weird detonation issues

[WJM]

ok, my 9.5:1 turbo engine.

 

At high revs, 4500+, i get detonation past that, all the way to where ever I shift. Also, at about 10 inches of mercury (vac), i get detonation.

 

heres the thing...sometimes I do, and sometimes I dont. Does not depend on cold/hot/warm engine conditions, air intake temp, or anything. Its just random. For example, 1st gear WOT to 6k, it will do it, 2nd gear, no...3rd, yes and then no, 4th, yes, 5th, yes...no...yes no...no...yes yes...no yes. Then, either yes until i let off, or no. Its just RANDOM.

 

I was wondering, maybe the disty is a bit stuck on no being able to retard at times? mechanical failure in that mechanism? The knock sensor appears to be doing the job, it works form time to time...when the disty actually retards.

 

Check for loose/corroded connections? I am going to do that. But what about the disty??????? Timing light and tap on knock sensor??

 

Or just slap a different dist in?

 

Ideas/suggestions?

[Do It Sidewayz]

pop the cap off the Disty, and take a piece of emery cloth to the terminals. Clean them off so they are shiney.

 

Try going to a colder spark plug.

 

 

What kind of gauges you have in the car?? EGT?? Air/Fuel??

[WJM]

I certinly WISH i had an EGT or AFR guage....I am already running a colder plug. 6 is what NGK calls for stock...and I put an 8 in it. NGK goes, high number cold, low number hot. Everyone else is bass ackwards.

 

Will do on the terminal cleaning, i have planned to do that. Cold, dark and rainly out right now tho...that better change by the morning so I can get this done before the autocross sunday...

[Myxalplyx]

If you do anything else, please get an EGT gauge. And air/fuel ratio would help also but you need to know just how hot your exhaust gas temperature is getting.

 

You said you are already running colder plugs, how about colder water temp sensor? I dunno, colder plugs, lower water temp sensor and higher octanes are givens and I'm sure you already did those.

 

Do you have anything to retard timing? I haven't went through your old posts to know. I'm starting to think it's timing related since you've hit on other parts. I know my Impreza's timing was VERY aggressive but I didn't notice any detonation. Even still, it loved to push the timing to the limits at the higher rpm ranges.

[WJM]

im running a 180 thermostat as compared to the stock 192, if that is what you mean.

 

I have a 10mm sockect on a long extension and speed handle to retard/advance the timing. Otherwise, the STOCK ECU along with the stock vac advance and stock knock sensor is supposed to be able to play with it by about 5 deg.

[scoobie steve]

Did you wideband the car on the dyno. I am guessing the car is running lean. Try backing off timing by 2 deg's if that doesnt help then i would say its running lean. Try getting a FPR and cranking up fuel pressure a bit, or a rrfpr. Egt isnt the best tuning tool, many things can cause high egts and who is to say what is too high. 1550-1600 about a inch from exhaust port is pretty hot. A wideband is a much better tuning aid! An air/fuel gauge is useless, dont bother.

[WJM]

I wonder how many times we have to say that the EA82T runs rich. No, no wideband or anything fancy like that. on the dyno it spit out unburned fuel furing its detonation tantrum the first run...on race fuel. once i backed the timing back down to stock, it didnt do that. Now that ive got pump 93 back in it, it detonates like hell, RANDOMLY. With race fuel on stock timing, its PERFECT to 6k. On pump gas and stock timing...crap past 5200.

i worked on some connection and grounding issues..and its better to 5k now.

The car is getting plenty of fuel...i had fuel problems befroe and i know what this engine does when it leans out due to lack of fuel Backing off the timing will do nothing but rob power from the already narrow powerband. I just wont take it past 5k until i figure something out. The RANDOMness needs to be solved.

[Myxalplyx]

Originally posted by scoobie steve

Did you wideband the car on the dyno. I am guessing the car is running lean. Try backing off timing by 2 deg's if that doesnt help then i would say its running lean. Try getting a FPR and cranking up fuel pressure a bit, or a rrfpr. Egt isnt the best tuning tool, many things can cause high egts and who is to say what is too high. 1550-1600 about a inch from exhaust port is pretty hot. A wideband is a much better tuning aid! An air/fuel gauge is useless, dont bother.

 

 

There is always a 'depends' on any aspect of tuning. I wasn't saying to use the EGT to determine what is causing high EGTs. Just noticing you have high EGTs can save your engine by you shutting down or letting off the gas pedal and preventing expensive engine damage. And I'll say, ANYTHING above 1600F is too high. I try to shoot for EGTs where the stock EGT is. But.....there's not point in this now because WJM does not have an EGT gauge.

 

On the wideband O2, you can actually run rich where your Subaru is supposedly theoretically safe and still end up with high EGTS or cylinder temps. Going too rich will do this and you want to prevent that also so simply dialing in for a specified air/fuel ratio isn't going to cut it. Every car is different.

