Knocking!!!!! [Archive] - SaabCentral Forums

: Knocking!!!!!


sherpapike88
6th October 2004, 04:25 AM
Hi guys.....I've had my 9-5 aero for about 9 months now. Though, for my first 3 months, not realizing I had to put in higher octane, had put regular 87 octance gasoline, rather than 92. So the situation is.....I started to hear sounds *rocks in a can sound. So I made an appntmnt to be brought into to the dealership. They diagnosed it: its knocking. So they drained the gasoline and cleaned something and told me to only put 92 octane from now on. So I have been filling it with premium gasoline for about 6 months now and from time to time, I can still faintly hear knocking when I accelerate up a hill. The sound is faint, though, I can still hear it. What can I do? :-?

Adrian W
6th October 2004, 02:57 PM
I've never heard audible knock on any of my Saabs.

You might want to check that your spark plugs are in good order. They are your 9-5's knock sensors.

If all else fails you might try buying some unleaded 100 octane "street fuel" from a local race shop. If it still knocks on that, what you're hearing may not even be knocking at all.

Does the boost gauge only go about halfway through the yellow section? If the car is detecting knock, and it should, boost should be able to be reduced all the way to base boost (8 psi).

Anyway, if you're going to change the plugs I'd suggest running BCPR7ES-11 plugs. You'll need to change them more often, but they allow the ECU to "sense" knock better. The Platinum on the stock plugs can sometimes, especially when the car is upgraded, interfere with the knock sensing.

Adrian~

XAAMOTTOMAAX
6th October 2004, 03:00 PM
2003 9-5 Aero BSR stage 1...Yesterday full throttle passing between two semi's in second, my engine knocked so bad it sounded like shrapnel in my engine. I immediately reinstalled the stock software until I can get myself to a dyno to check my a/f ratio. Hopefully there were just little rocks bouncing off my exhaust although thats only wishful thinking!

Adrian, my stock 2000 was filled with 87 octane by the dealer when I bought it. It knocked terribly as well. I think knock is a bigger problem than people realize with the B235R engines and surely has a lot (if not everything) to do with the piston failures we hear about.

sherpapike88
6th October 2004, 11:16 PM
I wish I could stay it was from upgrading, though, I have done nothing. I will bring it to a saab specialist tommorow.....scanwest....I hear they are the best in the US. I'll keep you guys updated....

Adrian W
7th October 2004, 03:37 AM
I think the knock on stock B235R's is a result of those nasty Platinum plugs.

The car senses knock through the Ionization of Gasses around the spark plug ... Platinum artificially ionizes those same gasses and could disturb the signal, theoretically anyway. The 6800Hz vibration should still show up in the signal current, but it might be distorted.

On Ca 91 octane (more like the 89 octane elsewhere) my Viggen put down 251 lb-ft to the wheels with only a 12.5-13:1 A/F ratio. No signs of detonation on the plugs. 14.7:1 is worst for knocking, and it actually improves slightly as you go leaner than that, though the power doesn't go up.

Making sure your ignition system is in perfect condition can make all the difference.

Even when my boost is reduced several PSI on hot days, with all the windows down I cannot hear any detonation at all. There must be a malfunction that is causing the detonation.

Adrian~

XAAMOTTOMAAX
7th October 2004, 09:36 AM
The plugs surely had something to do with it in the 2000 as the car had 39k with the original plugs. BUT once I got 93 in the tank the knocking stopped even with those same plugs. My 2003 only has 6k miles and has almost new BCPR7ES-11's.

Simon
7th October 2004, 09:40 AM
There have been several reports of this problem with other BSR tuned Saabs

I think speculation without anything to back it up is a better phrase to use rather than 'reports'.

XAAMOTTOMAAX
7th October 2004, 11:21 AM
Given I have not been on a dyno, there is a bit of speculation on my part BUT there surely was no speculation about the terrible knocking that was coming from my engine. The fact that the car is almost brand new with almost brand new plugs and no other problems whatsoever does not lead me to believe it is my car that is at fault.

Simon
7th October 2004, 11:34 AM
Fair enough. It's not really a touchy subject, but there are always people saying I've heard this and I've heard that and I have yet to see one of these 'rumours' born out by some concrete evidence, that's all.

Adrian W
7th October 2004, 05:50 PM
One of the tuners at Hirsch claims that the Mass AirFlow sensor frequently goes bad.

