Help! 95 Mustang GT 5.0 V8

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#1
I have got some car troubles.( No ford jokes please).
My 95 mustang GT is acting up. Heres what's happening:

1. Check Engine Light is on

2. From a stop, it will hesitate and act like it is gonna stall when you tap the gas pedal.

It drives normal, everything else seems normal. Its just the CheckEngine light and the rpm drop from a stop. It doesn't die, it just acts like it might.
Today I spent 270 dollars and it did not fix a thing. They said to bring it back on friday. They replaced the accelerator sensor and the coolant sensor sender, i believe.
I think that it may be a fuel related problem or a tuning problem. Something is off. It seems to be running Rich on fuel. I can see it from the exhaust and even smell it a little. I have changed the plugs not too long ago, and have a K&N air fileter in it. I have heard of some things causing strange things like a bad gas cap or something else obscure like that?

What should I check?
Anything like this ever happen to you?
Anything will help.

Thank you!:think
 
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#2
Sounds like the O2 sensor to me. If there is a check engine light on, then it is giving you a code. Look in the manual for the code retreival procedure.
 

MX265

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#3
Creric,

I have 0 experience with Mustangs, but the first 4 months I owned a used '96 Windstar, I spent $4000.00 repairing it. The list is way to long to put here and yes I bought it from a reputable dealer, that has since lost my business.Come to think of it, Ford has since lost my future business as well. Praise Toyota. OK enough Ford bashing. Sorry. But I had a similar problem with the Windstar. Basicly you mentioned the gas cap. These computers on the Ford seem to be very sensitive to slight changes. My check engine light was on and it ran rough. So rough that if I moved the steering wheel while I was stopped at a light, sometimes it would stall. Well, I had to bring the car in for an emmissions inspection (required in GA). The only thing that failed was the gas cap. I replaced it and the car ran great afterwards. The check engine light never again came on. I only owned that vehicle for a year before it got traded in. I won't go into detail though as you said no Ford jokes. But I thought I would share my similar experience in hopes that it may help. The little things soimetimes make a difference.

Andy
 

firecracker22

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#4
I too would vote for an O2 sensor. Another thing to check would be your emissions system--some of those oddball EGR systems do funny things when they get a few miles on them. How about your fuel filter? I doubt your PCV valve would cause that much of a problem but it's not a bad idea to replace it too, they're like $5. I'd also look into some fuel injector cleaner, the good stuff that's $10-12/bottle. Don't do it for more than 2 gas tanks in a row though. Keep us posted on what works and what doesn't.
 

70 marlin

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#5
couple thing's you might want to check©

you have a small fuel pressure regulator up nexted to your throttle body, pull the vaccum line and check for fuel© if fuel is present, replace© also you'll need to replace the O2 senser because the overly rich conditon will take out the senser© did the dealership tell you if you had any fault code's? from your puter© on my aerostar van I just replaced the map senser & my second O2 senser {thank goodness for bosh life time parts} but you might want buy a good manual!!!!! also the EGR valve can give you a hesitation© if you have one? just make sure you buy life time warrantied parts! and if you have any type of failure in the emission system, always replace the O2 senser its the root of all faults©
NOTE: after any maintenance or repair to your fuel delivery or emission system© you need to disconnect your battery for at least 1 min© to clear the codes from the puter, then run your engine, turn lights on and of heater ect, drive the vehicle threw all the gears© then have the codes read again to see if theres any more problem?
 
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wrench

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#6
creric,

Before I put in my .02

I need to know if any modifications have been done to the exhaust/intake system, ie; Cats removed, high flow mufflers, oversize throttle body or Mass air sensor (you already mentioned the K&N air filter) did you just replace the OE style filter or did you get the whole "fresh - air" setup. OBD-II computer systems are VERY sensitive to changes in air/exhaust flow. If you speed it up too much, the computer goes nuts trying to keep up.

If you have only put a K&N in the stock air box and none of the other mods have been done, then .... the first thing is to get the DTC codes retrieved from the computer. I'm going to guess that you will have a EGR/EVAP "low flow" code as well as some others. Address the other codes first.

Check the vacuum source for the MAP sensor, it may be clogged or cracked. This will cause the problem that you have described, and may save you a trip to the shop for code retrieval. What ever you do ... do not clear the computer memory until you are sure that you have solved the problem. The memory codes and historical data that is stored will be tremendously helpful to a driveabillity technician. If the problem is fixed and the codes are not erased ... the car will run fine. They only act up if the problem is still there, not from a stored code.


wrench
 
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#7
Great car! I have a '94 Cobra, and I love it! I was going to suggest going to the Corral, it's a forum like this one, but only for mustangs. But several helpful people including wrench stepped up to the plate.

Have you don't any modifications recently?
 

jeffd

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#8
Originally posted by spanky250
Sounds like the O2 sensor to me. If there is a check engine light on, then it is giving you a code. Look in the manual for the code retreival procedure.
Spanky beat me to it. I might add:

-Do check the O2 sensors located on the exhaust H-pipe.
-Since you are running a K&N Filter, I would check the Mass Air Sensor to make sure the filter oil hasn't mucked up the sensors located in the MAF.
-Do get a new fuel filter ('sposed to change 'em every 10k miles).
-Check your EGR valve.
-Make sure that your SPOUT connector is still there and all sensors connected to the throttle body and MAF are secure.
-Pull the codes from the computer.
-If you can't read the codes, then re-set the processor by disconnecting the battery for a few hours.

