Hesitation at WOT >5000RPM

[spencerhut]

I've got a bad hesitation at WOT from about 5000RPM on up. Can't rev it past 6250RPM it gets so bad. I've been reading the forums and changed the spark plugs (BPR7ES @ .028) and have no (significant) boost leaks. I do have a tiny leak around my BOV where I did a crappy welding job. I can't imagine it's enough to cause a problem. But heh, I'm here asking right? Since I'm just starting to tune with the S-AFC2 I've go the boost set at 10PSI with some fairly wicked creep to 15+ by which time the car starts to hesitate really bad and I let off.

I'm logging and I have ZERO knock and .93 on the O2

Is this being caused by my tiny boost leak?

Or is this still a spark issue? I've got new 10MM Taylor wires and I checked the coil packs before I put the engine in a couple weeks ago.

Fuel Pressures is set at 38PSI. Tried 43PSI and there was no change. FP Solenoid is bypassed.
I did a stupid and forgot to hook up the vacuum line to the FPR on one set of runs and it didn't hesitate at all all the way to redline. But I was getting 25+ knocks starting around 6000RPM. Doh!

660cc Injectors, 16g, 2G MAS, etc . . .

Thanks,

Spencer

 

[kpt4321]

Is the car simply tuned way too rich?

 

[spencerhut]

Could be. I'm new at the S-AFC thing. I added fuel until I got zero knock and then stopped. O2 is .91 to .93

It's kind of hard to tell if I'm too rich over 6k since it just bucks and hesitates and I let off. The O2 is all over the place once it starts to hesitate .79 to .93

Spencer

 

[kpt4321]

What are your SAFC settings? Do you have access to a wideband?

When a car is misfiring the O2 voltage will be all over the place, that's normal.

 

[spencerhut]

The car is at home and I'm at work. If my memory is correct it's set like this.

THLO @ 25%
THHI @ 75%

-8 @ 800
+3 @ 1200
+11 @ 2000
+14 @ 3000
+17 @ 4000
+21 @ 4600
+23 @ 5000
+23 @ 5600
+26 @ 6000
+27 @ 6600
+28 @ 7000
+30 @7400

Thanks,

Spencer

 

[terminaltsi]

YOU are way too rich. take some away at hi.

 

[kpt4321]

Holy crap!

Your AFR is probably like, 1.5:1.



Lean it out like, 20-30%.

 

[spencerhut]

Went home and checked my S-AFC and here are my real settings

-8 @ 800
+9 @1600
+11 @ 2000
+12 @ 3000
+14 @ 4000
+17 @ 4600
+16 @ 5000
+19 @ 5600
+20 @ 6000
+23 @ 6600
+34 @ 7000
+40 @ 7400

So if these settings gave me zero knock at >.93v on the O2. I'll lean it out 20-30% from 5k on up and see how it responds. What is the next step if it pulls well past 5k but then I start to get knock?

Am I shooting for .91v on the O2?

Thanks,

Spencer

PS - I'm a little slow on the replies since I'm out and about a lot a work.

 

[terminaltsi]

don't really worry too much about o2 voltage. just keep taking fuel away until you start losing timing/getting knock. on your setup you really shouldn't have to add very much at all.

 

[spencerhut]

Okay. This ought to be good for a little pucker factor later tonight . . .

Thanks,

Spencer

 

[spencerhut]

Did a few pulls (3rd gear) tonight and here is where I am at now.
-10 @ 800 No Data
+6 @ 1600 No Data
+6 @ 2000 KNCK 0 TIMA 36
+5 @ 3000 KNCK 2 TIMA 23
+6 @ 4000 KNCK 9 TIMA 22
+5 @ 4600 KNCK 7 TIMA 22
+5 @ 5000 KNCK 11 TIMA 21
+4 @ 5600 KNCK 9 TIMA 24
+4 @ 6000 KNCK 8 TIMA 25
+2 @ 6600 KNCK 7 TIMA 19
+2 @ 7000 KNCK 6 TIMA 15
+2 @ 7400 KNCK 9 TIMA 15
O2 was a solid .91 all the way. Injector duty cycle peaked at 96% @ 7187RPM.
Some missing from 6500 on up. But not too bad. I ran out of time or I'd have done a few more pulls.

What do you guys think?


Spencer

 

[kyle h.]

getting better, increase the fuel pressure. and see what it does.

im dealing with some creap now too and it makes it harder to tune...so try to fix that creep problem or jack her to 15psi

you're timing is real low too, is the mas missing any honeycombs?

 

[kyle h.]

also from 3000 rpm to 7400 rpm, goto +6% and then adjust from there. that might cure some knock.

 

[spencerhut]

I'll try going to +6 from 3k on up and adjust from there. The MAS is untouched.

Thanks again,

Spencer

 

[norice4me]

ok at 5800 my car starts sputering not bad but i dont know what to do is it the plugs or a boost leak or is it too rich thanx guys i dont have a fpr

 

[5150DSM]

Did a few pulls (3rd gear) tonight and here is where I am at now.
-10 @ 800 No Data
+6 @ 1600 No Data
+6 @ 2000 KNCK 0 TIMA 36
+5 @ 3000 KNCK 2 TIMA 23
+6 @ 4000 KNCK 9 TIMA 22
+5 @ 4600 KNCK 7 TIMA 22
+5 @ 5000 KNCK 11 TIMA 21
+4 @ 5600 KNCK 9 TIMA 24
+4 @ 6000 KNCK 8 TIMA 25
+2 @ 6600 KNCK 7 TIMA 19
+2 @ 7000 KNCK 6 TIMA 15
+2 @ 7400 KNCK 9 TIMA 15
O2 was a solid .91 all the way. Injector duty cycle peaked at 96% @ 7187RPM.
Some missing from 6500 on up. But not too bad. I ran out of time or I'd have done a few more pulls.


Spencer

What do you guys think?

I can't imagine why you would need a positive correction on the AFC with 660's and a S16G. To me it looks as though you are still way rich; my suggestion is to zero out your AFC settings and start tuning from there. I would expect your correction factors to look more like -10% to -12/15% up the curve, ignore the 02's and just tune for knock and timing advance.