strange rpm drops?

rusty2407 · September 3rd, 2008, 01:17 PM

when im accelerating my rpms will without notice drop, and cause the entire vehicle to shudder. I have replaced the tps, and the cap and rotor, and checked the plugs. I also checked the ohms on ignition coil and it read between 7-8 which is what my friends reads and his works fine so I dont think this is the problem. If anyone knows what it could be please help.

rusty2407 · September 6th, 2008, 06:52 PM

nobody?

Breakout · September 6th, 2008, 06:54 PM

MAF? You make that angry and it'll do that to you.

Hunt_chevs · September 6th, 2008, 09:09 PM

yea, clean the maf with throttle body cleaner, check game after that

rusty2407 · September 7th, 2008, 02:11 AM

thanks ill do that tm and let you know

rusty2407 · September 12th, 2008, 04:42 AM

not the maf

rusty2407 · September 12th, 2008, 04:44 AM

i should add its not neccessarily on acceleration. if im sitting at a light, i can hold the rpms at any give rpm and it will randomly "misfire" for lack of a better word to describe it.

1989Gt. · September 12th, 2008, 05:10 AM

my car dodes the same thing when i get into the higher rpms and i dont know why....

rusty2407 · September 12th, 2008, 12:23 PM

ya but mine is throughout the entire rpm range, i cant even drive it its so bad

Bigfatts · September 12th, 2008, 01:15 PM

Sounds like a spark problem. Check to make sure none of your plug wires are grounding. How old are they? Check your distributor cap for cracks or other problems. If it looks iffy, replace the cap and rotor. When my car did this it turned out to be the distributor going bad. The magnetic pickup inside it had come loose and was rattling around. It started occasionally and progressively got worse. Couldn't tell it to look at it while it was in the car but as soon as we got it out the pickup fell out.

1989Gt. · September 12th, 2008, 04:04 PM

for some reason i think its my trans... cause it doesnt seem to be shifting .... like its suppose to or its just misfireing i cant tell....

my plugs and wires are brand new.... i know its not them

Hunt_chevs · September 12th, 2008, 04:16 PM

bad icm?

Bigfatts · September 13th, 2008, 12:05 AM

for some reason i think its my trans... cause it doesnt seem to be shifting .... like its suppose to or its just misfireing i cant tell....

The trans wouldn't make the rpms drop while driving. If anything, if the transmission was slipping it would make the rpms spike. You say it isn't shifting right, what's it doing? Do the rpms just keep raising past where it would normally shift or what?

1989Gt. · September 13th, 2008, 06:01 AM

oh yeah that does make sense dude no its dropping.... whats
icm?

1slo5.0 · September 13th, 2008, 09:03 AM

Originally Posted by rusty2407

not the maf

Did you test it? A real simple test is to start the car and let it idle. Then tap the MAF with the palm of your hand or even the butt of a small hammer. Use a little bit of force but not too much. If the wire is broken inside tapping on it will jar wire and cause the engine to stumble. If the engine does stumble then the MAF is bad.

The symptoms you are having are symptoms of a bad MAF.

1slo5.0 · September 13th, 2008, 09:07 AM

Originally Posted by rusty2407

i should add its not neccessarily on acceleration. if im sitting at a light, i can hold the rpms at any give rpm and it will randomly "misfire" for lack of a better word to describe it.

Well that is different from what you originally described. So it is not just a stumble on acceleration but it is a misfire at any rpm whether accelerating or not?

R0B0T · September 13th, 2008, 10:17 AM

strange, i was at the track last night and my car did this in third gear.
foot to the floor, rpms dropped like the car shut off, i let off the gas and got back in it, worked fine.

Breakout · September 13th, 2008, 10:53 AM

none of your cars are throwing codes?

R0B0T · September 13th, 2008, 03:36 PM

my CEL bulb is out.
and nobody has an OBD 1 code reader around me.

rusty2407 · September 14th, 2008, 05:28 PM

ya itll misfire at any rpm once the engine heats up. when its cold it doesnt seem to have a problem, and i already replaced the cap and rotor, and the plug wires look decent along with new plugs themselves. could be the distributor tho.

