2 topics: Base ignition timing and Seafoam

[Talamascan]

My (latest) mechanic says that the base ignition timing on our engine is 5 degrees (at least in a '93). Is this correct, because if it is, it differs from both the NA and TT 300zx engines (which tend to be from 10 to 15 depending on year).

Also, since three mechanics (including my latest) have now given up on figuring out why my engine has suddenly decided to detonate virtually all the time in medium throttle imputs with good gas, clean MAF, no vacume leaks, good fuel pressure, no CEL or trouble codes and functioning injectors, o2 sensors and knock sensors, I'm now focusing on potential "mechanical" causes.

With that in mind, has anyone here had experience with using Seafoam or something similar in an attempt to clear out suspected carbon or other buildup around their valves, pistons or rings, and if so, did it appear to eliminate the suspected problem? Obviously, in my case, the suspected problem is buildup causing hot spots leading to premature detonation. I do not appear to have a sticking valve, but if the treatment appeared to alleviate such a condition, I'd love to hear about it.

[swimshark]

its 15 degrees btdc. check to make sure the cas is in tolerance.

[yodawill2000]

If your J is set to 5 BTDC then "there's your sign"

[Talamascan]

Agreed. It's nice to be right sometime. I actually told the mechanice that I thought that it was 10-15 degrees BTDC because of what the Z cars run, but he insisted that it was 5 in the J.

Good mechanics are hard to find...

[yodawill2000]

Not sure where you live T but any sizable city is bound to have a Nissan shop that see's many a Z32 roll through.

[Talamascan]

I live in Honolulu, and would rather kill myself than go to the lone Infiniti dealer. Guess I'll start looking at the various tuner shops to see which ones work often on Z32s (which are becoming scarce around here).

[Talamascan]

Up date:

Turns out my timing is within spec, so just for sheits n giggles (and because I'm out of ideas) I stuffed two bottles of Seafoam into my car's throttle bodies, created a mountain of smoke, then drove it like a stole it. Amazingly, the pinging has been reduced by about 70%. Quite astonishing, considering that my car never pinged until 3 weeks ago when I replaced a bad injector and flushed the other injectors. Whatever deposits that were apparently now heating up and causing the premature detonation must have been building up for some time. Go figure.

In any event, Seafoam works.

[the_jay]

Up date:

Turns out my timing is within spec, so just for sheits n giggles (and because I'm out of ideas) I stuffed two bottles of Seafoam into my car's throttle bodies, created a mountain of smoke, then drove it like a stole it. Amazingly, the pinging has been reduced by about 70%. Quite astonishing, considering that my car never pinged until 3 weeks ago when I replaced a bad injector and flushed the other injectors. Whatever deposits that were apparently now heating up and causing the premature detonation must have been building up for some time. Go figure.

In any event, Seafoam works.

I've got a 93 myself and also seafoamed it. Didn't notice the spectacular performance gains you mention but I will say I did seafoam a few times and the latter few, it smoked less so maybe I did get some crud out . I used the brake booster line that goes into the plenum.

Check your PCV valves too. Passenger side is easy enough to get to but the driver's is a bit worse (anyone have any tips on how to get at the drivers side one?) I've gotten one out and it was pretty cruddy and the rubber tube it connects to had so much crud in it that simply turning it on end made crud fall out. Both items are currently soaking in carb cleaner.

[fourdrinie]

to get the driver's side PCV out I used two 3/8 swivel joints to let you make the angle needed to break the pcv valve loose...