 614600, 698298
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