Ouch....

[Sparetire]

So I went out tuning today on my new 2.4. (About 1300 miles on it now) I am just trying to get a decent rough tune for the sake of safety and mileage. Its only running an E3 16G on stock boost right now~12.5psi

Little background:
I have heard a rattling noise since the install of the new motor. Its not a spun bearing, and I am positive its not lifter tick. Might be a exsaust leak (E3 02 housing does not exactly like my DP) might be something in the driveline. Its a rattle that I can only induce in the higher gears under moderate load. So say 4th from 2600 to 4000 and 50% throttle I will hear it. It sounds almost like a peice of ice rattling in a can. Clutch holds fine. Shifts great. Awesome oil pressure. Awesome temps. No codes. Mint condition knock sensor. I have checked my oil with magnets. I have spit polished my oil dran pan and then inspected the oil for any shavings at all. Nothing. Compression is 170-180 on all cylinders. So its not some weird piston slap issue.

Other than idle surge (should have blocked the FIAV:rolleyes:) and the stupid oil return line leaking a bit, it has no issues at all.

Feels strong, though I have had it running pretty rich. Fuel is a Walbro 255HP, SAFC, and 650CC injectors. DSMLink coming soon. Possibly 850s, but I dont know that I'll need them for awhile.

Anyway, the point: At first, it was way way to rich. Broke up at about 4K. Inaccurate stock 02 readings in the .94-.96 range. I leaned it quite a bit, but subsequent pulls were still .92-.94. After I leaned it out, the breaking up at 4K disappeared.

But: Knock in the really rich runs was about 20 counts. Knock on the much better feeling only pretty rich runs was 25, then an instant jump to 40-43 counts. This is at around 4K rpm, 13psi E3, on 650CC injectors fed by a 255, leaned 20% on an SAFC. Its getting all the fuel it wants. I know the stock 02 is crap for accuracy, but when I'm running those settings with 650s on a small turbo and low boost and it says .96, I think its reporting the gist of whats going on. Smelled rich too. I stopped none the less, that kind of knock scares me.

So I conclude that the "knock" I am reading is not from detonation in the cylinders. It's something else setting off that sensor. The sensor on your average 2.4 is not in the same place as on a 4G63 block. I have mine right by the #1 cylinder. I figure thats the hottest cylinder, it will detonate early on relative to the others. I dont think thats a sginificant factor here.

So (finnaly) my question: Am I right that its not real detonation the sensor is picking up? I did not hear "the noise" at all during the runs, but thats not really definitive.

I really hoped it was detonation to be honest. The alternative is something mechanical rattling around in my shiny new bottom end. Crap.

Hey, I'm learning a lot at least:p

Derek

[Paul]

Inaccurate stock 02 readings in the .94-.96 range. I leaned it quite a bit, but subsequent pulls were still .92-.94.

Derek

So what makes you think they are inaccurate?

Paul

[Sparetire]

I have always heard that the stock 02 readings are not safe to use as a basis for a tune, and that to really get it right you need to look at EGT and knock of course. Better yet, 5V wideband. I can see why. Ive played with AF before and even though the EGTs chage, the knock changes, and the feel of the car changes, the stock 02 readings hardly change at all. Most people who really get the best out of a setup seem to use the dyno as well, and thus WB02 most of the time. I've seen an ideal tune on WB will look like sure death or pig rich in the 1v stock 02 system.

So I always take that data with a grain of salt. In this case though I think the 02 readings are consistent with what I smelled/felt/think. Except of course for the fact that my knock is way out there and thus timing looks like crap.

[Carl Morris]

Feels strong, though I have had it running pretty rich. Fuel is a Walbro 255HP, SAFC, and 650CC injectors. DSMLink coming soon. Possibly 850s, but I dont know that I'll need them for awhile.

Anyway, the point: At first, it was way way to rich. Broke up at about 4K. Inaccurate stock 02 readings in the .94-.96 range. I leaned it quite a bit, but subsequent pulls were still .92-.94. After I leaned it out, the breaking up at 4K disappeared.

But: Knock in the really rich runs was about 20 counts. Knock on the much better feeling only pretty rich runs was 25, then an instant jump to 40-43 counts. This is at around 4K rpm, 13psi E3, on 650CC injectors fed by a 255, leaned 20% on an SAFC. Its getting all the fuel it wants.
<snip>

So (finnaly) my question: Am I right that its not real detonation the sensor is picking up? I did not hear "the noise" at all during the runs, but thats not really definitive.


