What's wrong with my car?

JCClanton · Jan 24, 2011

I have a 1993 Ford Mustang w/ the 2.3L. Its an automatic. I have did a tune up, thermostat, air filter, battery, and radiator. When I crank it up it vibrates and when i give it gas sometimes the exhuast pops. it loses power also. what do you think is wrong with it? pls help.......

Delray Dude · Jan 25, 2011

1st things to check would be coil packs, DIS system module, and the computer.

Usually the coil packs are to blame, but DIS units fail eventually too and the computer.

I had the packs go bad on mine, replaced them and ran great for a few months then the DIS went bad, got one off a 96 Ranger, ran great for a few more months then the computer went out. Found one that was a fresh rebuild in the junkyard and put it in, runs like a champ again.

JCClanton · Jan 25, 2011

could a plugged cat cause this?

Delray Dude · Jan 25, 2011

JCClanton said:
could a plugged cat cause this?

It is possible that the cat (or both) is plugged up and results in power loss.

But it would be consistently bad and would have been getting progressively slower. If the car had been running decent and all of the sudden starts acting up - the usual problems are the coil packs and DIS as stated above.

From a general standpoint, if you can, I would hollow out the cats at minimum to gain some much needed horsepower. the 93 or 94 Ford ranger header helps in that department too - and it's almost a bolt in deal. Doing both and removing the air muffler in the intake tube will wake up the engine some and help with power and mileage - but I suspect the problem lies in the electrical.

If you can unbolt your exhaust at the end of the manifold and move the pipe out of the way and drive it around the block (it will be loud) you can see if it eliminates the problem - if so then the cat is plugged.

Delray Dude · Jan 25, 2011

I suspect you might have one dead coil pack and the other is failing on one (or more cylinders) from time to time.

You can check the coil packs fairly easy. Unplug one of the modules - I'd start with the front one because it's easy to get to. Simply unplug the connector at the base of the coil pack - it's right up front. Fire the engine (or attempt to) if it runs like it has been then atleast the majority of the back coil pack is working. If you get no fire at all, then the whole coil pack is bad. Plug in the front one and unplug the back one. Same deal as above.

If unplugging both yields the same running condition - I would look at the DIS going bad. This is the module bolted to the front of the lower intake manifold - its grey and has conncetions on the top and bottom. Usually when it's messing up - the tach starts acting erratic and reads wrong. New ones are not cheap - but a mid 90's Ranger 2.3 has the same module - and usually can be found for 10 buck in the junkyard.

JCClanton · Jan 25, 2011

ok so i can just unbolt the cat and drive without it? thanks

Delray Dude · Jan 25, 2011

JCClanton said:
ok so i can just unbolt the cat and drive without it? thanks

I have hollowed mine out (both a 93 and 88 car) and have had no problems for years. The O2 is ahead of the cat and the computer has no post cat input so it doesn't care if you have one or not.

If you do remove them, but sure to disconnect the battery for 10 minutes to allow the computer to relearn it's new breathing capabilities - it goes out and relearns everything when you kill the memory - takes about a day for it to relearn idle settings and such, but will help out.

Red_LX · Jan 25, 2011

Might also check out the MAF...could be a leak somewhere behind it that's making the car act weird.

JCClanton · Jan 25, 2011

the module your talking about is the ignition module right? And what toold will i need to have to get the cat from under there?

JCClanton · Jan 25, 2011

Red_LX said:
Might also check out the MAF...could be a leak somewhere behind it that's making the car act weird.

MAF AIr Flow Sensor?

Delray Dude · Jan 25, 2011

JCClanton said:
MAF AIr Flow Sensor?

MAF sensor is located on the top half of the air cleaner box. you'll see a 3 wire plug going to it. then the tube from that to the intake on the top of the engine. make sure that tube is good and sealed (no leaks) because the MAF
Mass Air Flow tells the computer how much air is entering the engine - any air that gets in past it, the computer doesn't know about and causes problems.

Delray Dude · Jan 25, 2011

JCClanton said:
the module your talking about is the ignition module right? And what toold will i need to have to get the cat from under there?

Yes. DIS = Distributorless Ignition System. Takes a pulse from the crank sensor on the front of the engine and fires the coil packs accordingly.

Delray Dude · Jan 25, 2011

JCClanton said:
the module your talking about is the ignition module right? And what toold will i need to have to get the cat from under there?

Basically, a few sockets, a cutting blade, and air tools help.

The air tools to get the rusty bolts loose at the exhaust manifold - I think they are 13 or 14 MM. undo the to bolts on the flange in front of the muffler, and the cat section should wiggle out of the mount on the transmission.

to get to the cats cut the pipe near the ends - mark a line so you can weld them back in the same place. get long screwdrivers, instruments of doom and start chiseling the material away. it crumbles easily and takes time, but it'll come out.

zonker · Jan 25, 2011

you replaced your spark plugs?

i think i would double check you put your plug wires back on in the right firing order... if you have a couple wires crossed that will give you all the symptoms you're talking about.

JCClanton · Jan 25, 2011

I had a major tune up done to this car by a shop. And a couple weeks later it started the vibrating stuff and shaking. it ran good before i got them to do the tune up.

AngelApollus · Jan 26, 2011

The 93's have MAF?

I feel so left out, does sound like DIS though. I (luckily) haven't had mine go out. *knocks on wood*

Delray Dude · Jan 26, 2011

AngelApollus said:
The 93's have MAF?

I feel so left out, does sound like DIS though. I (luckily) haven't had mine go out. *knocks on wood*

91 to 93's have mass air. 87 to 90 have speed density on both 2.3 and 5.0

from what i understand.

Red_LX · Jan 26, 2011

'87-90 2.3's were speed density, yes.
'91-93 were both DIS and MAF.

In Rangers, they got the DIS 2.3 starting in '89 but I don't know if it was also mass air starting that year or not.

5.0's were SD from '86-88, and mass air from '89-93.

JCClanton · Jan 26, 2011

JCClanton said:
I had a major tune up done to this car by a shop. And a couple weeks later it started the vibrating stuff and shaking. it ran good before i got them to do the tune up.

Does this help?

Delray Dude · Jan 26, 2011

JCClanton said:
Does this help?

some. The DIS or coil packs can pop at any time.

What's wrong with my car?

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