Power loss - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Jay B. · 02-12-2016, 10:48 AM

I took my 2000 S in the other day to well know Porsche mechanic in my area because my spark plug tubes were seeping so he said lets change out the spark plugs as well since they looked aged and oily so I said do it so when I got the car back I noticed some power loss especially on the top end.
When I took the car in before the work the car ran great with lots of power so now it has lost that burst of power it use to have. I questioned the spark plugs he put in there and he said he replaced my 2 prong NGK's with some 4 prone Bosch spark plugs and he said that the spark plugs he put in there would have nothing to do with the power loss so he ran all kinds of tests and the MAF was fine and nothing was found of any vacuum leaks so then he tells me the computer in the car needs to basically reset itself to run right again. Is this BS or is this true?

jb92563 · 02-12-2016, 11:13 AM

Resetting the computer couldn't hurt but replacing Plugs should not cause a power loss or NEED the computer to be reset.

So reset the computer and I think your car is also eGas electronic gas pedal and it needs to be reset as well. (Search the forum for the simple DIY procedure for that)
Drive it for a couple days and see if it comes back to its previous power.

I would suspect the MAF first if power is not what it used to be, those things are so fickle just looking at them wrong could lose you HP.

thstone · 02-12-2016, 11:53 AM

Could be true.

If the old plugs were worn, the timing and fuel mix might need to be re-optimized for the new plugs. Not likely, not normal, not typical; but theoretically possible.

I'd drive it for a hundred miles or so and see if the ECU re-adjusts and the power comes back. If not, I'd take it back to the mechanic.

stelan · 02-12-2016, 01:09 PM

Unless the mechanic left them loose

Jay B. · 02-16-2016, 09:29 AM

Update.... so I put a few hundred miles on my car since I had the new spark plugs installed per my mechanic's advise to let the car basically reset the computer and my S still does not have that burst of power it use to have before the new plugs were installed. I called the mechanic today and he advises we change the MAF out and see if that takes care of the power loss. I still think the new 4 prong Bosch spark plugs might have something to do with it because that's all they did to my car but I don't know. Fingers crossed a new MAF fixes my power loss.

Lapister · 02-16-2016, 10:35 AM

I would go back to the plug type you were running. I've had the same issue on another car, went from NGK to Bosch and resulted in power loss. Went back and have always stayed with oem plugs. It's probably a heat range issue. It's not too hard to get to them from below the car. Loosen hold down bolts for coil pack, pull out then replace plugs. If your car is running fine I would pass on Maf clean, different plugs as long as they are firing properly will not show Cels anyways. I really think your mechanic has good intentions but plugs are all different. You noticed a difference and it may be other drivers just never do.

Dlirium · 02-16-2016, 11:06 AM

Quote:

Originally Posted by Jay B.

Update.... so I put a few hundred miles on my car since I had the new spark plugs installed per my mechanic's advise to let the car basically reset the computer and my S still does not have that burst of power it use to have before the new plugs were installed. I called the mechanic today and he advises we change the MAF out and see if that takes care of the power loss. I still think the new 4 prong Bosch spark plugs might have something to do with it because that's all they did to my car but I don't know. Fingers crossed a new MAF fixes my power loss.

do keep us updated on this...was about to change to bosch plugs myself

jb92563 · 02-16-2016, 11:11 AM

I just went back and checked which plugs I installed in 2014. Got them from Pelican

Bosch Spark Plug - Bosch FGR-6-KQE, (7413), Beru 14 FGR-6 KQU, NGK BKR6EKUB (7969)
Part #: 999-170-207-91-M14

They run great and I have not had any issues with them.
I did not notice any change in power when I swapped out the old ones.

RandallNeighbour · 02-16-2016, 11:45 AM

If the mechanic didn't get those coil packs fully seated on the spark plugs and tightened down properly you'd experience a power loss... I'd have him recheck his work first before doing anything else.

Jay B. · 02-16-2016, 01:16 PM

Yeah when I took the car back the second time they did look over their work and nothing was found and that's when they ran all the tests for vacuum leaks , MAF functionality etc. I'm no mechanic in any way but I'm just putting 2 & 2 together but the mechanic is so adamant that the plugs would have nothing to do with the power loss even though they are different plugs then what was in there before and once again it ran like a champ when I brought it in. I know parts can fail at anytime but its just weird that I noticed the issue when I got the car back. They still have my old NGK's so I may have them put them back in there and see if that changes anything. I'll keep everybody updated on this issue because I'm not going to settle until they put the " S " back in my car.

