1997 Ford Mustang car lags when I floor the accelerator

JVMOSCOSOR

MEMBER
1997 FORD MUSTANG
V8
2WD
AUTOMATIC
152,000 MILES

Hi, my mustang runs fine when going slow but when I hit the accelerator the car shakes and feels like a missfire but I had this problem before I changed the coils and the wires and the engine light went off. It has not turned back on and now the problem is back. So the computer does not even download any codes. I dont know what else to do. Its does not have the torque or the horses it should it takes very long to pick up and the take off is not very good. One time I even floored the accelerator and I got to about 90mph and then the car could not go any faster. It is very slow. Please help. Thank you very much.

5 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok lets get some info first so I better help. What all has been checked and what have you replaced? When the engine light was on did you get the code at that time and if so what was the code. Do you have a digital multi meter if needed? Get back to me and we will go from there.

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Thursday, June 3rd, 2010 AT 11:12 AM

JVMOSCOSOR

MEMBER
3 POSTS

I do not have a meter. And the codes said that cylinder 4 and 8 were missfire. When I changed the coil and the wires the codes went away and the computer is not saying anything is wrong anymore. I don't know if maybe a tune up would help or what else might be the problem the engine is not making any noise it does not seem to be the motor and it only does this when the car is in motion when the car is parked and I rev the engine it accelerates fine. When the car is in motion it lags and takes time about 20 seconds or more to get to 60 and from there it is very hard to get any faster. It shakes a little and feels like a missfire but am not sure what it is.

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Thursday, June 3rd, 2010 AT 12:47 PM

RACEFAN966

MECHANIC
5,029 POSTS

Ok with out a meter we can't do any testing. However what you can do is pull a couple of plugs like 4 and 8 and see how they look if in question replace all. Also check the air filter and get some mass air flow cleaner (nothing else) and clean the mass air flow unit ok. Is there a performance mods added and if so what? Let me know how it goes and we will go from there.

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Saturday, June 5th, 2010 AT 9:19 AM

JVMOSCOSOR

MEMBER
3 POSTS

OK I changed the plugs with motorcraft platinum plugs and this solved the problem of hesitation and the sense of misfire when I accelerate and the mass air flow is fine. I found that the catalytic converter is loose and possibly broken however the emissions is still being read properly. I was wondering if the converter would have anything to do with it. The only problem left to solve is the horses are still very low the car does not pull like it should. The car is completely stock, I wanted to add a cold air intake however I did not want to add any mopney to the car without solving this issue. (Let me know if I should do it anyway) thank you for all the help youve been great. Definetly going to add some more $ to my question thanks.

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Wednesday, June 9th, 2010 AT 4:15 PM

RACEFAN966

MECHANIC
5,029 POSTS

Ok if the cat is broken internally and plugging off any of the exhaust this can cause a loss of power. Also if the Mass Air Flow Sensor is dirty so can it, this is why I ask it to be cleaned. I clean mine on my Mustang once a year. If you can have the exhaust flow tested at a muffler shop this will answer the question if the cat is a problem. As for mods I have many on my Mustang I have a BBK cold air and love it I also have flowmaster cat back system and BBK throttle body and much more and it all has made for more power and in some cases more mpg. Let me know what you find on the exhaust and we will go from there ok.