Ford Mustang 5.0 Misfire Problem Help Asap - Forums at Modded Mustangs
 
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post #1 of 9 Old July 25th, 2010, 06:55 PM Thread Starter
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Exclamation Ford Mustang 5.0 Misfire Problem Help Asap

89 ford mustang 5.0
Upgrades:
Vortech v1 supercharger
30lb injectors
E303 cam
Ford svt roller rockers
351 heads
Stock block with less then 65k
Trick flow intake
Bbk headers
Bbk fuel pump
Calibrated maf (76mm for injectors)
Vortech fmu

Ok problems
Car starts and idles rough, also when I rev it, it will cut out and miss fire.
When I drive it it keeps sputtering and missing

I bought the engine used with cam new installed.
I dropped the engine in myself and installed sc

Check plugs, wires, fuel pressure is good (34psi idle) (42psi throttle)
Check maf, vac lines, and its getting good oil pressure.
I tried disconnecting the supercharger and tried running it but still nothing

I'm clueless and need help asap
If I can't get this car fixed then I'm about to sell it.
It was going to be my daily driver
I'm also running 87 pump gas but I don't think that's problem
I checked all wiring also plugs, ground plugs, I had people look at it and there clue less
Please please help
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post #2 of 9 Old July 25th, 2010, 09:31 PM
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Did this problem start as soon as u put the vortech on? And do u kno what ur timing is at?
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post #3 of 9 Old July 25th, 2010, 09:40 PM
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Have you run KOEO and KOER tests yet? Did you hear the engine run in another car before you bought it?
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post #4 of 9 Old July 26th, 2010, 01:02 PM Thread Starter
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I never heard engine run, I'm going to take the sc off and see what's happening
Its more like its missing and cutting out but throws no codes???
All my plugs are carbon fouled if that helps anyone out
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post #5 of 9 Old July 26th, 2010, 01:03 PM Thread Starter
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I never heard engine run, I'm going to take the sc off and see what's happening
Its more like its missing and cutting out but throws no codes???
All my plugs are carbon fouled if that helps anyone out
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post #6 of 9 Old July 26th, 2010, 01:04 PM Thread Starter
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Timing is at 15degrees won't idle with anything less and it gets worse when I drive
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post #7 of 9 Old July 26th, 2010, 01:46 PM
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First. You have to get it to idle..
Do you still have PCV attached and the oil fill tube hose attached to the throttle body? Do you have a breather or an oil cap on the filler tube?

Set your base fuel pressure to somewhere in the mids 30's (set it there with the FPR vac line disconnected and reconnect it when done adjusting). 30# injectors can be tricky with idle quality higher than that with the stock computer. See what happens.
Then carefully clean the maf with some MAF cleaner and set your timing back down to 10.
Does it idle yet?
Look around here or google for the base idle reset procedure and clean the IAC if needed.

Once it idles at conservative 10 timing, start working on the breakup under load..
Is it missing before or only when actually making boost?
What do the plugs look like, are they almost new and are they plain old copper plugs (should be) and what are they gapped at (important with boost, should be somewhere in the 30's to start).

Other things to consider and I'm just throwing these out there. Double, triple, and quadruple check your firing order and wires. Seems redundant but it happens more than you think. Maybe your harmonic balancer outer ring shifted and the timing marks are off and maybe shaking the engine and not really a miss at all (again, it happens and can be confusingly similar). Do you have good fuel and filter? Plug wires good and not all crossed up and leaking? Unfortunately you may have inherited something with internal unknowns.

Everything above can be done with little to no money. I'd start with looking at and checking that stuff before throwing random parts at it.


Last edited by nolife; July 26th, 2010 at 03:49 PM.
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post #8 of 9 Old July 26th, 2010, 01:52 PM
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Yea 15 degrees is too much if ur running a blower, and there is a base idle reset thread in the stickys of the 5.0 page,, hope it helps
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post #9 of 9 Old July 26th, 2010, 09:02 PM Thread Starter
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Everything is hooked up and yes all that was checked out I turn timing down and car dies and gets worse. Could the timing chain be off a tooth? Looks like that's the only thing left
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