miss firing

hopper · May 26th, 2007, 09:04 PM

i have been having major prob with this dam car... someone please help... 86 5.0 fuel injected, speed density,, the cars starts great and rund great for about 500 yrds. Then under load at lower rpm i get miss and popping or backfiring through the exhaust,,,, if i cruise it runs great at idel it runs great just under load it acts shitty..
any suggestions

neverfastenough1 · May 26th, 2007, 10:58 PM

Sounds like fuel starvation. Clogged injectors, clogged fuel filter, pinched line, etc.

usmcsawgunner · May 26th, 2007, 11:27 PM

check the maf and the tps and the throttle body and all the stupid stuff like that

hopper · May 26th, 2007, 11:54 PM

i'm thinking starvation aswell,, what is the MAF

neverfastenough1 · May 27th, 2007, 12:01 AM

You don't have it. You have the speed density. But it is a common upgrade from speed density to maf.

hopper · May 27th, 2007, 12:11 AM

thaught so.... people trying to pull a fast one on me.
So i guess the main prob to create popping is a fuel shortage

SALIV8 · May 27th, 2007, 12:35 AM

whats ur timing at?

neverfastenough1 · May 27th, 2007, 02:22 AM

Originally Posted by hopper

thaught so.... people trying to pull a fast one on me.
So i guess the main prob to create popping is a fuel shortage

LoL, I don't think he was trying to pull a fast one, just didn't realize you said you had speed density or saw it was a 86. It could be fuel, timing, or even poor spark. Number of things, I just like to start with the easy stuff to check.

hopper · May 27th, 2007, 02:26 AM

timing and spark is all good.. Like i said at idel it is top notch,, only under load does it act funny,,, now, could this be a possible Oxygen sensor prob??

neverfastenough1 · May 27th, 2007, 03:24 AM

Yes, but more than likely it would be a stored failure in your computer and you would get a light. Your o2 sensor does determines how rich or lean your car runs. Also check your air filter to make sure you are getting enough air, but I think popping is too much air and not enough fuel. Sorta like an acetelyne (sp?) torch. Too much oxygen and it will pop and shut off. Still check it out to see if it is clogged. I just told someone else that a clogged cat will cause hesitation, but I am not sure if it will cause popping. You can check that at night by looking to see if it is red after driving.

tording92lxnotch · May 27th, 2007, 10:19 AM

Originally Posted by SALIV8

whats ur timing at?

I know you said your timing is good but what is it actually set at?

Sounds like it could be a timing issue.

chadjones99 · May 27th, 2007, 06:53 PM

my 86 was doing that, but it is a mAF converted car. it turned out to be bad o2 sensors and i had a broke o2 wire, the car thought it was running rich so the computer was leaning it out way to much.

hopper · May 28th, 2007, 09:23 AM

timing is set to 13 degrees.. and o2 sensors are brand new.. I will however check the air intake for clogs. i'm getting really close to scrapping the whole EFI and switching over to carb and intake...lol

chadjones99 · May 28th, 2007, 07:27 PM

have you checked your cap and rotor ?
and plugs, i have had problems with the ford racing wires before.

B.A.M302 · May 29th, 2007, 09:56 AM

Check and make sure a vacuum line is connected to your fuel pressure regulator. Mine did the same damn thing. Its definitely a fuel problem.

hopper · May 29th, 2007, 10:19 AM

o.k I went through all the wiring, cap rotor,, and everything else...shit..... Then i ran a comp test and came out with codes 67,81,& 82.... code 82 delt with the MAP sensor so i tries to change it and took it for a run and same old crap,, and same readings keep coming up on the diagnostics check.

neverfastenough1 · May 29th, 2007, 12:47 PM

Did you address the fuel pump and ect trouble codes as well. If you have a voltmeter this link will show you how to check the ect. If it is not working properly it will affect the air fuel mixture. You would need to check it because other things can affect the ect to have it trip a code. ECT engine coolant temperature sensor.

