Anyone use these plugs in there XK8? The reason I ask is I replaced the NGK Iridium's with the above Bosch plugs and I am told they are the wrong plug for the vehicle (2003 XK8).

???

 

Denso and NGK have consistently built the best iridium plugs for years now. Why did you go with Bosch? Did you get a significant deal on them?

 

Not really Jon, $6.99 ea., the NGKs were not available at our Zone. The vehicle seemed to run fine with the Bosch plugs. It seemed to start a bit easier with the new plugs but still has a hard start problem.

My OBD II reader did not pick anything up as far as codes. So I sent Joel (yep the old S Type Joel) to the dealer to have it diagnosed there in Raleigh. The dealer told him that the Bosch were not correct plugs. Today I called the Zone and they were listed as the premium plug they had in stock for a 2003 XK8. Comparing the NGKs to the Bosch they appeared to be the same.

BTW if you haven't read, the plugs are a breeze to change.

 

Rick,
I have been using Bosch+4 in my XK8 ever since I got it. It has not blown up, melted or any other strange things that has been suggested the only problem is that Jaguar does not have it listed as recommended. Let me ask you this how many non Jaguar parts are on your car simply because it works just fine. What do you think Jaguar is going to say about that? I would not be concerned over the plugs as long as they are listed by the manufacture to be suitable for your car.

 

Having used Bosch consumables in the past, I now avoid the brand where possible.

 

Oh I hear what you are saying Gus.

When I get the vehicle back in a couple of weeks to wrench on some other issues with it, I may or may not swap out the Bosch plugs.

Plums, though I do not use Bosch parts that often, I have never had an issue with them failing as I recall.

 

Are they so diffrent? In Sweden Bosch stads for quality

 

They certainly make damned good dishwashers and I've been running on these for nearly a year (plugs not dishwasher - that's been running for six years!).

 

i have bosch plugs in my 5.4 ford (to replace the horrible ford plugs that break in half), and bosch in my prius, both run peachy. in regards to them in a jaguar...not sure why it would make a difference, is the brand That issue prone? (asks the guy with a blown up xk8 in the driveway...lol)

 

Are the bosch plugs pre-gapped correctly? My NGKs were spot on, every stinkin one of them.

Here's a TSB from Gus's website (love that library Gus!) about gapping, if it idles oddly, perhaps may help starting too?

 

Matt, yes the Bosch came pre-gapped at .050. Every stinkin' one of them

 

Rick - correct gap for a dishwasher ?

 

Ouch Steve!

Rick,

It has been said in the PAST that they do not work well with Supercharged but I can tell you they work just fine in a 4.0 XK8 & 3.0 S-Type.

 

Steve I prefer ASKO over the Bosch dishwahsers.


Gus what about the 4.2s? Any word on them disliking the Bosch plugs?

 

Most automotive aftermarket manufacturers try to cover as many applications as possible with as few part numbers as possible in order to maximize margins.

Some take it further than others. Some are not even manufacturers in the usual sense of the word in that they license out their brand name in various markets to different manufacturers. The part you buy in one country may not be the same part in another country.

Bosch spark plugs seem to have a problem with vibration of the ground electrode:

bosch spark plug "broken electrode" - Google Search

The problem is more pronounced in forced induction applications. That is, turbo or supercharged.

It might also have something to do with piston to electrode contact. As compared to the Jaguar recommended NGK plug, the Bosch listed substitute extends further into the combustion chamber.

The Bosch oil filter listed for Jaguar applications is a "one size fits all" being shorter in length so that one part can fit applications that require the shorter dimension and those that do not.

So, dishwashers and brand image aside, while Bosch parts might be a viable choice ... it might not be a great choice.

BTW, the head of Kenne-Bell has endorsed Denso plugs as the recommended plug in their supercharger applications.

 

You should also take in consideration that no one will re-write the book of specs for older Jags. Take a look at the availability of other parts from our cars. Look I do not want to beat this horse to death but the problems with Bosch was a long time ago and they would be stooped to not correct the problem by now. Who is to say the problem was not from the person installing the plug and readjusting the electrode improperly causing it to fall off. Bosch has been a long standing leader in the racing business and I myself cannot turn my back on that.

