Stumbling over 4000

Fox Body · 09-10-2003, 11:36 AM

Let's say I'm racing someone and through just about every gear (but not always), when it gets above 4000rpm, the engine starts stumbling. You can see the tach needle jumping, as if something's missing. I've changed and/or checked vacuum hoses, fuel filter, spark plugs, plug wires, and TPS (and cleaned out TB with STP fuel injection TB cleaner) and all of those are fine. Any other ideas as to why the car does this? Every once in a while, it surprises me and pulls through the gears fine without any stumbling, but most of the time you can count on it.

silver_pilate · 09-10-2003, 12:57 PM

Check the ignition coil. It may be crapping out on you at higher rpms resulting in a miss.

--nathan

Fox Body · 09-10-2003, 10:02 PM

Cool, thanks. I'll see if I can switch out one with a friend and see what happens.

Any other ideas???

Coupe Devil · 09-10-2003, 10:09 PM

Thats not fair he stole my answer... Seriously I'd start there.

ols0051 · 09-12-2003, 09:55 AM

I have a similar problem at 2100 rpm. It sometimes starts to stumble or hesitate, but the problem quits at 2200 rpm. Did all the same things you did with no change. I then bought a msd coil, but that didn't help either. I'm starting to think it could be an injector problem. Does your stumbling problem continue through 4k or does it go away after a certain rpm?

Fox Body · 09-13-2003, 11:44 PM

It continues through 4k. Sunday, gonna get a coil and see if that helps...

tireburner163 · 09-14-2003, 12:15 PM

Check your coil and TFI module.

ols0051 · 09-15-2003, 01:18 PM

I was thinking of changing the tfi module before going after the injectors. Mine was never in for the recall about 6yrs ago.

MATTKNIGHT · 09-15-2003, 06:06 PM

I had a similar problem with my car. Loss of power above 4000 rpm's turned into stubling and bucking and just plain heartache when driving the car. The longer i put up with it the worse it got. I replaced almost all of the sensors for the FI and it turned out to be the mass air meter. The minute I put the new one in my car came back to life, never been happier. I hope this helps you. wish someone could have given me the same advice for my car! Let us know how it goes.

Fox Body · 09-15-2003, 10:58 PM

Quote:

Originally posted by MATTKNIGHT
I had a similar problem with my car. Loss of power above 4000 rpm's turned into stubling and bucking and just plain heartache when driving the car. The longer i put up with it the worse it got. I replaced almost all of the sensors for the FI and it turned out to be the mass air meter. The minute I put the new one in my car came back to life, never been happier. I hope this helps you. wish someone could have given me the same advice for my car! Let us know how it goes.

Thanks for chiming in. I forgot to mention, though, a friend of mine let me use his MAF and the car did the same thing. Now, it is possible (highly unlikely, though) that his was bad too, but he said it worked fine in the car it use to be in.
Mmmm. I never have weird, hard-to-trace problems like this in my '79...

Fox Body · 09-16-2003, 11:10 AM

Man...

seems like I was too quick to start complaining .... Seems like it was the coil. Simple. I just put a new one in and the car is doing fine over 4000, smooth all the way to 5000+. Gonna drive it around today and make sure. Thanks.

silver_pilate · 09-16-2003, 11:46 AM

WOOOO WHOOOO!! SCORE!

Glad you got it tracked down. Hopefully that will take care of it.

--nathan

09-10-2003, 11:36 AM	#1
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	Stumbling over 4000 Let's say I'm racing someone and through just about every gear (but not always), when it gets above 4000rpm, the engine starts stumbling. You can see the tach needle jumping, as if something's missing. I've changed and/or checked vacuum hoses, fuel filter, spark plugs, plug wires, and TPS (and cleaned out TB with STP fuel injection TB cleaner) and all of those are fine. Any other ideas as to why the car does this? Every once in a while, it surprises me and pulls through the gears fine without any stumbling, but most of the time you can count on it. __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

