98 Cobra ignition or computer issues. *HELP*

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
The start of the problems were a few months back when the car... after sitting, it would have a hard time starting and then idled very low for a few seconds and then corrected itself and drove fine. I also noticed that the half dozen or so times that this happened...when I got in the car, I could smell fuel BEFORE I turned the key. I thought it might be the fuel cap was venting into the cabin, since the trunk is not sealed well at the filler opening.

In the mean time, the alternator was making noises from the main bearing failing and at start up the battery light would come on for about 15 seconds then go out.

So I leave the house the other day, 5 minuted in, just easy driving in the neighborhood and the car started sputtering bad out of the blue, to the point that accelerating made the car buck. I got no CEL at that point. Got the car home and in the dark when revving the car, I could see all kinds of points where the plug wires were shorting out on the engine (I know, I'm a dumbass for not changing them earlier). I hooked up the OBDII scanner and there was 2 codes for misfire cylinder P0302 and P0306 for cylinder 2 and 6 (which are on 2 different coil packs). I don't know how old the codes are so I clear them and at first, no codes return and no CEL.

So I ordered new Ford plug wires and in the down time, I check the coil pack OHMs and got acceptable readings off the secondary @ around 13.50 and a little high on the primary 1.3-1.6 (which strangely is the same readings as the new coil packs).
So I reconnect everything and make sure the wires going to the coils were not damaged and now the car will not run unless I feather the gas and work it up to around 1500 RPM and hold it. I try swapping the coils and no change. I immediately get a CEL and codes P0353 and P0354 (ignition/coil C and D primary and secondary circuit malfunction) and clearing the code brings the CEL and code back again immediately.
Next I get new Autolite plugs and find that the old plugs are mostly fouled or smell like gas. So I install the new plugs, fuel filter and alternator and absolutely no change.

Today I got 2 new coil packs and now the car fires right up with a roar and idled pretty well but still had a slight miss. I pull out to take the car to the gas station and immediately I think the car is fixed, until I try to accelerate. The car sputters and stumbles until I get up to about 5k RPM then seems to clear up for the most part. If I baby it and accelerate slowly through the gears, it is not too noticeable.

So I get home and turn the car off and check to make sure I got everything back together correctly and decide to unplug the negative battery and pull the plug off the PCM under the passenger side kick panel for about and hour.

I get back in and there's no real change and I take it for another quick drive and come back. I shut the car off again and look under the hood for something I missed. I start the car up and now it seems the miss at idle is pretty much gone and so I take it around the block again but the sputtering continues when accelerating.
It is REALLY bad if you are in a high gear and try to accelerate it.

I hope someone has any idea what is going on and maybe this helps someone else with a similar problem in the future. I read as much as I could about my problem and found no answers, but saw that many people claim that coil packs seldom go bad and read that many issues are corrected by resetting the PCM.
Thanks for any help!!
Dave




splug2.JPG

splug1.JPG

splug3.JPG
 

crazycarlo

Well-Known Member
Established Member
Joined
Jul 31, 2005
Messages
6,116
Location
Savannah, GA
What did you set the gap at o the plugs? Also you sure you didn't get a plug wire on the wrong place?
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
I gapped them at .52 and I checked the plug wires many times as well. :??:
I am going to shoot some video of it driving today.
Thanks!
 

svtcobralover

Active Member
Established Member
Joined
May 29, 2007
Messages
1,100
Location
Florida
You need to check the coil packs. They are reversable to each side. On each coil pack, the number in conjunction with what cylinder it's controlling is labeled. However there are two numbers per coil. Make sure you follow each number (whether the top number or bottom number with each coilpack and spark plug wire.) I know this sounds confusing but as soon as you look at them you will know what I am talking about.

I live in New Tampa if you would like me to take a look at it for you.
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
Thanks for the offer, I may take you up on that if I can't figure it out soon! I replaced both coil packs, but I plan to swap them anyways and see what happens. One could be bad off the shelf. I also plan to pull the plugs tomorrow since I drove it about 30-40 miles today and see how they look. The exhaust smells normal, but I noticed at idle is misses at random times and accelerating in any gear causes the shuddering and sputtering, but is far worse in higher gears. However, at full throttle once it gets up past 4-5k or so it has more power than is did before all the problem started, but I am sure much of it was the bad plug wires grounding out at high RPMs.

Here is a quick video from today. It is hard to tell but as I accelerate you can hear the missing in the engine and see the shifter shaking from the shuddering of the engine. It feels far worse when driving than it sounds or looks in the video. My kid says it feels like I am pushing the clutch in and out really fast as I am accelerating.


