98 LSC Misfire After New Plugs and Wires .... SOS

Lazer LSC

Lazer LSC

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I have a 98 LSC, bone stock, and I noticed shortly after purchasing it that it misfired a bit after pulling away from a stop light or at idle some times. Since it was not terrible, and did not misfire all the time, I waited about 2 weeks, untill it got a bit worse, and then decided to put some new coils and plugs in it.

Than about a week ago, I put in some yellow and black generic coils in it that I found on ebay for about $40, and Motorcraft Platinum plugs, gapped at 45. I took it on a test drive and the car ran fine. The next day I went out and had to run several errands and drove the car all day long,and it was fine till about 4pm, As I was pulling away at a stop light, I felt a bit of a misfire, but nothing else till about one hour later, when the misfiring became very bad, and the car stalled out on me twice, at low RPM, trying to get out of a parking lot. At this point I drove the car home, I was very close by, and it was scanned by a friend who said cylinder 1 and 5 were misfiring. The car had a rough idle and was running poorly so I figured that those cheap coils I purchased were no good, and quickly ordered 8 new dg 543 motorcraft coils. I got lucky and got them the next day and stuck them in there, and Presto ! The car ran like a top again.... Test drove it, it ran great, I thought done deal !

The next day I took the car out a couple of times and it ran fine, untill later in the day I felt a small bit of a misfire taking off from a stop light, but I drove it home and no other signs or issues. So... Today, I take out the car this morning and I head out and everything is fine until about my third stop, and again misfiring at low RPM pulling out of a parking spot, and the car did not even go while giving it some gas. It stalled on me twice while leaving the lot, but finally composed itself, and I drove it home. 30 minutes later I had to go get my kids at school, car fired right up and drove fine. I drove it for about 20 minutes, and made a stop at the supermarket, got in the car, it started right up but when I put it in drive to exit the lot, there was hesitation for it to go and some more misfire !!!!!!!

I checked the IAC, and it looks clean, so does the throttle body .....

SOS ! I have no idea now. Any assistance would be greatly appreciated ! Thanks
 
These engines don't like anything besides the OEM style copper plugs. Try using the autolite coppers.
 
soduka said:
These engines don't like anything besides the OEM style copper plugs. Try using the autolite coppers.
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Really ??? I have seen countless threads on a bunch of forums, where people are running platinum motorcraft plugs on the marks.

I would like to hear some other suggestions or comments, and thanks, if nobody else chimes in, I will try the copper plugs...
I have a feeling its not the plugs though ....
 
I always run coppers but platinum should be fine
But when you put in the second set of coil packs and NEW Boots you should also have checked for fouled plugs.
There's no oil on them right?
After that I'd say you should clean the mas.
 
I took the car out again today, and same thing happened. While it was cold, it ran fine. It ran fine for two short 5 to 10 minute trips I took this morning. However...... at 2pm, I went out and drove around for about 20 minutes and made a stop, shut the car off for about 5 or 6 minutes and got back in it. While pullin g out of the parking spot, I noticed a rough idle, and As I gave it some gas, some sputtering....... I drove down the road and again, when I came to a stop, I noticed the rough idle and sputtering on take off .

My observation is that the car runs poorly when the temp increases. The other day when we scanned the cars codes, the car was running at 210-212 degrees. I dont know if that range in temp would cause misfire ??? I have already purchased a new thermostat at NAPA, and I am going to put it in as soon a s I can. I dont know if that would solve the issue .....??????

Any feedback is welcomed and appreciated. I really love this car and want to get it in top form, for a daily driver.
 
Investigate the intake/throttle body gasket and the IAC gasket for tears or missing pieces. On a Gen 2 intake this is a cake walk. I had similar symptoms from half my throttle body gasket being missing. Starts feeding your engine air that isn't being measured or accounted for. Also clean your MAF.
 
