I'm still getting a flutter when over 3000rpm's,i also have a slight miss at idle,could a burned valve only show symptoms at the rpm's I'm getting the flutter at??

is there something thats is supposed to close when that rpm is reached that maybe is stuck and not closing??

i should add,that the rpm is varied,but it is definatly over 3000rpms,duration is varied as well

any help would be much appreciated

Thanks Jerry

 

Sounds like a clogged fuel injector to me.

 

anyone??

 

If your truck is doing it stock then I would think its either a coil pack of fel injector.If you have a chip,pull it out.I had the same thing and it was in fact detonation.It could also be a bearing ready to shoot but i need to know more about chip.or not.

 

if you get a chance e-mail or call sal at psp, because he used to be a ford mechanic and knows his stuff!!!

 

does it make the fluttering sound mostly when you "get on it" (WOT)? sounded like a helicopter was following me.

mine did this & it turned out to be a bad coilpack.
pull all plugs & check them also..

 

yes thats it exactly!!I planned on pulling the plugs and changing them anyway.


Is there anyway to determine which coil pack could be bad???

Im not getting an SES light

Thanks Jerry

 

i wasn't getting a SES light either.. i just pulled coil packs & checked plugs... something didn't look right about one pack, so i changed it, been running good ever since.

 

It could be a leaky EGR valve? Too much EGR flow can cause surging at cruise speeds. If you replace it, make sure you get a valve with the exact same stamped code located on the top of the valve.

The DPFE sensor may be bad.

Dan

 

I dont think its the EGR,what is the DPFE sensor??

Thanks Jerry

 

http://www.borg-warner.com/techtips/bw_sen.html

Background.

This vehicle was purchased new North Carolina and had experienced no problems with its performance. The "Service Engine Soon" light first came on six months before the car was brought in for this case study. The owner tried to solve the problem by replacing the filters (air, etc.) and by putting better gas in the car. Despite these efforts, the light continued to go on and off. The light would go off when the car was filled with gas and during long trips. If the car had been producing visible emissions or had experienced a drop in performance, the owner would have taken it to the dealer.

Introduction.

This vehicle was a 1997 5.0 liter V8 Ford Explorer that came to the NCVECS as part of a research project on OBD II. The complaint was that the MIL light was illuminated. OBD II regulations require a light to be illuminated in the event of a malfunction of any powertrain components which can affect emissions and which provide input to, or receive output from, the on-board computer(s); or the malfunction of the on-board computer(s) itself. The MIL shall be of sufficient illumination and location to be readily visible under all lighting conditions. The MIL shall illuminate in the engine-run key position before engine cranking to indicate that the MIL is functional and shall, when illuminated, display the phrase "Check Engine" or "Service Engine Soon." The word "Powertrain" may be substituted for "Engine." OBD II vehicles shall also be equipped with an on-board diagnostic system capable of identifying the likely area of the malfunction by means of fault codes stored in computer memory. These vehicles shall be equipped with a standardized electrical connector to provide access to the stored fault codes.

Before we can determine the cause of an illuminated MIL, we must retrieve the code(s) that are causing it to light. We do this by connecting a scanner to the standardized OBD II connector inside the passenger compartment. On this truck I was able to retrieve a code P0402 via a generic scanner. Enhanced mode did not reveal any other codes. What does code P0402 mean?

Deciphering the code.

Generic OBD II codes are written in a standardized format according to SAE J 2012 guidelines. The first letter indicates the vehicle function: Body, Chassis or Powertrain. Code P0402 begins with the letter "P", which indicates a powertrain code. The next character tells us whether it is a generic or manufacturer specific code. "0" is generic, so P0402 is a generic code. The next three characters tell us more about the problem area. In this case a "4" indicates an auxiliary emission control code. The last two characters tell us what the code refers to which is "Excessive EGR Flow".

Freeze Frames

Now that I know the code definition, I can begin the diagnosis. Freeze frames are another OBD II function and can become very useful when chasing intermittent problems. The freeze frame the last time code P0402 was set is shown below.

