Yesterday I posted a thread regarding a 98 I30 that was having a tough time starting. Remember I said we used Bosch plugs in it at the 60K tune up? Well after 15K miles on the Bosch plugs they were DISTROYED. The car ran fine up till about 2 weeks ago when the hard starts and rough running started to happen.

We pulled the plugs out and put in the NGK's last night. ($12 bucks/plug at my local dealer). The Bosch plugs had absolutely NO electrode left. It was totally gone. There was only a spot on the ceramic isolator where the electrode once stood. I was amazed that the car even ran like this.

So for those who say that Bosch plugs are OK to use in our VQ motors. FORGETABOUTIT! I saw first hand that the ignition system in our cars is powerful enough to consume cheap spark plugs in only 15K miles.

And by the way, that freakin fuel filter is a B_I_T_C_H to change.

 

well before people start flaming.. i have found that 50% of maxima's have problems with bosch and some don't.. i did.. deezo didn't.. so before people start flaming i would like to say that...

oh I am going to flame you now ....

#1 my NGK plats are $6 at my dealer but you should be using copper anyway

#2 with a CAI and no ABS the FF is a 8 min change

 

Don't I know it. Last year I had the imprint of engine parts on my forearms.

 

Bosch may not be able to stand up to the type of driving you do.

Yeah, I've had no problems as far as driveability goes and I get great gas mileage too. My car does start like the injectors need to be overhauled though. I won't blame the plugs on that issue though because I have 90,000 miles now so maybe its just time to have the injectors cleaned.

 

Took me 2 hours to do mine

And, if 50% of people have a problem with the Bosch (the 4 tipped platinum ones, right?), that's huge.

DW

 

I don't get why people are using non-suggested sparks. GRR! Oh well. Speaking of which...I should probably be replacing mine in another 5k miles......

 

Testing reasons. My Toyota pickup ran fine with the stock plugs that was recommended but when I threw the Bosch plugs in there, it was night and day. I had more road HP with the +4's. I think they're good plugs but the VQ need a more durable plug. I'll be changing my plugs in the next couple of months and I'll take pics of my Bosch +4's to show what they look like.

 

heh...I think I'd rather be safe than chance it for the 1 hp that might be seen, but that's just me, babying the car, I guess.

 

Was there just as huge a difference in your VQ with the +4s? That is the question.

DW

 

We also had no drivability problems and good gas mileage, actually the car ran great until the hard starts started happening.
If I were you I'd pull your plugs and take a peak. I bet you find something similar to what I found last night. The hard starts were the first sign that things weren't right.

I'd be curious to know what you come up with. Would you please let me know what you find if you pull them and take a quick look. Thanks

 

Why do you think he should be using copper plugs, instead of platinum?

 

It'll be a couple of months but I will give an update soon I get pull them out.

 

Platinum is popular because it lasts longer. Copper doesn't last anywhere near as long, but when the plugs are good it has less resistance and therefore a hotter spark.

Gene

 

better spark.. they last 30 k as oppose to 60k that plat last.. i don't mind spending $50 less every 30k miles.. but thats just me

 

Copper = more resistance than platinum, not less.

A more conductive material in the spark plug is a good thing, as this allows for a higher percentage of the voltage drop to be available to jump across the spark plug gap. And the spark that crosses the gap would be more a function of the size of the gap and the available voltage to jump across it. Putting higher resistance materials in series with the spark plug gap only serves to increase the voltage requirements of the entire ignition system without necessarily strengthening the spark. It it would make more sense to use platinum plugs gapped at .47. Tell me again why copper is better?

 

i just posted above

 

I ran Bosch plugs for about 2 weeks. My car felt like crap. Revability was slow, it showed signs of mild detonation after 5000rpms, and overall the car felt flat. I pulled the plugs and they were whiteish and showed signs of detonation and overheating. IMO, the Bosch plugs can't handle the ignition system of the VQ. I changed out the plugs to OEM NGKs and my car ran much better.

There's a saying that your shouldn't run German plugs in a Japanese motor. This seems to be true with the VQ. Some cars don't care what plugs you run, but the VQ obviously does.



Dave

 

Ok...for the copper vs platinum resistance...go here. http://www.ibiblio.org/obp/electricC...Ref/REF_3.html

See the table about half way down

 

I agree with that.

