Good afternoon and happy Friday to all. I have couple questions on my 2001 S-Type 4.0l. I have been chasing a slight misfire and hesitation under power. Check engine light is on constant amber but my code reader keeps giving me a 'link error'. Decided to check plugs and coils. After cover removal immediately noticed passenger side rear coil was epoxied to head. Chipped it out and removed coil; coil screw was stuck in head insert which came out. Believe I can use JB Weld to reset screw sleeve back in head. That plug was torqued so tightly I had to use a breaker bar and cheater bar to slowly break it loose. Threads were good. Funny thing is 6 plugs were Autolite Platinum - well worn and the rear plugs on both banks were NGK Iridium (looked like original and never been changed) - car has 170,000 miles. I got Bosh Iridium plugs since OEM recommends iridium and couldn't afford NGK (Bosh were $6.99 ea.). I noticed what appeared to be anti-seize on old plugs.
My questions are: Do you recommend using anti-seize on the threads and is there a way to test the coils off the car? Would like to test them before installing. The one that was epoxied looks older than the others; probably the original one.
My last question: Is there a way to search the forum for a specific topic? I'm sure my questions have been asked and answered many times before so it would be good to search and not post a question that's been asked and asked.
Thanks for all the help. On my last post I received several very good ideas and suggestions that worked out well.
Rick
2001 S-Type 4.0
1988 XJ40

 

There are various ways to Search, so yes. E.g. near the top of the page

The NGK's are already anti-seize and must not have more. Don't know about whatever you bought. Read the maker's site

 

Thank you very much for both answers.
The Bosh #9652 I bought no not have anti-seize on them. Only say Double Iridium and to torque to 21 ft. lbs.
I'll check their site. Very good suggestion.
Thanks - Rick

 

JagV8 suggested I check the Bosh internet site about using anti-seize on the Bosh Double Iridium plugs #9652, I followed his direction and found the correct answer.
Thought I would share what I learned.
According to Bosh Auto Parts the Bosh Double Iridium plugs have a Nickel-Plated thread surface that requires No anti-seize on the threads. The Nickel-Plated surface was intentionally designed to Not use anti-seize in any heat range use. They thread clean and easy and work exceptionally well when torqued to 21 ft. lbs.
Thanks JagV8 for your answer and expert direction.
Rick

 

Hi Rick,

Define "misfire" please. Do you mean just a general rough-running or low power? In OBD speak, misfire has a pretty specific definition. It basically means low power output (for any reason, not just ignition) from one cylinder (or more) relative to the others. Generally the computer can isolate the low power to the exact cylinder(s) at fault, which makes for an awesome troubleshooting aid. That's why I'm curious to know exactly what you've got going on.

Your code reader and its link error? Take your car to an auto parts store that will read codes for free. Then you'll know if the car or your reader is at fault. I'm betting on the latter. Be sure to get the exact code. It should be a single letter followed by four numbers, such as P0301. Some codes are Jaguar-specific, so don't rely on the generic description on the store's reader.

After you know the exact code, it's time to troubleshoot like a pro. Once you get the hang of OBD diagnostics, you'll never want to go back. So much old-fashioned guesswork is eliminated with code data. For example, your car might have a code for a vacuum leak as opposed to a cylinder-specific misfire. I'd highly suggest troubleshooting that way, instead of making potentially expensive guesses. Obviously clean up the known issues first, such as that prehistoric spark plug. But after that, get the codes and use them for troubleshooting. Your wallet will thank you.

 

I have found that the NGK plugs do last a lot better than all other makes.
I guess this is why Jaguar used them and gave them a 100,000 mile service life?

 

Thank you kr98664 for your answer and question. I apologize for my delay in answering. Have been sick and at VA for several days.
By miss fire I mean I can hear the miss while idling and the tack dips in RPM very briefly. Idle is only slightly rough at idle. When I accelerate and put it under power, it has a very bad stumble that it won't recover from and of course won't downshift.
I replace all the plugs (old were badly worn and 6 were cheaper Autolite Platinium and the back two were NGK Iridium looking like they were original with 170,000) . I put Bosh Iridium plugs in - couldn't afford the NGK. One coil was 'dead' (no primary reading and secondary 0 ohms). It was on bank 1 plug 2. The rest of the coils checked at 7.6 +- Ohms and the new ones checked at 5.6 Ohms, so I believe all coils were breaking down under heat and load. After replacing all plugs and coils I have No "check engine" light and car idles very smoothly and has plenty of power under acceleration.
As to the ODBII thing. My reader will scan through all the protocalls, through many engine system checks and almost at the end of the scan I get the "link connection error'. My reader reads codes fine on my 2003 Avalon and my 2003 Silverado K3500. It also read the code on a friends 2003 Jag. I checked the ODBII fuse and the wiring behind the plug. All looks good. Am planning on ordering a Bluetooth code reader that is recommended on this forum.
Thanks for all your help.

 

Thanks for the suggestion and information. When I pulled the plugs there were 6 Autolite Platinium and 2 NGK Iridium (both back plugs on each bank) that looked like they were original - car has 170,000 miles. I couldn't afford NGK Iridium so bought Bosh Iridium 'thin-wire' plugs and replaced all the coils at the same time. One coil tested dead and the rest showed high ohms. Probably the reasons for my slight miss at idle and bad stumble under a load.
After replacing all plugs and coils it runs like a champ! Smooth idle, very good power, and great acceleration with downshift (wouldn't downshift before with stumble).
Thanks for you answer, thoughts, and information.