September 3rd, 2008, 01:17 PM	#1
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	strange rpm drops? when im accelerating my rpms will without notice drop, and cause the entire vehicle to shudder. I have replaced the tps, and the cap and rotor, and checked the plugs. I also checked the ohms on ignition coil and it read between 7-8 which is what my friends reads and his works fine so I dont think this is the problem. If anyone knows what it could be please help. __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

September 6th, 2008, 06:52 PM	#2
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	nobody? __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

September 6th, 2008, 09:09 PM	#4
Hunt_chevs Hardcore Enthusiast 2002 Gt Not Slow Join Date: Aug 2007 Location: SJ-CA, 50-ft elev. Posts: 1,649 iTrader: 1 reviews	yea, clean the maf with throttle body cleaner, check game after that __________________ 2k2 Gt Eibach pro kit, bbk cold air, exhaust, 4.10s, 6k hid's

September 7th, 2008, 02:11 AM	#5
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	thanks ill do that tm and let you know __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

September 12th, 2008, 04:42 AM	#6
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	not the maf __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

September 6th, 2008, 06:54 PM	#3
Breakout Tree Fiddy Z 2006 Nissan 350Z Join Date: Dec 2006 Location: Central Florida Posts: 2,018 iTrader: 0 reviews	MAF? You make that angry and it'll do that to you.

September 12th, 2008, 04:44 AM	#7
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	i should add its not neccessarily on acceleration. if im sitting at a light, i can hold the rpms at any give rpm and it will randomly "misfire" for lack of a better word to describe it. __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

September 12th, 2008, 05:10 AM	#8
1989Gt. Hardcore Enthusiast 1989 Mustang GT Join Date: Apr 2008 Posts: 2,799 iTrader: 0 reviews	my car dodes the same thing when i get into the higher rpms and i dont know why....

September 12th, 2008, 12:23 PM	#9
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	ya but mine is throughout the entire rpm range, i cant even drive it its so bad __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

September 12th, 2008, 01:15 PM	#10
Bigfatts Regular Badass Mother 3000 Twice as fast as your ass! Join Date: Apr 2008 Location: Lutz, Florida Posts: 234 iTrader: 1 reviews	Sounds like a spark problem. Check to make sure none of your plug wires are grounding. How old are they? Check your distributor cap for cracks or other problems. If it looks iffy, replace the cap and rotor. When my car did this it turned out to be the distributor going bad. The magnetic pickup inside it had come loose and was rattling around. It started occasionally and progressively got worse. Couldn't tell it to look at it while it was in the car but as soon as we got it out the pickup fell out.

September 12th, 2008, 04:04 PM	#11
1989Gt. Hardcore Enthusiast 1989 Mustang GT Join Date: Apr 2008 Posts: 2,799 iTrader: 0 reviews	for some reason i think its my trans... cause it doesnt seem to be shifting .... like its suppose to or its just misfireing i cant tell.... my plugs and wires are brand new.... i know its not them

September 12th, 2008, 04:16 PM	#12
Hunt_chevs Hardcore Enthusiast 2002 Gt Not Slow Join Date: Aug 2007 Location: SJ-CA, 50-ft elev. Posts: 1,649 iTrader: 1 reviews	bad icm? __________________ 2k2 Gt Eibach pro kit, bbk cold air, exhaust, 4.10s, 6k hid's

September 13th, 2008, 06:01 AM	#14
1989Gt. Hardcore Enthusiast 1989 Mustang GT Join Date: Apr 2008 Posts: 2,799 iTrader: 0 reviews	oh yeah that does make sense dude no its dropping.... whats icm?

September 13th, 2008, 10:17 AM	#17
R0B0T Banned 12.8@103... stock motor 11.8@113...150 shot Join Date: Apr 2008 Posts: 464 iTrader: 0 reviews	strange, i was at the track last night and my car did this in third gear. foot to the floor, rpms dropped like the car shut off, i let off the gas and got back in it, worked fine.

September 13th, 2008, 10:53 AM	#18
Breakout Tree Fiddy Z 2006 Nissan 350Z Join Date: Dec 2006 Location: Central Florida Posts: 2,018 iTrader: 0 reviews	none of your cars are throwing codes?

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September 13th, 2008, 03:36 PM	#19
R0B0T Banned 12.8@103... stock motor 11.8@113...150 shot Join Date: Apr 2008 Posts: 464 iTrader: 0 reviews	my CEL bulb is out. and nobody has an OBD 1 code reader around me.

September 14th, 2008, 05:28 PM	#20
rusty2407 Regular 1991 Ford Mustang LX Join Date: Apr 2008 Location: Norfolk Posts: 102 iTrader: 0 reviews	ya itll misfire at any rpm once the engine heats up. when its cold it doesnt seem to have a problem, and i already replaced the cap and rotor, and the plug wires look decent along with new plugs themselves. could be the distributor tho. __________________ BBK CAI and Shorty Headers, Cobra Upper/Lower Intake, Walbro 110, 24# Injectors, larger throttle body, maf, Drilled and slotted front rotors, King Cobra clutch, Cobra wheels w/ sumitomo tires, flowmasters

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