396V8

hi

i built a 396 with AFR210cc heads, 234/238 .565 lift 112LSA 288/292adv
and an Accel single plane EFI

car is a manual six speed

my problem is, i have some off idle stumble...

when i blip the throttle in neutral, the engine takes gas fine and smoothly..

but, when i want to accelerate quickly from a stop, some hesitation and slight bogging occur, until i reach higher rpms...

i have modified the AE tables , mask $8D

i also organised my some .bins for reference, e.g. Minirams, which should come close, but still driveability suffers...

when cruising, or giving spontanous throttle when driving, everything ok..

only when i take off, i have the problem..

can you point me in a direction, how to successfully tune the single plane?

thank you

gta324

Do you have a WB?

My guess it a lean spot, you may need more AE.

Try to raise the AE vs TPS alot ( 50-200% maybe)to see if it helps.

Do you have a scan over the problem?

junkcltr

iTrader: (1)

In the $8D:

TPS AE is done by injecting fuel async.
MAP AE is done by injecting fuel sync.

I don't like having a lot of TPS AE fuel. It will fix the low throttle problem when you increase it a lot, but will be too much at high rpm TPS changes.
I usually disable TPS AE by setting the CAL values high so it is not active. I then tune MAP AE and get it where it seems reasonable. After that, I turn TPS AE back on and tune it to where it works well at low rpm TPS changes and high rpm TPS changes. The big problem with the TPS AE is that it just does a calc based on a lot of things and one of them is not rpm.

You will find most people like a lot of TPS AE fuel. I never found that to work well at all rpms. It really gets ugly with engines that can make high MAP (90+ KPA) at low rpm (less than 3000 RPM) and low TPS (less than 30%) values.

396V8

ok, i installed my WbO2 today. and out come the following...

my AFR at idle is about 14.00 in closed loop, about 16.00 in open loop (i blame this on the AIR, i measure at the collector)

when i blip the throttle, the AFR goes down to 12.5-13.5, without hickup, then goes to about 15-16, than goes back to 14.00


now....i drive, first gear, rpms near idle...then i open the throttle, AFR goes down to 12.5 sth. then goes up to 15-16..and thats now, where the bogging occurs...then, when i´m over this, i have normal values, about 13.5-14.00


i have tweaked the

AE TPS Mult vs TPS
AE delta TPS PW factor vs Coolant Temp
AE delta MAP PW Mult vs delta MAP
AE delta MAP PW Mult vs coolant Temp
AE delta MAP PW decay factor vs Coolant


im not that far away, and compared to, how the driveability have been in the past tunes, its wayyyy better...

the car takes gas fine, everything, just the "takeoff hickup" is disturbing...

thank you very much

Ronny

iTrader: (1)

junktlcr: interesting that you favor AE-MAP over AE-TPS. i am running 8746EBL. my tune is heavily favored to TPS-AE. i always thought TPS-AE arrives sooner than MAP as the sensor is faster. also i was told TPS is for a movement of gas pedal in attemping to accelleerate and MAP was a steady pedal but change of MAP like climbing a hill. anyway what iam seeing in my WB logs is an AE spike of short duration(11.5/1) with change of TPS- AE is used up-goes lean(14.0/1)- and then PE enrichens to 12.6/1. not a smooth transition AE to PE. a jagged read even with smoothing. i already have PE at 50%. only option i see is putting PE at 40%? or increase the duration of AE. that was my Q? i may just flip the values in TPSvs MAP and see how that works. i already have posted this Q today but did not hear back.

Craig Moates

I'm also running a single plane NA setup on 730. The bog is pretty tricky to address, but I'd side with Junk on this. Spend some effort on the delta MAP AE. From your observations it sounds like your delta TPS AE is OK (the fast initial delivery) but that the more sustained characteristic (delta MAP) is needful. That'll govern the first 1-2 seconds after 'stabbing' the throttle.

How does it do when shifting gears quickly? Does it 'stay in the game' so long as you stay in it? I had mine so that it did, and still had the initial bog. Seemed like the engine was taking a break (one-thousand-one...) and then it came in clean with full PE. The MAP PE cleaned it up to where the tires just roasted continuously from the get-go.

