[cfg83]

Hello -

More bad news for Pulstar plugs, at least in Saturn S-Series waste-spark ignition systems. I sent my used set to a far more qualified individual than me with the same Saturn DOHC engine on saturnfans.com :

Pulstar Spark Plugs - SaturnFans Forums

I jumped in at post #23 :

SaturnFans Forums - View Single Post - Pulstar Spark Plugs

Results were catastrophic failure :

Pulstar Spark Plugs - Post #28

...
Pulstar Plug Test

Thanks again to cfg83 for providing the plugs for the cost of postage only.

I received them yesterday and installed them this evening after performing some electrical measurements on them, as well as on some NGKs and Bosch Super+ (standard) plugs I have.

The NGKs have the lowest resistance (the internal RFI suppression resistor). The Bosch was in the middle. The Pulstars have almost 4x the resistance each on average (see list below).

The Pulstars also have about 50x the capacitance from tip to connector, and 4x the capacitance from connector to the body as the other two. This immediately raised concerns for me.

Based upon these readings I think I know what they are doing internally and it is not good IMHO.

************************************
Readings for all four Pulstar Plugs (pre-install)-

Resistance- 11.81k, 11.83k, 11.78k, 11.84k (ohms)

Capacitance (tip to connector)- 99, 97, 106, 103 (picofarads)

Capacitance (connector to body)- 40.8, 41.0, 41.3, 41.2 (picofarads)
************************************

Comparison numbers for sample "standard" plugs-

Resistance- 6.27k (Bosch), 3.16k (NGK)

Capacitance (tip to connector)- 2pf (Bosch), 2pf (NGK)

Capacitance (connector to body)- 11.9pf (Bosch), 11.6pf (NGK)
************************************

The high resistance of the Pulstars alone could cause misfires on "S" series cars because there are two plugs in series with each coil AND the plug wires have 6,000-10,000 ohms resistance per wire. So it adds up to around 35,000 ohms, which is a LOT of resistance in ANY coil circuit.

OK, now for the road test.....well sort of......

I gapped the Pulstars at 0.035", exactly the same as the plugs I pulled out (ACs). The literature sent with the Pulstar plugs says explicitly to gap them "per factory recommendations", and that is the FSB gap for my car.

I reset the engine computer as they said to do by disconnecting the battery for about 1 minute. The plugs were installed carefully.

Upon starting the car it IMMEDIATELY ran very rough and barely idled. Even so, I pulled it out onto the street and tried to go down the block. I got about 200 feet when the SES light began to blink (hardly a surprise, really).

It ran so poorly that I instantly turned around and pulled it back into the garage. So my test run was a total of about 500 feet.

The code was a cylinder 2 misfire. So I decided to pull the #2 plug and swap it with the #3 plug to see if the misfire followed the plug. The #2 plug was very black and sooty (see photo). I wondered if it was a "polarity" problem since the #2 and #3 plugs share the same coil (as do #1 and #4).

I decided to also re-gap all of them down to 0.032" to see if that might help.

When I tried to pull the #1 plug its ceramic insulator came off completely inside the connector boot.


END OF TEST.....

Now, there was no indication of any problem with the #1 plug before installing it, and I was very gentle with all of them (padded socket, etc). I didn't drop them or anything else.

Upon examining the #1 plug remains it is very clear that it had been arcing badly internally (see photos). This almost certainly cracked the insulator by means of thermal shock. It appears in fact to have been doing that for some time, much longer than was possible in my 1 minute, 500 foot run.

I put the ACs back in, and the car ran perfectly again. Ran it entirely around the block this time and it seems very happy.

So, what can I conclude based upon this "extensive" test run?

1) The plug on cylinder #1 may have been already cracked but this seems unlikely because of its electrical measurements being "within range" of the others, no looseness noted, no discolorations of the insulator, no carbon tracking (internal resistance to ground), etc.

2) The misfire was not on the #1 plug, it was on the #2 plug, and despite being cracked the #1 plug tip is still clean! So the #1 and #4 plugs must have been firing. Also, the #3 plug which shares a coil with #2 was firing.

3) The high resistance of the plugs means that they probably are not good for "S" car ignition systems in the first place.

4) The #1 plug was likely defective from the factory. I can only guess that it was not right from the start, arc'd internally, and it just decided to give up on my car.

5) The #1 and #2 plugs are on the opposite sides of their respective coils. That may mean that they run opposite polarities, or it may mean nothing because of the way the coils are driven. I don't know.

Summary-

There is NO WAY I would recommend these plugs for use in Saturn "S" cars. Period, end of story, not even if more were given to me.:drool:

If cfg83 and I just got a bum plug (or two), for $25 a pop this is totally inexcusable.

Even if I assume that the #1 plug breaking was a fluke, the #2 plug was the one that misfired terribly!! So #2 was not working right, #1 cracking is just another defect.

cfg83 had similar misfires which was why he took them out. Something was wrong with them from the start it seems, at least as used in our "S" car ignitions (waste spark system).

Perhaps the pulse circuit does not like being reverse polarized and cycled back and forth. Maybe given their very high resistance they simply overheat. We'll probably never know.

So, my ultimate conclusion- A poor product at best, snake oil at worst. SAVE YOUR MONEY.

Since they appear to be mechanically similar to the plugs used in our garden tractor, I think I'll take #3 and #4 and try them in it. Who knows, since it is NOT a waste spark system, maybe I'll get 40 lawn cuttings to the fill.....

Oh well, I've spent $5 on worse things and gotten less out of it.

...

CarloSW2