My thought is that it's "real", but you're not going to hear it. So if I'm understanding you correctly, the only compensation you have for running 650s instead of 450s is an AFC pulling 20% worth of fuel? If so, I'd agree that you are probably very rich, which can contribute to knock in some circumstances (I don't know why). I'd expect you to need to pull at least 30% worth of fuel to get it right, except for the increased deadtime of the bigger injectors will need more fuel at idle and light loads.

I found that the stock timing is a bit too aggressive in the midrange where boost is first coming on, and using the AFC to pull fuel is going to make the timing even more aggressive. If that's the problem, then you need an EPROM or the DSMLink to really make it stop. Until then, you could bring your base timing down until it stops, but that'll compromise your performance a bit at other rpms. Or you could run better fuel all the time and continue to pull fuel until the high trim is right.

[Sparetire]

Im embarassed to say that I just checked my base timing. It's a bit...ahh....off.

That and what you said might help to explain a lot of what I logged.

Additionally, I agree that I should pull more fuel. Granted this is a 2.4 and a 16G instead of a 14B 2.0, but with the 255 pump and the 650's I figure its a bit less than 50% more fuel all else being equal. I figure I have at most 30% more airflow than a 2.0/14B at equal boost right now. So yeah, only 20% out via the SAFC is very rich.

Once I get my timing set and actually do this right, I may well find I can pull a lot more fuel out of it without knock. I have to run it on 91, its my DD. Thats the direction of this project, a really versatile pump gas car. Not that some VP Import or good old 100 octane pump wont find its way in there occasionally :)

[Carl Morris]

Im embarassed to say that I just checked my base timing. It's a bit...ahh....off.

Well, there you go :-), assuming it was "off" in the advanced direction.


Additionally, I agree that I should pull more fuel. Granted this is a 2.4 and a 16G instead of a 14B 2.0, but with the 255 pump and the 650's I figure its a bit less than 50% more fuel all else being equal. I figure I have at most 30% more airflow than a 2.0/14B at equal boost right now. So yeah, only 20% out via the SAFC is very rich.


FYI, your thoughts on the injectors giving you about 50% more fuel (ignoring dead time) is correct, which means pulling about 33% (1/1.5 = 66.6%). Your thoughts on the increased airflow are not correct unless you are running speed density, which I assume you are not since you have an AFC. The mass air meter will measure the extra air going in and compensate automatically so additional displacement and any other VE improvements shouldn't affect A/F at all. It will see the load (g/rev) as higher so it will run a bit less timing, so that factor is actually helping you on timing. You said you want to get it right for pump gas, an EPROM will make a huge difference in that area if you put in a better timing table and extended maps so that it continues to pull timing as the boost goes above 14psi. Oops, that's assuming 1g. 2g is already set up pretty good for pump gas.

[Sparetire]

Well, there you go :-), assuming it was "off" in the advanced direction.

It was advanced enough to make me look retarded so to speak.:p



FYI, your thoughts on the injectors giving you about 50% more fuel (ignoring dead time) is correct, which means pulling about 33% (1/1.5 = 66.6%). Your thoughts on the increased airflow are not correct unless you are running speed density, which I assume you are not since you have an AFC. The mass air meter will measure the extra air going in and compensate automatically so additional displacement and any other VE improvements shouldn't affect A/F at all. It will see the load (g/rev) as higher so it will run a bit less timing, so that factor is actually helping you on timing. You said you want to get it right for pump gas, an EPROM will make a huge difference in that area if you put in a better timing table and extended maps so that it continues to pull timing as the boost goes above 14psi. Oops, that's assuming 1g. 2g is already set up pretty good for pump gas.

Yep. I have an EPROM in my '93, and it will be used for DSMlink. I can not wait. Even before I started using the SAFC I knew how limited it was and now I know first hand. I got it in the first place so that I could pass emmisions by leaning on it a bit down low. When my injectors started acting up awhile back it was handy for running the 650s I have now. But after investing this much into the car I am definitely going with DSMLink.

That also explains why I dont need to be leaning as much I thought for the 650s.

Thanks!

[Sparetire]

So I got the timing set. I set my base timing at 4 degrees advanced instead of 5 for a small cushion. Incidentally, the timing light I got at harbor freight for $30 is pretty nice. It lets you advance on the light so you can set for say 5 degrees advance while using the dead center mark on the T-Belt cover. Cords a little short though......

I went out and did a 3rd gear pull on an on-ramp. .94-.92 on the 02, max of 8 counts of knock at 4500, mostly 5ish throughout the run. Not deadly but not good. Timing advance hovered around 16 degrees throughout, started picking up a but around 5300. I went from 3500 to 6000.