http://fordfuelinjection.com/?p=28

hopper · May 29th, 2007, 01:16 PM

oh shit... i have an aftermarket temp senser, with the origonal wiring harness unplugged... I mentioned this to other people before and they said that the coolent sensor has nothing to do with the computer and the way it acts upon the rich and lean functions..
quick question:: the sensor we are talking about, is it the one on top of the manifold right behind the coolent return hose?? If it is that is the one that has been replaced by the aftermarket sensor

hopper · May 29th, 2007, 01:20 PM

by the way,, i am pretty sure the car is running way too rich.. I have nice stainless pipes that i wiped down before takeing the car out for a little rip (about 1-2 miles) when i returned the inside of the pipes were pretty built up with a skin of carbon.

hopper · May 29th, 2007, 03:17 PM

o.k i am retarded, i mixed up the temp sending unit and the ECT.. but does the origonal temp sendingunit have to be plugged in or can an aftermarket one be used in its place

May 26th, 2007, 09:04 PM	#1
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	miss firing i have been having major prob with this dam car... someone please help... 86 5.0 fuel injected, speed density,, the cars starts great and rund great for about 500 yrds. Then under load at lower rpm i get miss and popping or backfiring through the exhaust,,,, if i cruise it runs great at idel it runs great just under load it acts shitty.. any suggestions

May 26th, 2007, 10:58 PM	#2
neverfastenough1 Hardcore Enthusiast 2002 Mustang GT Join Date: May 2007 Location: Savannah, Ga Posts: 2,777 iTrader: 3 reviews	Sounds like fuel starvation. Clogged injectors, clogged fuel filter, pinched line, etc. __________________

May 27th, 2007, 12:01 AM	#5
neverfastenough1 Hardcore Enthusiast 2002 Mustang GT Join Date: May 2007 Location: Savannah, Ga Posts: 2,777 iTrader: 3 reviews	You don't have it. You have the speed density. But it is a common upgrade from speed density to maf. __________________

May 27th, 2007, 03:24 AM	#10
neverfastenough1 Hardcore Enthusiast 2002 Mustang GT Join Date: May 2007 Location: Savannah, Ga Posts: 2,777 iTrader: 3 reviews	Yes, but more than likely it would be a stored failure in your computer and you would get a light. Your o2 sensor does determines how rich or lean your car runs. Also check your air filter to make sure you are getting enough air, but I think popping is too much air and not enough fuel. Sorta like an acetelyne (sp?) torch. Too much oxygen and it will pop and shut off. Still check it out to see if it is clogged. I just told someone else that a clogged cat will cause hesitation, but I am not sure if it will cause popping. You can check that at night by looking to see if it is red after driving. __________________

May 27th, 2007, 06:53 PM	#12
chadjones99 Regular Join Date: Aug 2006 Location: Tonopah,az Posts: 86 iTrader: 0 reviews	my 86 did the same my 86 was doing that, but it is a mAF converted car. it turned out to be bad o2 sensors and i had a broke o2 wire, the car thought it was running rich so the computer was leaning it out way to much. __________________ 1986 stang ,Edelbrook intake, aluminum heads, E303 cam ,70 MM throttle body ,24lb injectors ,373 gears , 10:1 pistons set up,no cats , flowmaster mufflers , short shifter , 255 fuel pump , smog pump delete , A/C delete , Aluminum Radiator , MAF convertion

May 26th, 2007, 11:27 PM	#3
usmcsawgunner Regular 1993 Mustang GT 13.2 @98.54 Join Date: Apr 2007 Location: Kaneohe Bay, Hawaii Posts: 433 iTrader: 0 reviews	check the maf and the tps and the throttle body and all the stupid stuff like that

May 26th, 2007, 11:54 PM	#4
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	i'm thinking starvation aswell,, what is the MAF

May 27th, 2007, 12:11 AM	#6
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	thaught so.... people trying to pull a fast one on me. So i guess the main prob to create popping is a fuel shortage

May 27th, 2007, 12:35 AM	#7
SALIV8 Enthusiast Join Date: Dec 2006 Location: the MURDER CAPITOL Posts: 520 iTrader: 0 reviews	whats ur timing at?

