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Bojames
User
Jun 14, 2012, 1:14 PM
Post #1 of 27
(6348 views)
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MisFiring Mustang
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Year of vehicle 1990
Make of vehicle FORD
Model of vehicle Mustang
Engine size 5.0 HO
Working on this "stang" for a friend...Need HELP!!!!
This car came to me with what apeared to be fuel problems.
Pressure test showed low pressure so we replaced with a new fuel pump.
Fuel pressure is now up but car has developed what I believe to be electrical.
Engine starts OK but runs really ruff, will hardly accelerate, and removing plug wires
(1 at a time) doesn'ft seem to have much effect. If the engine does pick up enough
to let it "rev" at all it backfires out the exaust. Yes I checked the firing order......
Also pulled and cleaned cap terminals and the rotor.
Seems the more we work on it, the worse it gets.
I am an old "shadetree" mechanic (pre computer/catalic converter) and know
very little about the newer technology.
If it had a regular fuel pump, caberutor, points and plugs...I could make it run.
D%* new fangled crap !!!!!
Thanks for any help in advance "Shade Tree Mechanic"
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Bojames
User
Jun 14, 2012, 1:45 PM
Post #3 of 27
(6299 views)
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Re: MisFiring Mustang
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"Your car is 22 years old." LOL
Hammertime,
You are correct but to me anything auto wise since mid 70's in new "crap."
When they started hiding "functional" parts in little black boxes I knew it
was about over for me.
And No, the engine light only comes on before starting.
The "cats" on this car have been gutted a long time ago.
Only a few counties in TN require all the "crap".
other info....This car sat in a basement for about 10 years and was bought by a friend
2 years ago. He had the fuel tank cleaned (rust) and it ran great for a while.
Had the tank removed and cleaned again along with new fuel filter and, again it ran OK.
This time when it malfunctioned he brought it to me, and the story continues as the
more I do to it, the worse it gets.
Nice car, everything (except engine at present) works...Worth fixing up!
Thanks..I await your next question/advice, Shade Tree Fix it Man
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 14, 2012, 2:34 PM
Post #4 of 27
(6289 views)
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Re: MisFiring Mustang
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If this engine (near sure) picks up air on passenger's side make sure firing order is correct. I think this engine rotates counter clockwise as diagram should show. Just crank it watching distributor rotor and make sure firing order is correct. Then test with it on TDC, #1 that valve timing has it right at top with valves closed as this may have the original plastic timing cam gear trick and they don't age well or firing order is for the regular 5.0 either could be wrong and cause the backfiring. Double check the basics of the order as you would in the 1970s as this is primary. I've seen tons of these but never and no clue why worked on one with the backwards upper intake (plenum/manifold) meaning throttle body is picking up air on passenger's side not driver's side. Check on that. BTW - 10 years is a long time to sit unless totally dry and stored or run once in a while but sounds more like it just sat, T
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 14, 2012, 3:35 PM
Post #6 of 27
(6264 views)
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Re: MisFiring Mustang
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Bojames:I hear you about the flaming magic boxes that really are doing the same stuff that was ever done just without adjustments - the car decides on things all thru it as they get newer so this one is basically just fuel injected, electronic ignition in place of carb and points so otherwise not way too much wildly different.
Cat converter thing. To my knowledge if bored out is not going to ruin the engine running on a 1990. If still plugging away know that as they got newer it's part of the show and defeating them is a waste and can be the problem. If good the exhaust doesn't have any advantage by removing or altering them as they can flow just fine.
Re reading this with the fuel issue and tank cleaning. That seemed to work for a while so toss the fuel filter again, drain it backwards into clear glass and see if it is still dirty with rust. Do not re-use the clips that hold lines onto fuel filter. They come with new ones or available separately. No clamps on those and don't try that if you try anything with them. Same as ever, check for leaks when back together.
Some crap with the old now 5.0s.......
