Stumped...why no power on my 1995 Mustang GT?! - Ford Mustang Forum
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post #1 of 20 (permalink) Old 07-31-2009 Thread Starter
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Unhappy Stumped...why no power on my 1995 Mustang GT?!

This has been an ongoing problem and I refuse to get @$$ raped by the dealer, but I'm sure someone else had this problem:

I'm getting almost no power from the V8...it runs like a 4-cyl 2 liter car...my moms 7-year old malibu has better acceleration.

New catalytic converters (problem existed before this...so unrealted)
Clean K&N
Car runs smooth, accelerates smooth, runs great but no power, poor accel.
Starting is hard...I have to crank/prime the fuel pump 3-7 times.
New MAF sensor
New fuel filter

Relatively new plugs,wires, and distrib cap (about 8k miles on them)...I'm 99% certain that timing is good (there is a VERY slight ping at high rpm)

No codes...not a single one.

I can't do the base timing check with the spout? (computer-timing tweaker thing) disconnected when runnning codes...car just doesn't start.

The only thing that makes a substantial and very noticeable performance improvement is disconnecting the IAT (intrake air temperature sensor)...then it drives much much better. I don't think it's the fuel pump b/c disconencted IAT seems to fix the problem..but it's a hack workaround.

The car has 165k on it.

What can this possibly be guys? What are some serviceable parts that I should replace myself?

Thanks you all!
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post #2 of 20 (permalink) Old 07-31-2009
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Quote:
Originally Posted by JesusOnIceSkate View Post
This has been an ongoing problem and I refuse to get @$$ raped by the dealer, but I'm sure someone else had this problem:

I'm getting almost no power from the V8...it runs like a 4-cyl 2 liter car...my moms 7-year old malibu has better acceleration.

New catalytic converters (problem existed before this...so unrealted)
Clean K&N
Car runs smooth, accelerates smooth, runs great but no power, poor accel.
Starting is hard...I have to crank/prime the fuel pump 3-7 times.
New MAF sensor
New fuel filter

Relatively new plugs,wires, and distrib cap (about 8k miles on them)...I'm 99% certain that timing is good (there is a VERY slight ping at high rpm)

No codes...not a single one.

I can't do the base timing check with the spout? (computer-timing tweaker thing) disconnected when runnning codes...car just doesn't start.

The only thing that makes a substantial and very noticeable performance improvement is disconnecting the IAT (intrake air temperature sensor)...then it drives much much better. I don't think it's the fuel pump b/c disconencted IAT seems to fix the problem..but it's a hack workaround.

The car has 165k on it.

What can this possibly be guys? What are some serviceable parts that I should replace myself?

Thanks you all!
Some info on the car please...year, transmission, mods

2000 GT 14.5 sec @ 98 mph
SCT tuner...SLP powerflo catback...JLT short ram intake...Typhoon intake manifold...Professional products throttle body...C&L intake plenum...Steeda underdrive pulleys...Steeda tri-ax short throw shifter...05-09 Mustang GT shift knob...Steeda adjustable clutch cable, firewall adjuster, and quadrant kit...Eibach front sway bar...Steel strut bar...Tokico shocks...Polyurethane spring isolators...J&M rear lower control arms...Powerslot rotors...Nitto tires
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post #3 of 20 (permalink) Old 07-31-2009
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Does the car have the oringinal cats still on it? sounds like you could have clogged cats.
Sorry didn't see the line on new cats. Try running a compression check on all cylinders. Check fuel pressure. Clean the mass air meter and the IAT.
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post #4 of 20 (permalink) Old 07-31-2009 Thread Starter
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its 1995 GT, no mods other than k&n and flowmasters, completely stock. Engine runs smooth and clean, nothing odd in the exhausts. All cylinders firing...seems like a lean fuel mix or? But why does disconnecing the IAT help?
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post #5 of 20 (permalink) Old 07-31-2009
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when you put the new maf in did you reset the ecu? if not disconnect the battery for 20-30 min then start the car and let it run for 5 to relearn the ecu it worked on my car. also are you 100% sure there is no clog in the exhaust? that will rob you of tons of power.and a compression test cant hurt. from reading the fuel issue i would have the fuel pressure checked your pump might be going out

1995 SVT COBRA:K&N Intake, chip'd, short shifter, underdrive pulleys<smog pump delete>,Full MSD ignition, Shortyheaders, 2.5 inch from the engine back, O/R H pipe followed by flowmaster40's, tracklok rearend w/4.10 gears, aluminum driveshaft,Mishhimoto aluminum radiator, Kenny Brown front & rear strut tower brace, subframe connectors, Eibach pro-springs and sway bars. Eibach Shocks &Struts,Mickey Thompson Street Comp Ties 245/45R17 all around.

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post #6 of 20 (permalink) Old 08-01-2009
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Quote:
Originally Posted by JesusOnIceSkate View Post
its 1995 GT, no mods other than k&n and flowmasters, completely stock. Engine runs smooth and clean, nothing odd in the exhausts. All cylinders firing...seems like a lean fuel mix or? But why does disconnecing the IAT help?
The ecu uses the input from the IAT to alter fuel and timing. Disconnecting I would guess puts the ecu into some default mode. For the sake of $30 I would be inclined to replace a 14+ year old sensor. Same with the O2 sensors if they haven't been replaced. The ecu also relies on the O2 inputs for fuel management.

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post #7 of 20 (permalink) Old 08-01-2009
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Make sure your MAF isn't defective and clean it. You can clean Your IAT. Usually poor acceleration is because of the MAF. If your Pinging you need to start using premium gas.

Clean all the sensors and get some of that stuff that helps electrical connections pass current better. and make sure to reset your computer.

and are you using a OBD-I code reader?

Get a fuel pressure gauge.

