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no luck tuning with vs cam >_<

F

fst

New member
So yesterday I headed down to cecil dragway and see how the car’s running. First pass I ran my WB was showing 12.7-13.0 with knock so I lowered the timing during the drive down the track, but the most was from the dig right when I went into PE with as much as 9* of burst knock retard. Picked up my slip and it was 13.8@101

Second pass I richened up the 8-11 range in the MAF via AFC 2.2. again off the car bogged due to burst knock up to 9* and it zeroed out as I continued to hold throttle. WB was showing 11.7-12.0 with minimal knock through 1st gear but started getting KR towards the top of 2nd into 3rd, like 4-5*. I ran a 13.9@101.

Last pass of the night I was pissed. Richened the 8-11 way above usual and lined up. once ***ing again I bog off the line because of the burst knock but again, it’ll zero out and the WB was showing 11.3-11.6. im thinking sweet, go pick up my slip and I ran a 14.1@100!?? W…T…F….?
As I pulled over to the pit area I looked through each log. Areas where I had no knock my timing was at 15-16* of timing , YET my timing commander was adding add’l 5*, which should of made timing set at 19* with zero knock. My NB for the second and third runs were 990-1025, wayyyyy rich but the WB showed different otherwise. I believe either the WB sensor crapped on me a while ago, since at idle and cruise it would show “LEAN” or i bet my rear header has a major leak that it’s that bad to throw off the sensor as well as my LTFTs at idle/or off throttle shoot to +16.4.

By the way, this was with the 3.3” MPS and no alky. Tires were set at 26psi and the track didn’t appear to be very well prepped/sticky. Ran with a quarter of 92oct gas.

/end rant

im really debating swapping back to 1.9stock modified rockers since i had better luck tuning that than the cam:th_jester::th_nervous:
 


So your LTFT's shoot to 16.4 at idle? Doublecheck the egr tube for leaks and also check the welds around it on the headers, often they are cracked. Do you still have the EGR hooked up? I know on the pacesetters that the tube is larger than the opening on the headers. Check for any other leaks as that would throw off your tune.
 
yea im gonna try to loosen and realign the rear header later today as well as after i i get off work tomorrow. the fel-pro gasket is off a bit. if i take all the bolts from the rear header, what else should i loosen to be able to wiggle the header to match up to the gasket? loosen the front crossover bolts or loosen the catback?
 
fst said:
yea im gonna try to loosen and realign the rear header later today as well as after i i get off work tomorrow. the fel-pro gasket is off a bit. if i take all the bolts from the rear header, what else should i loosen to be able to wiggle the header to match up to the gasket? loosen the front crossover bolts or loosen the catback?
Click to expand...

I don't know how you have your PS installed, but yah, probably try and rock the engine as far forward as you can, loosen the rear header and see if you can get it to drop down a little or push back. Stock gaskets FTW!! lol

I'd doublecheck for other leaks before you go ahead and do all that.
 
believe me it was a hard task getting the rear in there. also the gasket is a fel-pro i got from rock auto, its the aluminum gasket, which i dont like as much since the front one went bad and caused an extreme exhaust leak by the #5 primary(sounded like a bad lifter). yea, sounds like i'll need to loosen the top dog bones, loosen the front crossover, and use a ratchet strap to pull and hold the motor forward. does that sound covered?
 
A bad exhaust leak will make your O2's read crazy. 16+ fuel trims indicate you have a vacuum leak somewhere after the MAF....check everything. it could be a TB gasket or something. There's no reason why you shouldn't be running consistent 13.2's with that cam.

How does the burst KR look? As Dave asked me a couple weeks ago....does it instantly come on when you take off and ruled out TM?

He told me to add 5-8% more fuel right at the 0.0 mark on the PE table, and it completely cured my problem.
 


the burst knock comes on right when PE hits, which is roughly 7250-7800hrtz as much as 9* of KR. i dont think i have a vac leak as my boost gauge reads ~16-18VAC and my IAC is ~45counts, plus the needle on the boost gauge is very reactive when i apply throttle. when i had a vac leak the needle was somewhat slow and did not move as much in relative to throttle adjustments. TM, i'd need to look in my PT tables, but honestly which should i look at and what changes, if need be, should be adjusted?


reptile, can u explain a bit more on this comment, "He told me to add 5-8% more fuel right at the 0.0 mark on the PE table, and it completely cured my problem." please?
 
the +16 fuel trims almost lead exclusively to some type of leak somewhere. Fuel trims should not be that far out of line normally.

If you open up the PE Time vs RPM table, you'll see the very first window in seconds is 0.0. From 400rpm down to 4400 RPM (or so) increase the fuel there by 5-8%. That dumps fuel immediately, and then it will clean out across the PE table, just don't touch anything else in the tables. It looked odd to me at first, but it's a trick I'll remember from now on.

Did you ever get your Alky figured out?
 
Reptile said:
the +16 fuel trims almost lead exclusively to some type of leak somewhere. Fuel trims should not be that far out of line normally.

If you open up the PE Time vs RPM table, you'll see the very first window in seconds is 0.0. From 400rpm down to 4400 RPM (or so) increase the fuel there by 5-8%. That dumps fuel immediately, and then it will clean out across the PE table, just don't touch anything else in the tables. It looked odd to me at first, but it's a trick I'll remember from now on.

Did you ever get your Alky figured out?
Click to expand...
LTFTs lock in at -2.3. the PE Time vs RPM is zeroed out all the way from 0 to 25 seconds. The AFR vs TPS is also zeroed out from 10.7 to 14.7 thanks to eddie. However, does the table go by point values to add/subtract from the commanded PE set at? So, as of now my PE AFR is set at 11.6. so from 400-4400 RPMs I’d add, -0.58 in each cell?
 
It should gradually add fuel over the course of 14 seconds, then stay flat after that.
Them locking in at -2.3 isn't the issue though, it's the idle that is screwed up. I'm not home to look at the laptop, so I can't tell you exactly what mine is set at, although it wouldn't matter much since I have the XP. I "think" that in that first cell I actually have it set at the -1.50 range, but I've left the rest of the table alone with exception to the webracin tune that's been slightly leaned because of the alky kit.
I think that the AFR on command you're looking for out of the hole is close to 10.5, and if that's too much right there, then back it off a bit.
 
reptile u think u can take a look at the pe vs rpm table and get back to me how yours setup like please? thx!
 


btw, both ABS and tcs lights are on, assuming either my wheel speed sensor’s bad, ebcm or a bad wheel bearing, that still means the traction control is turned off correct?
 
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