At this point I will yield to any and all persons that personally used Bosch and had a serious problem with it. All I am hearing is hearsay with no bite and I would venture to say most comments are from articles written and read on the net. I know I believe everything on the net all the time>>!@#$%%&^*()??!

Rick I am unable to say a problem would exist with a 4.2 I can say that you noticed a little improvement and that your car and you have not gone to hell for installing Bosch. I have them and use them in my cars and I have not gone to hell either. 2000 S-Type from 66,000 to 100,000 24 to 28 MPG Highway, 1999 XK8 60,000 to 125,000 22 to 28 MPG Highway.

I think you need to read the links they are not all you think they are.

 

There is no need to rewrite Jaguar specs due to availability. The original spec double Platinum NGK is still available. The aftermarket NGK of similar design in either single Platinum or Iridium is available. A very nice upgrade design is available from Denso. And was on special at Jegs two nights ago for $1.99 each.

The projection of the spark plug nose into the combustion chamber is sometimes published by spark plug manufacturers and is sometimes a consideration by those selecting a replacement. In the case of the Bosch application chart, the recommended spark plug substitute is visibly longer in nose projection than the equivalent NGK when examined side by side in the store. I cannot say by how much because the stupid blister pack was in the way, but it was not trivial.

Same deal for oil filters. Most of the other name brand oil filter manufacturers manage to sell both the longer and shorter versions depending on original Jaguar or Land Rover application. Bosch has chosen a shortcut and only lists the shorter version in their application guide without bothering with a footnote for the change. Unfortunately, there's a short one sitting in the spare parts bin when there should be a long one


A member on another forum s no less or more credible than a member here. They could be less skilled or more skilled. Now, if the author is the president of Kenne-Bell and he is writing in that capacity about the results of dyno tests about Denso plugs, then yes, he gets a boost in credibility.

If you insist that a JF member experience is somehow more valid than that of a non-member, then yes it has been mentioned on JF within the last two years.

As for problems being "a long time ago":

05.14.2012
Timing blowing electrode off sparkplug? - Page 2 - JeepForum.com

05.08.2011
The tale of the broken electrode... - MG-Rover.org Forums

I have used Bosch plugs and filters in the past. I no longer use them and avoid them like the plague. The reasons are as stated above in the descriptions of their "close is good enough" approach to matching original designs. If they are willing to shortcut there .. then what else was "streamlined"?.

A 0.75 inch shorter filter might be ok, just change it out faster to get rid of it. But, there is no way a plug with a longer nose projection than anticipated by Jaguar engineers is going in.

They might be really good at pretty packaging and marketing, but the products don't seem very special once in hand. It brings to mind that Fram was once great at making filters, then they were acquired by Honeywell and it just went downhill from there.

 

Plugs, oil, petrol - all goes round in circles with no result.
All I can say is I checked the length of the Bosch plugs (from the US) and they were identical with the Denso. They immediately got rid of a 'fluff' warming up in open loop, my mpg went up and no engine components have come out of the exhaust (yet).

 

Well first, are Denso's the factory plug on your model year?

And which length? The important one would be from gasket face to furthest point on the electrodes. In a Bosch vs. NGK comparison they are different.

And then, fresh plugs got rid of a "fluff". What were the old plugs like? If they were tired, pretty much any plug is going to be an improvement.

 

Oh boy, I really did not intend for this to become another "what oil should I use" thread. Sorry guys.

I have to agree with Steve, when I opened the Bosch and compared them to the NGKs in a side by side comparison, they appeared to be identical in all aspects. I did not break out the micrometers.

The NGKs that were removed were in pretty good shape actually. They appeared that they were changed before the 120k + miles. I was almost hesitant to replace them.

Plums I am going to have to came back and check out those links. You and I know there is alot of reading to do here before I wonder off and not perform my forum duties.