Try swapping the #2 fuel injector with the #1 injector and the #6 injector with the #5. If you misfire code moves to the other cylinder you have a fuel injector or 2 that is on its way out. Ive seen it happen to a few Fords over the years, its kind of common. Also buy a can of carburetor cleaner and spray anywhere you have a vacuum line or where something attaches to the intake manifold and where the intake manifold meets the IMRCs and where they meet the heads. Theres only really 2 reasons your car would do this when its warm. after being heat soaked (when the car is warm and parked for a short period of time then restarted) electronics that are on their way out show their age, and where gaskets meet tend to expand and you get vacuum leaks , or a tired coil tends to show up. You changed the coils so you eliminated 1 of 3 things. Now you just have to narrow down the other 2.
 
93mark8rules said:
Try swapping the #2 fuel injector with the #1 injector and the #6 injector with the #5. If you misfire code moves to the other cylinder you have a fuel injector or 2 that is on its way out. Ive seen it happen to a few Fords over the years, its kind of common. Also buy a can of carburetor cleaner and spray anywhere you have a vacuum line or where something attaches to the intake manifold and where the intake manifold meets the IMRCs and where they meet the heads. Theres only really 2 reasons your car would do this when its warm. after being heat soaked (when the car is warm and parked for a short period of time then restarted) electronics that are on their way out show their age, and where gaskets meet tend to expand and you get vacuum leaks , or a tired coil tends to show up. You changed the coils so you eliminated 1 of 3 things. Now you just have to narrow down the other 2.
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Sounds like a some good ideas here. Perhaps its old electronics, acting up when hot. My wife drove the car for 2 weeks to work every day, before I started using it. She drives about 10 minutes in the morning, and drives straight home after work. No issues at all while she drove it. The problem really arose after I began to drive it on a daily basis, and I drive around a lot throughout the day, and make several stops, while I work as a Realtor. The heat is most certainly a factor here. The car runs fine for 15 to 20 minutes, and then it starts to act up .....

I will search for a vacuum leak, however, I do not think thats going to be the case. This vehicle runs absolutely perfect untill it warms up. And now with the new Motorcraft coils and plugs.... it runs like a sewing machine, that is for about 20 minutes, and then it begins the sputtering and stalling etc ...
 
Have you changed the fuel filter? Also if you have access to a fuel pressure gauge I would check fuel pressure when it's acting up. I've seen fuel pumps not flow enough fuel after they get hot.
 
I agree with Charger, I bought both of my marks with around 130k on them and both still had factory fuel filters in them. Most people forget about them. If your even only slightly handy you can do it your self. You just have to remove a bunch of Philips head screws and 2 push pins to remove the passenger side wheel well to get the filter. Then its just a couple clips to remove it and replace it. I know when I drained mine it almost looked like mud came out of it.

Also with cars when you make stops and starts like you do when showing houses the under hood temperatures get much hotter than if you were driving all day with out stopping because when you stop the car there's no more air rushing into the engine compartment and the heat just builds. Back when I worked as a mechanic, someone would come in with a problem like yours and we would tell them to get a full tank of gas before they came. Then we would drive their car for any errand we could think of and keep heat soaking it, until the car would act up so we could diagnose it.

By the way when you swap the fuel injectors, make sure you pick up some motor oil or transmission fluid and get the fuel injector O ring set from the autoparts store its usually about 5 dollars. Grease each O ring with the oil of your choice before stuffing it in, otherwise you may tear the ring and get a vacuum leak or a fuel leak, which will just throw another wrench in the works for you.
 
Thanks for the input. I actually ordered a Motorcraft fuel filter, that I have in my garage for this car. I have not put it in yet, but I will this weekend. I also have a new thermostat thats going in tomorrow, and Im going to dump all the old coolant and refill with new.

After I put in the new Motorcraft coils, it still has not lit up check engine light, so at this point I know its sputtering and misfiring, just dont know where from...... I need this chapter in my life to come to an end !!! Just want to drive this thing, and spend my free time looking for some gears and trak lock .....
 