Since this knocking appears to be a "hit and miss" sort of phenominon, I again would suggest that something is fautly on the car, and that the MAF sensor could easily be the culprit as well.

If you have a friend with a Trionic 7 Saab who's car is NOT knocking, see if they will let you borrow their MAF sensor for a short period to see if it fixes the problem.

Worth a shot?

Adrian~

XAAMOTTOMAAX
7th October 2004, 06:39 PM
anything is worth a shot and if the MAF is to blame, that would be a much more comforting answer than the software being bad. I truley believe it is not likely for a MAF to fail in less than 6k miles but when dealing with machines, anything can fail. I don't have any MAF to swap...given the car is under warranty, I can have it checked at the dealer.

but dont forget...according to WIS, the MAP sensor is resonsible for fuel mapping during rapid load changes :wink: now, wheres the peanut gallery to pelt me with rotten tomatos for speaking such MAF blasphemy! :cheesy: oh yeah they hide on another forum. :lol:

I have been running an oiled JR filter for about 3k miles...could be the culprit!

Adrian W
7th October 2004, 07:05 PM
"I have been running an oiled JR filter for about 3k miles...could be the culprit!"

Indeed ... might try some carburettor cleaner. Sounds risky, but I took the risk and have since had no ill effects. I'd imagine it to be riskier on your engine not to keep those PTC resistors clean somehow. Electrical parts cleaner might be better, but I tried that too and it didn't appear to clean well. I think the PTC resistors are built tough enough.

I eventually cleaned mine thoroughly and then went back to the stock airbox, just with a fresh Saab filter and no resonator-snorkle.

Also, when the WIS says "quick load changes", it's referring to quick transitions from off-to-on throttle. The MAP sensor will only be used for maybe 1-2 seconds.

Adrian~

Adrian W
7th October 2004, 09:23 PM
Here's another thought:

Try the 82C degree t-stat from the 9000 Aero. You can order it at www.thesaabsite.com ... and I've noticed that it's significantly changed the sensitivity of my engine (B235R same as Aero) to detonation.

The stock thermostat is an 89C degree unit. The coolant temp gauge will read the same as it levels at 80C, and the T7 ECU doesn't seem to mind one bit.

The swap is also fairly easy. Took me less than one hour. It should help abate knock. Your gas mileage may go down slightly, but I haven't noticed any change. If you can get your fan programmed to come on at a lower temp that'd be good too. I may do that soon. Normally it comes on at 100C (212F) I'd suggest 90-93C (194-200F).

Adrian~

DrBoost
18th October 2004, 02:25 PM
Hej !

The problem with knocking is that what you hear is more of a cosmetic problem, it is actully considered to be normal under some circumstances. It's what you don't hear that can do some really harmful things to your engine.

Well, as the s-plug is being used as a sensor, it's important to use the correct type. Many Saab owners an tell stories that their tuned 9-5's runs better with BCPR7ES-11, compared with stock platinum plugs.
This is true, because the BCPR plugs will "hear" a different noice, it's like wearing earplugs ! This is why the engines runs better, LESS knocking is reported back to the ECM.
Resulting in less ignition reatardation and boost reduction.
If this is good or bad, well guys, this time you will have something to think about before going to sleep.

We also know that airmass meters can be upset by cotton filters like JR, K&N and others. IF you're luck, it can be cleaned with some "electrical solvent".

I also really recommed that you use good gas, with higt octane ratings, as written in the owners manual.

There is a lot that can be written in this subject, but I have other things to do this evening.

XAAMOTTOMAAX
18th October 2004, 03:24 PM
I don't know what to make of that post to be quite frank. On one hand I have everyone from different tuners to other Saab owners to my Saab dealer giving me the ok and thumbs up on the copper plugs and now I have a Saab engineer (notedly conservative in his approaches) telling me the exact opposite. What is the difference between the two that causes a different ion sensitivity? I thought there was a difference in heat and a difference in longevity. Someone tell my why there is a difference otherwise or why a difference in heat or longevity would alter ion sensitivity.

I can appreciate inaudible knock being dangerous but have a hard time dismissing the sounds I heard as "merely cosmetic" or "normal under some circumstances". If I am missing something here, please let me know what you are referring to or why this would be considered normal.

The air mass meter theory is a valid one but with only 3k miles of use with said JR filter, I HIGHLY doubt this created the issue. Keeping the MAF clean is important however and going back to a paper filter is not out of the question.