 

Now, since not gauges (O2 sensor, EGTS) are being used, timing is being controlled, colder spark plugs, colder thermostat (I kept saying water temp sensor...sorry ), nice rich mixture, what can be causing detonation?

 

1: Intercooler isn't being efficient enough or it's heat soaking,

 

2: turbo is blowing too hot air,

 

Wait, I have a cheap suggestion. Instead of the 180F thermostat, how about trying out a 160F thermostat instead. Since our older engines are notorious for running hot anyway, and you have taken things one step further by turboing a higher compressioned 'hot' engine that would use 180F thermostats to help it stock...it's worth a try. The engine should/will run cooler. Perhaps add a touch of water wetter. It's cheap so I figure it'll be something u could do to hold you over. I'm no tuning expert though. Perhaps Scoobie Steve and offer more input.

[WJM]

I think the fact that I DONT have an IC is one thing...but then again, when I run RACE fuel ,100 octane, i dont have this problem. Also, i dont think a 160 would help this particualt situation. It did the same with a 192 (stock) as it did a 180....but the engine was stronger. Also, I am not able to get a 160 around here...otherwise, id try it.

 

Water Wetter? whats that?

 

I am about to go mess with the fuel system again, just for kicks, and see what happens...im bored, and i cant sleep.

 

I was hoping to have a WRX IC fitted before the autocross tomorrow...but that didnt pan out, and I didnt get the oil cooler installed...to cold out...and Installtion is...rather tricky. Space is needed...and I dont have what I need...got to re-engineer some stuff!

[Myxalplyx]

Originally posted by WJM

I think the fact that I DONT have an IC is one thing...but then again, when I run RACE fuel ,100 octane, i dont have this problem.

 

I automatically assumed you did. Sorry! Then I'll point a BIG finger at the fact that you don't have an intercooler and you are getting too much hot air in your engine at high rpms. :cool:

[scoobie steve]

So you are saying all EA82t run rich???? Even ones with 9.5:1 CR and free flowing intake/exhaust and more boost. You are only putting down 99whp, maybe 15hp more then stock, There is something majorly wrong and if you dont want to put a wideband on it to tune your fuel curve you can have fun blowing it up. Detonation rarely happens at high rpms and if it does its because of a lack of fuel or way too much timing. All you have to do is invest in a $300 wideband and tune your engine. Maybe then you wont need race gas to put down 99whp.

 

Blowing raw fuel out the exhaust IS NOT a sign of running rich!

 

I wasnt aware you didnt have an intercooler either, please measure your charge temps and post your findings!

 

Myxalplyx is right, a little know tuning fact is over rich can cause high egt's and DET. But i highly doubt this is WJM problem!

[WJM]

First off, and I will say this one last time...I am NOT RUNNING MORE THAN STOCK BOOST!! Every post ive posted i have said stock boost over and over. I will NEVER intentionally run more boost than factory set on this 9.5:1 engine setup, IC or not.

(although I admit that I did not mention it here due to the fact that I had thought everyone was aware of the fact.)

 

With a stock turbo bottom end...that would be different. and I would have an IC before i boosted more than stock.

 

I know, i know...and ive been working on it for months now, I need an IC.

 

Even with a wideband, how am I supposed to tune the car? spend some x amount of $ i dont have and will never have for some LINK ecu? All these goodies are all well and good, and im all for it and I think its for me...but i DONT have the $. Yes, i might blow up, but this was an experimental engine to begin with. I do think that there are issues that the wagon has with timing that the RX doesnt have...and i am trying to chase that down.

[Subarutex]

Have you reset the ECU? May or may not help anything. Take of the neg. battery cable for like an hour or so. Seems to have helped with my car in the past.

 

For $150 you can grab an SAFC and use that to tune the A/F. Its pretty effective too. Couple that with $100 fuel cut defender and you have yourself a simple system of piggyback computers to help control your engine.

 

Yes, that is a crude method. But, its also cheap, and effective.

 

For added safety you can pick up a Knock Link for close to $200 and that will let you know when your engine knocks.

 

Gauges are cheap, you should be able to get a discount on them since you work at Napa.

 

Also, i bring to the table that your detonation is could be caused by the shape of the combustion chamber you have created. SPFI pistons and turbo heads... what does that chamber look like? Perhaps thats the reason.

[WJM]

All very good point Tex...thanks.

[RedRX]

What IS blowing unburned fuel out the exhaust a sign of?

[Skip]

Red, my bet incomplete combustion due possibly to

(a) the spark plug energy getting "blown out"

( way too much fuel causing a Lambda of 0.5 or less

 

Have any of yin's ever read up on "squish zones" in the combustion chamber??