93mark8rules said:
I agree with Charger, I bought both of my marks with around 130k on them and both still had factory fuel filters in them. Most people forget about them. If your even only slightly handy you can do it your self. You just have to remove a bunch of Philips head screws and 2 push pins to remove the passenger side wheel well to get the filter. Then its just a couple clips to remove it and replace it. I know when I drained mine it almost looked like mud came out of it.

Also with cars when you make stops and starts like you do when showing houses the under hood temperatures get much hotter than if you were driving all day with out stopping because when you stop the car there's no more air rushing into the engine compartment and the heat just builds. Back when I worked as a mechanic, someone would come in with a problem like yours and we would tell them to get a full tank of gas before they came. Then we would drive their car for any errand we could think of and keep heat soaking it, until the car would act up so we could diagnose it.

By the way when you swap the fuel injectors, make sure you pick up some motor oil or transmission fluid and get the fuel injector O ring set from the autoparts store its usually about 5 dollars. Grease each O ring with the oil of your choice before stuffing it in, otherwise you may tear the ring and get a vacuum leak or a fuel leak, which will just throw another wrench in the works for you.
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My friend and I put in the 180 degree thermostat this morning and a new fuel filter. This car had been running at 212 degrees before the new stat, and today after the new one it ran at 183, much cooler, and should do me well, being I live in South Florida where it is big time hot down here.

The fuel filter looked like the original one, and it was gross, so we threw in the new Motorcraft filter in there, and thats also going to be a big plus. Now, we did not find any vacuum leaks, and the car ran like a top all morning. I drove it again this afternoon for about 25 minutes and no issues either....

What we did notice is that the passenger side catalytic converter is probably not that good, and it does rattle a bit at times. My friend, who is a mechanic said he thinks that the toasted catalytic is what may have been causing the poor idle, sputtering and stalling .. I am not that sure of that , so would like to hear what you all think on here ?????

He advised that I should get a resonator, and cut out the bad cat, and have the resonator welded in there,in place of the bad cat ..... He also said I should see some minor power gains if I cut them both out and put the resonators in there instead.....
 
I think the fuel filter was most likely the culprit, especially if it was the original. Before condemning the catalytic converter, make sure it's not just the heat shield around the converter that's rattling. Very common on Ford products. If you do end up removing the converters, make sure the exhaust has some kind of back pressure or these cars lose quite a bit of torque for everyday driving.
 
The Drivers side exhaust manifold on a mark 8 has the Catalytic Converter built in. So without some good welding youll never be able to eliminate the cats. You can switch to Cobra exhaust manifolds but then you have to modify the steering column. I have a slight leak in my drivers side manifold and havent done a damn thing about it, because you have to drop the subframe to remove it. So keep that in mind too.

Drive it around a little and just see how it is before you go changing things.
 
93mark8rules said:
The Drivers side exhaust manifold on a mark 8 has the Catalytic Converter built in. So without some good welding youll never be able to eliminate the cats. You can switch to Cobra exhaust manifolds but then you have to modify the steering column. I have a slight leak in my drivers side manifold and havent done a damn thing about it, because you have to drop the subframe to remove it. So keep that in mind too.

Drive it around a little and just see how it is before you go changing things.
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For sure ... I drove it around today, I took it out on several trips, and ran perfect, no signs of any BS .... Perhaps its running a bit cooler and the a new fuel filter made the difference. I also ordered a new Motorcraft IAC a couple of days ago, and when it gets here, will put that in as well. HOPEFULLY>> This is the last of that BS ! Maybe now I can get to attacking that rear end, and get rid of the crap 3.27 in there for some 3.73 ..... I already eliminated the stock tires for some BF Goodrich 255/50/16 all around, and they are awesome and a big improvement.

I thought the Cobra manifolds were direct bolt on ? What needs to be done in order to use them ?
 
So..... Today more BS !

