replaced spark plugs, now car runs like ****

cavdo · 12-15-2002, 06:35 PM

hey guys,

i replaced the spark plug wires on my 98 mustang GT engine (71K miles, 4.6L) with Plantinum bosh 4+. and the car ran like ****. then i took the bosh spark plugs and replaced them with the motorsport spark plugs, and my car still runns like ****. when i say that my car runs like **** i mean that my car jerks a lot. before the spark plug replacement, my car ran perfect.

do you guys have any suggestions? are my ignition wires busted, or are the plugs bad, or what could be going on?

PS: the jerking is really bad between the idle and 2000 rpm range. in higher rpms i notice significant power loss.

Any advice would be helpfull,

thank you,
avdo

The Deuce · 12-15-2002, 06:59 PM

Did you put new wires on too, or just plugs? Check all 8 wires for a good snap when you put them on, or just pick up some Motorsport 9mm's.

As far as plugs go, I run champion coppers (forget the model #) at .054, and they're great. No need for platinums on these motors.

The bucking, hesitation and power loss all sound like you are getting bad spark of have a dead cylendar. How'd the plugs you pulled out look? My stock wires were bad, one didn't snap down, and it sucked real bad up on top. I thought it was my fuel pump, but it turned out to be a wire.

SteveGT · 12-17-2002, 04:09 AM

I had the same problem. Believe it or not, I had a bad number 7 wire from MSD.

I am 99% sure the problem lies in the wires. Either their seating or quality.

mlambrecht82 · 12-17-2002, 04:18 AM

you also might want to double check your gap setting. Make sure its where you want it, and don't let the electrode hit when you slide the plug in.

Dark_5.0 · 12-18-2002, 04:37 PM

I bet money you got the wrong wire on the wrong plug

94GTConv · 12-18-2002, 07:19 PM

Depending on how bad the jerking is you either:

If it's jerking but not to the point where it's about to die
A: Bad plug/wire

If it's jerking and the idle is jumping up and down enough where the car is close to dieing.
B: You put a couple plugs on the wrong cylinders.

VicRattlehead · 12-23-2002, 03:44 AM

Quote:

Originally posted by Dark_5.0
I bet money you got the wrong wire on the wrong plug

im guessing that too, if thats not the case, my second guess is bad wire somewhere.

IMO my recommendation for plugs is Motorcraft AWSF-A22C's they are 1 heat range colder than stock, that helps keep detonation down, if your sc'd or using n2o id go with the AWSF-A12C's thoes are 2 heatranges colder. NA gap around .054 nitrous/sc'd id go .035

cavdo · 12-26-2002, 10:55 PM

good news everyone, I fixed it.

it was a bad wire #7 from MSD. surprizingly enought.

I just wanted to thank you guys for you support,
avdo,

5.0 Pony · 12-30-2002, 01:16 AM

weird, both bad wires from MSD were number 7......

slow98 · 12-31-2002, 05:41 PM

would gapping a copper plug @ .060 be a bad idea ive heard alot of people boasting it adds a little power on 4.6s ....would the stock ignition even jump that gap?

The Deuce · 12-31-2002, 05:49 PM

It might. Its only .006 bigger than the stock gap. I'm going to mess with the gaps next time I change the plugs. I might start by splitting that diff and go with .057 or there abouts.

12-15-2002, 06:35 PM	#1
cavdo Registered Member Join Date: Dec 2002 Location: salt lake city, utah Posts: 5	replaced spark plugs, now car runs like ** hey guys, i replaced the spark plug wires on my 98 mustang GT engine (71K miles, 4.6L) with Plantinum bosh 4+. and the car ran like . then i took the bosh spark plugs and replaced them with the motorsport spark plugs, and my car still runns like . when i say that my car runs like ** i mean that my car jerks a lot. before the spark plug replacement, my car ran perfect. do you guys have any suggestions? are my ignition wires busted, or are the plugs bad, or what could be going on? PS: the jerking is really bad between the idle and 2000 rpm range. in higher rpms i notice significant power loss. Any advice would be helpfull, thank you, avdo

