ok well, i decided to finally go for some datalogging runs tonight. it's the first time since it's gotten cold out. anyway, the car has been running great, however, i guess i must not have gone WOT yet this winter. i made some WOT pulls and it immediately started to get some detonation as soon as i got to like 3-5psi at WOT. i let off the gas as son as i heard it. i don't get any during part throttle accel. anyway, the problem is that my fuel trims are fine, in fact i'm at around -8 ltft most of the time. egt's are perfect. they're never even near 1600. highest they've gotten is like 1500, and very rarely. anyway, tonight they weren't even near that, although i didn't get to stay WOT for long b/c of the det. i richened it up about 2 psi of fuel press. and now my ltft is around -11 - -15 most of the time. i couldn't get a good o2 reading because of the fact that i had to immediately let off, again. the only thing i can think of are my plugs have about 7k on them. could they be the cause? it's weird cuz it only happens at WOT, and it doesn't seem like i'm lean according to the fuel trims. i've never gotten det before.. only thing that's changed is the temp and old plugs.

oh yeah, and my timing under WOT was around 17-18* adv. what'yall think?

How old are your plugs? Are you SURE it's detonation and not TOO much fuel? What's your STFT look like? Change your plugs and then see what happens. I got a LOT of hesitation from old plugs. When I changed them, it was like a whole different car!

aside from the actual pinging sound, there are no other symptoms of anything going wrong... no hesitation, car ran strong even while the pinging was happening. at first it sounded like it was coming from the back of the car, but it happened every time i tried to pull hard at WOT in boost. like i said though, no hesitation. it's just that the plugs are all i can think of. i doubt it's gettin too much fuel. nothing has changed since the summer, so if anything it will get slightly leaner. last time i checked WOT o2's they were around .96. and like i said above, i didn't stay WOT long enough to get a good o2 reading.

my stft's are always between +-8 because the ltft compensates rather quickly. and when i said above that i raised the fp by 2psi, i meant static.

plugs are about 7 months old.. about 7k miles.

What is WOT? No one has ever told me .

wide open throttle. aka. flooring it, pedal to the metal, and so on....



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

ok, let's stay focused here :-)

EDIT: just to add.. i'm using the hrc blackbox now, well for the last 5 months or so. according to the datalogger the map reading is at 94-96 at WOT. however, if the blackbox was the culprit and clamping the map too low, then the result would be timing advance, right? as i said earlier, i'm only seeing 17-18* adv during WOT.

in addition to changing your spark plugs, check the gap. i use 30 mills (.030")

the HRC black box can clamp the voltage to less tan 4.5 volts at WOT. this has happened to be before, it has also happened to other board members like Jason. i think his was clamped to something nuts like 3.8 volts or something.

if this happens, the ECU will think there is less of a load on the engine and reduce injector duty cycle and advance timing accordingly.

a good indicator of this is if you know you have MORE than enough fuel for X psi of boost, and you're still getting .75-.85 volts from your oxygen sensor, the black box can be the issue.

ok, just changed my plugs and did some other little things. in the process i did a comp test and got 210-213-210-210 cold, so compression is same as before turbo.

my plugs looked odd. the middle 2 cylinders were normal, but the outer 2 were half grey and half black. it wasn't even that uniform, but there were grey patches around the circumf. of the plug head. also, the gaps were large - around .038-.040. i always gap my plugs to .033ish. anyway, i haven't been able to do any runs yet.

NATE: if the black box was the issue though, wouldn't i see the advance in the datalogging? the timing at WOT is 17-18* adv. again, weird thing is it only detonated at WOT in boost. it didn't happen at part throttle in boost.

another thing to consider is, i was just told that NY is now using a new additive in their gas for environmental reasons, and detonation is a possible side effect of it. heard it on the radio. that's not cool.

Also take into consideration that colder/cooler air is denser, thus, you'd need more fuel at WOT. Are you sure it's detonation?? Your egt and O2 seems to show that you are actually towards the rich side. Although 17-18 degrees of timing is still acceptable, I would probably want to see 18-19 degrees at WOT. Do you have any timing control, i.e., ignition module with timing retard? If you have a voltmeter, you might want to check your MAP sensor to make sure it's good, before pointing your fingers at the HRC black box:-)

YOur timing sounds just a bit high. Should be around 14-17. Could be the HRC black box. Mine went bad, and clamped at 4.1 volts at WOT. It caused me to run too lean, even if i upped the fuel pressure by 15-20 psi at WOT. If you have a voltmeter, turn the key to the run position with the motor off, and measure your voltage on the pos and neg wires that the FCD is connected to. It should read 4.5 volts +/- .1 volts. If its outside of this, the FCD is bad. Although you say your EGT's are around 1500, which sounds like you have enough fuel, so not sure if thats the issue. I just think 18 degrees advance is a bit too much. Crappy gas will cause it too! What octane rating do you use?

i'm using 93 oct. i thought 19-21* adv at WOT was optimal? dino mentioned that in one of his recent posts. anyway, lemme just make sure that it is in fact det that i'm hearing. i hear, what sounds like a very faint duhduhduhduhduhduh... u get the point, but really fast. like 4 "duhduh"'s every sec. but it' s not very loud. it's barely audible. sounds like rattling. i've heard pinging on older cars, and i seem to remember that being louder, anyway, it's been awhile since i've heard real "pinging". i know it's been described as bb's shaking around in a can, but it's hard to compare. all i know is it's not very noticeable, i just happened to have no music on and noticed the sound.

what would ~4.5v from the map convert over to in kpa? i have a voltmeter, but can't test it now.. i do, however, know what my map reading at WOT is from the datalogger.