* Distributor will have a module on side that takes a special socket or will need to grind down a 7/32 -- 1/4 drive socket so walls are thinner to fit in if still original. Easy and try not to break the little bolts. Generally those modules either work right or not at all. Pick up coil inside distributor may be dirty or a spider web in there. Blow it out with air first.
* The lower gear on distributor shaft has been reported to shear which of course messes up the show. Same game as older stuff that this.
So far I think since cleaning fuel tank and filter seems to work or did for a while this is fuel delivery related and just hope the filter caught anything first before getting to injectors.
That sitting around for 10 years is going to take its toll on this thing but most things are fairly easy to deal with as it goes. It would be trouble at the age for any technology before this era,
T
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Bojames
User
Jun 14, 2012, 4:14 PM
Post #7 of 27
(6253 views)
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Re: MisFiring Mustang
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Daigrams are correct and the Dist does rptate counter-clockwise.
(this can usually be identified by which side the Dist sits on the Cam)
To the best of my knowledge (which seems to be dissapearing daily)
is that Ford V8's have 1 of 2 firing orders...(I did check this knowing that
the car ran OK before having this "hissy-fit" before the firing problem arose).
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Bojames
User
Jun 14, 2012, 4:25 PM
Post #8 of 27
(6252 views)
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Re: MisFiring Mustang
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You stated "No, you are wrong. The Federal government requires it"
(lets be realistic...Federal Government requires a lot of stuff that is
ignored on a daily basis).
Please understand I am not try to cause an argument or "stir" up anything.
What I meant by this statement >>Only a few counties in TN require all the "crap",
is that older vehicles in most TN counties don't have to pass Emission standards,
thus: Liscensed Mechanic, and Exaust shops WILL NOT remove them !!!!
Doesn't mean "Bubba" can't take his off or gut it.
Personally I have never removed 1 that was not clogged so bad the vehicle
would not pull itself, and then suggest to my customer they get it replaced.
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Bojames
User
Jun 14, 2012, 4:40 PM
Post #9 of 27
(6248 views)
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Re: MisFiring Mustang
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Tom,
I have tried most of the "back to the Basics" but will go through them again.
This thing actually ran good enough this morning to back it up on ramps.
We pulled the tank, removed the filter and the pump, strained the gas through
a white T-shirt (it showed very very small amounts of rust color on the rag).
Put in a new filter, pump (new clips on all the connectors), reinstalled the
tank. Car started right up....did test drive (took off well) up the road and
the further we went (1 mile) the worse it ran. After we got it back to the shop
and raised the hood the thing was missing like it was running on 4 cylinders.
Like I reported earlier, pulling the wires seem to make little difference......
I know anything is possible but do you believe it to be fire or fuel?
Extremely loud backfire out the exaust leads me to believe fire because of
just putting in a new pump which shows sufficient pressure.
Thanks again guys for any/all input.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 14, 2012, 5:05 PM
Post #10 of 27
(6243 views)
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Re: MisFiring Mustang
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I say forget spark for now as messing with fuel stuff seems to respond for a while. If you can rig it up safely let fuel come out of fuel rail till clear. Coffee filters will save your white T-shirts
I know you are being a nice guy for a friend so don't run up unless you want to, too much in special tools but I tend to think the thing should get a new gas tank. Especially since you are still seeing rust which wont clear out with magic crap in a can. Not sure if injectors if rust flakes are involved can effectively be cleaned out. I wouldn't even think of tossing bucks a new injectors till fuel is known clean and good.
Fuel tank should be full of baffles so cleaning them out is a maybe only in my opinion. Never did cut one open even when washed out with soaps and water to dispose of them then squish them as flat as I could - don't ask how but hard to dispose of the old ones.
Again - so far I'd concentrate on fuel issues,
T
(on edit) I'm not worried about the laws with converters on this. It needs to run right first. I was aware stuff like that can be altered in some places but as things get newer than that - you just run into problems with before and after sensors which it shouldn't have nor involved in this problem for now. They could always be replaced if needed later.........)