I took the car out in the morning, it was fine. An hour later I went out again in it and drove it to Costco and back, about two 12 minute drives, and it was fine. About an hour later went to get my kids at school, and the idle was rough, and so was the take off from a stop......

So... I put in the new IAC from Motorcraft in it, and hoped for the best. Two hours later I had to go out, and it was fine for about 15 to 20 minutes, I got caught in some rush hour traffic , and then again more BS !!! The car idled poorly and rough take off ..... On the way home the check engine light came on. I have to wait now for my friend to scan it.

Im very concerned, at this point. Any suggestions ????
 
If the substrate in the catalytic converter is broken and rattling, it can sometimes rattle around then plug up the cat. I'd disconnect the exhaust from it and shine a flashlight in the cat to see if it is plugged. If it is, you can break up the remaining chunks and remove them, so they don't plug it up anymore. Put it back together and test it out.
 
slowmkviii said:
Did you clean the mass air flow sensor as we suggested?
It's fast and free/cheap.
Click to expand...

Mass air has been cleaned. Today we took a fuel pressure check and it was only at 20psi. We disconnected the vac hose from the regulator and it stayed steady at 20 psi. My friend said that has to be the problem. He said replace the regulator, and if that does not work, to put in a new fuel pump.

Im getting tired of cars ! Gonna get a skateboard ....... This BS is been going on for 8 weeks now ...... At the end of the line with it, and its just getting to expensive, putting in a lot of money into these cars, when they are not worth anything ...
 
Put a pump in it... The regulator is not your problem. If it was leaking fuel that would create the problem you see but it would also be leaking when you pulled the vacuum line off.


Du
 
My money is on the fuel pump. It probably got better temporarily with the filter until it sucked up more junk. Do you run it low? I never run my car below a quarter tank.
 
My Great 8 said:
My money is on the fuel pump. It probably got better temporarily with the filter until it sucked up more junk. Do you run it low? I never run my car below a quarter tank.
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I run it low at times, yes...

This may be the ANSWER ! Perhaps this is why when the tank is full, it runs better, and once it gets to about 1/4 tank is when theres more issues. Also the fuel pump is an electrical component and it runs OK when its cold, but once heat soaked it malfunctions.

I looked at the 255 lph walbro, its $80 on ebay. I hear with very little modification it will work well in the 2nd Gens.

At this point im going to try it, just pisses me off that I dont know for sure it WILL solve the problem... I hope so.
Any other input is appreciated.
 
Gen 2 uses a completely different system of fuel delivery than the Gen 1. I do not think they are readily modifiable to be cross-compatible, so make sure you are indeed getting one that people have identified as working in Gen 2 Mark VIIIs.

http://www.lincolnvscadillac.com/tech/lincoln-mark-viii-walbro-fuel-pump-installation/

This article identifies the 1996-1998 Cobra Mustang Walbro pump as the one compatible with Gen 2 Mark VIIIs. I believe this corresponds to part # Walbro: GSS342
 
soduka said:
Gen 2 uses a completely different system of fuel delivery than the Gen 1. I do not think they are readily modifiable to be cross-compatible, so make sure you are indeed getting one that people have identified as working in Gen 2 Mark VIIIs.

http://www.lincolnvscadillac.com/tech/lincoln-mark-viii-walbro-fuel-pump-installation/

This article identifies the 1996-1998 Cobra Mustang Walbro pump as the one compatible with Gen 2 Mark VIIIs. I believe this corresponds to part # Walbro: GSS342
Click to expand...

I saw the gss342, however on ebay, I checked the compatability chart, and it says the 342 is good for Gen 1 but not for Gen 2 ????? I actually ordered it, and canceled the order just now because I am not sure. Can you clarify or send a link to the correct pump for my gen 2 ?
 
I used a svt focus pump.
There are people who have run the walbro with no problems and some fail .
They weren't designed to be on a pulse with modulation car.
 
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