The Radium King · 02-16-2016, 02:07 PM

where is the power loss happening - low rpms? at hgher rpms? when hot? can you still feel the cams roll over? is the resonance flap still actuating? rag stuffed in the airbox? knock a connector off an injector?

Lapister · 02-16-2016, 02:21 PM

Did you know that there can ONLY be ONE ARC at a time when your spark plug fires????
Sorry, but you will NEVER EVER have two, three or four electrodes fire at once.
It's called " Physics". Take out a plug and lay it on your engine block and see for yourself. Just have a friend crank your engine and see. Go ahead.
Thats why a single electrode is the hottest most efficient source of spark.
The double sand quads only have an advantage if the plug becomes "fouled" on an electrode.
Then one of the others will be able to continue in a best case scenario.
My friend is an engineer for NGK. He's the one who told me all the skinny on this.
All of it is Marketing to sell more expensive plugs to people who are not informed.
Now you are informed.
Don't waste your cash.

I am not the author, i just copied from another forum! I am in no way saying this is your case. Just things to consider.

jb92563 · 02-16-2016, 08:29 PM

I often wonder if the spark is "sheltered" a bit under the single electrode vs the fully exposed spark of the multiple electrode style, makes any difference in the combustion process?

Also wonder if the Platinum coated plugs effect the combustion process, since platinum may change the process somewhat acting as a catalyst?

I suspect the differences may be negligable and more of a new and more expensive is better marketing strategy.

I suppose the racing guys here would know whether there are any gains to be had by the different types of plugs?

Dlirium · 02-17-2016, 08:29 AM

Here is an interesting theory, but potentially irrelevant :-)

Gap makes a HUGE difference in older cars. I have a 351 Cleveland in a 1972 Pantera. Changing the gap from the traditional 35 thousands to 45 thousands yielded a LOT more power. Mostly due to the modern MSD ignition that can handle the larger gap, but just that would easily account for the equivalent of an "S" vs a base in power...

I know the plugs come "pre gaped", but may be worth comparing the NGK's to the new Bosch?

BYprodriver · 02-17-2016, 01:21 PM

Quote:

Originally Posted by Lapister

Did you know that there can ONLY be ONE ARC at a time when your spark plug fires????
Sorry, but you will NEVER EVER have two, three or four electrodes fire at once.
It's called " Physics". Take out a plug and lay it on your engine block and see for yourself. Just have a friend crank your engine and see. Go ahead.
Thats why a single electrode is the hottest most efficient source of spark.
The double sand quads only have an advantage if the plug becomes "fouled" on an electrode.
Then one of the others will be able to continue in a best case scenario.
My friend is an engineer for NGK. He's the one who told me all the skinny on this.
All of it is Marketing to sell more expensive plugs to people who are not informed.
Now you are informed.
Don't waste your cash.

I am not the author, i just copied from another forum! I am in no way saying this is your case. Just things to consider.

Don't test spark visually on any late model vehicle, the spark intensity will damage you &/or the vehicle!

Electricity, like water & most humans will seek the easiest path. The spark arcs to the easiest ground which is a clean sharp edge. As the arc wears the edge, the spark degrades. Having additional electrodes to ground on gives more surface area to wear, potentially extending peak performance life. Superior plug materials should last longer too.

OE Boxster plugs are 4 prong, so are my wife's Lexus V-6.

I have never replaced worn plugs with new & not noticed a performance improvement, especially cold starting.

To the OP, I'm guessing your mechanic bumped a spark plug gap during install so he should inspect the plugs.

BYprodriver · 02-17-2016, 01:26 PM

Quote:

Originally Posted by Dlirium

Here is an interesting theory, but potentially irrelevant :-)

Gap makes a HUGE difference in older cars. I have a 351 Cleveland in a 1972 Pantera. Changing the gap from the traditional 35 thousands to 45 thousands yielded a LOT more power. Mostly due to the modern MSD ignition that can handle the larger gap, but just that would easily account for the equivalent of an "S" vs a base in power...

I know the plugs come "pre gaped", but may be worth comparing the NGK's to the new Bosch?

Wider gap allows better combustion, IF the coil etc provides enough energy to bridge the gap.