PCV venting to atmosphere is another modification I have considered for later down the road. Dr. Boost, any comments on Saab's lack of quality assurance in regards to head bolts loosening over time? Everyone knows about the PCV issues but recently a correlation was made between the loose head bolts, increased oil blow by and clogged PCV lines. Is the PCV update merely a "band aid" fix for a larger problem (loose head bolts)? It goes something like this...

Loose head bolts lead to increased oil blow by which could lead to 2 things..

1. overpressurized crankcase from clogged PCV lines
2. reduced fuel octane from increased amount of oil and fumes in the intake air

loose head bolts...a possible correlation with piston failure in B235R applications?

I would HOPE my head bolts would not have loosened after only 6k miles so I again highly doubt this has anything to do with what I experienced. It is brought up more for the sake of general discussion.

Dr. Boost I know questioning the quality of the Saab factory and engineering staff will "light a fire under your britches" and hopefully stir you to put aside part of your busy evening to discuss these matters here on the forum. As always thank you for the input and discussion.

DrBoost
19th October 2004, 03:27 AM
Hej !

a) About plugs, I understand why tuners say thay you should use the BCPR7ES-11, the engine runs better.
Maybe they do not know or do not whant to tell you about the spark plug function ?
But to answer a question that most Aero owner ask ?
Q: Will my engine be damaged if I use BCPR7ES-11 ?
A: Normally, probably not.

BTW: Using a BCPR plug vs. a fine tip double platinum will result in a LONGER ignition delay and a slower pressure bulid up. This is the same thing as retarding the ignition timing. You know the result of that, right ?
The stuff that the tips are made of and the shape will alter the ion sensing, not primarily the heat range.

b) Knocking, as I read my post, I see that I need to comment.
Constant (audible)knocking is a sign that something should be done to avoid knocking. Intermittant knocking can normally be considered to be "cosmetic".
And difficult to avoid. Modern engines runs very close to the knock limit.

c) About oil film on AMM elements. I know that it happens, too many owner think that using a lot of oil when oiling the clean filter is better This can casuse an oil film on the AMM elements, causing a false reading. I use a Saab paperfilter in my 9-5 Aero.

d) I can not comment "lack of quality" related q's.

e) The PCV-fix is not a band aid for loose head bolts.
Loose head bolt will cause a much bigger problem....
Personally, I recommend that the bolt should be retighted when the new car has been driven for a while.
(Do not do this too early)

Adrian W
19th October 2004, 03:44 AM
Well, as the s-plug is being used as a sensor, it's important to use the correct type. Many Saab owners an tell stories that their tuned 9-5's runs better with BCPR7ES-11, compared with stock platinum plugs.
This is true, because the BCPR plugs will "hear" a different noice, it's like wearing earplugs ! This is why the engines runs better, LESS knocking is reported back to the ECM.
Resulting in less ignition reatardation and boost reduction.

The reason I think platinum plugs are a poor choice in the Saab ECU is because Platinum artificially Ionizes Carbon Monoxide (an end gas in combustion) because it is an oxidation catalyst. (More about why that's bad later.) Carbon Monoxide also has a tendancy to "stick" to the platinum catalyst until there is Oxygen to complete the catalyzation to CO2. That oxygen may not be available during the stages of combustion where knock occurs.

The exact current flow across the spark-plug gap is the parameter used to detect knock, and this current is dependant on reaction rate, and cyllinder pressure. The sudden "spike" in cyllinder pressure at 6800 Hz (or therabouts) when knock occurs, causes a corresponding "spike" in current at the same frequency.

Here's an image that shows what knock looks like in relation to cyllinder pressure:

http://www.aquamist.co.uk/info/images/knockcrankcycle.gif


And here's an image that shows the relationship between the current signal from the Saab ECU and that previous pressure trace:

http://img.photobucket.com/albums/v14/SaabTuner/IonCurrent_vs_Pressure.jpg


See how the pressure that the ECU "sees" is based on the current flow? If Platinum artificially ionizes the CO, this current reading will no longer be directly related to cyllinder pressure, and thus the ECU may not get an accurate reading. Based on response from tuners I would say this is the case. It may in fact be the case that the platinum plugs both cause the ECU to not see knock it should see in some cases, and see knock where there is none in others.

Good reading: http://www.fs.isy.liu.se/~larer/Projects/main.html#SECTION0003

FWIW, a cooler PFR7H-10 is still within the specs for the B235R, and as long as it isn't getting fouled (check frequently if you're not sure), it should slightly reduce the interferece of platinum since cooler platinum doesn't oxidize as well; hence the need for catalyst warm-up.