(This post was edited by Tom Greenleaf on Jun 14, 2012, 5:15 PM)
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 14, 2012, 5:53 PM
Post #11 of 27
(6232 views)
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Re: MisFiring Mustang
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If your getting rust from the tank, probably wouldn't be a bad idea to replace the fuel tank. You might have to replace the fuel pump hanger and sender if they are rusted out too.
You don't want that stuff in your injectors or you'll be pulling the fuel rail.
Might want to get you a spark tester and check to see how the spark looks at the plug. Could be a coil breaking down when it gets hot.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 14, 2012, 6:00 PM)
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Sidom
Veteran
/ Moderator
Jun 15, 2012, 10:08 AM
Post #12 of 27
(6176 views)
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Re: MisFiring Mustang
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Ok.....I can relate to all that. Get us what info you are comfortable getting....If you can, post the numbers....Low & good can be deceiving. What you believe to be good, might be bad and your problem child.
Post the fuel pressure. Take a vacuum reading at idle & high rpm. I believe this one uses a mass air flow sensor. disconnect it and see if it will run any better. If by chance is uses a MAP instead, disconnect that & run it.
Pull #1 plug bring it up on compression, put the timing mark on 0° & see if the rotor is pointing to #1 in the cap
Just because the cats are gutted doesn't rule out an restricted exhaust system. If you can drop the pipes off the manifold or pull the O2 sensors, do that and see if that makes a difference in the way it runs...
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Bojames
User
Jun 15, 2012, 12:41 PM
Post #13 of 27
(6160 views)
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Re: MisFiring Mustang
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This AM, pulled the Bosch Platinum plugs (blacked over bad).
Cleaned them, got #1 to the top on "0" timing mark and rotor
points to #1 location on the Dist Cap.
Also replaced a quetionable Coil wire.
Fired the ca, it ran good for about 1 1/2 miles and went crazy again.
Engine won't rev and idles BAD.
I'm going to let cool down and try it again...
Fuel pressure 5o+
Don't have a vacuum gauge but it has great vacuum at idle when it's cold.
Havn't checket it hot
The hunt continues
Thanks guys
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 15, 2012, 1:18 PM
Post #14 of 27
(6157 views)
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Re: MisFiring Mustang
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The first thing you need to do is get rid of those plugs. they are junk and that car wasn't designed to run on them. Put in a set of Autolites. (non-platinum)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 15, 2012, 1:19 PM)
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Sidom
Veteran
/ Moderator
Jun 15, 2012, 3:49 PM
Post #15 of 27
(6146 views)
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Re: MisFiring Mustang
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Bosch plugs????? Oh man I totally agree with HT....get those outta there!! Those plugs are total crap.
If they all are dry black, then that would be an indication that it's getting too much fuel... A lot of stuff can cause that...
Did you disconnect that sensor to see if it made a difference on the way it runs...... I'm away from my database but it is either using a MAF or MAP sensor. After you get some decent plugs in there if it's still running bad disconnect the sensor to see if it makes a difference......Pull the vacuum line off the fuel pressure regulator while its running and make sure gas doesn't come squirting out of the regulator, those were good for rupturing diaphrams & sucking fuel thru the vacuum line....
It would be nice if you could pull the codes on that.....thats an old OBD I system so I don't believe it has memory codes just KOEO & KOER, I think it may have a basic datastream but I can't remember for sure....
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 15, 2012, 5:40 PM
Post #16 of 27
(6135 views)
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Re: MisFiring Mustang
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A bad coolant temperature sensor signal is a possibility too.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Bojames
User
Jun 16, 2012, 11:07 AM
Post #17 of 27
(6095 views)
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Re: MisFiring Mustang
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OK Guys,
You all are helpful and I thank you for your input.
All this information gets me to thinking...(I know, ususally causes headaches).
An engine, basically, is an air pump.... air in, air out.
Thus, a chamber, fuel, and an ignition source is what creates combustion to makes it a pump.
We all know that the combination of these items in the right mixture at the right time
is where we get our performance.
