TraviZ

iTrader: (2)

Running 42# injectors with my SD resulted in poor results. SHould I learn to tune them down? Will even a wideband o2 telling me how rich i am make any difference in the ecm to be able to even efficiently cut down on the fueling that these injectors produce? Would I be better off running 24's again?

RednGold86Z

iTrader: (1)

The pulsewidth commanded by the computer is what puts the fuel in. The way to do that is by telling the computer what the injector flowrate, displacement, and most importantly, VE, are. Your engine's VE will not even resemble a factory VE table. Learn to tune the VE table.

Are you trying to tune in closed loop? If so, adjust your VE until the BLMs and INT come into the 120-130 range.

42's are a bit big for your combo, though. I'd have used 36's in your setup. 42's might be tough to get a stable idle with closed loop on. If you want to, use closed loop to get the main VE correct, then turn it off, and run all open loop, and get your idle smooth. A wideband will help a lot, and keep you from popping another motor.

TraviZ

iTrader: (2)

the thing is, i can get it to idle without a problem. i do have my injector constant and displacement correct. only thing is i have no idea how to correct the VE. I plan on purchasing the wideband off moates tomorrow but even once i have that in. im just not sure. I want to tune it mostly for wot since i mostly use the car for racing. is changing the ve gonna even matter at wot?

RednGold86Z

iTrader: (1)

VE matters EVERYWHERE, even at idle, and WOT. The only time it's not used is during fuel cutoff, and cranking.

You could use closed loop and look at INT and BLM at up to about half throttle to see how close your VE is, and make changes to make BLM happy, and then later go open loop.

BLM being happy means getting it close to 128. When BLM is happy, then WOT will be happy and somewhat match what the PE tables say.

TraviZ

iTrader: (2)

Ok, only thing is, I am not sure, maybe I am using the wrong program (tunerpro) to datalog. Is thier a better program out there? I am familiar with the blm value. When I am recording my session do I just follow the blm value and say its reading 120 at one point, I go to that map/rpm value and lower the VE number to remove some fuel at that point?
Isnt the blm a direct reflection of the o2 readings?

On a second subject, how would it benifit me to always run open loop once the VE is dialed in? is it because of the cam?

3.8TransAM

Bosch 42/42.5 injectors are known to have erratic idle issues and are not a linear injector over the entire range as a whole.

Do some searching over at turbobuick.com and the like for multiple graphs and test.

Make sure you set timing/injector size/engine size accurately to what you are running.

Even moreso that you are a beginner.

Also with your cam I would try pulling out like 10-15% of the fuel at all ranges under 1500 or so and see what happens.(assuming changes are on a stock bin)

Also due to the erratic nature of the 42's after you get fueling in the 120-130 range, if the integrator is rolling up and down you might need to play with the 02 PID's.

Also 60/65# Motron injectors will idle clean and crisp at a 1.3ms pulse width, so any good linear 42# should be able to be tweaked into submission(again 42's do have known issues)

later
Jeremy

doc

42s are way too big for your engine, you should not need larger injectors than 30s. I run my 395 cu.in. stroker with 24s and run 12.19 and 12.20s ETs.

For 42s to be required, you got to have a power adder. Take them out.

TraviZ

iTrader: (2)

I was thinking and pondering ideas around, What if I dropped the pressure to 20psi and set the injector constant to 28?

junkcltr

iTrader: (1)

I went with the Ford 42#/hr injectors. I heard that they are bad from many people. Some said they are OK. For the price, I had to find out for myself if they are usable.

I have been using them for about 8 months. They seem to work fine. I am using them in double fire batch mode and the idle BPW is about 1.2ms. The main thing was learning to tune them. You need a flat idle VE table. I think you have that figured out though because you said your idle is fine.

I think most people have trouble with them because they don't take the time to tune them properly. I tune with a WBO2 and that makes it a lot easier. I think it is cheaper to buy an WBO2 and tune that way than buying expensive injectors.

Opinions will vary. A WBO2 is worth the money.

RednGold86Z

iTrader: (1)

Don't drop the pressure that low. I wouldn't go below 38 psi.

You've got about 460+ horsepower in there, I'd guess. The injectors will work fine when you're doing anything other than idle. Idle will be tricky, no doubt, but it's possible. You don't HAVE to take them out.

It's almost all in VE tuning with SD. Then get the afterstart fueling and warmup, and cranking.

Grumpy

42's are not even close to being linear in nature, and thus for a new gy can be a lot of heacaches. Heck, even some experienced tuners have troubles with them.

The smaller the injector the quicker you're going to use up the AE. Some combos need alot of AE to get the car to move, and have off idle problems due to a too lean AE.

I use 60 PPH injectors in my 231 V6, and it idles better then a stocker..

TraviZ

iTrader: (2)

I really appreciate the help your doing for me man, One quick question I still need to verify. How do I know how to adjust the VE tables? I am thinking I watch the BLM value and say at 2000rpm, and the map is reading say 70kpa, and blm is reading 120. I would go to that cell 2000/70 and lower the number correct?

RednGold86Z

iTrader: (1)

Yeah, that's the basic idea (120/128 = .94 multiplier). And when first roughing in the table, you can take a few points on the table and interpolate in between the points (and guess a little at points outside the table) to fill the table in to get it closer and more drivable.

junkcltr

iTrader: (1)

It is hard to compare a SEFI ECM (squirt once) to a double fire batch ECM (squirt twice). Tuning the 60s in an SEFI is like tuning (60/2 = 30#/hr) in a double fire batch. The double fire ECM is more affected by open/close time.

TraviZ,
You have the right idea with tuning the VE tables. I tend to drive at the VE table RPM values (constant RPM...no accel or decel) and collect data at various MAP locations. Then go into the VE table and adjust the VE like RednGold86Z said at the RPM and MAP values that you have. Smooth out the locations of VE for the MAP and RPM that you don't have. It sounds like you are making good progress.

Your part throttle cruise BPWs will be in the neighborhood of your idle BPW so you need to be really accurate with the VE table around these low MAP values. That is, you need to make small VE changes to hone in on the AFR.

TraviZ

iTrader: (2)

Ok cool guys, I am for sure gonna start playing with it tomorrow. Next question, Is there a blm/VE ratio I can do? Such as the blm down a certain value meaning I adjust the VE a certain ammount? like 1:1 or like RednGold86Z, its a 1:.94 ratio?

Oh and, I user tunerpro for dataloging, Is there something that is going to be more accurate or easier to read for me?