But that's really just for the REAL skeptics. :wink: I've had no trouble with the BCPR7ES-11's ... and so far, no one else I know has either. It may in fact be the case that the PFR6H-10 plugs are like "wearing ear-plugs", rather than vice versa.

No definitive answers yet; and I've heard no correlation between blown engines and running either plug. Just theory, and some good reading!

Adrian~

Adrian W
19th October 2004, 04:01 AM
BTW: Using a BCPR plug vs. a fine tip double platinum will result in a LONGER ignition delay and a slower pressure bulid up. This is the same thing as retarding the ignition timing. You know the result of that, right ?
The stuff that the tips are made of and the shape will alter the ion sensing, not primarily the heat range.

b) Knocking, as I read my post, I see that I need to comment.
Constant (audible)knocking is a sign that something should be done to avoid knocking. Intermittant knocking can normally be considered to be "cosmetic".
And difficult to avoid. Modern engines runs very close to the knock limit.

I didn't know about the delay. It must be something platinum specific, or ignition system specific, as a larger tip requires a higher ionization energy, and should make a hotter spark, hotter spark usually means a sharper flame development angle, and thus earlier Peak Pressure Position. Buuuut ... maybe the ignition system takes longer to build that energy? That makes sense. Either way.

I agree about audible knock on most cars ... maybe some people just "hear" it better than others? I've yet to hear it on mine, and I KNOW for a fact that it is pulling timing, and boost from knock, so there is definitely knock occurring.

I was under the impression that Saab ECU's usually detect knock well before it becomes audible these days. That's been my experience with them ... but maybe I just don't hear knock easily.

Also, the Saab ECU will retard the ignition first when it detects knock anyway, so if your car is already knocking, putting plugs in which have the same effect will result in the ECU advancing the timing until it hears knock again. Either way the ECU should still arrive at the same cyllinder conditions IMHO.

Just more theory though. On both sides, and I do so love playing devil's advocate. :D

Adrian~

Adrian W
19th October 2004, 04:26 AM
Sorry to make some many replies at once. :oops: Just one more thing to add ...

The the shape will not hurt the ion sensing, and platinum is a worse material for Ion Sensing than Nickel, which is what is normally used for plug tips.


Yes, it will alter it, but based on all the doctoral research I've been able to read at Linkoping University, the shape doesn't affect it very much. This is theorized (by the individuals writing the papers) to be due to several things (If you like I can try to take exact quotes/images later.):

1. The electrical fiel exists throrought the combustion chamber, and not just at the sparkplug. All of the metal surfaces exept the center electrode will pick up the + ions because they are connected to the - side of the electrical system. This was proven by a combustion "bomb" where some of the ion current spiked when the wave reached the bomb's walls.

Normally it was assumed that no ions could be picked up on the cyllinder walls without the corresponding opposite ions being picked up at the plug tip to constitute a "circuit" ... but again this was proven false; probably due to the artificially induced voltage bias between the center electrode (positive), and the outer electrode (negative), the latter of which is connected to the cyllinder head, and thus the battery, which acts as a "buffer" and allows significant current flow in one direction for short periods.

2. The actual tip-diameter which constitutes the gap is not the only place where the field exists (just the place where the spark jumps), and even the exposed sides of the electrode pick up current. Usually, the total exposed surface area of two similar heat-range plugs is more or less the same.

3. Detonation only needs to be a "spike" as described before. Therefore, even if the sensor were slightly less, or slightly more, sensitive, as long as it is sensitive enough to discern the 6800 Hz "spike" it will be able to detect knock adequately. [b]The reason I think platinum will affect this adversly is because the rate at which it oxidizes CO->CO2 is variable, and that reaction not only generates current in the platinum, which could show up as noise by the ECU, but it also varies the rate at which the CO buffers the plug from seeing some of the current.

Also under #3, the "spike" in pressure will produce current against the walls of the cyllinder, against the piston, and against the cyllinder head. All of which will pick up additional + ions at exactly the frequency of the "spike". So the function of the system is not compromised by a sight change in plug size or material, as long as the resistance across it is roughly the same, and it does not have any unusual characteristics. (Like platinum's tendancy to catalyze CO, which I would consider an "unusual characteristic" ... )

Again though ... just more theory. This is something which has facinated me for some time, but there's still no way to know with 100% certainty if platinum will significantly affect the IGS system or not.

