Hi guys, I got to take the HSR'd 327 to the track last night. It's about 1-1.5 mph slower than when it was carb'd, although not really any slower ET. One problem still exists, which I also had when the car was carb'd -- I can launch the car from 2500-3000 rpms, sliding the clutch, and get it to hook up, but then when I open the throttle fully (PE mode) from this slow rolling speed, the car bogs and then slowly recovers -- this results in terrible 60 foot times of 2.4x. In the past, I have gotten faster 60 foots (2.2x, still really bad) blowing the tires away, because this avoids the full throttle, low speed bog. The bog is occurring in the 1500-3000 range at low road speeds (I have 3.73 gears and a 4 speed manual by the way). I don't have a wideband unfortunately. Does this sound more like a lean PE problem (especially with the big plenum Holley Stealth Ram) when I'm opening the throttle fully, or a too-rich PE problem and the engine is recovering? I have 28% PE at 800-1200 rpms, and then 22% from 1600 to 4000 rpms and 24% ramping to 37% from 4400-6400 rpms. It looks like the bog/recovery when I crack the throttle is all within the flat 22% PE range. I do not get any popping or stuttering, it just smoothly loses power and then gradually recovers (it is quite slow to recover, it takes at least a second for the power to pick up, if not more.) I am certain that the 2.02/1.6 open chamber heads, 8.5:1 compression, and big choppy cam (I'm shifting at 6300 rpms for best ET's, it is not a small cam) are setting me up for soggy low end power, but hopefully tuning can at least get me out of this hole faster. I think the loss of mph was due to the stock 1989 GTA intake duct and stock air cleaner housing I'm using, which I've heard is very restrictive. I am also pegging the MAF at 255 g/s, and am adding around 15% fuel at top end based on nothing in particular, just my guessing, so this will need to be figured out on a dyno with a wideband some day. Any insight is appreciated!!

 

I'm a little fuzzy on this but wouldn't 28% be 10.6afr and 37% = 9.3? Seems a bit rich. Almost like you're subjecting the motor to "higher" compression and masking it with too much timing. This is easy to do with an HEI.
Have you tried removing timing in those area's and I must say, run a wideband if the numbers are starting to look really far off. It's an easy trap going with too much fuel and too much spark... especially on a low compression motor. I'm not sure about the big cam but I'd think that would also be masking this issue. I've done it, a lot of us have done it and it feels pretty good until you get it right.
So get a wideband and quit guessing . If you're still contemplating the wideband might try an experiment where you take out 10% of the PE fuel (ex 28% before, 18% now) in that area of the tune, and in another you add 10%, or less, just to see what happens. Take notes and if it backfires through the intake on the 10% lean then you know you were too lean.

 

Without a WB, you'll just be guessing at what to do, and possibly in trying to get by with one, miss the tune completely. At ~$300 they're a cheap investment. Figure out how much wear and tear you'll do in the long run trying to *save* the 300.

A dyno only gets you right for running on a dyno. It's hardly even cost effective, IMO, compared to buying a WB. Heck even going to a dyno with something you've worked out with a WB can afford a huge cost savings.

Datalogging with a WB is just the way to go, IMO. At least for those of us without access to 5 gas analysers.

 

JPrevost, I have 22% PE in the PE vs temp table for operating temperature, 6% in the PE rpm table at 800 and 1400 rpms, and 0% in the PE vs RPM table for 1600-4400 rpms. Above 4400 rpms in the PE vs. rpm table, I have 2%-15%. This gives me around an 11.8:1 commanded AFR below 4400 rpms, and a max of around 11.3:1 at high rpms, as indicated by my datalogs. This is not too far from stock.

 

The LC-1 WB while hard to get, is only $200.
But it requires a WB patch or another method of datalogging
Mine should show up in the mail eventually.

 

I would guess it's too much AE, and maybe a little too much PE, assuming it isn't knock retard. Lean AE will tend to "buck" or jerk more than "bog" if I had to try to differentiate the two. If it's so rich that it's bogging, someone would probably be able to see some puff of black smoke, but US gas really doesn't like to smoke as easily as this Chinese gas. A PE only bog would not recover.

PE A/F is calculated easily as 14.7/1.xx=A/F where xx is the total PE added, i.e. 14.7/1.28=11.48. A while ago I posted the fix to the $6E .ecu's that had one of the PE's showing double what its actual contribution was. To get 12.5:1, you'll need about 18% PE, which is usually a safe place to start with NA engines.

 

A PE only bog would recover though, since the engine's fuel requirments change as the revs rise. If I'm giving it enough PE fuel that it is losing performance, but still accelerating (which it is), I end up getting out of the hole and then into higher rpms where my cam really turns on, and the engine likes the amount of PE fueling. I feel that its rich, as I got this same condition with a carb, only when the throttle was opened fully from a low speed roll in 1st gear. At this point the Holley double pumper was giving the car quite a blast of fuel (30cc primary pump, 50cc secondary), and it would recover and then take off.

 

Yeah, the pump shot is the same as the AE fuel. PE fuel is like the jets in the secondaries. An engine shouldn't really bog if it's actually at 11.5:1. It'll take low to sub 10's to really bog, which AE can do.

Does it bog the WHOLE time while the RPMs are low? or is it just after slamming the throttle?

