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End of My Rope 95 GT Still bogs when idling above 2,000 rpm

3K views 31 replies 5 participants last post by  Mr.Five0 
#1 ·
Okay fellow 5.0 lovers I have just about reached end of my rope. Car starts right up, dash mounted in line fuel pressure gauge reads 40 PSI at idle.
Still bogs when idling above 2,000 rpm or in drive when I hit the gas, Thus far replaced.

OEM Motorcraft plugs and Wires
Motorcraft 02 Sensors
Performed smoke test vacuum leaks, slight bleed EGR bladder replaced EGR Valve
IAC
Motorcraft Mass Air Meter and sensor complete
TFI Module
Ignition Coil
Cap Rotor
Distributor
Harmonic Balancer
PCV Valve
Motorcraft Canisister Purge Valve
Anyone have any thoughts?, with time and parts cost I have:blink: spent about 1/3 the cost of Coyote crate factory motor
 
#3 ·
Fuel Filter

I have OEM one in the box came with tune up kit, did not go that way because car has 40,000 orig miles last changed fuel filter at 28K, I use strictly 100 octane unleaded since new....but yeah cant hurt will lift get under there tomorrow and swap it our, keep you posted, thanks
 
#10 ·
Have you run your codes?
What is your timing set at?
How does it drive without going WOT?
So you spent $2,000 in what you listed...........?
 
#11 ·
No time to detail by item but 13 items at average price of $125 gets me to an easy $1,750. since I did harmonic balancer, O noticed Fords proud plastic 23 year old radiator was ever so slightly starting to leak a shaft base of cap, so I pit in aluminum mishimoto 3 core unit, Since all that was apart a decided to add SVT Tranny cooler. You must be a bean counter by day, thought this was TMI for the purposes of getting knowledge base on root cause, EOD spent more like $2800, keep ya all posted taking off weds to get some gas on me
 
#18 ·
just remembered cats long gone, tube welded off from air pump so I through the paper weight away and replaced with LMR billet air pump delete pulley :angel:
Also, not sure on your Mustang, but when I deleted the air pump on my truck, there was a vacuum hose that needed to be plugged. I assume that there are no open vacuum lines causing a leak on your machine?
 
#16 ·
Well, on the bright side, I think that the only other items that you haven't replaced is the Throttle Position Sensor and the fuel pressure regulator... Your fuel pressure seems to be within specifications, except for possibly the regulator is not increasing the pressure fast enough to prevent a bog from idle? It can be tested using a vacuum pump and a guage... And a Google search for the proper procedure, of course.
Same goes for the TPS. It can be easily tested using a multimeter.

Other than that, you've pretty much covered the engine management diagnosis. I suppose that next would be a compression/leakdown test to determine the internal health of the engine.
 
#20 ·
Well, on the bright side, I think that the only other items that you haven't replaced is the Throttle Position Sensor and the fuel pressure regulator... Your fuel pressure seems to be within specifications, except for possibly the regulator is not increasing the pressure fast enough to prevent a bog from idle? It can be tested using a vacuum pump and a guage... And a Google search for the proper procedure, of course.
Same goes for the TPS. It can be easily tested using a multimeter.

Other than that, you've pretty much covered the engine management diagnosis. I suppose that next would be a compression/leakdown test to determine the internal health of the engine.
I know the TPS voltage should be below 1 volt, need to test, I had done compression test on all cylinders like a month before illness started, all good almost identical. Thanks for the pressure regulator tip, I did add a baseline regulator when ATI was installed back in 95 maybe its bad,or OEM is bad... keep you all posted. thanks again
 
#22 ·
Case of the Missing diaphragm

Good morning gents, so I decided to order a new adjustable fuel pressure regulator from LMR arrives today, in the meantime I proceeded to remove and disassemble my 1994, 24 year old adj. regulator and VUALA!!
where the diaphragm is supposed to be are only slight remnants of what looks like residue from a white medical glove..I will be sitting in my driveway all day bird dogging the mail man arriving with my new regulator.more to follow!!
:dance:
 

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#24 ·
BOYCOTT USPS THEY SUCK!! So USPS lost my fuel pressure regulator, after traveling to 4 counties in Florida and arguing with idiot so called site managers, I located it this morning in Miramar FL, I went ahead and installed it, adjusted the baseline to 42 PSI, still have same bogging issue. I ordered a OBD1 scanner, I know some guys use jumpers whatever to pull 3 digit codes, I don't get that. I have a brand new OEM Ford TPS in the box, I know should be .97 or less, waiting for friend to come by weekend with good Volt Meter and OBD scanner to arrive from Amazon, did I mention USPS sucks, BOYCOTT!!!!
 
#28 ·
Throwing ib the towel, today I got OBD1 scanner and ran it, got only one code 563 Fan circuit fault, which does not make sense because the 1st thing scanner does is run electric fan, works fine. Going to try and limp car to an old school mechanic 15 miles from home, I did find another post guy with similar problem was the sock on OEM fuel pump in tank disintegrated and was causing this issue, I will post final resolution.
 
#29 ·
The fan code might be because the fan didn't complete a full cycle, or something like that. Probably doesn't mean anything.
I was hoping that there would be a code to point the diagnosis in the right direction. I still suspect a fuel delivery problem. Have the mechanic test the vacuum signal to the fuel pressure regulator, if he can't find anything obvious that is wrong.

Good luck!
 
#31 ·
Is the manifold sealing? Is there a crack you have yet to notice.

I agree with Stray that it sounds like a fuel issue, but too much air that isn't monitored will lean the A/F mixture out and the car will not idle correctly.

Check the PVC hoses, and everything that vents into the intake.
 
#32 ·
OK Gents the final verdict, some very patient guys at Kovac Automotive in Davie FL, found the following, bad TPS, replaced , after market Dynamod TFI I replaced was defective, replaced with Motorcraft OEM, main fuel line slight leak losing volume although baseline pressure looked good at 50 psi, the VSS went bad along with speedo gear which had basically deteriorated, speed sensor was bad, #DY1205, car back to normal.
 
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