Hmmmm...Detonation.

[cjthor]

oookay.. Car runs fine all the way to 11 pounds..After that I think im getting detonation. Can anyone tell me what it sounds like exactly? Kinda like a bad bearing noise? marbles in the engine? Anyone with an ear for destruction should know this. Thanks!!!

[natural born honda killer]

well when mine detonated i didnt hear anything which is the wierd thing. it just all of a sudden had no power. def make sure its not det as im having to replace pistons and rebuild motor and its not fun. def get it checked though to make sure. ive heard that its kind of a knocking sound. if that helps.

[maldo]

Set your boost to 8psi, go to your local speedshop and pick up an EGT gauge. This is the best tuning tool that you can possibly use, far more useful that a few lights moving back an forth. Once you have the gauge installed, tune for 1550' at WOT at 12psi and go from there.

[boostedmx]

it will loose all power and sounds like your valves are out of adjustment. almost like marbles are in your cylinders

[cjthor]

Marbles definately. Also I do have an egt sensor but i never get over 1200. Ill try a lil more tonite. Thanks for the info fellas!!!

[maldo]

Where is your probe mounted? I was hitting 800' at warm idle, 1250-1350 cruising and 1500 at full wot at 12psi with the probe mounted in cylinder #1 using the heatshield bolt hole. Now that I am n/a, I am still hitting 1250 cruising spiritedly.<p>What is your timing set at? Bad fuel or has this happened before? Try an octane booster and see if the symptoms persist.

[Manach]

Humm, interesting dicussion here..<p>On my new engine, I'll install the probe on the GT-X Manifold, that's what I was suggested at Flyin' Miata.. They use the same engine, and there gauges are not that high.. They got the A/F and EGT in the same Gauge.. <p>Is it close enough? My O2 sensor will be move in the Downpipe.<p>To lower the temp, I know that we need to add gaz, with a FMU or Piggy.. I order an Apex'i to adjust that.<p>And about octone booster, choose wisely. As some claim a boost by 4 pts in octane, but really do 0.4 pts..

[JWMotorsports]

You can still detonate even when running the correct air/fuel ratio. What happens in this case is that the cyl pressure has rissen sooo high you ignition will fire before the piston even gets to TDC. Thats why you have to retard the timing. Higher Octane gas helps you run the timing a bit more advanced because the higher the Octane, the slower the burn. It's kinda like retarding the timing but gives you a longer more stable power stroke. You CANNOT tune soly on boost pressure. The reason being that a small turbo at 12psi would flow LESS air than a BIG turbo at 8psi, just depends on which turbos you compair. The key here is CFM's per pound of boost. Not to mention that a T3 at 12psi is putting a MUCH cooler charge into the engine than the VJ-14 at 12psi. <p>To fix your problem you need to do as the guys have told you (make sure your Air/Fuel is Stoich). I'd recommend running a hair rich in a street car (runs cooler and better gas milage). Do this a 9psi or so. Then SLOWLY increase boost little by little, correting the mix back to Stoic. If you start hearing detonation (marbles, loose change etc... in the motor) retard the timing until it goes away. You are most likely to detonate at higher rpms in 4th and 5th gear. Thats where you need to do the final tuning. Once you get rid of it then your good to go, just keep listening.<p>MSD & HKS both sell knock SENSING devices. How ever for a pretty penny you could go with the J&S Knock Gaurd system which will automatically correct timing accordingly to knock so you motor will be safe. Your other bet is to swap in the 90-94 323GTX ECU.<p>Good Luck!