12-15-2002, 06:59 PM	#2
The Deuce Registered Member Join Date: Apr 2002 Location: Atlanta, GA Posts: 2,325	Did you put new wires on too, or just plugs? Check all 8 wires for a good snap when you put them on, or just pick up some Motorsport 9mm's. As far as plugs go, I run champion coppers (forget the model #) at .054, and they're great. No need for platinums on these motors. The bucking, hesitation and power loss all sound like you are getting bad spark of have a dead cylendar. How'd the plugs you pulled out look? My stock wires were bad, one didn't snap down, and it sucked real bad up on top. I thought it was my fuel pump, but it turned out to be a wire. __________________ 1997 Mustang GT "The Freak" - 13.80 @ 101.70, 2.07 60' 1995 Honda VFR750 - not much @ really fast (actual data pending.) 1964.5 Mustang 289 Rice Haters Club Member #13

12-17-2002, 04:09 AM	#3
SteveGT Registered Member Join Date: May 2002 Location: St. Louis, MO Posts: 42	I had the same problem. Believe it or not, I had a bad number 7 wire from MSD. I am 99% sure the problem lies in the wires. Either their seating or quality. __________________ "Ricers make baby Jesus cry." 2003 Sonic Blue Cobra Coupe K&N Air Filter w/ sliencer removed 10" MTX sub with Kenwood amp & Mach 460 On the way: 4 lb. blower pulley & belt Bassani X-pipe, Undecided on Muffs

12-17-2002, 04:18 AM	#4
mlambrecht82 Registered Member Join Date: Oct 2002 Location: Fresno, CA Posts: 101	you also might want to double check your gap setting. Make sure its where you want it, and don't let the electrode hit when you slide the plug in. __________________ _________________________________ 04 Cobra densecharger CAI BBK off road X pipe Custom Electronic Exhaust cut outs Tuning via Diablo Predator Ported and polished Throttle body and plenum Line locker (for the smoke shows) Stock boost 412 rwhp 379 rwtq

12-18-2002, 04:37 PM	#5
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	I bet money you got the wrong wire on the wrong plug __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

12-18-2002, 07:19 PM	#6
94GTConv Registered Member Join Date: Feb 2002 Location: So California Posts: 65	Depending on how bad the jerking is you either: If it's jerking but not to the point where it's about to die A: Bad plug/wire If it's jerking and the idle is jumping up and down enough where the car is close to dieing. B: You put a couple plugs on the wrong cylinders.

12-26-2002, 10:55 PM	#8
cavdo Registered Member Join Date: Dec 2002 Location: salt lake city, utah Posts: 5	THANKS FOR YOU HELP GUYS good news everyone, I fixed it. it was a bad wire #7 from MSD. surprizingly enought. I just wanted to thank you guys for you support, avdo,

12-30-2002, 01:16 AM	#9
5.0 Pony Registered Member Join Date: Jun 2002 Location: Nebraska Posts: 127	weird, both bad wires from MSD were number 7...... __________________ 1988 Mustang 5.0 LX Convertible -Mac Cold Air Intake -K&N Cone Filter -9mm FMS Spark Plug Wires -Hedmann Headers 2.5" O/R H-Pipe -Flowmaster 40 series 2.5" Catback

12-31-2002, 05:41 PM	#10
slow98 Registered Member Join Date: Apr 2001 Location: draper,va,us Posts: 206	would gapping a copper plug @ .060 be a bad idea ive heard alot of people boasting it adds a little power on 4.6s ....would the stock ignition even jump that gap? __________________ 1998 mustang gt/manual..373s,bbk offroad h pipe,flowmaster cat back,c&l 80 mm maf,steeda triax,eibach springs,steeda ud pulleys,upr timing adjuster,screamon demos coil packs,motorsports 9mm plug wires,steea aluminum lca's,steeda heavy duty uca's and just over 100 k on the clock

12-31-2002, 05:49 PM	#11
The Deuce Registered Member Join Date: Apr 2002 Location: Atlanta, GA Posts: 2,325	It might. Its only .006 bigger than the stock gap. I'm going to mess with the gaps next time I change the plugs. I might start by splitting that diff and go with .057 or there abouts. __________________ 1997 Mustang GT "The Freak" - 13.80 @ 101.70, 2.07 60' 1995 Honda VFR750 - not much @ really fast (actual data pending.) 1964.5 Mustang 289 Rice Haters Club Member #13

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