I said earlier that the car is "back-firing" out the exaust.
What this tells me that unspent fuel is being ignited either with the exaust valve open
or in the exaust system it self. Only does it when it gets to operating temperture. No
"back-fire" in the intake side at all.
The black plugs also told me it is not burning the fuel being delivered which again leads me to
be ignition related and not fuel problems.
I could be wrong....wouldn't be the first time :0)
We started the car about an hour ago, runs smoothly, accelerates well, and the fire (when you
pull a plug wire from Dist cap) you can hear as well as see a difference in the performance.
The fire will jump aproximately 3/4 inch and bit you if to close.
When the car gets hot, idles roughly, won't accelerate, and no spark gap that you can see or hear.
Someone please correct me if I assume (yes I know what that means) this is a Ignition Coil problem.
With "Ignorance" of new technology and limited resources, it is hard to figure this stuff out.
You sure can't get any information (and it is sad) from Auto Parts stores where the first
question they ask you is "What is your phone number"
As usual, thanks guys
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 16, 2012, 11:17 AM
Post #18 of 27
(6094 views)
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Re: MisFiring Mustang
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If your spark is getting weak when the thing heats up, a coil is a possibility if it has some windings shorting out when it gets hot. Kind of hard to tell if it is a coil winding problem without using a scope to current ramp the coil. You can easily tell a shorted out coil with an o scope. It would also be important to make sure that your coil voltage supply from the ignition switch isn't dropping when it gets hot too. You can watch that with a volt meter back probed into the coil connector.
Another possibility is the dwell (coil on time) is shorter when the problem is occurring which is causing the coil to not build up (saturation) which results in a weak spark. Coil dwell and timing is controlled by the ignition module on the side of the distributor which receives its information from the stator and the spark out signal from the ECM. Once again it is hard tell if you have dwell problem without using a graphing meter or scope.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 16, 2012, 11:24 AM)
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Sidom
Veteran
/ Moderator
Jun 16, 2012, 11:37 AM
Post #19 of 27
(6087 views)
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Re: MisFiring Mustang
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Like DS said, your aren't going to find this kind of a failure with an ohm meter. You need to check it while the failure is happening and that is when it's hot.
One thing you could do that is fairly cheap would be to get a spark tester from a parts store, $4 or $5 bucks.
When it's running like crap wind the test out to 40kv and check the spark, it should be strong & blue, if it's weak & orange or no spark, then more than likely you have a bad coil..
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 16, 2012, 11:49 AM
Post #20 of 27
(6081 views)
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Re: MisFiring Mustang
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Again...........
GET RID OF THE BOSCH PLUGS!
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
Veteran
/ Moderator
Jun 16, 2012, 11:52 AM
Post #21 of 27
(6077 views)
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Re: MisFiring Mustang
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Yea.....that has cured many a problems for me....
All this other stuff is after there is a fresh set of autolites in there and if the problem remains...
But definitely those plugs need to go 1st no question..........
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 16, 2012, 11:55 AM
Post #22 of 27
(6071 views)
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Re: MisFiring Mustang
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Yes, I agree with HT and Sid on that. Ditch the Bosch plugs.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 16, 2012, 11:56 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 16, 2012, 2:24 PM
Post #23 of 27
(6048 views)
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Re: MisFiring Mustang
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Even my Kitty says get rid of those plugs!
T
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Bojames
User
Jul 11, 2012, 2:51 PM
Post #24 of 27
(5914 views)
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Re: MisFiring Mustang
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Guys,
Sorry about taking so long to get back to the postings (medical stuff)
We put on a new Coil and Dist module and thought we had it fixed.....
BUT>>>> Drove the car about 2 miles (smiling) thinking the problem was solved.
Engine started missing and quit...Did restart but eventually died !!!!
Any more ideas for this confused old man???? 02 sensors ?????
D&# piece of "crap"
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 11, 2012, 3:03 PM
Post #25 of 27
(5910 views)
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Re: MisFiring Mustang
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Did you replace the plugs?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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