May 27th, 2007, 02:26 AM	#9
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	timing and spark is all good.. Like i said at idel it is top notch,, only under load does it act funny,,, now, could this be a possible Oxygen sensor prob??

May 28th, 2007, 09:23 AM	#13
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	timing is set to 13 degrees.. and o2 sensors are brand new.. I will however check the air intake for clogs. i'm getting really close to scrapping the whole EFI and switching over to carb and intake...lol

May 28th, 2007, 07:27 PM	#14
chadjones99 Regular Join Date: Aug 2006 Location: Tonopah,az Posts: 86 iTrader: 0 reviews	have you checked your cap and rotor ? and plugs, i have had problems with the ford racing wires before. __________________ 1986 stang ,Edelbrook intake, aluminum heads, E303 cam ,70 MM throttle body ,24lb injectors ,373 gears , 10:1 pistons set up,no cats , flowmaster mufflers , short shifter , 255 fuel pump , smog pump delete , A/C delete , Aluminum Radiator , MAF convertion

May 29th, 2007, 09:56 AM	#15
B.A.M302 Regular Join Date: Jan 2007 Location: maryland Posts: 89 iTrader: 0 reviews	Check and make sure a vacuum line is connected to your fuel pressure regulator. Mine did the same damn thing. Its definitely a fuel problem. __________________ Crate 302, Trick Flow Intake R, 75mm MAF, bbk 75mm throttle body, bbk 76mm EGR spacer, 351 Winsor heads ported and polished by Bennet Racing, Lunati cam, 30 pd. Injectors, TKO 500, aluminum drive shaft, bbk mid length headers, bbk off road H pipe, 3:55,

May 29th, 2007, 10:19 AM	#16
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	o.k I went through all the wiring, cap rotor,, and everything else...shit..... Then i ran a comp test and came out with codes 67,81,& 82.... code 82 delt with the MAP sensor so i tries to change it and took it for a run and same old crap,, and same readings keep coming up on the diagnostics check.

May 29th, 2007, 12:47 PM	#17
neverfastenough1 Hardcore Enthusiast 2002 Mustang GT Join Date: May 2007 Location: Savannah, Ga Posts: 2,777 iTrader: 3 reviews	Did you address the fuel pump and ect trouble codes as well. If you have a voltmeter this link will show you how to check the ect. If it is not working properly it will affect the air fuel mixture. You would need to check it because other things can affect the ect to have it trip a code. ECT engine coolant temperature sensor. http://fordfuelinjection.com/?p=28 __________________

May 29th, 2007, 01:16 PM	#18
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	oh shit... i have an aftermarket temp senser, with the origonal wiring harness unplugged... I mentioned this to other people before and they said that the coolent sensor has nothing to do with the computer and the way it acts upon the rich and lean functions.. quick question:: the sensor we are talking about, is it the one on top of the manifold right behind the coolent return hose?? If it is that is the one that has been replaced by the aftermarket sensor

May 29th, 2007, 01:20 PM	#19
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	by the way,, i am pretty sure the car is running way too rich.. I have nice stainless pipes that i wiped down before takeing the car out for a little rip (about 1-2 miles) when i returned the inside of the pipes were pretty built up with a skin of carbon.

May 29th, 2007, 03:17 PM	#20
hopper Regular Join Date: Apr 2007 Posts: 390 iTrader: 0 reviews	o.k i am retarded, i mixed up the temp sending unit and the ECT.. but does the origonal temp sendingunit have to be plugged in or can an aftermarket one be used in its place

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miss firing

miss firing

my 86 did the same