[oddcomp]

well you can build a do it yourself wideband o2 sensor

you can build a do it yourself fuel injection ecu thats programmable

that being said i would almost bet you have eitehr some sharp edges <carbon chunks cracks ect> in the heads that are glowing

and causing the preignition

maybe the timing belt is a tad loose and alowing the timing to bounce around alot at high rpm

crappy bushings in the dist causing spark scatter and detonation

 

lets see your running colder plugs so chaces are they are not getting hot enough to keep the carbon buildup burnt off

and the carbon is causing the preignition <seen it before on v-8's and other motor's>

 

i run el cheapo gas 8mm accel solid core wires stock coil almost stock timing setting just a smidge retartded i think

and stock heat range plugs

and a 180 tstat

and have i would say 95% no detonation issues except for the occasional burp here and there

and my hearing is very well for picking up odd noises like detonation and other things that don't belong there

 

but for fun try hotter plugs and some marvel oil down the intake works great for getting rid of carbn

[Myxalplyx]

Originally posted by scoobie steve

Detonation rarely happens at high rpms and if it does its because of a lack of fuel or way too much timing. All you have to do is invest in a $300 wideband and tune your engine. Maybe then you wont need race gas to put down 99whp.

 

This is an interesting point! Lets say someone was to put their car on the dyno but they can not audibly tell the car is knocking (They are deaf for instance. ). If the timing is too aggressive or advanced in the higher rpm range (where it starts to affect power), how will this manifest itself on the dyno plot/chart? If you say what I think (hope) you say, you would give me an idea. :cool: Thanks!

[WJM]

I am going to put together a proper turbo engine for this, and see what it does.

 

Thanks for all the suggestions guys, and I apologize if I had sounded harsh at any time.

[Myxalplyx]

Originally posted by WJM

I am going to put together a proper turbo engine for this, and see what it does.

 

Thanks for all the suggestions guys, and I apologize if I had sounded harsh at any time.

 

Actually I like the junkyard-style approach. Keep it up! Everyone doesn't have $$$$, including me. So anything you find out that is cheap and affective would be cool.

 

*Now to look at exactly what turbo you are using [stock I'm assuming again]* If so, a cheap Legacy unit would sure be nice. --Don't worry about telling me/us yet again. I'm searching now.--

 

*Edit* Nevermind!

http://www.ultimatesubaru.org/usmb/forum/showthread.php?s=&threadid=10371

[oddcomp]

detonation in a dyno will show up as a powerloss

the amount of power loss will depend on the degree of detination

[scoobie steve]

HEHE, Kevin I saw your dyno plot and the first thing i thought of was detonation up high, when the line get squiggly.

[Myxalplyx]

Originally posted by scoobie steve

HEHE, Kevin I saw your dyno plot and the first thing i thought of was detonation up high, when the line get squiggly.

 

EXACTLY! Off goes the ProECM Powerchip tomorrow afternoon and time for some more tests.

 

Note: Not to sidetrack this thread but I did a little research on my 'history'. The PRoECM Powerchip is supposed to help you gain hp/torque by advancing the timing throughout the powerband. I noticed on my older dyno runs where I was having MAJOR problems with the Apexi SAFC making the car run lean. I only had one run with the squiggly lines up high in the rpm range and that was on the first run. For the most part, runs 2-3 where smoother or smoother up high.

 

ttp://mywebpages.comcast.net/thomasck/Dyno1.JPG

http://mywebpages.comcast.net/thomasck/Dyno2.JPG

http://mywebpages.comcast.net/thomasck/Dyno3.JPG

http://mywebpages.comcast.net/thomasck/Dyno4.JPG

http://mywebpages.comcast.net/thomasck/Dyno5.JPG

 

If you notice, all the runs where done on March 15, 2002.

 

I was wondering if I had the ProECM Powerchip during that time and had to search a bit to see I had posted anything about it at the Yahoo XT6 group board. Then I found this post:

http://autos.groups.yahoo.com/group/xt6/message/6691

I stated I had the ProECM installed 'yesterday' which would've been on March 19, 2002.

 

What does all this mean? Well, the 'chip' is designed to advance the timing provided you run higher octane. I've been running 93 octane even before the chip (bad nitrous runs.... ). If my top end smooths out when the chip is removed, perhaps these cars (Older Scoobies..some of them anyways) don't like timing to be advanced high up in the rpm range, especially with mods. That's a bold generalization so I'm not going to go there, especially with all these high tech scoobie gods here. :-p If it is a timing issue that gets resolved by the removal of the chip, then perhaps you are suffering the same problem. Turbos usually hate advanced timing up high anyways.

 

Suffer some low end powerloss with timing reduced slightly further and see if it helps your situation. Then you would know for a fact but I think u already know this and you stated u didn't want to go that route anyways.

 

Oh well! I'm just excited and perhaps I can gain a hp or two removing my squiggly lines.