 

Just a FWIW, for those tuning in:

When you have an ecm bench, you can run it in more or less a steady state mode, and then compare numbers to a data log. Doing so allows you to enable/ disable PE, and then see how much is AE. You can then baseline those numbers, make a change, and again compare the Datlog to the bench. What takes hours and numberous passes, can be reduced to just a couple, one to establish a baseline, and then several to see EXACTLY what's going on. Having a datalog with a WB, makes it even simplier, and faster.

 

Ah, I'm still confused, lol

 

The max if 22%+15% = 37% and 14.7/1.37 = 10.7 AFR

 

https://www.thirdgen.org/techbb2/sho...hreadid=259424

See this for $6E PE fuel calculation.

There was a .ecu with one of the terms saying it was double of what it was supposed to be.

From that post:
OK, got it now:

For PE vs RPM
Multiplier = .390625
Offset = -50

For PE vs Ctemp
Multiplier = .390625
Offset = 0


This way, if you add the numbers they will total the total added percent. So, if you want 12.5:1, you simply take 14.7/12.5*100-100=17.6%, and the two PE's must add to 17.6%.

If you want 13:1, take 14.7/13*100-100=13.07% total PE.

Cool eh?

 

Annoying when I've been so used to AFR modifiers. I like the open loop AFR table and the AFR +/- modifiers but I'm spoiled. With xdf I might just go and change the 6E file to display AFR instead of %. Would make it a tad easier to do the math in one's head.

 

hehe, yeah, a little annoying, I guess. I'm totally used to %PE though. There's probably a way to do it that way in the old TP RT. I haven't checked though. The math is a little funky when there's 2 terms. You'd have to do 14.7-14.7/(1+(%added/100)) for both, I think. Something like that anyway, if you just want to see the modifier (convert that to hex first, and the 100 and % and all that goes away when the math is done in the simplest terms).

 

Redngold, under the right conditions (first gear, throttle fully opened from a slow roll), it bogs and does not recover until the revs have reached much higer rpms (actually around 4500 when I look at my datalog of the 1st 1/4 mile pass). The narrow band hits 941 mV as soon as I hammered on it from around 30 mph in 1st. Here's what the O2 was doing during the slightly less than 2 second bog

941.28
808.08
794.76
852.48
941.28
785.88
927.96
785.88
794.76
941.28
781.44
785.88
785.88
825.84
781.44
785.88
785.88
936.84
785.88
785.88
808.08
794.76
794.76
923.52

Once I'm recovered from the bog going down the track I never see O2 readings quite this high again -- the O2 peaks in the 800s, occasionally slightly over 900, the rest of the time

It does look like I'm rich, but could AE cause an almost 2 second bog?

 

Looks like it's too rich to me, so get a wideband and lean it out. Try try again, or if you want to prevent wear and tear on the motor get a bench and datalog the wideband with pulsewidth.

 

I'm running 6E maf. If AE was indeed causing this extended bog (could it really? how quickly does it decay out, ballpark), what AE parameter do I change? The only AE term in 6E that seems to apply is AE vs. delta LV8, is this what I'm looking for? I think I'm going to lock out PE and go for a spin and see if the bog is still there.

 

Well, AE lasts for less than a half a second after the pedal stops moving, but a rich bog has to clean out the manifold and the plugs, so it can take longer.

I guess the real question is: Did you modify AE from stock?

If I were to guess, the stock settings wouldn't be terrible start. Maybe the cam is calling for less quick DTPS AE, and the manifold may want a little more slow DTPS AE. Just SWAG though.

 

Hi, I don't see a delta tps AE in 6E, only delta LV8. I am running stock AYPY values

 

There is "AE Factor vs delta LV8", "AE Decay Factor vs CTS", "# of AE pulses vs CTS", and "AE LV8 Factor vs CTS".
As for TPS AE in the $6E, this is all I could find in the hack;
Do a search on 6E AE tuning, should turn up some help.

 

UPDATE. I took the 76cc big valve, big chamber heads off the 327 this week -- the pistons I found in the engine were actually speed pro forged, which gave me only 8:1 compression w/ the big chamber heads. I installed a clean, reworked set of 461 305 heads for 10:1 true compression, and then took the car out for a spin. It ran excellent, but still experienced the bog when going WOT from a slow roll in 1st. I took 10% out of PE from idle to 3000 rpms, and guess what, no more bog, the car will spin the tires from a slow roll and pulls strong. So, as I had guessed, yes too much PE can definitely cause a rich bog that the car will then recover from.

 

Not to argue, by any means, but it's probably the combination of AE and PE that's bogging. Then AE decays out quickly, the plugs clean up, and runs with PE only.

 

Sweetness! Glad you got it rocking and rolling. AE really isn't a big deal with port injection, near stock works well on n/a engines for 90% of the drivers WHEN they've got their tables all squared away. Like Grumpy's tuning article, get the idle and steady state cruising all squared away before jumping head first into the PE and fast throttle movements.
Having the MAF upstream of the throttle body also adds to the transient delay by a smidgen... not much, but it's there. Some new designs are coming out that have the MAF meters in individual intake ports, I wonder why .

 

MAFs on each intake port? Wow! That would be incredibly awesome.