I've always seen 18-21* and considered that optimal. Lower could work as well, as long as it keeps climbing all the way to redline. If it levels off or drops, it's pulling timing due to knock.

in these outside tempatures (20 to 40 degrees) i have about 18 degrees of advance at ~3500 RPM's and about 20 degrees at redline. i run 17-18 psi of boost using 40lb injectors with .96+ for oxygen sensor voltages... 93 octane. 175-175-180-180 compression (8.6:1). runs nice.

Originally posted by 97eclipseRS
what would ~4.5v from the map convert over to in kpa? i have a voltmeter, but can't test it now.. i do, however, know what my map reading at WOT is from the datalogger.

Your not concerned with your datalogger reading as much as you are with volts. I mean, none of us are absolutely sure of the the conversion chart. I'm guessing 4.5v might be about ~101-105 kpa's depending on where you are in the country, but you're better off hooking up a voltmeter to your MAP sensor.

If it were me, I'd invest in a missing link.

i'll check it with a volt meter then. my guess is it is clamping the voltage too low. i do have a ML, but i'm one of the few people (nate's another one) who the ML just lets too much boost through in transition for our freak super sensitive ecus. dunno if you remember, but i've discussed my ML journeys in the past... my car just doesn't like it. so i had no choice but to hook up the black box.

i do know that (don't know why i didn't think of this earlier) when datalogging with just the ML, i would see around 100-101kpa at WOT. with the clamp i only see anywhere from 93 - 96kpa at WOT. looks like it's shot. i did notice this when i first installed it and did some datalogging, but i figured that it wasn't a problem because it didn't seem to be keeping the ecu from going into open loop(which is ultimately the problem w/ clamping the map too low right?). my ltft and stft were locking at 0 at WOT, so i figured the lower map wasn't causing any harm. this is still true though.. in all my datalogs now, when i hit WOT, my fuel trims lock at 0, so if it is going into open loop, how could the black box be at fault?

i'll probably pull it and run the fuel cut promoting ML until i get a new one... any suggestions on volt clamps? i know this hasn't been asked since the old days. any new ones out?

The Map really doesnt have anything to do with kicking the motor into open loop, thats mostly done with the TPS sensor. I can build at least 10 psi in closed loop with part throttle...If the map is clamped to low, it will keep your injectors from spraying the needed fuel at your WOT boost. The car's ecu thinks its not at WOT air flow, so it keeps the injector duty cycle a bit lower. Just measure the MAP voltage to either blame it, or rule it out. 20 degrees advance IMO, will cause detonation, esp in higher boost...dont know how you guys do it...My datalogger usually shows around 14-17 advance no matter what rpm..no matter what boost, and stays very steady to redline..

i did know that open loop was mainly determined by the tps, but for some reason i thought the map was taken into consideration also. anyway, i'll check the map voltage.. i won't be able to until tomorrow though, so i was just trying to get ideas. if anything though, wouldn't it be more likely to det at part throttle under the same boost? i did some testing yesterday and found that i could hold it at part throuttle in 3rd but enought to keep it pegged at full boost(6psi), and there were no probs, then as soon as i went all the way to WOT it started. weird.

another lead pointing towards the black bos is the fact that i know i'm running pretty rich, but i still only get like .9-.91 o2's if i'm lucky, and egt's are low

just an update - i clipped the black bos and went out.. no more detonation, however on my datalogs i see anywhere from 14-20* adv at WOT. also, i turned the fp back down, but it's still real rich. i'm gettin' a steady .98 at WOT in 2nd, and .96 in 3rd. feels slower too, guess that timing adv gave some extra power. i still have the ml on but it gives me fuel cut at transit into boost. so, i do need another fcd.. any recommendations?

did you try cleaning out the ml with carb cleaner? and changing/cleaning the filter in it? i would recomend doing the egr block off mod. and clean out the intake manifold. i had a fuel cut problem with mine also. cleaned everything up, and blocked off egr, and i have never had that problem since.

Originally posted by grain
did you try cleaning out the ml with carb cleaner? and changing/cleaning the filter in it? i would recomend doing the egr block off mod. and clean out the intake manifold. i had a fuel cut problem with mine also. cleaned everything up, and blocked off egr, and i have never had that problem since.

been there, done that.. i've even worked w/ the ML manufacturer.. had multiple ML's and MAP's. i'm just one of the few w/ super sensitive ecu's. i'm not gonna mess w/ it anymore, i've accepted it :) i do need another fcd though