Timing at WOT

[EagleTalonTim]

Well, I decided to hook up my logger and get my fuel trims readings and see how thing were doing as far as my last tune and to my surprise, I am getting 10 to 14 degrees timing at WOT in third gear! My IDC is 77% @ 6500 RPM with my 590cc injectors and an EVO III 16g boosting 21psi. Base timing is set to 5 degrees at 750 rpm. Fuel trims are at 81 L, 91 M, 81 H which means I need to turn down my fuel a bit. The only problem with turning down my fuel is if i do that, I start seeing knock all the time....even if I go down 2psi. Should I adjust my timing to 6 or 7 degrees or should I go lower to 3 or 4 or should I just leave it at 5? I run 93 octane all the time and hardly see any knock once the engine is warm. Any suggestions on my tune? I just feel that running 21psi from my 16g is just not putting the power down I think it should.

 

[jeffo]

Tim,
If I recall, your car has always been rather knock-happy, right? I don't remember you having a wideband, but have you logged the O2 volts as you turn up the boost, to see if you are leaning out? If the O2's are holding fine at .85 or more, then I would have to assume you still have too much timing advance for your compression. The one reason it might get better when the car is hot is the octane value might be getting decremented while you drive, reducing timing automatically.

 

[EagleTalonTim]

O2 voltage stays around .85v at WOT. The lowest it goes is .83v. So turning my timing closer to TDC maybe 4 or 3 degrees would probably benefit me a little?

edit : the knock was from a loose O2 sensor

 

[91tizzy]

Man in all honesty I feel your experiencing phantom knock. You have checked the sensor? Mechanical timing in check? if everything is checking out then I would suggest bumping up the timing....power is in the timing....target around 18-19 psi and jack the timing up as much as you can (within reason) before experiencing knock. Are your lifters revised? and if they arent 3g's are they making noise? How about the balancer/timing area? I feel determined to help you with this . I was feeling what you are now when I was on my 14b setup....never ended up feeling much power out of that setup so i broke down and went with a big frame turbo....but to be fair I never did get the setup exhaust leak free which was hurting the tune and everything else...

Edit: hah while I was writing this you replyed

 

[Calan]

...My IDC is 77% @ 6500 RPM with my 590cc injectors and an EVO III 16g boosting 21psi...

Without airflow numbers it's hard to tell, but I think you should be seeing higher IDC's than that with 590's and a 16G @ 21psi if you are running 10.5 to 11.0 AFRs and stock fuel pressure.

Just a gut feeling (with a few beers as well)...but I think you are running lean.

 

[EagleTalonTim]

that is the problem though.... I don't know how I could be running lean getting 12 to 16 mpg. I also have a cracked exhaust manifold which I will be replacing this weekend with a 2g manifold. I wonder if that would cause any of my problems.

 

[Calan]

An exhaust leak will definitely throw off the O2 sensor...even a small leak.

If that's the case, the ECU could be over-compensating and using more fuel than necessary during closed loop, causing the poor mileage. But you could still be running lean at WOT. And the O2 sensor voltage isn't really reliable outside of the narrowband switching point, even with no exhaust leaks.

 

[camfast]

Im running 102% IDC with my 550's and fuel pressure at 43psi. This is at 18-19 psi so i think that you are most likely lean.

You may look at getting bigger injectors if you have something to tune them with and your car will pull much better.

 

[Calan]

^^^ Yep.

At 22-24psi @ 37psi FP, 650's on an E316G, Wally 255hp and pump gas, I was almost always pushing 95% IDCs to hold 10.5:1 AFRs. This was pushing 38-40lbs of air.

I think you're lean.

 

[EagleTalonTim]

so what is the best way to richen things up without maxing out my fuel trims in my ECU? I have tried to go a little leaner and a little richer and either way, my car starts running REALLY bad. Richer, I get solid black smoke out the back. Leaner, I see knock starting at 3k to 4k and all the way up.

 

[awdmonster1904]

A boost leak can also genorate knock
I had the same issue when I had it boost leak it would knock from 3k all the way to redline. Check for boostleaks

 

[Calan]

so what is the best way to richen things up without maxing out my fuel trims in my ECU? I have tried to go a little leaner and a little richer and either way, my car starts running REALLY bad. Richer, I get solid black smoke out the back. Leaner, I see knock starting at 3k to 4k and all the way up.

Fix all the exhaust leaks and any boost leaks first. If you have either of those, you're gonna be chasing your tail.

 

[toofast82]

Fix all the exhaust leaks and any boost leaks first. If you have either of those, you're gonna be chasing your tail.

I couldn't agree more.
Then post up some logs for us to see if anyone can shed some light

 

[EagleTalonTim]

I am going to get my manifold fixed this weekend and see if that changes anything. I recently did a boost leak test and the test results were 2 psi loss per 3 seconds from 15psi. I could not track down any leaks using soapy water. I also got a few logs and reviewed them.....

1 count of knock max. 67% IDC at WOT and 6000 rpm. O2 readings stayed around .75v. Timing stayed between 14 and 16 all the way up. 14 degrees was at lower RPM's below 4k RPM. I would post a log, but my logger completely died on the way back home from work. I will post it as soon as I can.

 

[PieEyedPiper]

Perhaps this is redundant but I agree that you must be lean. Narrow band o2 values ought not be so low as .75 and your .8x value you logged seems lean too, even for a 1g.

 

[91tizzy]

.75 is to lean...I recently had a problem that was quite hard to diagnose and ended up being the wally filter sock had gotten clogged by loosened up rust in the tank after using some ethanol. o2 volts looked like yours.

Now it could also be showing lean from the cracked exhaust manifold alotting more oxygen at the sensor making it "think" its running lean. This is also evidenced in the low timing table the ecu is using.

Fix the manifold situation and report back

 

[pneumo]

Here's some critical info- the trims are only used during closed loop cruising. High trim is used up to approx 375Hz, above that the ecu used open loop and doesn't look at the trims.

Since your profile says you have a SAFC, subtract about 5% from the lo throttle settings to raise your trims closer to 100. Then add about 8% to your hi throttle settings to add fuel during WOT. It's nice how the SAFC has separate hi and lo throttle settings so you can tune cruise and WOT separately. Make sure the throttle points are set around 20% low and 75% hi.