Adrian~

DrBoost
23rd October 2004, 10:46 PM
Hej !

It's a quarter to five in the morning here, belive I'll have to go to bed soon...
But, just one comment, maybe it's at matter of definition of words....

Tha shape of the electrodes do affect the "knocksensing".

Adrian W
15th November 2004, 02:20 PM
Hej !

It's a quarter to five in the morning here, belive I'll have to go to bed soon...
But, just one comment, maybe it's at matter of definition of words....

Tha shape of the electrodes do affect the "knocksensing".

That was proven false in 2000. You can read the full explanation on page 10 here: http://www.fs.isy.liu.se/Publications/Lic/02_LIC_962_IA.pdf

The Yoshiyama-Tomita model was able to sucessfully prove that the second flame peak, which is used for detonation detection, is not related to the spark plug.

Here's a quote:

"The first ion peak (not generally used for detonation sensing) appears when the flame is near the spark plug in all cases. The second peak appears only for the case when the [cyllinder] wall is connected to the negative electrode and when the flame reaches the wall."

Because the actual "ion sensing" is done by the cyllinder walls, and not the spark plug itself, the actual shape of the plug has minimal effect on the current.

Saab, and Mecel AB based their theory on the Saitzkoff-Reinmann model, which is older and obsolete.

Even if you were to use a drastically different plug, the cyllinder walls would still send the knock signal to the ECU. Of course, the BCPR7ES-11 plugs aren't drastically different, so they should definitely be ok from a purely detonation sensing standpoint. :D And the later, but hotter, spark should raise the flame development angle enough to compensate for any delay.

Sorry to post again so late. Took me a while to find that paper again. :oops: I knew I had read this, but couldn't remember where. (I've read quite a few of the doctoral dissertations from Linkoping. Very good reads!)

Enjoy!

Adrian~

DrBoost
23rd November 2004, 10:54 AM
Hej !

It was proven to be correct back in -87, and still is. 8)

zetor
9th December 2004, 08:44 AM
Hej !

It was proven to be correct back in -87, and still is. 8)

After the distinguished comments and arguments from Adrian W, I'm a bit disappointed in this reply, it's almost as if I would say "my dad's stronger than yours", no offence. Is there some evidence/facts to back this up? :suprised;

-zetor

Turkish Aerolines
29th September 2008, 05:49 AM
I found this old thread while trying to figure out which spark plug is good for a stage 3 tuned engine. I currently have factory spec PFR6H10.

erh7771
30th September 2008, 12:27 PM
EVERYONE!

There's gas shortage in the SouthEast part of the country and non reputable station owners are swapping gas.

Al's Red Wagon
30th September 2008, 01:26 PM
Thanks for the warning...but our cars can handle 87 with just lost performance...

the 6 in your part number refers to temperature...there are 7's and 8's(i think) out there...since they are so cheap and easy to change, I'd get a set of all three and test the differences...

B~P
30th September 2008, 05:00 PM
i can vouch for the gas woes here in atlanta over the past two weeks. couldn't find gas anywhere in the metro atlanta area last week at all, and this is not an exaggeration. the 8 or 9 gas stations i pass between work and home were bone dry. and the few stations that were lucky enough to get some had long lines and were empited out within a matter of hours. people were trailing tanker trucks on the highway like a funeral procession. and to top it all off all we're getting is 87 octane! :( no word on when premium is coming back. :cry:

luckily the reinforcements started coming in today and things aren't as dire as they had been.

Thanks for the warning...but our cars can handle 87 with just lost performance.....

true our cars will run on 87. but there are some unscrupulous station operators trying to make and extra buck by passing of 87 as 93. for those of us with tuned cars this could be damaging if we're pushing it hard with 87 in it.

i haven't seen any 93 available anyway, so my stage 3 aero is getting babied as long as 87 is all we have. and when we do get 93 back i'm changing oil, filter, spark plugs, might even do the fuel filter. and even then i'll probaly run a few tanks through before i return to the "normal" pedal to the floor mat driving style. :cheesy:

Raven18940
1st October 2008, 12:12 PM
I found this old thread while trying to figure out which spark plug is good for a stage 3 tuned engine. I currently have factory spec PFR6H10.
Use whatever plug your tuner recommends.

erh7771
1st October 2008, 03:57 PM
Thanks for the warning...but our cars can handle 87 with just lost performance...

the 6 in your part number refers to temperature...there are 7's and 8's(i think) out there...since they are so cheap and easy to change, I'd get a set of all three and test the differences...

