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Author
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Topic: HELP! Missfire killing me...
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MistaFosta
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Member # 4068
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posted
 
 
First off, this is a 90 LX 5.0 (Ex CHP) It has a mac cold air, and a set of underdrive pulleys, otherwise it is stock.
A little while ago, I developed a strange missfire over 3000+ rpms under full or almost full throttle. It acts pretty much like a rev limiter, causing a complete loss of power (Can't even get past 3200 rpms). It only does it once the car warms up, and only under heavy throttle above 3000 rpms. Otherwise the car runs absolutely perfect.
I have either swapped with known good, or replaced these parts. Distributor, module, coil, plugs, wires, cap, rotor, fuel filter, fuel pump, MAF, intake air temp sensor, water temp sensor, put the stock intake piping back on, TPS, and I checked all my grounds. Also tried another computer. I gapped the plugs at 50 and 45, no difference.
If anyone has ANY suggestions, please let me know. This car is really pissing me off..
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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nitrous_bob
CAFords OG
Member # 77
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posted
hook up a fp guage to rule that out for sure...
watch the fp when it starts to stumble.
if it's good...gotta be spark.
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5.0 OG since 1990
Posts: 1402 | From: st clair shores MI | Registered: Nov 2000
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FasterDamnit
Bad Attitude
Member # 442
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posted
Codes?
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'92 LX T5
Looked stock, went 11's 11.90 at 115mph.
'65 Mustang 347
www.fordmuscle.com
Livin' in the Carolina Pines
Posts: 2971 | From: NorCal | Registered: Sep 2001
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MistaFosta
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Member # 4068
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posted
It has a EGR code, but it throws that when it is cold, and has done that for about 6 months now...
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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PunkINa5.SLOW
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Member # 10
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posted
How did swapping out the cheap ass plug wires you have on that thing work for you?
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OUTTA THA DRAMA
R.I.P. MIKE STARKEY MY BABY BROTHER
12/8/77-5/17/03
Posts: 2495 | From: MTZ | Registered: Sep 2000
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PunkINa5.SLOW
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Member # 10
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posted
oh my bad I see that you swapped out the plug wires.
Tell you what hook that MSD box up and see if it makes any difference just for GP
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OUTTA THA DRAMA
R.I.P. MIKE STARKEY MY BABY BROTHER
12/8/77-5/17/03
Posts: 2495 | From: MTZ | Registered: Sep 2000
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PunkINa5.SLOW
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Member # 10
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awww screw it come back over in the morning and Ill actually go for a ride in it with you this time to try to help you isolate
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OUTTA THA DRAMA
R.I.P. MIKE STARKEY MY BABY BROTHER
12/8/77-5/17/03
Posts: 2495 | From: MTZ | Registered: Sep 2000
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six 5.0
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Member # 3153
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posted
I have an 86, It does the same the shit ![[Confused]](confused.gif) mine does it when it's cold. It fuccin pisses me off, I can not figure it out either. I have had suggestions to change my cats and my mufflers (stock). Maybe you yau should look in to doing the same, if thier stock.
good luck ![[patriot]](graemlins/patriot.gif)
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IwishIwasan03COBRA!
Posts: 4425 | From: SAN MATEO | Registered: Aug 2003
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MistaFosta
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Member # 4068
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posted
quote:
Originally posted by PunkINa5.SLOW:
awww screw it come back over in the morning and Ill actually go for a ride in it with you this time to try to help you isolate
Lol, I gotta work 730 to 430. Id be happy to lend you the car to feel the problem yourself. I trust you with it. I have my brother's car for the next 3 weeks, so Im trying to fix the problem soon. Could it be plugged cats? Maybe I will try running open header...
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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Hungry Hippo
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Member # 537
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posted
bad grounds on the back of the heads?
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05 S4 Avant(wagon)
09 C6 H/C/I
Posts: 2959 | From: east bay | Registered: Nov 2001
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DaveG
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Member # 1606
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posted
With a DVOM, sweep the TPS and look for a bad spot. I'd double check for a TPS code.
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DaveG
96-0029 S-351
Supercharged Speedster
613rwhp, 633rwtq
Posts: 112 | From: San Jose | Registered: Jul 2002
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MistaFosta
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Member # 4068
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posted
quote:
Originally posted by DaveG:
With a DVOM, sweep the TPS and look for a bad spot. I'd double check for a TPS code.
Put in a TPS last night... No change. I also checked those grounds, they look fine, no corrosion, no opens.
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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PunkINa5.SLOW
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Member # 10
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posted
I think somehow you did something wrong when you put the fuel pump in just my .02
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OUTTA THA DRAMA
R.I.P. MIKE STARKEY MY BABY BROTHER
12/8/77-5/17/03
Posts: 2495 | From: MTZ | Registered: Sep 2000
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MistaFosta
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Member # 4068
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posted
quote:
Originally posted by PunkINa5.SLOW:
I think somehow you did something wrong when you put the fuel pump in just my .02
I guess i will pull it and check it again then. Its not really hard to pull, so no biggie...
What could I have done though, since it has the problem with a full tank also?
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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MistaFosta
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Member # 4068
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posted
K, checked fuel pressure, when stumbling is happening. Rock solid 41 psi...
So, Im guessing its the wiring for the ignition, primary or secondary. Any ideas still?
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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forced331
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Member # 1270
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posted
If you have an aftermarket ignition, that would cause the problem your dealing when an igition is bad.
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1992 Ford Mustang LX (Original Owner)"Titanium Frost" 331stroker S-Trim, 5spd
2014 Ford Mustang GT- daily driver
Posts: 1154 | From: Sonoma County | Registered: May 2002
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MistaFosta
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Member # 4068
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posted
quote:
Originally posted by forced331:
If you have an aftermarket ignition, that would cause the problem your dealing when an igition is bad.
Stock ignition. Tommorow Im going to try puttin in an MSD just for fun...
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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forced331
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Member # 1270
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posted
Check for a pinched fuel line?
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1992 Ford Mustang LX (Original Owner)"Titanium Frost" 331stroker S-Trim, 5spd
2014 Ford Mustang GT- daily driver
Posts: 1154 | From: Sonoma County | Registered: May 2002
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MistaFosta
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Member # 4068
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posted
Wouldn't I see a loss in pressure?
Posts: 82 | From: Pleasant Hill, CA | Registered: Jan 2004
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DaveG
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Member # 1606
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posted
Pinched / kinked fuel line you wouldn't necessarily loss in pressure, but a loss in volume.
Posts: 112 | From: San Jose | Registered: Jul 2002
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