Also running big cam, higher MAP at lower RPMs, 6 speed.

396V8

Hi Craig

thanks for chiming in....

have you taken a look at the word document above? there are my AE MAP Tables for reference...

so, which AE MAP tables would you recommend me to modify?

AE delta MAP PW Mult vs delta MAP ?
AE delta MAP PW Mult vs Coolant Temp?

AE delta MAP PW Decay Factor vs Coolant Temp?

from what i understand, the Decay ia also an important factor..can you enlighten me on this?

ok, when im driving, and shifting gears, no problem, takes gas in the moment i step on the throttle...
i think, we are in the same boat...when driving, with normal rpms (above 2000, or so) , the car drives near stock,....

which tables would you modify?

ps: your ostrich is a nice device!!

junkcltr

iTrader: (1)

You are correct about TPS AE and MAP AE. MAP AE is for when the MAP is changing and TPS AE is for TPS changing. The only way to test the two is hold one constant and jab the throttle. When tuning the two, first I start off with no TPS AE and a little MAP AE (just to keep it drivable) and then find a good hill to climb where I can hit high MAP at various RPMS (slow roll on the throttle....foot brake helps). This allows the upper VE KPA areas to be tuned properly. It is very important that low RPM, high KPA is correct in the VE table. A lot of people end up trying to cover up a bad VE table with AE. I know I was one of these people when I first installed the SD code.

I also set my PE MODE to gradually bring the AFR rich. Once the VE table is fine, then I give it more MAP AE and later move on to TPS AE. I run the $8D code and do not know how the EBL does it. The thing with the $8D is that it squirts the injectors twice during an engine revolution. At high RPM that can be a squirt every 10ms, so TPS AE injecting NOW can have a big affect. At low RPM it will squirt on the order of every 25ms. The AE will have less of an effect. MAP AE is always based on the sync BPW so it is just a multiplier like the PE MODE AFR is. This is much more smooth at high RPMs than TPS AE is.
When TPS AE is injected, the ECM reduces the Sync BPW accordingly. It doesn't work out quite right at high RPM.

I once had my TPS AE pumped up for the LT1 intake because most people siaid that it needed it. Now, I have the VE table correct, a little more MAP AE, and less than stock $8D TPS AE. It seems to work well on this engine/vehicle. If it was a tow vehicle, the MAP AE and TPS AE may be set up very differently because of the high KPA when towing. Small MAP deltas would occur when TPS changes, but it also would be a low revving torque engine so more TPS AE wouldn't hurt up top. Gearing and weight have a lot to do with it.

Check that your high KPA, low RPM VE table is correct and go from there.

RBob

iTrader: (1)

396V8, not sure how hard you are hitting the go-pedal, so have different ideas. If this is just regular to a snappy pull-out, can increase the VE% in those areas that are hit. This is common practice and works out well. Look at a log file to see the RPM & MAP the engine transverses and up the VE values.

A little additional SA timing can also help. A lean mix burns slower and increased SA gets it lit off sooner.

If this is more of a mash the throttle, then what Craig mentioned is required. Getting the ECM into PE mode sooner. $8D has 2 TPS% vs RPM tables for this. One for high engine temperatures.

RBob.

396V8

hi all

i just checked my datalogs, and VE seems to be near perfect between 124-128...

when i take off slowly, i have no problems...

the problem occurs, when i pull out a little harder, not full throttle, just a good start...

i think, i have to tweak the AE MAP tables...

i will drive again tomorrow, and will let you know, what come out

thanks again

396V8

no good news....i was not able to drive, its been raining heavily...i still hope for some sunny, dry days to make some test drives...

brutalform

396V8, anything new? Did you get the problem corrected?

Never mind, I found your other thread.

396V8

Hi!!

unfortunately not....its a bit better, but i think, i still do have to add some VE in the lower tables....

especially from 1000-1600rpm and 85-100kpa

is it possible that i have up to 80% VE in that Area??