Only fun til 4k rpms?

Atomyk · August 16th, 2011, 08:57 PM

So, I just picked up a 5 spd 87 GT. Its got BBK chrome shorties, an aftermarket cam that neither myself or the previous owner know the specs of, a chopped up h-pipe, and dumped factory mufflers. I just did a full tune up (dist. cap, rotor, plugs, wires, fuel filter, base idle reset, checked TPS voltage, cleaned MAF, TB, and IAC) to help the idle, but it falls flat on its ass at WOT above 4k rpms. It seems to stop revving as quickly and just kinda sits there... so... anybody know why? It has been converted to mass air by the way.

StangBanger302 · August 16th, 2011, 09:31 PM

Why? Maybe the cam he put in is a shitty one and makes low end grunt but no steam up top. Stock 5.0s only make power till about 4K, shift around 4,800-5,000 depending on the car.

Atomyk · August 16th, 2011, 10:46 PM

Oh... That makes sense. Well dern. I figured with the way it lopes it would have more top end. Figures... So far, this car has been one big let down after the other.thanks for the help!

ryanw · August 16th, 2011, 11:10 PM

put on a good set of cylinder heads and intake, that should help some, but ya, the cam may be the problem but if you dont know any thing about it then its just a guessing game

1SICK5.0VERT · August 27th, 2011, 03:18 AM

Check your plug wires and boots. Make sure all the wires are plugged onto the plugs and cap properly. I had a similar issue and it ended up being an arcing problem. Let the car run in the dark and have someone give it gas while you watch for an arc. Hope this helps

91cobra5.0 · August 28th, 2011, 07:13 AM

could be a fuel pump issue

Stdyhand · August 28th, 2011, 08:42 AM

My engine is mostly stock right now and it doesn't make much power over 4k so I don't rev it that high very often. A Ford Tech said the stock 5.0's made their most power at around 2500-3k rpm which feels about right in my car.

If you want top end, you'll have to build it that way. I prefer most of my power down low since most of my time is in the city.

gripthenboost · August 28th, 2011, 04:20 PM

check your ignition system and your coil. Might not be getting enough spark to make her go. Does it run rich or lean when you start dying out.

August 16th, 2011, 08:57 PM	#1
Atomyk Newbie 1987 Mustang GT Nope Join Date: Aug 2011 Location: Moore, OK Posts: 9 iTrader: 0 reviews	Only fun til 4k rpms? So, I just picked up a 5 spd 87 GT. Its got BBK chrome shorties, an aftermarket cam that neither myself or the previous owner know the specs of, a chopped up h-pipe, and dumped factory mufflers. I just did a full tune up (dist. cap, rotor, plugs, wires, fuel filter, base idle reset, checked TPS voltage, cleaned MAF, TB, and IAC) to help the idle, but it falls flat on its ass at WOT above 4k rpms. It seems to stop revving as quickly and just kinda sits there... so... anybody know why? It has been converted to mass air by the way.

August 16th, 2011, 09:31 PM	#2
StangBanger302 Hardcore Enthusiast 1992 Mustang LX 13.0 @ 105 Join Date: Jun 2010 Location: New York Posts: 2,230 iTrader: 0 reviews	Why? Maybe the cam he put in is a shitty one and makes low end grunt but no steam up top. Stock 5.0s only make power till about 4K, shift around 4,800-5,000 depending on the car. __________________ As I lay rubber down the street I pray for traction I can keep But if I spin, and begin to slide Please dear God, protect my ride

August 16th, 2011, 11:10 PM	#4
ryanw I Post Entirely Way Too Much 1991 Ford Mustang GT Join Date: May 2007 Location: San Diego, California Posts: 6,063 iTrader: 0 reviews	put on a good set of cylinder heads and intake, that should help some, but ya, the cam may be the problem but if you dont know any thing about it then its just a guessing game __________________ DART 331ci stroker, AFR 185 heads, Trick Flow R intake, Accufab 70mm tb, 75mm pro m Maf, 30lb injectors, jba headers, 2 1/2" x pipe flowmaster super 10 mufflers, 255 fuel pump, 3:27 gears

August 27th, 2011, 03:18 AM	#5
1SICK5.0VERT Regular modded 95 gt vert Join Date: May 2011 Location: cleveland ohio Posts: 176 iTrader: 0 reviews	Check your plug wires and boots. Make sure all the wires are plugged onto the plugs and cap properly. I had a similar issue and it ended up being an arcing problem. Let the car run in the dark and have someone give it gas while you watch for an arc. Hope this helps __________________ BLACK ON BLACK 95 GT VERT FULLY CONVERTED TO A 95 COBRA AND MODIFIED WITH ALOT OF GOODIES AND A BB SINGLE T67 TURBO KIT. 526.14RWHP 496.00RWTQ @6PSI. RAN OUT OF FUEL @5500RPM PROJECT CAR AKA MONEY-PIT LOL!... TUNED BY GEORGE @ AKRON HP.

August 28th, 2011, 04:20 PM	#8
gripthenboost Hardcore Enthusiast 91 Mustang GT 1991 sliver GT Join Date: Apr 2010 Location: New York Posts: 1,213 iTrader: 0 reviews	check your ignition system and your coil. Might not be getting enough spark to make her go. Does it run rich or lean when you start dying out. __________________

August 16th, 2011, 10:46 PM	#3
Atomyk Newbie 1987 Mustang GT Nope Join Date: Aug 2011 Location: Moore, OK Posts: 9 iTrader: 0 reviews	Oh... That makes sense. Well dern. I figured with the way it lopes it would have more top end. Figures... So far, this car has been one big let down after the other.thanks for the help!

August 28th, 2011, 07:13 AM	#6
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	could be a fuel pump issue

August 28th, 2011, 08:42 AM	#7
Stdyhand Regular 1991 Ford Mustang GT Join Date: Apr 2011 Location: Missouri Posts: 213 iTrader: 0 reviews	My engine is mostly stock right now and it doesn't make much power over 4k so I don't rev it that high very often. A Ford Tech said the stock 5.0's made their most power at around 2500-3k rpm which feels about right in my car. If you want top end, you'll have to build it that way. I prefer most of my power down low since most of my time is in the city.

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