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Author
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Topic: Running condition
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MR GO FAST
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Member # 2088
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posted
 
 
Vehicle:1986 Gt with stock FI-Still a speed car
Condition: One out of every 5 times the car lags (when Im grabing gears)a little then kicks in like if the timing was being held back and then released. I just installed a fuel regulator and I have been playing with pres but nothing seems to change it.
Comments: I noticed while changing the fuel presure that there is little to no vacuum coming from the port.
Questions: If the map is bad will the computer still not pick up a trouble code? Could the map leak internally to be causing the faulty timing advance? How much vacuum should I read at the fuel regulator port and at the map port?
Thanks
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
Do you have cats on the car?...Sounds a little like bad cats...
The FPR should have manifold vacuum at idle of around 10psi (I believe)
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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mtbaughs
Road Racer
Member # 4052
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posted
Well with a stock cam I would think you would be seeing anywhere from 12-13 on a cold motor and 13-15 on a warm motor with the idle set about 900-950 RPM's as idle speed will affect your vacuum readings. This problem could be a number of things. Does the car have a recent tune up, new plugs,wires,fuel filter,and cap and rotor? Are you maintaining fuel pressure under load? Theres a strong chance that if your regulator isn't seeing enough vacuum that is affecting fuel control. Sometimes I've found vaccum leaks with map gas as if the motor is able to suck the map gas in at a leaking point the motors RPMS will jump
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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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Blind
2.3L
CAFords OG
Member # 3052
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posted
how much vacuum should I read on the tree of a speed density car?
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89 LX Notchback ex 4cyl, 14psi
02 Harley F150, 15psi
Posts: 8521 | From: Fairfield | Registered: Jul 2003
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mtbaughs
Road Racer
Member # 4052
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posted
Damn your going to make me bust out the books here in a sec. Honestly i wouldn't think it would be much different than what i listed above or even the same. Whats different between speed density and mass air cars is that speed density relies on vacuum for engine control where as a mass air car regulates the motor through the meter. hense the reason why speed density cars hate big cams and mass air cars except them. small profile changes throughout the years have affected vacuum to an extent so i would expect not all year 5.0's to have the same #'s
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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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MR GO FAST
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Member # 2088
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posted
quote:
Originally posted by Black94 5.0:
Do you have cats on the car?...Sounds a little like bad cats...
The FPR should have manifold vacuum at idle of around 10psi (I believe)
no cats...here is a list of parts i have replaced in the last 10k miles. OH and I just replaced the old crappy 86 intake for 92 factory unit. I dont get a miss at all it just feels like the motor wants too but the computer doesnt.
cap
rotor
plugs (autolites)
wires (motorcraft)
fuel filter
pcv valve
tps sensor
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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MR GO FAST
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Member # 2088
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posted
quote:
Originally posted by mtbaughs:
Sometimes I've found vaccum leaks with map gas as if the motor is able to suck the map gas in at a leaking point the motors RPMS will jump
Map gas??
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
quote:
Originally posted by MR GO FAST:
quote:
Originally posted by mtbaughs:
Sometimes I've found vaccum leaks with map gas as if the motor is able to suck the map gas in at a leaking point the motors RPMS will jump
Map gas??
Yeah, Map gas???
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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MR GO FAST
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Member # 2088
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posted
One time the motor did race too 3000rpms at start up when i just after sitting for 5 minutes
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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JoeT
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Member # 298
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posted
you guys are insane with your idle vacuum readings!
stock cam,normal 302 HO, 800 rpm idle-- 20"
comp cam 274-HR, stock compression, 12-13" @900
N-41 anderson cam 14-15" @900
stock 94 cobra motor (stock cam etc) 21" @800
or my gauge is off. lol.
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1984 Ford Tempo AOD--- RIP
Posts: 6785 | From: San Jose | Registered: Jun 2001
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MR GO FAST
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Member # 2088
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posted
Did a cylinder balance test and it passed the three times that I did it. Got the following codes 34/44/94. Would an h-pipe cause the following codes to appear? Would the egr be causing the previous mentioned running condition?
34-egr/egr solenoid faulty
44-thermatic air system faulty
94-diverter valve failure
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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mtbaughs
Road Racer
Member # 4052
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posted
Mapp gas. You know the little bottle torches you see at home depot. Open the valve on the bottle and let the gas blow onto areas that might be suspect for a vacuum leak. Old school method. Anyhow I would bet the smog valves are giving you trouble.
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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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MR GO FAST
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Member # 2088
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posted
getting the diverter valve, egr valve and sensor and clearing code ![[patriot]](graemlins/patriot.gif) s. hope for the best...thanks.
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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mtbaughs
Road Racer
Member # 4052
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posted
They are really spendy. I have a used set that I believe works if you want to make a drive out to livermore. The only thing I am uncertain of is if I have the egr valve. I will check on that if you are interested
[ April 29, 2004, 09:38 PM: Message edited by: mtbaughs ]
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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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MR GO FAST
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Member # 2088
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posted
replaced egr and upstream check valve. cleared codes and went for a 20 mile drive. no codes reappeared. Still had a slight stuble. Replaced map sensor and now she runs like before and got my gas mileage back...24mpg to and from Sac. Thanks everyone who PM'd me and helped me. ![[Whoo Whooooo!]](graemlins/woowoo.gif)
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1986 Gt that is faster than FOSTANGS pinto
Posts: 3729 | From: ATWATER/SANJO/RWC | Registered: Nov 2002
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