My Lterm BLM's are 106 and 116, how would i get them closer to 128? I want to try to get it 118 and 128 first, or 123 and 132, then correct each side accordingly. But how do I tune the car using tunercat to lean the car out so they car closer to 128.

 

Very simple. Go to the MAF table, and decrease the table by a small %. Try it, then do it over. Make small changes and see what happens. Only make changes where the BLMs are off.

For example, if your BLMs are always around 128 when your MAF readings are over 100, leave those alone. It really helps to have a scanmaster or datalogger to know what the MAF reading is when the BLMs are off.

What you are doing is telling teh computer there is less air coming in than there really is. The extra air leans the car out.

Good luck,
Ryan

 

increasing your injector constant will raise BLMs in all cells. the cells i mainly look at in my car are 06 10 14 to determine if anything needs adjusting since these are off idle with usually enough RPMs to rule out reversion as being a factor in splits and such. now since you do have a big split its likely you are either experiencing some reversion or just have an exhaust leak on the high side. so fix that problem first and then go about raising the BLMs with the injector constant. after you have done that you may still have some low spots like for instance cell 06 is 125/125 and cell 10 is 119/119 then what youd do is look at your MAF value when the BLMs are 119. take that.. lets just say its 35 gps.. to your LT1 edit or tunercat, find the MAF tables and find 35 gps or close to it. then just decrease the value to 33 gps or maybe 31 gps... whatever will get you close. so injector constant affects the entire range of cells and the MAF table is for fine tuning.

 

I have 36# svo's and I changed my injector constant from 38 to 40 and the Lterm blms changed to somewhere around 108 and 118, but that wasnt after long driving like the first. Should I raise it more, or just do some more driving and see if that works.
I plan on putting new valve seals on sometime in the next 2 weeks, and will take off the heads to do this so new exhaust gaskets will be installed. I really dont think I have any leaks now, but I will see if the numbers even out a little afterwards.

 

How old are your O2 sensors?

I tried a little experiment with my 2 year old ones... I cleaned the driver's side off with some rubbing alcohol and reinstalled.

Now the driver's side BLMs read about 5-7 points higher than the passenger's.

So, if your sensors are crudded up from running rich in the past, you might try cleaning them.

 

Yeah, I was thinking about cleaning or buying new o2's but wasnt sure how to clean them. Im going to be working on the car the next few weeks so during that time ill take them out n clean them w/ some alcohol, unless theres something better?

 

you could try cleaning them but to make sure they are working properly... they should fluctuate from 0-900 mV. if they stick or only fluctuate from say 400-600 mV then they are bad. usually they tend to read high as they slowly quit working.. thats been my experience.

are you O2 sensors in the header collectors or in the y-pipe?

but about the split... you could just be in a low RPM cell where you are experiencing reversion. if you get some RPMs turning like at least 1800 then that will keep enough air moving thru the intake that the cam overlap wont affect your BLMs as bad.

 

what Ryan said and turboz is the best way to adjust it.
Ryan

 

I am running true duels, and the o2 sensors are in the piping just after the collectors. So I assume if the car had a y-pipe instead of x, my answer would be in the y-pipe. In freescan sometimes I notice the o2 sensors jump from 800 to 200, is that a sign that they need cleaning/replacement?

 

the O2 sensors are supposed to jump that the fuel trim working. cleaning them wont do anything its whats inside the sensor that reads the exhuast. best thing is to replace them

 

you probably have a leak in the Y-pipe instead of at the header flange. the O2 sensors are supposed to be placed in the collectors themselves so if you have a leak at the y-pipe... the sensors wont be affected. that will cause your BLMs to rise and could explain why you are 10 points higher on that one side.

 

Did you change your injector offsets vs batt voltage for the new injectors. Every injector has its own offsets. You can usually get them from the manufacturer

Bill

 

No I did not change the offsets, I bought them used but know what brand they are, is it possible to give the company serial #'s and them give me the offsets, or will I have to get them flowed and tested?

 

The offsets have to do with the delay in opening of the injector after the voltage is applied. Flow testing will tell you nothing. Contacting the manufacturer or searching the web will be your best bet. As a comparison the stock injectors have an offset of around 300+ Microsecs at normal operating voltage, while my Lucas 42's have around 110, and an MSD 50#er has almost 1000 (they are quite heavy)

Bill

 

Here's a link to some injector offsets. Make sure you get the right ones!

http://carprogrammer.com/Z28/PCM/Injector/injectors.htm