I've had my Jun3's in my ITR for over a year plus with zero problems. I am running the JUN ECU, with an adj FPR and a mugen thin headgasket. The Jun3 setup has been perfect, and I love it. However, yesterday I was merging on the Interstate and I punched it around 5500rpm's, and noticed a something that sounded like a bunch of tiny rocks bouncing around in my engine. I couldn't figure it out, then it dawned on me it probably was detonation. Has anyone had this problem? Is this the likely problem?

I find it strange all the sudden it's doing this. I would like to fix the problem before it leads to anything bigger. I live in the PNW so warm weather isn't the factor either.

Any suggestions guys?

 

bad gas? definitly sounds like it was detonation, knew all about that with my R

 

How can you correct this problem? I think I may be experiencing this same sound.

 

have you ever dyno'ed the car? what was the a/f ratio? i turned fuel pressure up a bit for the winter

 

I can't recall the A/F ratio offhand and don't have the dyno plot on hand. What are potential problems which may arise if this problem is not corrected soon?

 

if you had it on a dyno, that kinda indicates that decent a/f ratio was there at the time. i don't know which potential problems may arise from this, but make sure its not your exhaust/heatshield rattle/other parts rattle.

 

I've had the mods for a while now and I think these sounds have been around for a while, if nothing has happened yet, should I be concerned about problems arising? Or does it take a while for the detonation to create problems?

 

Did you check your timing and spark plugs ?

 

Check your cam gears also.

 

What should I look for when I check my spark plugs and cam gears? My cam gears (Toda gen 2) are set at 0,0

I don't think its any of my heat shields or exhaust ect, it only happens when I floor it. I also have not dynoed my car since I put the Jun3's in. It's been running in tiptop shape for the past year. I want to correct this problem ASAP. Thanks for all the help guys.

 

What's your compression?

What heat range are your plugs?

 

If you get too much predetonation you could crack a piston, which leads to other problems. Of course the tolerances of engines vary, it would be nice to hear someones experience with B18C5's. hint hint

 

[QUOTE]What's your compression? [QUOTE]
I have stock compression.

What do you guys mean check cam gears and spark plugs? Cam gears for rattle and spark plugs for being burnt, I assume?!?

 

Hey, it has been really cold, dense air in our area over the last week, which could contribute to any detonation.

The only thing I can think of that hasn't been mentioned yet is that your timing belt may have jumped a couple teeth.

 

Check to see if the cam gears slipped and are causing the knock. I created this problem on the dyno pretty easily.

 

get it back on a dyno and check the numbers rather than just guess at what may be causing it. if you are able, turn back the timing some and see if it still does it. If its pinging you will be able to fix it with either timing or fuel adjustments.

by the way, if you are running a mugen gasket, your compression is no longer stock. im pretty sure you knew that and probably meant your compression was stock because you still have the stock pistons.

 

How often do you tune up your car, what gas and compression are you at?
If it was me I'd first give my car a complete tune up you know plugs, wires, distributor, redo valve lashing, check fuel pressure and replace the fuel filter.....Do a compression test and last check you timing

 

Since this problem just popped up recently after over a year without problems it is probably something relatively easy to correct. I doubt the timing belt jumped a tooth, as that would have been obvious as soon as you started the car.

Things to check would be spark plugs, fuel filter, fuel injectors, timing setting, cam gear settings (possible slippage of the intake cam gear can screw with your ignition timing), O2 sensor. Somebody else mentioned bad gas, which is also likely.

Check all of your heatshields too. You never know. A heatshield can rattle at specific rpm.

Detonation can kill an engine instantly. I'd advise a prompt check-up.

 

Thanks everyone. I'll be checking things out, and i'll get back with you.

My compression #'s should not even be an issue. I am at 11:1 at the very highest, which should be NP on 91 pump gas.

 

Stock is 10.6:1, Mugen claims an increase of 0.4 in your compression...so according to them you should be 11.0:1...I believe that it's closer to 10.9:1...but that's me.

Austin

 

Yeah, it looks as though I will be taking my car to a good friend/mechanic and having him look at all the parts (cam gears, spark plugs, heat shields, etc) and then to the dyno to get it retuned.
Anyone have any suggestions to where I can get my Power FC tuned near Santa Monica or Thousand Oaks? Thanks for the help guys.

 

DO it yourself at the dyno with a wideband. We can help you on the power FC list.

 

I would do it myself but I don't have the Commander unit that goes along with the Power FC, I tried to save some money back in the day (1 year ago) when I bought it and now I'm kicking myself.

 

I forgot to mention, I am using Denso Iridium plugs, I should prolly switch back to stock though, it's about time to switch anyway.

 

So buy one now. Or if you are near TN I will be happy to help you tune it with my commander.