 

Oh great. My next upcoming project. I look forward to it.

 

I've used Platinum and Copper NGK's in my car, and I can't feel any difference, except in my wallet. The only reason I use them is 'cause I wanted a set of normal and cold plugs (for when I hook up the bottle) and didn't want to shell out $100+ for them. $20 was much better.

I put Bosch copper plugs (not +4's) into theblue's car, and it felt just fine. He hasn't complained since.

 

seeing as links don't seem to last long, I'm going to post that table so that it will come up when someone searches. Anyone mind? Thanks.

Coefficients of specific resistance
Specific resistance at 20o C:

Material Element/Alloy (ohm-cmil/ft) (ohm-cm)
================================================== ==================
Nichrome ------- Alloy ---------------- 675 ------------- 112.2-6
Nichrome V ----- Alloy ---------------- 650 ------------- 108.1-6
Manganin ------- Alloy ---------------- 290 ------------- 48.21-6
Constantan ----- Alloy ---------------- 272.97 ---------- 45.38-6
Steel* --------- Alloy ---------------- 100 ------------- 16.62-6
Platinum ------ Element --------------- 63.16 ----------- 10.5-6
Iron ---------- Element --------------- 57.81 ----------- 9.61-6
Nickel -------- Element --------------- 41.69 ----------- 6.93-6
Zinc ---------- Element --------------- 35.49 ----------- 5.90-6
Molybdenum ---- Element --------------- 32.12 ----------- 5.34-6
Tungsten ------ Element --------------- 31.76 ----------- 5.28-6
Aluminum ------ Element --------------- 15.94 ----------- 2.650-6
Gold ---------- Element --------------- 13.32 ----------- 2.214-6
Copper -------- Element --------------- 10.09 ----------- 1.678-6
Silver -------- Element --------------- 9.546 ----------- 1.587-6

Note:The "-6"s are x10 to the 6th power. Also notice that platinum is 6 times the resistance of copper. I'm going to have to try and find iridium. I think the good thing about iridium is it can have a finer tip than platinum.

 

Good info rcrdps

 

very interesting that most of the smarter guys around here own third gens

 

Guess I'll have to pull a plug and see what it looks like. I put the Bosch's in around 35k miles ago and at start up and sometimes when it's cold I get rpm drops. I'll let everyone know after the weekend.

 

i have been running those super expensive denso irdium plugs. no problems at all. i have not checked them in a while but when i do ill post up what they look like.

 

Yes you are correct about the resistance of copper VS. platinum, I was wrong. But the advantage of a platinum plug is that the platinum is obviously more durable that copper. This allows the electrode tip to be made much smaller than a copper tip. This decrease in size intensifies the electric field at the tip. This increase in electric field intensity will allow a spark to jump a gap of X size with a lower voltage than would be required at the tip of a larger copper electrode. If you have a voltage at the electrode tip of a platinum plug equal to the voltage at the tip of a copper plug this would also allow you to have a wider gap with a platinum plug. A wider gap = a longer spark. If however you choose to have an equal gap with a platinum VS. a copper plug this would result in greater reliability with a platinum plug.

Copper also has it's advantages. The wider electrode diameter of a copper electrode VS. a platinum electrode can and will result in a physically wider spark that can be produced with a platinum spark. This is obviously a good thing. However, under some circumstances a copper plug will misfire where a platinum plug would not due to it's decreased voltage requirements.

Finally the electrical resistance of copper VS. platinum appears to me not to be the prime consideration. It is electrode tip size which determines which metal will be used as a smaller tip is subject to tremendously increased abuse. Copper would not stand up if it's tip was as small as a platinum plugs tip.

 

If you

A) Have small hands

B) Have a Maxima without ABS

Then, the feul filter change will be easy. If not. . .




DW

 

Yes,... I agree with all that. That is why the iridiums are better than the platinum even though they have more resistance. But a longer spark doesn't always mean better burn. I think that is one of the things MSD claims vs the others. A higher voltage and sharper tip will jump a larger gap, but a hotter spark will ignite the fuel better. You need to jump the gap, but then you want current flow to make it hot....which is where the copper and smaller gap are good. The coppers may have a higher chance of missing, but if you're not missing you will have a hotter burn. I guess it's an issue of quantity or quality. I prefer the hot spark.

