another 2002 ls v8 misfire issue/question

[tkswan]

2002 ls v8 Misfire question:

I have already changed both valve cover gaskets and 6 of the OEM coils. The car has performed flawlessly ever since. Yesterday, it started misfiring again. CEL came on very quickly this time Misfire on cyl 6. ...it usually has to chug around a lot longer before it throws a code.

Cly 6 had an old coil on it so I got a new coil. Still misfiring. So I pulled the plug. It looked like a cantidate for replacement so I go get 8 plugs and replced the 4 plugs on the exaust (left) side. Still Misfiring...

...am I correct on the placement of cylinder 6?

2002 LS 3.9L V8

WINDSHIELD

(r)4---8(l)
(r)3---7(l)
(r)2---6(l)
(r)1---5(l)

HOOD

if so what next outside of going to pay to use Fords in depth scan tool?

[shorod]

Yep, you are correct on the placement of cylinder #6. Was there any evidence of oil on that coil?

Do you have a scan tool with a datastream mode? If so, and the misfire occurs often enough, you could use the datastream mode to monitor B2S1 oxygen sensor and determine if the mixture goes lean or rich just after the misfires occur. If rich, that would indicate a loss of spark. If lean, that would indicate a loss of fuel (maybe an injector issue).

You could also check the compression on cylinder #6, but I haven't read much about problems with these engines unless a timing chain goes out, which doesn't seem to be too common.

-Rod

[danielsatur]

Does a 2002 Lincoln LS have a electronic control module for the Throttle body?

If the Air,Fuel,Spark,and compreshion isn't right (TIMING),we will have Random misfires.

I have seen a stickey throttle plates (AIR) on electronic control throttle bodies,causing radom misfires.

MCGIVER

[tkswan]

Rod,
The coil was clean of oil. I cleaned all those holes when I changed the valve gaskets and they are still clean. I knew what you was going to say about the scan tool. I just want to do all the troubleshooting I can before I pay Ford 100 bucks to plug it in.

MCGIVER,
I thought the timing on this engine was controlled by knock sensor?

All,
On the onset of the issue, I would get a misfire under load and when the rpm reaches 30k.

Now the misfire is happening when the car is cold. You can feel every bump, and the exaust fumes reek of raw fuel.
When it reaches operating temps it running great but every now and then I still feel a single bump or misfire. Won't throw a code. By the way, I replaced the plugs with the Autrocraft OEM cross refrence. No Platinum plugs going in this car under my watch.

[danielsatur]

Missing Air in Time is the same effect as a missing spark,fuel,and compreshion.

I have seen more Issues with MAF sensors + dirty throttle bodies on
the late models LS's + JAG's.

Please read AF Forum > Jaguar > Stype > Misfiring

Alot of times, it's cleaning the throttle body with a little WD40 + Fogging oil.
Clean the throttle body on the car,and exercise the throttle plate.


How many miles are on this car?

I only use NGK Iridium Spark plugs!

MCGIVER

[shorod]

Wow, 30k rpms!?! No wonder you have a misfire, these engines weren't intended for more than 7-8k rpms.

You may want to consider replacing the coolant temperature sensor and Intake Air Temperature (IAT) sensor as they should cost less than the trip to the dealer to have the scan tool installed. Actually, I think the IAT is part of the Mass Air Flow (MAF) sensor, so maybe the step would be to clean the MAF with MAF Sensor cleaner. A MAF that's dirty enough could cause a misfire, although I suspect you'd get a code if it's that dirty. Worth a try anyway for the cost of a $8 can of cleaner.

The electronic throttle bodies on the LS were first used on the 2003 model year. I agree with the NGK Iridium plugs. I either use OEM or Iridiums and have not had issues. I have however experienced problems with multi-conductor/electrode platinum plugs on more than one occasion though.

-Rod

[tkswan]

Well, I meant 3k rpm. Anyway, this thing is flakey. I ve drivin it all weekend and not a single misfire out of it. I push it a little here and there and nothing. It has 97k miles on it danielsatur. All the plugs were evenly worn when I took them out. They indicate that all is well in there. I read that the LS does not like platinim plugs.

I guess I will just clean up the MAF sensors and spray some carb cleaner in the throat when I change the oil this weekend.