Missfire over Half Throttle?

cschulzy · 11-21-2002, 05:04 AM

Hi guys, I need some help, My 89 GT 5 speed has developed a missfire over half throttle. If I accelerate slowly it seems to be ok. Its not rpm related either, same deal if I accelerate slow she will rev smooth all the way. I checked cap, rotor,wires, put in new plugs, but no change. I ran the tps through full range with a meter on but no indication of short or open cct, no codes from the computer either. She dosn't have O2 sensors or cats cos the car is in Saudi Arabia. Thanks

Chris Schulz

88workcar · 11-21-2002, 06:37 AM

Here lately a few of us have had this problem. For at least three of us it has worked out to be a faulty distributor. I am not sure which part of it though, I just changed the whole thing.

PKRWUD · 11-21-2002, 07:22 AM

Make sure the plug wires going to #5 & #6 are completely separated from each other, from the cap to the plugs.

Take care,
~Chris

cschulzy · 11-21-2002, 12:24 PM

Thanks guys, I'll try that. It will take a while to get another dizzy as I am out in the middle of nowhere here. I'll let you know what happens. Cheers
Chris

cschulzy · 11-21-2002, 12:32 PM

Thanks guys, I'll try that. It will take a while to get another dizzy as I am out in the middle of nowhere here. I'll let you know what happens. Cheers
Chris

Capri306 · 11-21-2002, 01:41 PM

I'd be willing to bet on a fuel pump and/or regulator.

Is it really a "misfire" or just leaning out? That's what I'd want to know. Read the plugs to get an idea. Still betting on the fuel pump/regulator, though. Hope not for your sake, FWIW!

sn95gt19 · 11-21-2002, 01:58 PM

i have heard this same problem about 20 times. i have had the problem on 3 of my stangs and 2 of my buddies have. most likely the culprit is a bad mass air meter (sensor). this has been the fix for all that i have heard having this problem. if you know someone with a stang, just switch their sensor out and see if thats it.

ols0051 · 11-21-2002, 08:56 PM

I have had a on going 2000 rpm missing problem.Never above or below that rpm on my 89.replaced plugs wire's cap rotor and it did it before all this and it is still doing it, if not getting worse.Changed the fuel filter also.Could it be the tfi module?

sn95gt19 · 11-21-2002, 09:12 PM

COIL OR MASS AIR SENSOR

joe4speed · 11-22-2002, 01:31 AM

Quote:

Originally posted by sn95gt19
COIL OR MASS AIR SENSOR

LOL yup./... check the damn coil... you might remember the post "odd" I had running for months about that.

http://forums.mustangworks.com/showt...threadid=24058

11-21-2002, 05:04 AM	#1
cschulzy Registered Member Join Date: Jun 2001 Location: Saudi Arabia Posts: 27	Missfire over Half Throttle? Hi guys, I need some help, My 89 GT 5 speed has developed a missfire over half throttle. If I accelerate slowly it seems to be ok. Its not rpm related either, same deal if I accelerate slow she will rev smooth all the way. I checked cap, rotor,wires, put in new plugs, but no change. I ran the tps through full range with a meter on but no indication of short or open cct, no codes from the computer either. She dosn't have O2 sensors or cats cos the car is in Saudi Arabia. Thanks Chris Schulz

11-21-2002, 06:37 AM	#2
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	Here lately a few of us have had this problem. For at least three of us it has worked out to be a faulty distributor. I am not sure which part of it though, I just changed the whole thing. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

11-21-2002, 07:22 AM	#3
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Make sure the plug wires going to #5 & #6 are completely separated from each other, from the cap to the plugs. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

11-21-2002, 01:58 PM	#7
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	i have heard this same problem about 20 times. i have had the problem on 3 of my stangs and 2 of my buddies have. most likely the culprit is a bad mass air meter (sensor). this has been the fix for all that i have heard having this problem. if you know someone with a stang, just switch their sensor out and see if thats it. __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

11-21-2002, 09:12 PM	#9
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	COIL OR MASS AIR SENSOR __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

11-21-2002, 12:24 PM	#4
cschulzy Registered Member Join Date: Jun 2001 Location: Saudi Arabia Posts: 27	Thanks guys, I'll try that. It will take a while to get another dizzy as I am out in the middle of nowhere here. I'll let you know what happens. Cheers Chris

11-21-2002, 12:32 PM	#5
cschulzy Registered Member Join Date: Jun 2001 Location: Saudi Arabia Posts: 27	Thanks guys, I'll try that. It will take a while to get another dizzy as I am out in the middle of nowhere here. I'll let you know what happens. Cheers Chris

11-21-2002, 01:41 PM	#6
Capri306 Moderator Join Date: Sep 1998 Location: Grand Rapids, Michigan, USA Posts: 1,001	I'd be willing to bet on a fuel pump and/or regulator. Is it really a "misfire" or just leaning out? That's what I'd want to know. Read the plugs to get an idea. Still betting on the fuel pump/regulator, though. Hope not for your sake, FWIW! __________________ Capri306, Moderator The Mustang Works Online 1979 Mercury Capri 1987 5.0L Mustang LX Notchback 1993 5.8L Eddie Bauer Bronco

11-21-2002, 08:56 PM	#8
ols0051 Registered Member Join Date: Sep 2002 Location: cent.wis Posts: 203	I have had a on going 2000 rpm missing problem.Never above or below that rpm on my 89.replaced plugs wire's cap rotor and it did it before all this and it is still doing it, if not getting worse.Changed the fuel filter also.Could it be the tfi module?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Need Throttle Body & Idle Conrol Valve Info	BigBobsL	Windsor Power	2	02-10-2004 01:16 AM
throttle cable removal on an 88 lx 5.0	c3racer2000	Windsor Power	5	02-10-2003 12:45 PM
Missfire over Half Throttle....Fixed	cschulzy	Windsor Power	2	12-16-2002 09:50 AM
under half to full throttle..	wade73	Modular Madness	0	05-26-2002 11:03 PM
Throttle Cable hook up	Ponch65	Classic Mustangs	2	05-06-2000 02:48 PM