Misfiring ???

My friends mustang has been misfiring for the last two weeks or so.
We have replaced:
Spark plugs
Wires
Distributor cap
Rotor
Fuel filter
Air filter

It is a 1995 mustang GT
I seriously dont know what else could be causing it :screwy:

Has the timing been adjusted recently? Try reseting the computer so it can re-learn the new degree if so. It could also be the ignition itself.

did u double check the firing order when u put the dist back on? ive done that before, and it'll run like crap.

Definitely check the timing before you go any further. Does the temperature outside or moisture(i.e. rain, fog, snow) play a role this at all?

Has the timing been adjusted recently?
Nope

The cap was checked. I think I am going to check the wires again just to make sure he didn't mix one of them up. Does any one know what order the wires go into each cylinder.


Definitely check the timing before you go any further. Does the temperature outside or moisture(i.e. rain, fog, snow) play a role this at all?

I'm not sure what you mean by the temp. Do you mean that, like only in the rain or snow it misfires. Then no. It does it in snow, rain, and a sunny day.

Nope

The cap was checked. I think I am going to check the wires again just to make sure he didn't mix one of them up. Does any one know what order the wires go into each cylinder.




I'm not sure what you mean by the temp. Do you mean that, like only in the rain or snow it misfires. Then no. It does it in snow, rain, and a sunny day.

if you have a haynes manual, it'll tell you the firing order, or autozone.com has it also. Then you can go from thier and figure out which wire goes where.



i believe he means that does it misfire only on say a day when its 50 degress outside, or when its 80 degress outsdie, or does that play a role.

The firing order is fine. The misfiring is orcurring whenever, the misfire does occurs in rain, sun, snow and everyday.

He just told me that he does NOT have an CEL

I rode in his car again, it is very bad. When he started his car it seemed fine, but then as it warmed up a little bit. It got terrible.
He also has a huge exhaust leak in his H-pipe, could that have anything to do with it?

HAHAHAHA Don;t mean to laugh but I'm willing to bet money that I know what it is.

INSPECT ALL PLUG WIRES!

Is sounds like once the car heats up, a plus wire is touching/rubbing on a header and it ate away the rubber so now it is grounding out against the hot surface. This happened to me and a buddy of mine. It feels like it's running on 7 cylinders and it studders like a BEOTCH!

Good Luck!

Matt

I will tell him to do that.
But I don't think that it is the problem. It was misfiring before and after we changed the wires, also we took all the wires out when we replaced the plugs yesterday, and it was doing it before all of that and it still is :(

I will tell him to do that.
But I don't think that it is the problem. It was misfiring before and after we changed the wires, also we took all the wires out when we replaced the plugs yesterday, and it was doing it before all of that and it still is :(

Well it sounds like you guys have your bases covered! That's why I figure it must be something freak like that. Good Luck and keep us updated.

Matt

Well I will tell him too check it.

I was just wondering what does the wire in the middle of the distributor run to. It is a box looking thing. What is it? Could that be causing it?

Well I will tell him too check it.

I was just wondering what does the wire in the middle of the distributor run to. It is a box looking thing. What is it? Could that be causing it?

That would be the ignition coil. That can be tested at any Autozone or something like that.

lol... O ok, I'm not familar with a distributor setup.
EDIT>>> BTW how hard are they to replace. I know on my car the coil is SUPER easy. But I don't remember exactly on his car if it looked hard or not. Hopefully it is easy :)

Ok so we went to NAPA and they said the coil can just be good or bad. And none of the wires are touching the headers.

What else could be causing this. This is driving me nuts and its not even my car :)

Could it be one of the sensors...
Do these cars have water temp. sensors ??

yea they have water temp sensor. ive heard of o2 sensors creating bad gas mileage, never heard of it making it miss though....maybe stopped up converters (if they are stock and still on) u can have an exhaust place check it (should be for free) all they do is use a thermo gun thingy on either side of the converter.

Could it be one of the sensors...
Do these cars have water temp. sensors ??