98 Cobra shuddering on acceleration - YouTube
 

NOVA98Cobra

Street Defiers
Established Member
Joined
Oct 8, 2009
Messages
779
Location
Arlington VA
I have some stock coil packs that worked fine when I took them off. You can just have them if you pick up shipping just for testing if the packs are the problem
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
I just tested the voltage going to the coil packs and from the center positive lead to the outer leads show 10.30v for the left and 10.32v for the right.

If I connect the meter to the center positive lead and a regular body ground or negative battery terminal I get 12.22v left and 12.23v for the right. Can someone verify or check to see if this is correct?
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
100 more dollars, still not fixed.

The only logical thing that I could think of that could be causing the lingering sputtering problems now...as a result of the bad coil pack was the upstream O2 sensors. I remember when I was trying to figured out what was wrong originally, that the car had one huge backfire, so I figured I fried the O2s. Nope! What else could a faulty coil pack and plug wires (or large backfire from overloaded cylinders of fuel igniting) that could cause something else to fail? It also still randomly sputters/misses at idle as well. But If you take it up through the full RPM range slowly and nail the throttle @ around 4k... it screams to life and pulls hard right up to near 6500 RPMs.
So far this is what I have replaced:
plug
plugs wires
both coil packs
fuel filter
alternator
both upstream 02 sensors

I am running out of money and ideas. :nonono:
 
Last edited:

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
Absolutely no codes. I have since checked and cleaned the IAC, tested the EGR sensors and valve, TPS and MAF.
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
Today I checked the vacuum and it held pretty firm at 24 in at idle. I also checked the fuel pressure and it idled at 32psi and jumped to around 40psi when I hit the accelerator to about half throttle. According the book, the vacuum and fuel pressure are within specs.
vacuum.JPG

fuelp.JPG


The IMRCs are not too bad, but the valves below the IMRC butterflies are MEGA-LOADED with carbon deposits! What is the best course to clean these without removing the heads?

imrc1.JPG

valve1photo.JPG


I have officially checked everything I can think of or that has been suggested and unless cleaning these IMRCs somehow fixes the problem, I am back at square 1.
Next step is taking the car to a shop and hope they don't bend me over the counter. :nonono:
 

Expurple

Member
Established Member
Joined
Jan 4, 2012
Messages
369
Location
Ankara, Turkey
My car started stumbling from time to time as if one the spark plugs was not firing. What caught my eye was that THEFT was blinking. I'm thinking it might be a faulty transponder if your car does this from time to time.

Try disabling the PATS.
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
Well, I got the IMRC, valves, intake and throttle body cleaned and put back together and it didn't fix the problem and I now think I have a leak somewhere as the idle is going crazy. I did leave the TPS attached when I cleaned the inside of the throttle body, could that have screwed sopmething up?
I just realized that about 2 weeks back, my power steering started leaking (I had it on the lift and couldn't tell where it was leaking from, but the pump and stuff around it were pretty wet) and it was shortly after that the problems started. I just read that the camshaft position sensor is located behind the pump. Any chance that this sensor getting soaked in fluid could cause the problems?
Here is 2 quick vids on the new idle problem....
98 Cobra reving standing still - YouTube

98 Cobra idle when moving - YouTube

I see another intake and IMRC removal ahead :(. Only thing I can think of, is maybe a gasket shifted when setting the manifold? Other than the idle going nuts, accelerating is still crap and I exchanged the coil pack for a new one, no difference.
 

shelbygt

Member
Established Member
Joined
Feb 18, 2002
Messages
133
Location
Hudson Fl
Oh, and when I unplugged the IAC valve, it idled fine and and didn't stick up high and when I unplugged the TPS, the idle jumped to about 2000 RPM.
 

USMC53CHIEF

Active Member
Established Member
Joined
Jan 4, 2011
Messages
1,228
Location
Medina, Ohio
Just for shits and giggleberrys, Change your plugs... we (advance auto parts here in ohio) have had a bad batch of autolite plugs recently. Whether or not you got them from advance or where ever, they all come from the same place. I couldn't get my cobra to run right until I out motorcraft SP432 back in gapped at .054.

I also had a TERRIBLE ping noise coming from car when I started it post rebuild, here I drew the wrong pic for the plug wires I was pulling off and installed them completely wrong...(in conjunction with sp433 motorcraft plugs) still ran tho.

Check the plugs and verify wire locations... I know it sounds dumb..but the wires have served me a slice of humble pie before
 

Users who are viewing this thread



Top