The only other thing i can think of is TPS.

1994 GT AODE, Performance Automatics Street/Strip Valve Body , 3.55, BBK(H PIPE, Equal Length Shorty Headers, UnderDrive Pulleys -minus Alternator Pulley, Spring Insulator & CAI), FlowMaster Super 44's Dumped, MSD(Distributor, TFI Blaster Coil & 8.5 Super Conductors), Ford Racing B Springs, KYB AJX Adjustable Shocks, AJE(Tubular K-member, A-Arms & 5.0 Solid Motor Mounts), Stiffler Transmission Crossmember, SVE Rear Upper & Lower Control Arms, Explorer Intake, A/C Delete, Smog Delete
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post #8 of 20 (permalink) Old 08-01-2009
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Try unplugging the maf sensor and drive it. This will set the pcm to default strategy for maf. If vehicle runs noticably better then check to see if elements are dirty or restricted.
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post #9 of 20 (permalink) Old 08-01-2009
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Quote:
Originally Posted by JesusOnIceSkate View Post
The only thing that makes a substantial and very noticeable performance improvement is disconnecting the IAT (intrake air temperature sensor)...then it drives much much better. I don't think it's the fuel pump b/c disconencted IAT seems to fix the problem..but it's a hack workaround.
Try replacing the IAT (it's actually ACT or air charge temp.) sensor.


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JLT 3 CAI, DIY CMDPs, Steeda UDPs, FRPP X-pipe, Brenspeed 91 tune
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Quote:
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Try replacing the IAT (it's actually ACT or air charge temp.) sensor.
Except Ford refers to it as an IAT (intake air temperature) sensor in their 1995 service CD.

Richard
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Quote:
Originally Posted by toyman View Post
Except Ford refers to it as an IAT (intake air temperature) sensor in their 1995 service CD.
Well that thing anyway.
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My 95 is also having the same issue. And I too found that by unplugging the IAT or Air Charge sensor that the car became a rocket again. SO....I went to my local Autozone and picked up a new sensor for $17. Didn't help too much. Maybe a little more power, but nothing like when the sensor is unplugged. I'm at a loss....

In response to previous suggestions...I have a fuel pressure tester and my test is normal and not normal at the same time.....When I first key on the ignition before starting the pressure builds to 30 psi and suddenly drops to 0....Yet while the engine is running the pressure is great, 30 at throttle closed and 40 at WOT. Also, after I turn the engine off the pressure drops to 0. According the service manual the system should not loose more than 5 psi over 5 minutes. So, I know I have a problem somewhere in the my system. But why would unplugging that sensor suddenly make things work perfectly? When the check engine light is on the computer automatically switches to a full rich mode......but if the fuel system was struggling wouldn't a full rich mode only amplify the fuel problems?

I bought this car 6 months ago and I am in the process of restoring it....latemodelrestoration.com rocks.....I have significant engine mods planned for the future but currently everything is bone stock. The 351 im building for the car will not be ready for sometime...and while the new engine will have aluminum heads, edelbrock intake, fuel rails including new regulator, 30lb injectors, larger MAF, larger throttle body, and require at least a 190lph fuel pump (im going with the 255lph never know when your gonna wanna add a supercharger), It would be nice to have the stock 302 running well enough to cruize the town and destroy a few honda's on the weekends. So any help anyone can provide would be greatly apreciated.
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It would be nice to know how JesusOnIceSkate solved his problem so it would help you solve yours.
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Quote:
Originally Posted by JesusOnIceSkate View Post
This has been an ongoing problem and I refuse to get @$$ raped by the dealer, but I'm sure someone else had this problem:

I'm getting almost no power from the V8...it runs like a 4-cyl 2 liter car...my moms 7-year old malibu has better acceleration.

New catalytic converters (problem existed before this...so unrealted)
Clean K&N
Car runs smooth, accelerates smooth, runs great but no power, poor accel.
Starting is hard...I have to crank/prime the fuel pump 3-7 times.
New MAF sensor
New fuel filter

Relatively new plugs,wires, and distrib cap (about 8k miles on them)...I'm 99% certain that timing is good (there is a VERY slight ping at high rpm)
If you're getting pre-det (or pinging) at high RPM, then your timing IS NOT good. You need to check your timing.

No codes...not a single one.

I can't do the base timing check with the spout? (computer-timing tweaker thing) disconnected when runnning codes...car just doesn't start.
I don't understand, you're disconnecting the spout to check your codes...?
Either way, you NEED to check your timing. Retarted timing will cause poor acceleration. So you need to make sure your timing is at least set on 10* BTDC, but I would advance it to about 12*.

The only thing that makes a substantial and very noticeable performance improvement is disconnecting the IAT (intrake air temperature sensor)...then it drives much much better. I don't think it's the fuel pump b/c disconencted IAT seems to fix the problem..but it's a hack workaround.
I doubt your IAT sensor is what is causing the problem. Although, you might want to get a new sensor.

The car has 165k on it.

What can this possibly be guys? What are some serviceable parts that I should replace myself?

Thanks you all!
My first guess as to what is causing your problem would be a clogged fuel filter. How long has it been since you've chaged the filter? And are you running the 10% ethonal gasoline in your car?

-1994 Mustang GT "The Red Baron": 3.73 gears,K&N filter,GT40 tubular intake,BBK Full Length Headers,modified midpipe & Flowmaster muffs, timing at 12*. Best time- 14.74 @ 93.16
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I did a complete tune up about a month ago, fuel filter, wires, cap, rotor, plugs, air filter, pvc valve, the works. I'm not sure of the the ethanol content but I always fill up with premium.

But again, if it was a fuel filter clogged why would the car have good power with the IAT unplugged? If the filter was clogged wouldn't the car run crappy no matter what?
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