Read on here for instructions on getting the codes:
http://www.mustangworks.com/articles/electronics/eecTech.html

-jeffd
('94 GT now and former owner of a modded 94 GT and a stock 95 GT)
 

wrench

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#9
motopuffs, send me your e-mail addy.

Originally posted by jeffd


-If you can't read the codes, then re-set the processor by disconnecting the battery for a few hours.

-jeffd
('94 GT now and former owner of a modded 94 GT and a stock 95 GT)

I am always amazed at how quick people are to clear the codes from the computer. Could someone please tell me how this will effect a "fix" to any drivability problem without actually fixing said problem first??????

It reminds me of the "universal cure" to a PC problem .... F Disk ... what was actually the problem ????? Did it get fixed ???????

There are plenty of things that can cause a drivability problem without ever turning the "check engine" light on much less, set a DTC.


wrench
 
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#10
YO!
Whats up fellow stanger?
If either of the O2 sensors, you have 2, one on each side of the H pipe are disconnected the car wont run. They may very well be the problme if they are faulty, again the error code will help with this . If you have never tried to remove one, get ready to learn some new curse words and use liquid wrench .
Also, the 95 dose not have a MAP sensor on th fire wall like the 86 to 87 and like most other current EFI, it has the MAS air sensor. This sensor is dynamic unlike the MAP, it compesates for motor upgrades by measureing the volume of air going into the motor and not just the vacume like the MAP. The Mass air sensor is a windmill looking fined wheel inside the air intake tubing. It spins faster as more air moves through the duct, IE faster RPM. It must spin freely and not be obstructed. Since you said about changing the filter, maybe something got cought up in it.
Also, what RPM is the car ideling at. It should be at about 950. Get a good manual and a Digital Multi Meter and mesure the voltage of the TPS, Throttle Position Sensor, located on the throttle body. This is how you adjust the idel on the car, it should be as close to .999 Volts as you can get it with out exceding 1V DC. If it is over 1 V or ideling over 1000 RPM, the car thinks your driving it and trying to supply more fuel than a motor with idel load needs.
Did you by chance over oil your air filter? Was the air filter a recent upgrade relative to the car running bad?
Good luck brother!
 

jeffd

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#11
Re: motopuffs, send me your e-mail addy.

Originally posted by wrench



I am always amazed at how quick people are to clear the codes from the computer. Could someone please tell me how this will effect a "fix" to any drivability problem without actually fixing said problem first??????

It reminds me of the "universal cure" to a PC problem .... F Disk ... what was actually the problem ????? Did it get fixed ???????

There are plenty of things that can cause a drivability problem without ever turning the "check engine" light on much less, set a DTC.


wrench
Wrench, you are correct. I only mentioned this as a last resort. I provided a link with very clear instructions on pulling the codes. Having owned (and modded) a few mustangs, I can testify that usually even if the codes are cleared by resetting the processor, chances are great that the condition will reappear unless the processor just suffered a hiccup since the root cause had not been addressed.

Do check the codes, and take the mass air flow meter off and check the air intake temperature sensor filament. Like I said, you are running a K&N and if it was over-oiled it could clog this sensor up.

-jeffd
 

MX265

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#12
Re: motopuffs, send me your e-mail addy.

Originally posted by wrench



I am always amazed at how quick people are to clear the codes from the computer. Could someone please tell me how this will effect a "fix" to any drivability problem without actually fixing said problem first??????

It reminds me of the "universal cure" to a PC problem .... F Disk ... what was actually the problem ????? Did it get fixed ???????

There are plenty of things that can cause a drivability problem without ever turning the "check engine" light on much less, set a DTC.


wrench
FDISK???? :think I was thinking more along the lines of Low Level formatting the heck out of a drive when in doubt. ;) Just kidding. You are correct. The only way to make sure a problem does not return is to take it step by step and troubleshoot it to death. I only wish cars came apart like computers.
 

wrench

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#13
Originally posted by JasonJ

Also, the 95 dose not have a MAP sensor on th fire wall like the 86 to 87 and like most other current EFI, it has the MAS air sensor.

You would be correct with this info ... I missed on the year model.

This sensor is dynamic unlike the MAP, it compesates for motor upgrades by measureing the volume of air going into the motor and not just the vacume like the MAP.

????

The Mass air sensor is a windmill looking fined wheel inside the air intake tubing. It spins faster as more air moves through the duct, IE faster RPM. It must spin freely and not be obstructed. Since you said about changing the filter, maybe something got cought up in it.

It sounds like you are trying to describe a "Vane" type Air Flow meter, not a MAS Air Flow meter that is used on the Mustang 5.0.
jeffd , I wasn't picking on you. Just look back at the posts and see how many solutions are teh "erase the Memory" kind.;)

wrench
 
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70 marlin

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#14
some times you have to!

when you have multible codes on top of codes,and they've been driving with the check engine light on for a long time© it's always been eaiser for me to just clear them , and then take a road test and have a set of fresh codes to work with© jason your correct on the mass vs the map, except on my fords it's not a vane type its a pedo tube type mass senser
 

jeffd

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#15
Originally posted by wrench


jeffd , I wasn't picking on you. Just look back at the posts and see how many solutions are teh "erase the Memory" kind.;)

wrench
No sweat. We are all on the same page. :)

-jeffd