Freeze Frame

Code P0402

Item
Value

RPM
673

Fuel System 1
Closed

Fuel System 2
NA

Coolant Temperature
198 Degrees F

Bank 1 Short Term Fuel Trim
- 1.6 %

Bank 1 Long Term Fuel Trim
- 5.5 %

Bank 2 Short Term Fuel Trim
- 1.6 %

Bank 2 Long Term Fuel Trim
- 5.5 %

Vehicle Speed
0 MPH

Engine Load
41.4 %




Analyzing this data tells me that the code was set at idle and since EGR flow should not occur at idle, I know that the PCM was told that there was EGR flow without an EGR command. Normally, the diagnosis would lead to checking the EGR system, but I decided to clear the code and see if it returned. This step is not always necessary, but I felt it would be interesting to see if the code would reset. It should be noted that some steps are taken for the sake of research and may not be necessary during a normal diagnosis. After clearing the code, all the monitors were reset to "Not Ready."

The next morning, with an ambient temperature of 70 degrees F, I started the vehicle and began a test drive. The test drive included some in-town as well as 50 MPH driving. Back in the shop I noticed all but one monitor flag reset to "Ready." The only one to say "Not Ready" was the catalytic monitor. No codes were set during this test drive and the MIL was not illuminated. The test drive did uncover a drivability concern that was noted. It had a noticeable surge off idle.




























Now for the diagnosis.

Ford uses a Differential Pressure Feedback EGR (DPFE) sensor on these vehicles to measure EGR flow. Ford tests to see if the EGR valve is stuck open by checking the DPFE sensor at idle. The DPFE sensor tests for a differential in pressure across a restriction. As flow increases, DPFE voltage rises. Typical DPFE readings at idle are around 0.6 volts DC. The code will set if this voltage exceeds 0.6 volts above the base voltage taken at key on engine off. So, is the voltage too high at idle? Using the scanner I find these readings:

Data at idle
Value

RPM
1000

Load
45 %

Coolant Temperature
91 Degrees F.

DPFE Voltage
0.62

EGRVR%
1.6

Trip Ct
9

TPS
16 % (closed throttle)



It seems to me the source of the code is evident. I needed a little more testing to find the exact cause but the likely culprit had been found. When I compare the two data values I see that both are indicating nearly the same load and both were taken at idle even though the coolant temperature and RPM were not the same. I know that the engine was idling smoothly when I took the scanner readings, so I can assume there is no EGR flow. The DPFE voltage confirms this assumption by indicating a voltage of 0.62. The freeze frame data also indicates that no EGR flow is occurring because the load is nearly the same as mine. Load is inferred from the mass air flow sensor, and excessive EGR flow would change the load reading.

My conclusion at this time is that there is a sensor malfunction and not an EGR malfunction. My experience tells me it is the DPFE, but I think another test is in order. I apply vacuum to the EGR valve with a handheld vacuum pump and watch the DPFE voltage on the scanner. It rises to 2.07 volts as the engine begins to stumble and idle rough. Next, I release the vacuum and watch the voltage. The engine immediately recovers and idles well but the DPFE voltage remains above 1.5 volts for several seconds before decaying towards the base reading. I shut the engine off and turn the key back on. The voltage is still falling slowly towards base. After several seconds it reaches 0.6 volts KOEO. This confirms my suspicions and I order a new DPFE sensor.

The new DPFE was tested under the same conditions and the voltage would change immediately to base after having the EGR opened. It also reached a higher voltage with the EGR open, 2.7 volts DC.

Observations.

This repair example provides a good example of OBDII system limitations. No component was specifically identified by the SAE code . The code directed the technician to a system, but did not identify what part of the system was malfunctioning. In this case, the technician=s knowledge and skill led to a successful repair. However, car owners that attempted a Ashadetree@ repair would probably replace the EGR valve, since the computer condemned that system. Despite the increasing complexity of on-board systems, technicians must still perform detailed diagnosis of the engine control systems. Since this repair addressed a monitor problem, and not an emission control component problem, the vehicle tailpipe emissions were unaffected. Once again, the OBDII system needed repair despite the fact that the car remained clean.



August 19, 1999

By Randy Bernklau


Dan

 

Lightninrod,

Thanks for the info,do you think its safe to rule out the DPFE sensor seeing as how im not getting anSES light??based on the info you posting i think this may be the case

Thanks for your help

Jerry

 

finally got around to changing my plugs today,had 2 of them burned up pretty badly,i also broke one of the bolts that hold down the coil pack,#3 cylinder on the passenger side.So im thinking i ran 12.5 on 6 cylindas yo!!!

problem fixed

 

well the problem wasnt fixed,so i removed the chip and MAF that was on the truck and put back on my old pro m and a different chip.I did that 3 days ago and havent had a problem yet,Im going to drive the truck for a couple of days and if the problem doesent come back im going to call the tuner i got my new chip from.