Ive been trying to tune my 730, 383 Miniram ported TF 23* ZZ409 4.10 gear T56 car and its been very fustrating. Ive been trying to read as much of the tuning articles as I can but I still have a below 3000 rpm driveabilty problem. It bucks and sounds like its missing at part thottle cruise and light load acceration. Ive seen my BLM's are about 112 round town and 128 on the freeway. Ive got 30# svo injectors and Im running 38* of timing in my spark tables. Ive tried running 42* down below 3000 rpm but it dosent really seem to make much of a difference. If I run the car pig rich on my VE tables below 3000 it does seem to get a bit better, but then my BLM's go to 108. I do have some datamaster scans and I also use a scan tool as well, but im new to this tuning so I could really use some help here. Does anyone have a simlar combo bin they could send me just so I could look at it and see what you guys are doing? Thanks in advance.

 

well, you've explored the limits of high timing, how about taking some timing out?

post your timing table for everyone to see.

you lose very little HP for being a few degrees below the optimum timing, but you can really have a monster of a tuning issue on your hand as soon as the timing goes above the optimum - and throwing gas at it to mask teh problem is not the answer.

simply for testing purposes, try running no more than 32* timing in the 80-90-100kpa areas, and no more than 34 in the lower load areas. taper the timing down with rpm.

anyways post your timing table so that we can make some suggestions.

you will probably find that when you pull timing out, your BLM's are going to change. that's expected.

 

Here is my lower SA table

23.9 23.9 24.3 24.3 23.9 19.0 19.0 16.9 12.0 6.0 6.0 17.2
25.7 26.4 26.4 26.4 25.7 21.1 20.0 17.9 16.9 12.0 6.0 17.2
29.2 29.5 29.5 28.8 29.2 25.3 25.0 23.9 21.4 17.9 12.0 18.6
32.3 32.3 32.3 32.3 32.3 29.2 28.1 27.1 25.0 22.9 16.9 20.7
35.2 35.5 35.5 35.2 35.2 32.3 30.6 28.8 27.1 25.0 17.9 23.2
35.9 36.9 36.9 36.9 36.9 34.5 32.3 30.9 28.8 27.1 22.9 25.0
35.5 38.0 38.0 38.0 38.0 35.5 33.8 32.3 29.9 28.1 27.1 26.7
35.5 38.0 38.0 38.0 38.0 36.6 35.2 34.1 31.6 28.8 27.1 27.1
35.2 38.0 38.0 38.0 38.0 37.3 36.6 35.5 33.0 29.2 28.1 27.1
35.2 38.0 38.0 38.0 38.0 37.6 36.9 35.5 33.0 28.8 28.1 28.1
35.2 38.0 38.0 38.0 38.0 37.6 36.9 35.5 32.0 28.1 27.1 28.1
35.2 38.0 38.0 38.0 38.0 36.2 35.5 33.0 28.8 26.0 26.0 28.1
35.2 38.0 38.0 38.0 38.0 34.8 31.6 28.1 26.0 23.9 24.3 25.7
35.2 38.0 38.0 38.0 38.0 33.4 30.9 27.1 25.0 23.2 24.3 25.3
35.2 38.0 38.0 38.0 38.0 33.0 29.9 27.1 25.0 23.9 24.3 25.0
35.2 38.0 38.0 38.0 38.0 34.8 31.6 28.1 27.1 25.0 26.0 26.0
35.2 38.0 38.0 38.0 38.0 34.5 31.6 28.5 28.8 28.1 28.1 28.1

 

purely for testing purposes, what I woudl personally do if that was my setup, would be to use tunercat and multiply that entire timing table by about 0.85.

That would take you down to 32* or so in your max timing areas, and a bit less timing everywhere else, too.

Will it be "optimum" from an economy/MPG perspective? Nope.

But it will tell you quite quickly if the motor doesn't like the timing you're running. And it's just for testing purposes.

can you post a data log?

 

Yea, Ill try the new timing table and then do a new log for ya, thanks for the help, I need it!!

 

another thought/question.

Do you really have bucking problems under cruise (no acceleration at all?) If the problem is only when getting on it, you might need to work on the AE a bit.

what cam do you have in it?

 

It seems to be the worst under lighter loads. (normal accelerate from a stoplight) @ cruise it doesnt buck at all. Right now I have a TPIS ZZ409 cam in it with 1.6 rockers on both sides.

 

Are you sure you ignition system is functioning properly? I had the very same symptoms as you, and found that the problem was 2 cylinders miss firing due to plug wire boot to header contact.

 

Yea, that was the first thing I checked out. I ended up putting a new Accel cap and rotor, plugs and new O2 sensor in, just to be on the safe side. I also ohm'ed my SVO 30# injectors and my Taylor 409 wires as well, all checked out good. The plugs were a little black, indicating that Im a bit rich.

 

She ran real good today after the changes, I guess I wasent pulling enough timing out the last time I checked it out. I still have a bit of a tip-in surge/bucking just off of a shift, but its not as bad as it was before.

 

As many have said, always run the *minimum* timing possible that equates to best performance.

You can review your datalog to see what rpm/kpa you're at when you experience the tip-in surge, and maybe pull a few more degrees.

or (in my opinion - more likely at this point) you need to work with the AE now.

you'll still want to experiment with your timing to see what your engine likes most. it could be that we took out too much, or not enough, or maybe it wants more (or less) in certain areas.

just a few thoughts.

 

Which one of the AE tables should I start with?

 

depends on the problem.

If it responds well but 1/4 second later stumbles and then catches back up, then look at the AE duration (decay factor) and do a little testing with it.

on the other hand, if you stumble/backfire the instant you touch the gas, then look at the TPS and MAP multipliers.

maybe someone with a bit more experience tuning a non stock cam can comment, as well?

 

A log of the below-3000 driving along with Wideband O2 data would be extremely helpful.

Tim

 

Thats the info I was looking for 91L98Z28. Thanks!

TRAXION, I can get you a Datamaster log below 3000 rpm, but I dont have the wideband just yet. Thanks for the help.

Im going on a trip and wont be back till next week.