Well, clearly if there are companies who believed they have found a fix to a pre-detonation cylinder pressure problem then it is very likely something ECU or sensor related rather than something mechanical.

Knock sensor, cam sensor(s), crank position sensor, etc.

I'm also wondering if this is something that happens more in, say, 03s than in 04s. That would also lend itself to being an ECU-related issue.

--Steve

 

I guess time will only tell . . .

*Jeopardy music*

 

Given the block I've inspected there appeared to be no top cylinder damage which would indicate prolonged detonation. A rod shouldn't bend via "detonation" alone and not show some amount of top side damage. Now it is possible that the condition being uncovered is "pre-ignition". Note this is a different phenomena than detonation. Even though detonation may be a pre-cursor to pre-ignition , pre-ignition can exist with detonation. Preignition could esaily bend a rod in a very short interval (even a forged one).

 

I agree....pre-ignition will kill a motor pretty much instantly vs. detonation that can be tolerated for long periods of time and slight detonation is even desirable for max fuel economy/emissions.

Someone better start spilling those beans....

 

Unfortunately, there's no beans to spill. The company is very tight lipped and I am waiting just as you are . . . Could someone regurgitate some of the common reasons for pre-ignition? (Discussion purposes only)

 

Try reading this:
http://www.streetrodstuff.com/Articl...ne/Detonation/

My guesses in SUSPECT order are:
1)Spark plug(run colder copper instead).
2)Ignition firing at wrong time(crank sensor problem?).
3)Hot spot in CC.

 

Not that any other used the J&S safeguard and had failures. Gurgen did. J&S uses a wasted spark to expand the timing conrtroller to 6 cylinders. I have never been a fan of this method. If anything it frys your plugs twice a quickely , but it could also increase the probability for a pre-ignition event. The safeguard can protect against pre-ignition , unless detnation exists as a pre-cursor. Ideally "gate" the signals to support 6 cylinders rather an Diode OR them (aka wasted spark).

 

Correction :The safeguard can "NOT" protect against pre-ignition , unless detonation exists as a pre-cursor.

 

I was considering that also, however few have J&S. I was also considering the eManage ignition "burnt coil" issue, however I don't think everybody has been using that harness/firmware either.

I'm suspect of things that are common to all like plugs, crank sensor recall(at least on VQ35 Maximas), and these new heads.

 

"crank sensor recall(at least on VQ35 Maximas"

now that is very intriguing. ..

 

Looks like it applies to 2003 350Zs also:
http://maxima.theowensfamily.com/tsb/NTB03-124.pdf

 

Dude , I think you really may be onto something.
Just as a CYI, "anyone" in the long block rebuild process should consider a new crank pos sensor.

 

Boost makes torque. Horsepower is a measurement of torque. Motors make torque, not HP. More Boost, more Torque, more Horsepower, More broken rods.

 

Sure, but in my block's case (from Fernadito7) only a few miles at 7psi on a GreddyTT, two rods were bent. No top cylinder signs of detonation, and the crank power levels for such a short interval would unlikely to be the root cause. Now a pre-ignition scenario could explain at least "this blocks" root cause. I am at least going to attmept to test the sensors duing my re-build.

 

god im thinking so hesitently about forced induction now.

any PE Z's blown their motors or just gurgen.
perhaps single turbo is the way.

 

Could you elaborate on the sensor. . . I'm still learning this stuff.

G

 

 

It's a stretch , but there is a TSB on some 2003 VINs to replace the 2xcam sensors and the 1x crank sensor. Apparently they could either act intermittently or fail altogther.

A full failure would render the engine in-operable or even cause a safety issues. It woudl be obvious.

An intermittent could cause many bizarre symptoms. The crank sensor basically indexes "Time zero" for all timing operations in the engine . The ECU uses this input (along with CAM phase sensors to generate all spark timing and injector pulse positions. FOR eaxample the Tach signal is derived from this input. If this signal(s) acted "weird" it is quite possible that.. A boosted engine could turn this burp into a boom. Its all conjecture , just fishing...

 

NICELY said....exactly what I'm thinking.

 

I do not recall the G35s being a part of that recall, anyone know? If that is the case then Gurgen's car may defunct that theory. I am still worried about the heat generated under the hood. It would be interesting if anyone had engine temp and oil temp readings when engine failure took place as heat could stimulate detonation or pre-ignition. Where does everyone live who has bent their rods? Hot climates? Which fuel? Larger oil pans? Better radiators? What about intercooler design? Maybe this is a stretch but this engine/ecu seems to react to heat more than any other car I have owned.