Had the '02 S-Type 4.0 plug in yesterday due to seeing the CEL come on then flash when I accelerated hard, only to return to staying on again when I backed off. Codes that cam up are PO420 and PO302. I have read about the codes online and I am wondering if these could both be coming from the same problem. Hope I explained this correctly. Any help would be greatly appreciated.

 

Flashing MIL = misfires so bad they are catalyst-damaging, so fix it SOON!!

Codes PDFs are in the stickies & JTIS - free. P0302 I know is cyl 2 misfire. Remove coil and check v carefully for dirt/damp/oil. Replace if in doubt or if you feel like it swap and see if fault moves but bear in mind your cats.

Cyl #s are in stickies, too - get Vehicle Specs PDF.

 

Your 4.0L most likely will have a bad coil or two like JagV8 said. Have the plug wells been checked for oil? You need to perform some basic maintenance like changing plugs/coils and cam cover gaskets. This just need to be done or you will be going in again and again to change them one at a time.

Have any coils every been changed?

As JagV8 said don't keep driving it with a flashing check engine light or you will also damage/destroy your catalytic converters too!

Read up as the early V8's have quite a bit of stuff that needs to be done to keep them running. I am talking about cam chain tensioners which are not cheap!
.
.
.

 

Thanks Guys. Have only had the car 3 days now. CEL only flashes when I get hard on the gas. Will def ck. the coils, etc. though. Light hasn't flashed during regular driving. Ran some Mr. Gasket Cat Cleaner through it yesterday. All fluids look good. New oil change, etc. but will check coils. Thanks again.

 

Yes they are just a wear item so don't think you got a bad deal on the car yet!!

Just suggesting things to save you work in the future.

Is the light on all the time?
.
.
.

 

Light is on steady all the time. Only flashes under hard acceleration.

 

Regard P0302 as "doing damage". Flashing as "doing Serious damage"

 

As in damage to what?? Please explain

 

Care to answer my question as to what JagV8 may be talking about.

 

Is it so hard to re-read?
Post #2. Your cats but I'd be afraid...

 

I now understand what you meant. I was unsure if there would be damage to something other than the cats. Going to check coils, etc. today. Will probably replace coil and injector in #2 cyl, today as well to be safe. Do I have to clear the codes myself or will the light go out if that was the problem?

 

I'd suggest moving the coil from cyl 2 to an adjacent cylinder first before replacing it and the injector. The reason behind this is to confirm the part that is at fault to ensure that replacement will definately cure it.
If you replace the parts and the fault still continues then you'll have spent $$$ with no result!

 

Light will stay on for I think it's 3 cycles so better to clear it yourself. Uncleared codes which no longer apply only erase after 40 (or 80) cycles so can confuse. If you can't easily clear them, disconnect battery for 5 mins.

 

Good idea Jagbuff. I have never worked on these. Is there a section which can show me how to replace/swap these?

 

To let everyone know. I gave the car a complete tune up and ran some Seafoam through the system. Car idles smooth as new, getting 26 mpg now and in the last 100 miles or so...No CEL at all. Car is running perfect. Only thing I did notice was some oil on the plug boots. I am guessing I have a leak. Need to know...How hard is it to replace the gaskets. New to this engine and want to do it right. If I need to go to a shop, I will. Let me know guys. Thanks for all your help with my, now past, problem.

 

Are you using Premium gas? Hate to admit this but I blew up a 4.0 S Type by not using premium and running it hard.

 

Sounds like gaskets are leaking oil. Tends to damage coils...

 

Nothing but Shell Ultra 92 in the tank.

 

Easy to do myself?? Or better left to a shop?? Couldn't find a thread

 

Passenger Side - Easy to do. Driver's side - a challenge, but doable - you need to remove the fuel line that runs across the top of the driver's side cam cover.

Looks like you need to do the passenger side for sure (P0302 Code) but I would certainly do both sides as a precaution...

You need: (To do the job 100% right the first time)

Cam Cover Gasket (Driver's Side - Part No: AJ88285 / Passenger Side - Part No: AJ88400)

Each of the following parts are interchangable for each side - Quantities listed for 1 cam cover (multiply quantities X2 if doing both sides)

4 - Spark Well Gasket (AJ87206)
1 - VVT Gasket (AJ82856)
2 - Center Cam Cover O-Ring - where the 2 center bolts go (AJ87242)
14 - O-Ring style for all outer cam cover bolts (NCA 2575CA)

Make sure you have a 7mm gear head flex ratcheting wrench for getting to the bolts on the bottom of the cam covers - you'll thank me later...