Mustang Has No Power

My '94 Mustang GT 5.0L 5 speed has no power. Well, maybe 100 horsepower. It shows flashes of normal horsepower, but only briefly, after a hot soak in hot (100-degree-plus) weather. After a minute or so, it returns to its "normal," which is an extreme lack of power and unwillingness to rev over 3800 RPM.

Here is the deal: 160,000 miles on the original engine. Good compression, clean looking (tan) plugs, no excessive oil consumption, normal (mid teens) city gas mileage. Engine is dead stock. No internal or bolt on mods. TPS voltage appears normal, as does fuel pressure (39 psi).

New Parts: Fuel filter, fuel pump and screen, High-flow catalytic H-pipe, O2 sensors, EGR valve, computer, plug wires, cap, rotor, 195-degree thermostat.

Codes: Consistent "EGR lean" codes (171 and 176), no other codes.

Any body with some wisdom on this? We are baffled.

Reply to
Randy
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The fuel pressure needs to be measured when the concern is present... in your case, that means while you are driving. Checking it at idle in the driveway is a lost cause and merely indicates that the pump can supply enough fuel to idle the engine.

HTH.

Reply to
Jim Warman

sorry the codes were that the o2 sensors read lean and the codes were

172 and 176
Reply to
Randy

Does it start good and run okay till it warms up?

Start by cleaning the MAF. Oh wait.. too late to 'start' there.

do a google search on how to..

Reply to
Backyard Mechanic

Has the fuel pressure been read when the concern is happening?

Reply to
Jim Warman

Have you tried the highly trained techs, with their analyzers, at your local Ford dealer?

mike

Reply to
Mike Hunter

Reply to
Randy

Reply to
Randy

Was this the same frient that installed the previous parts ?

Bill

Reply to
Bill Kitterman

THE POINT IS, the MAF works right but it READS WRONG.

becuase the maf uses a heated temperature sensitive resistor and measures temp by noting the current drawn.

Air passing over it cools the resistor, thus the current drawn relates to amount and temp of the air or the "AIR MASS"

Now, throw an insulating blanket of dust and oil on it, and guess what!

The OTHER possibility is you are overheating or the ECT sensor is reading wrong

Do what I TELL you dammit!

Next time it acts up, stop and disconnect the MaF harness, then drive it and report back. If it drives better, clean the damn thing.. if it's worse, you have another sensor problem, instead or besides.

And you never did say if there are any OTHER problems starting or running BEFORE the engine gets up to temp.

Reply to
Backyard Mechanic

Reply to
coryrhonda

all hail the Backyard Mechanic. the MAF was very dirty so i cleaned it and as soon as i put it back in the gremlins were gone and its running perfectly. Thank you so much.

Reply to
Randy

Would you have or have had a K&N air filter by any chance? This is a common occurance if it is over oiled not to mention it does not filter quites as well as an OEM filter.

Lugnut

Reply to
lugnut

Saved me also a couple years back. I forget what the dealer gets for this little operation not to mention the time saved.

Reply to
F. H.

no i have an OEM i think it might be getting old though

Reply to
Randy

Just wondering. It may be just a normal buildup but, another little item you probably should check is the PCV system. (IIRC, you indicated this is a 5.0L V8) Crankcase vapors can backup into the intake if the system is not working well. The 5.0L engine has a filter under the PCV valve that has a tendency to plug with sludge after a while making it useless. You can get at it by pulling the PCV and grommet and, use needle nosed pliers to pull it out. You'll need a new one. Kind of a bitch to get at but, may be worth the effort. This can also cause seal and gasket leakage.

Lugnut

Reply to
lugnut

where is the PCV?

Reply to
Randy

Top rear of the block behind the right side of the lower intake. You may have to just feel for it or use a mirror. I suppose there are more inconvenient locations but, I can't think of one off hand.

Lugnut

Reply to
lugnut

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