Would mixing some E85 in up the octane any?

Al's Red Wagon
1st October 2008, 07:48 PM
No idea...:confused:

wiSpeel
1st October 2008, 10:43 PM
Hi guys.....I've had my 9-5 aero for about 9 months now. Though, for my first 3 months, not realizing I had to put in higher octane, had put regular 87 octance gasoline, rather than 92. So the situation is.....I started to hear sounds *rocks in a can sound. So I made an appntmnt to be brought into to the dealership. They diagnosed it: its knocking. So they drained the gasoline and cleaned something and told me to only put 92 octane from now on. So I have been filling it with premium gasoline for about 6 months now and from time to time, I can still faintly hear knocking when I accelerate up a hill. The sound is faint, though, I can still hear it. What can I do? :-?

It would make sense to replace your spark plugs and do an oil change after that..

DrBoost
3rd October 2008, 06:36 AM
A blast from the past...
After the distinguished comments and arguments from Adrian W, I'm a bit disappointed in this reply, it's almost as if I would say "my dad's stronger than yours", no offence. Is there some evidence/facts to back this up? :suprised;

-zetor

Let me just explain one thing, were I work I have access to information not intended for the public, (also known as secrets) so some times you just have trust me...... This is the way it is, I hope that you all understand.

DrBoost
3rd October 2008, 06:40 AM
Would mixing some E85 in up the octane any?

Adding E85 (or ethanol) as an octane booster should, in general, be avoided. UNLESS you have done the proper adjustments and hardware replacement.

A "normal" Saab will with no problem handle an etanol content of 10% by volume. However, if it has been tuned this may not be true, the ethanol will make the engine to run leaner, possibly causing ill effects... :nono;

Raven18940
5th October 2008, 11:44 AM
That was proven false in 2000. You can read the full explanation on page 10 here: http://www.fs.isy.liu.se/Publications/Lic/02_LIC_962_IA.pdf

The Yoshiyama-Tomita model was able to sucessfully prove that the second flame peak, which is used for detonation detection, is not related to the spark plug.

Here's a quote:

"The first ion peak (not generally used for detonation sensing) appears when the flame is near the spark plug in all cases. The second peak appears only for the case when the [cyllinder] wall is connected to the negative electrode and when the flame reaches the wall."

Because the actual "ion sensing" is done by the cyllinder walls, and not the spark plug itself, the actual shape of the plug has minimal effect on the current.

Saab, and Mecel AB based their theory on the Saitzkoff-Reinmann model, which is older and obsolete.
Ok........ so if this is true this invalidates your argument that the platinum plugs are muffling the sensing due to CO sticking to them.

Even if you were to use a drastically different plug, the cyllinder walls would still send the knock signal to the ECU. Of course, the BCPR7ES-11 plugs aren't drastically different, so they should definitely be ok from a purely detonation sensing standpoint. :D And the later, but hotter, spark should raise the flame development angle enough to compensate for any delay.
I fail to see how the copper plug is going to generate a hotter spark than a platinum.

Reasons:
1. Platinum conducts better than copper. So less energy is spent moving current around and more goes straight into the spark itself.
2. The electrode on the platinum plugs come to a fine point. The same charge condensed on a single point will jump a gap better. Again, less energy spent trying to jump the gap and more energy in the actual spark itself.
3. The DI uses a capacitor based ignition event, meaning it charges and then fires all the energy in one shot. So each spark event has a predetermined amount of energy. So the less energy spent in the plug itself (conducting) and trying to jump the gap (finer point) the more energy will be in the spark itself.

Conclusion:
The platinum NGK plugs will generate a more distinct and hotter spark event and thus is supperior choice. If you have a highly tuned car, use a PFR7H10.

Turkish Aerolines
5th October 2008, 02:01 PM
If you have a highly tuned car, use a PFR7H10.

I believe this statement is true for stg3+ and still platinum is the way to go.

Jssaab
5th October 2008, 09:23 PM
Thanks for the warning...but our cars can handle 87 with just lost performance...

the 6 in your part number refers to temperature...there are 7's and 8's(i think) out there...since they are so cheap and easy to change, I'd get a set of all three and test the differences...

AL not on tuned cars can handle 87 ( and we are talking tuned car here) belienve me ( especially my BSR tune)