Do you mean coolant temp? Then yeah, all modern vehicles have coolant temp sensors.

R&R ignition coil..

1. unplug harness and primary wire

2. remove 4 screws

3. destroy old coil in a creative way

4. put new coil in, lightly tighten the 4 screws

5. plug it back in

6. start car

so simple a child could do it

does the car smell like it's running lean? i would have your injectors professionally cleaned (dont' use that 'injector cleaner' fuel additive, it makes it worse). could be that one cylinder is not getting enough fuel to ignite the mixture properly.

Well i think it is a sensor cause he told me that his temp gauge does not go all the way to the normal position. And this started when the misfiring started. (I got MAD that he did not tell me this before :() So I looked on the internet on some cars they have this problem, and it was a sensor, I think it was the EVO and their solution was the water temp sensor.

So I dunno...

Is a water temp sensor the same thing as the coolant temp sensor?
EDIT>> Doesn't the coolant temp sensor do some stuff with the a/f ratio... so i guess it is possible... isn't it.

We replaced the coolant temp. sensor today.
It did nothing :(

Any other ideas... the temp. gauge still does not reach normal position and the car runs like shit.

We replaced the coolant temp. sensor today.
It did nothing :(

Any other ideas... the temp. gauge still does not reach normal position and the car runs like shit.

i still suspect your fuel system here. did you check your plug gaps and all that? and your coil? do a pressure test on your fuel system. it's hella easy on a ford.

Plug gaps are fine... the thing is with the fuel system what does that have to do with the temp. gauge not reaching "normal".

So that is why I think it is a sensor.

If your thermostat is stuck open the gauge may very well read low. Does it take a long time for the engine to warm up?

The coil is very easy to replace but in 40 years of shade-tree mechanics, I've never really seen one go bad. It is a possibility, though.

You may want to run a compression test. If you know how to run a jumper wire into the test port, there are three tests you can induce. KOEO - key on engine off. KOER - key on engine running. And a Cylinder Balance Test. The last one will cut off each injector one at a time and measure the rpm drop. If there is not sufficient rpm drop on one or more injector cut offs, then the test will fail. Meaning, you have a low compession or "bad" cylinder.

Your computer can store fault codes and not necessarily trigger the CEL. I'm living proof.

You can buy an inexpensive Ford scantool that should cover these tests and how to induce them. Or, Autzone will do a basic scan for free.

The other way is to use the old compression gauge and take out each spark plug one a time, remove the coil wire, and turn the engine over 3-4 times for each cylinder. Cylinder pressure readings should all be within 10 or so pounds of each other. Somewhere around 165 psi is normal in a warmed up engine.

Another possibility is a vaccum leak somewhere. Check to see if all the hoses are attached or that none have cracks in them. A vaccum leak may cause a misfire - running lean. Sometimes the power brake vaccum line develops a leak.

As others noted, check the timing. You need to remove the spout plug when you do this. Factory timing is, as I recall, 10 degree BTDC.

Is there any particular event that you can tie the misfire to?? Did it just start happening all at once or did it gradually happen? I would definitely fix that exhaust leak, too.

Just some suggestions. These problems can be so very annoying. Good luck.

i have a 87 mustang gt 5.0 and i barely changed the spark plug wires and plugs because my car was not idling good. i also added a boot on one of the wires because the old wire got burned by the header. Now it doesnt even rev up past 3000rpm. Why!!! and also i barely installed a shift kit and my transmission lever wont let me go into overdrive and 1st gear!!

What else if left to check?? Have you checked the Injectors? Have you done a compression test on the Engine?

i have a 87 mustang gt 5.0 and i barely changed the spark plug wires and plugs because my car was not idling good. i also added a boot on one of the wires because the old wire got burned by the header. Now it doesnt even rev up past 3000rpm. Why!!! and also i barely installed a shift kit and my transmission lever wont let me go into overdrive and 1st gear!!

Do not bring up old threads. If you want ya questions answered start a new thread cause this one is closed.