My girlfriend has a 1995 Mustang with a 3.8L V6. She has been having some problems with it recently, and I thought it might be helpful if I got some opinions from all you trusty guys here. The following is what she posted, in her words, on a mustang forum:

I have a 1995 Mustang with a 3.8L V6. It currently has 157,800 miles on it and is in great condition other than the few problems that I have at the moment. Up until now, I really haven’t had any problems worth mentioning. I’m going to do my best to explain everything as clearly as possible.

Here’s my first issue. If I start my car with the air conditioning turned off, the air works fine. If I start my car with the air turned on, it comes out of the defrost vents on the dash. If I turn my air off while I am driving and then try to turn it back on before I turn my car off, it comes out of the defrost vents again. Sometimes it will be working fine and start to come out of the defrost vents while I’m driving but after about 30 minutes, it will start working properly. I don’t know what could be causing this but it is occurring more and more frequently and it’s essential that I have air conditioning due to the fact that I live in Florida.

Now for the other issue. I’m having acceleration problems as well. Yeah, yeah, I understand that I have a 3.8L so I know it’s not going to get up and go like a GT would. I’ve just been noticing that it has been less responsive than it used to be. I don’t know if that could be due to the fact that it has 157,000 miles on it or if after so many miles it just gets slower. It just doesn’t feel like it has power anymore. From a stoplight, it accelerates very slowly. It used to be slow to come out of first gear since I got it but it would quickly go through the other gears and I would be going 60mph before I knew it. But lately it is slow through all the gears. It takes about 12 seconds for me to get up to speed. Also, if I need to pass someone, it takes about 6 seconds after I push the gas pedal to respond and go into passing gear. I just remember it being more responsive than that. It’s getting to the point where I no longer feel as confident driving on a highway due to my car’s poor acceleration.

I hope I explained all of that clearly. Any help would be greatly appreciated.

Thank you.

So there you have it. I told her she probably needs some transmission work due to the fact that it's the original transmission and she has no idea when it was last serviced. I also suggested a complete tune-up. She said she has had the car for three years and has never had the spark plugs changed.

That's all the help I can provide her, so I figured someone here might have something useful to add. Thanks for your patience with the lengthy post.

Thanks

 

The AC issue sounds like a vacuum leak. Had the same problem on my old truck, found a crack in a small red vacuum line under the hood, repaired it and all was well.

As for the acceleration issue, I would give it a tune up if it hasn't had one in a while, plugs, fuel filter, air filter, pcv valve.

 

I concur with the vacuum leak for the A/C. The air control flaps are vacuum controlled and a leak will make them slow to operate. Could be the vacuum motors too. As far as acceleration, your MAF could be dirty. If the idle is bad, that is another indicator of a dirty MAF. Take off the intake tube and clean the MAF with a carb cleaner, or better yet, a spray that is meant for this job. Do the normal air cleaner check, spark plugs, wires change. Also, when was the last time the O2 sensors where changed? They are only good to about 60,000 miles. And the cats could be clogged. That is something a shop would have to diagnose. But that is a very likely candidate for the cause of your acceleration problems. What gas brand does she use? if she uses the cheap bargain brand gas, the intake valves could be carboned up. Only use top tier gas. Try this: take off one of the smallest vacuum hoses and put it in a glass of water while the car is idling. If the car starts to bog down, pull the hose out of the water until the idle settles down... then dip it back in. The cold water vapor breaks up the carbon deposits on the intake valve. That should help. And check all the vacuum hoses in the engine compartment. If you have a large vacuum leak there, your performance will suffer.

 

Hmm... that's all very useful info. I'll try that procedure you mentioned above as soon as I have an opportunity. And I'm sure the throttle body could use a good cleaning. I don't think the O2 sensors have been changed either, especially since the car hasn't had a tune-up since before she owned it over three years ago. That's assuming the previous owner took good care of it. I'm under the impression that he did, because the car is in excellent condition. My girlfriend takes good care of it too. She services it at regular intervals and doesn't abuse it. These issues are the first problems she has had with the car.

I'll share with her what you guys said and see what we can do with it. Thanks again for your time and help.

 

Not a problem.. just be sure to post back what you find...