cool55t

Im in the process of swapping to a 7427 PCM. I have started with a BJYL bin and made various changes to run the 700R4. At first start it seemed to run smoother then the 7747 did and drives nice. When I punch the gas it pops out the intake once and bogs down. I have read for days on this subject and have learned a lot and have tried various things and still cant get this ironed out. Iv ended up quadrupling the AE vs map and AE vs Tps. When I hit the gas I see a very quick rich spike to 11 afr on the wideband then it goes to around 15 afr and it has a slight struggle when accelerating then eventually smooths out with no intake pops now. All that is in over drive. In Drive it acts differently, it still has the struggle to itself like something is holding it back but then it smooths out and takes off quicker. Its very possible I have read so much about this that I have confused myself on what changes to make. I can attach a bin if necessary.

Edit: the timing table im using is the stock BRDW vortec van timing table

Ronny

iTrader: (1)

Is there a filter for AE in your def file? If so decrease it making AE last longer in msec....

cool55t

I dont think the $0D uses that for AE. It has the AE vs TPS which is for a short duration then the AE vs MAP which is for the longer duration. The tps is suppose to happen when you punch the throttle and it does according to the WB but then it drops down to around 15 afr and stays there struggling to get moving. What confuses me is i have the AE and PE turned off on my 7747 and it gets the truck going quicker then the 7427. The motor itself is stock. It has headers and 2.5" dual exhaust all the way back and an edelbrock performer intake. I dont understand why I have more then tripled the AE tables of a stock tune and it still wont go.

Ronny

iTrader: (1)

I was told that AE MAP is invoked with a change in MAP. A good example would be steady throttle and then keep throttle steady but start climbing up a steep hill. MAP increases and AE MAP is released with no TPS MAP.



Maybe your FP is falling off. Might want to check FP with gauge taped to windshield or have passangr hold gauge..

cool55t

in my xdf is states "Added AE based upon difference in MAP kpa. TPS AE comes in when you stab the throttle but is over after about .1 sec, then MAP AE takes over for approximately 2.5 sec. All AE BPW is done in Asynchronous mode because it is in addition to the synchronous pulses that normally fuel the engine."

When I climb a hill at a constant tps, it does not hesitate at all. Only when I give it more throttle going up the hill. I just installed a new fuel pump and filter. Pressure should not be a problem since I DD with the 7747 ECM plugged in and it runs and drives fine and will get up and go with no problem.

Ronny

iTrader: (1)

Do you have a WB? That may be helpfull. Can you datalog event?

Seems like AE is not working...

cool55t

Yes I do, as stated before when I punch the throttle I see the WB go to around 11 AFR for a split second and then drop to around 15 AFR and then stay there while struggling to get going. Before I increased the tables, i would get a pop out of the intake but the WB would never go in the red or past 16 AFR. Wouldn't a pop indicate a very lean condition? if so why wouldn't the WB peg lean? I can data log the WB with tunerpro using a hack but I would have to do some rewiring to connect it to the PCM.

Ronny

iTrader: (1)

350? what size inj's? What FP? What is your BPC? Is the FP vac referenced?

AE can required more fuel(msec) than PE...

cool55t

yes 350 gm crate with vortec heads. Injectors should be the stock 61# 5.7 injector and im running them at 12-13 psi last I remember. My gauge broke so I need a new one. Fuel pump is ran from the computer however that works and the FPR is stock but modified to be adjustable. BPC I do not know. in the bin it ask for the injector # rating at a given PSI and then it does the rest of the calculations.
I know that the current setup will not properly fuel this motor at WOT and I dont feel comfortable taking it to the max yet with only a few hundred miles on it but i dont see why i cant get it running good around town and at idle. once i learn what things do what with this new computer then i can bump up the fuel pressure and do a few datalogs to get numbers where i need them to be.

There are a bunch of random multipliers that may be giving me the problem. there is just so much stuff compared to the 7747 which is 4kb, the 7427 file is 64kb. I noticed a parameter set to multiply the AE by 1.5 when in off idle mode. Why is this extra stuff needed? it seems it would take days to disable and test run these things one by one to narrow down what does what and how it affects other things.

Ronny

iTrader: (1)

I will assume it basis then on 350 cid.

top down solutions can supply one one step stronger.

First time I heard of that. Must be a reason.

I would get the spring and consider adding 10% more FP at a time to see how it responds.

I would search "7427" some members have gone down the road you are on and you might PM them or locate threads on 7427.

ps. large intake plenum/runners need a whole lot of AE. 11/1 I dont believe is a whole lot of AE. Adding more may not provide AE at the combustion chamber. It may wet the walls heavily and add to duration. No AE filters huh? If you find one reduce the value.

cool55t

I have searched and searched and read about this computer swap for days and have found the same problem im dealing with. the problem is no one follows up on there thread saying if its been fixed or not. Or the application is very different then mine.

Im using the files from this site http://www.gearhead-efi.com/Fuel-Inj...Information-OD

BJYL 350 TBI 700r4.bin
Advanced $0D TP5 v251.xdf

this computer even has power steering spark compensation parameters.. its crazy

whatif3387

I'm running a stock L31 with full exhaust and 1.6 RR's and I'm at 15psi with 80lb injectors.

cool55t

Are you using a 7427 computer with a 700r4 trans?

Fast355

iTrader: (2)

Not nearly enough fuel and I bet you are still trying to use TBI like spark advance tables as well. I had a similar setup that would actually backfire if you tried to accelerate hard under 2,500 rpm.

cool55t

The timing tables im using are from the tbi vortec export van. a pain to find that bin file but i found it. If i slowly accelerate on a long stretch bringing the rpms up the wideband is showing that its getting the proper fuel. Its just when i punch the throttle it hesitates, and thats not WOT, only about 50% in 4th gear. But when its in 3rd gear it gets up and going quicker with not much of a bog. The 7747 runs this truck great and this computer does not which is why im ruling out fueling and anything mechanical for now. I know it will need to be changed in the future but im just trying learn how this new computer operates things.

whatif3387

Nah I'm using an EBL with a 7427 to control my 4l60e but I know that 61lb injectors at 13 psi won't feed an engine with vortec heads atleast in my own experience.

cool55t

I know it wont, as i previously said. I understand the pressure is not enough for full power. My 7747 runs this truck great and it will get up and go as is. The 7427 falls on its face and i cant get it to accelerate anywhere near like the 7747 can do. Which is why im here asking this question. I find it hard to think that a newer computer needs to max the injectors out to get it going when the old computer does not have to do that.

I have read and read for a long time about this computer and there is a lot of good information and just plain wrong info. I have tried changing new things for the past couple weeks before asking on here. The only success i have had is getting rid of the intake pop and flooding it on light acceleration when cold. Im hoping someone can spark my mind on how this thing works in the bin so i can try something new out, but the only response i get is up your fuel pressure. Sorry its been a long night at work and this truck is frustrating.

cool55t

To update in case anyone finds this in the future, i have solved the problem. I used a timing table from a 95 lt1 corvette and the truck really woke up and runs very smooth and accelerates great now. i didnt think the export l31 van table would make it act the way it did, so lesson learned.

Ronny

iTrader: (1)

There is also an iron head LT1 SA table posted here somewhere. Obviously less aggressive.