09-10-2003, 12:57 PM	#2
silver_pilate DURKA DURKA!! Join Date: Sep 1997 Location: Lubbock, TX...(TX panhandle) Posts: 1,418	Check the ignition coil. It may be crapping out on you at higher rpms resulting in a miss. --nathan __________________ '91 GT, Coast 347, 9.5:1 compression, full intake, Wolverine 1087 cam, exhaust, Keith Craft ported Windsor Jr. Irons (235 cfm intake, 195 cfm exhaust), AOD, PI 3500 converter, Lentech valve body, 3.73's (4.10's in the works), and Yokohama ES100's out back. Daily Car: '04 Infiniti G35 Sedan 6MT

09-10-2003, 10:02 PM	#3
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	Cool, thanks. I'll see if I can switch out one with a friend and see what happens. Any other ideas??? __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

09-10-2003, 10:09 PM	#4
Coupe Devil Moderator Join Date: Mar 2001 Location: Myrtle Beach SC Posts: 1,643	Thats not fair he stole my answer... Seriously I'd start there. __________________ 1990 GT, 347, TFS TW Heads, TFS Cam, TFS Track heat, Twin turbos, FMIC, T5. Built Ford Tough Moderator

09-13-2003, 11:44 PM	#6
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	It continues through 4k. Sunday, gonna get a coil and see if that helps... __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

09-12-2003, 09:55 AM	#5
ols0051 Registered Member Join Date: Sep 2002 Location: cent.wis Posts: 203	I have a similar problem at 2100 rpm. It sometimes starts to stumble or hesitate, but the problem quits at 2200 rpm. Did all the same things you did with no change. I then bought a msd coil, but that didn't help either. I'm starting to think it could be an injector problem. Does your stumbling problem continue through 4k or does it go away after a certain rpm?

09-14-2003, 12:15 PM	#7
tireburner163 It's a lot like a race car Join Date: Aug 2000 Location: Meridian, MS Posts: 4,130	Check your coil and TFI module. __________________ 1987 Buick T-type 1998 HD Electra Elide

09-15-2003, 01:18 PM	#8
ols0051 Registered Member Join Date: Sep 2002 Location: cent.wis Posts: 203	I was thinking of changing the tfi module before going after the injectors. Mine was never in for the recall about 6yrs ago.

09-15-2003, 06:06 PM	#9
MATTKNIGHT Registered Member Join Date: Jun 2003 Location: MOUNTAINHOME, IDAHO Posts: 20	had a very similar issue w/my car I had a similar problem with my car. Loss of power above 4000 rpm's turned into stubling and bucking and just plain heartache when driving the car. The longer i put up with it the worse it got. I replaced almost all of the sensors for the FI and it turned out to be the mass air meter. The minute I put the new one in my car came back to life, never been happier. I hope this helps you. wish someone could have given me the same advice for my car! Let us know how it goes. __________________ MATT KNIGHT 1995 5.0, msd 6al, msd coil, bbk longtubes, bbk offroad, 2 chamber flows, power tower shift, 98 gt wheels

09-16-2003, 11:10 AM	#11
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	Man... seems like I was too quick to start complaining .... Seems like it was the coil. Simple. I just put a new one in and the car is doing fine over 4000, smooth all the way to 5000+. Gonna drive it around today and make sure. Thanks. __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

09-16-2003, 11:46 AM	#12
silver_pilate DURKA DURKA!! Join Date: Sep 1997 Location: Lubbock, TX...(TX panhandle) Posts: 1,418	WOOOO WHOOOO!! SCORE! Glad you got it tracked down. Hopefully that will take care of it. --nathan __________________ '91 GT, Coast 347, 9.5:1 compression, full intake, Wolverine 1087 cam, exhaust, Keith Craft ported Windsor Jr. Irons (235 cfm intake, 195 cfm exhaust), AOD, PI 3500 converter, Lentech valve body, 3.73's (4.10's in the works), and Yokohama ES100's out back. Daily Car: '04 Infiniti G35 Sedan 6MT

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Vibration in new engine after 4000 RPM???	Ackbar00	Windsor Power	2	07-01-2004 08:58 AM
Clutch slipping in 2nd, above 4000 rpm?	Fox Body	Windsor Power	7	05-22-2003 06:27 PM
question about battery size and stumbling	HopingForAGT	Windsor Power	3	01-28-2002 11:01 PM