Just as an experiment, I gave it a bit more fuel, despite the rich tune I was already on. I wanted to see how it affected the knock with the timing I should have been running all along.:rolleyes:

So I went from -20% on the hi-throttle settings to -17% from 3K to 6K RPM.

On the next run, I had .94 accross the board. I hit 30 counts of knock at 4000! Timing advance was needless to say in the sewer. It also broke up a bit in the upper revs. I let off at 4700, there was no need to go any further with the car obviously not liking it.

Good to know. I guess I see why drowning knock with fuel does not work so well. It is in oversimplified terms like trying to put out a fire with gasoline. It can be done, but it's probably a bad idea.

A bit too much traffic right now and frankly theres a margarita calling me. So I'll finish this rough tuning business later. Hope this helps someone....

Nah, Im the only SAFC/Walbro/650CC newbie left. There will never be another...

[Sparetire]

So the car is running quite well now. Just to satisfy myself that I was truly dealing with detonation, I went and put in 6 gallons of 101 octane VP. Knock basicly went away. Thats good.

I can run it up through 3rd with no problem, even in nasty 100 degree plus heat with virtually 0 knock. Also good.

But in the heat uphill, knock city, even with the 101 octane in it. It really is amazing to me how much the load affects the tune. Similarly, in 4th or 5th I do get a bit of knock. Not higher than 10 counts, but thats too much.

And looking at the kinds of timing advance the ECU tries to run, I see what people mean when they say the 1G ECU is a bit too aggressive with pump gas. I get about 25 degrees advance by the mid 6s with what amounts to 96 octane. It was running low 20s on strait 91. As near as I can tell, one should shoot for about 18 degrees peak on pump. Add that to the fact that it's a 8.6ish to 1 static compression motor and it becomes clear why it wants to knock so much.

So DSMLink is next, to be used w/ the laptop Im on right now :). I think I can play with timing and get myself a nice pump tune, then go about the business of finally putting some real boost to this thing. Im thinking 16-18 PSI for my DD tune. Would be nice to see 300WHP with that and the intake/IC work I'll be doing, but thats a ways off.

Im not even thinking of race gas tuning untill I have the pump situation figured.

[ErikW]

water is your friend. In Arizona, I don't think it's any better than Colorado. So if you are running to much boost for this timing and your IC is heating up, then maybe you can get better results from water injection on pump gas.
You can even add a nozzel in the front of your IC from the WI system for better effect, perhaps. That would work marvels. Heat is our #1 enemy and you've got it there. So use your cooling options to maximize any modification stage you are at for the best of everything.
A quicker and (initially) cheaper fix is to run richer. But make sure you are not running to much timing and boost for your setup. Otherwise - boom - in the not to distant future. Way to much fuel and you can post-detonate as well, however. I'd think that's what you might be seeing if you are running to much boost for your IC system. ?
And yes. DSM Link rocks! even though my best tune on an S-AFC has prooven to reap better times, the DSM link will potentially squeeze more outta your car and in a safer way as well.
best of luck!
ew

[Sparetire]

Thanks!

I totally agree. I also checked my IC and it's pretty clogged up, which will degrade its efficency even further on repeated runs even with freeway airflow to cool it.

I have actually been tinkering a bit with a homebrew free water sprayer setup. How ghetto is this:

I pulled the rear wiper and washer off my car. I almost never use it, it was rattling a bit and its just weight for me. I also got rid of the fog lights about 24 hours after getting the car years ago. So I now have a pump, a line, and a tank that fits pretty much perfectly over in front of the drivers side front wheel, with a line that pretty much perfectly goes along the inside edge of the front clip over to the stock intercooler. It even has a nice little fill spout that could be routed up by the headlight area. I also have a unused circut right up there from the fog lights. I think you can see where I am going with this LOL.

I dont have a nozzle yet and I have not hooked this all up, but I think its a $5 IC sprayer. Now is that VFAQ worthy or what LOL.

Right now I am running stock boost, which on an E3 appears to be 12-13 PSI. Must be a bit stiffer spring in that actuator. It really doesnt knock much at all as long as I am smart. I was post-detonating due to excessive fuel. I will say it pulls pretty hard for that boost. Mike D was with me when I got on it for one logging session and said it feels like as much peak power as his mildy modded 16G 1G at 15-16PSI. So for now Im quite happy with it. None the less the plan is for 22ish psi on race gas, so I have work to do.

Link should be in by middle of Sept. Supra SMIC and pipes in soon after that. I am seriously pumped to have NLTS and all in addition to a decent tune. Hopefully by the time I get actually racing the thing will be running real boost and 0 knock.