Gene

 

It's funny how everyone feels so strongly about this plug or that plug. How much of a performance difference are we talking about here between plugs? 1-2 hp?? Can't verify that on a dyno because it's within the margin of error.

I guess it really comes down to 2 things, either save a buck and change 'em more frequently, or spend and fuhgetaboutit for a long while.

DW

 

I feel ya. There not a great difference of HP when getting the copper and you'll lose durability of the plug itself when used in the VQ. If I was a hardcore racer, I'd use the copper. Otherwise, I'll stick with the durability of the Platinum.

 

This is the theory behind Nology Hotwires. They have a capacitor in them, so the spark is much shorter in duration but much hotter than stock. When I first put them on my motorcycle, it ran very lean. I had to go two sizes up in jet size to compensate for the extra burn, and I had to switch to non-resistor plugs. I actually tried the test they ran in their ads so I could see the spark. The stock wire/plug combe was a tiny little zap. The Nology capacitive wire/non-resistor plug was a huge ZAP. Like comparing a headlight to a bolt of lightning.

 

I've been running Bosch +4's in my 95 Max for the last 30k miles. Car now has around 120k. Started missing while accellerating a couple of weeks ago. Felt like fuel cut out. Wasn't sure where to look. Anyway, my wife calls from the car. She's driving home (about 60 miles) car is missing worse and the check engine light came on. Today I read how to pull ECU codes. Pulled code 03 04 (knock sensor) and 06 06 (misfile in #3 cylinder). I hope these are the right codes, I'm going from memory. So I decided to try swapping plugs, and coils with other cylinders, and reseting the ECU to attempt to find the bad part. Pulled the #3 spark plug to find it covered in oil. All 4 electrodes are missing completely. Looks as if they have broken off and not melted. I feel that this was a faulty plug, and not something caused by the engine. What are the chances that the electrodes burned away and did no damage? If the cylinder is scored what are my chances of getting Bosch to pay for all or part of the repair?

Sorry this is so long, but I'm venting. Little worked up over replacing an engine because of faulty $4 spark plug.

 

I guess I should check my plugs sooner than later.

 

Same experience here. . . Cyl 5, with Bosch Plats, was covered in oil when it was pulled and the spark plug well seals needed to be replaced, also did VCG at the same time. All plugs showed the car was running lean, and I had noticed that the car sometimes picked up and other times bogged. After everything was fixed and the NGKs were in, the car felt smoother throughout the entire rev range and even though I didn't feel any difference in power, it feels like it is there consistantly now. BTW this is on a 95 5-spd and the plugs were in for ~25K miles.

 

What seals needed replaced? I'm assuming the valve seals. I just replaced mine with "normal" NKG's, not platinium (would have had to special order). Took it for a test drive, and it run's much better. Got home and reset the ECU. I'll check it again in a few days to see if the cylinder is still misfiring. I just wonder if the electrodes broke off or melted.

After doing searches on the new about missing electrodes, the article I found said that is is sometimes caused by a loose plug. The engine sucks air around the plug causing a lean condition and a very hot cylinder. When I pulled the plug it was only hand tight. When I put them in I turned them 1/2 turn past hand tight. With my new plugs I used a torque wrench and tightened them to 14ft/lbs. Which was approx. 1 full turn past hand tight. I highly recommend using a torque wrench now as hand tight is highly subjective.

 

Just a little hint, I don't believe anyone said Bosch was safe to use in the VQ. I have heard many stories from dealers to people on this board that Bosch is not the plug to be using or it could damage the engine. Only use NGK. So just a heads up hint....

 

Ditto. Had the Bosch Platinums last year but pulled them after about 4 months. All six plugs were markedly oily. A month after I replaced them with NGK, I pulled a plug to see what it looked like: PERFECT.

 

I had to replace the spark plug well seals, it is a seal that is somehow in the spark plug well that prevents oil from entering the well, and the Valve Cover Gasket. My spark plug was in there nice and tight and the chamber was full of oil. I would check yours again just to see if anything is covered with oil, it may not be necessary in your case.

 

Adidas_Boy thanks for the heads up. I'll pull that plug and check again. Do you know if the Haynes manual shows how to replace these seals?