If it is an airflow issue, it is a rarity, with him modifying the iac bypass feed and running as much as possible through the iac manifold for it to be airflow. You would have to blow the air back up the port and into the plenum and then it would bias to one side rather than the other. If there were reversion there are things that can be done there as well.

It is very likely (90% chance) a fuel injector related thing. Most of what is on the market today I wouldn't run in my lawn mower. The new bosch design 4 (ev14) is about the best I have seen, very linear, very low leakage, just about as good as it gets without going to a peak and hold injector and quiet to boot. Reason being gm spent a lot of money to keep saturated injectors so they could idle smooth and slow and still make big hp.

P.S. the standard static and dynamic tolerance for many widely available ev1 injectors is +-4% (worse in some cases). If you don't flow them you don't know which is which, and you get what you've got sometimes. There are also swear words used by manufacturers like, acceptable or expected leakage, and nonlinearity that are used to describe injectors that aren't worth a damn imo.

 

If there were a bad injector, if I switch them all side to side, and the BLMs roughly reversed. That would be a smoking gun, right?

FTR, this is what I am now using:
http://www.racetronix.biz/itemdesc.a...1D114x&eq=&Tp=

You said if there is a reversion, things can be done.
I know you can raise the idle some. What else?

 

I'm not really saying its A bad injector so much as its possible within the specs posted in that link for your injectors to flow anywhere from 35.5-38.5 and still be acceptable to sell. And that it may be likely one side is on the high side and one is on the low side.

With reversion there are things that can be done to the exhaust design if you have enough freedom to do it, mods to the intake and exhaust valves, and you can create steps in the port match between the intake and intake port with the manifold being smaller and the headers and exhaust port with the exhaust port being smaller. Sometimes on drag cars they will puke exhaust all the way up the runner back to the carb (ie the intake will look like an exhaust port). With a change in header design and collector length, many times after reassembly the intake will remain clean as the day it was put on.

Let me just say again, I don't think its worth the headache of putting a lot of time or money into when you have already bought parts and installed them. So long as your idle blms are not on the limits then what you have on either cylinder bank is an average air fuel ratio of 14.7. Also fuel consumption is so little at idle that improvements made there will be of little effect in performance and economy. Your exhaust is always going to smell like hell due to the closed loop function of the pcm. I would not even bother pulling it apart in any way. To put it another way, if you didn't have the logger you'd have never known because it has not generated any tangible symptoms, you're just worried about the numbers because that seems to be your nature. If you are going to spend money and time on it do it somewhere else where there are tangible gains to be had.

 

WS6terror,
Took your advice and had the injectors checked. I sent them to FIC and they were determined to be 100% accurate in terms of flow.

However the guy there said that one of the electrical pins was bent over to the point where the thing should have been and not spraying on the car. Obviously I think there is a very good chance that it may have really been dead when I was datalogging.

My question.
If I had a totally dead injector, would the datalogs be totally warped to one side and off the charts bad looking? Or could it certain areas of the logs still look maybe a little like normal while others areas like idle cell, still look bad?

I will have the injectors back in the car next week and weather permitting I can get some new logs.

 

Not sure if this was covered or not but if you've taken care of all the TB stuff and ensured all the intake bolts are secured to spec there is one more thing that I found this past week that can cause split BLM's. You would need an IR temperature sensing gun to complete this procedure. When tuning my injectors per cylinder via the temperature of each individual cylinder about 4" from the header flange each I found the #7 cylinder to be burning way cooler than the rest. I had about a 10-12 BLM count split in the long term BLM's to the left bank. Once I pulled the plug and gaped the TR6 spark plug from .035 to .042 or so the cylinder heated up and walla my split was cured.

This being said it would be good to check to see if you have anything like this occurring for you. It may be a simple spark plug gap change or maybe your fuel trims may need to be messed with a little bit. Anyway..........hope this can hopefully give you another angle to try.

 

Any injector or spark issue will look like hell at idle more so than anywhere else. Higher rpm means more pulses and more air/fuel flow and everything starts to smooth out. Vibration will also play a big role in poor electrical connections. I chased a wiring issue for a long time with a maf sensor that only showed up during startup and hard acceleration because of engine vibration/torquing causing the pin to position just right and lose contact. I'd have to see how the pin was bent before I could comment on its effects. Seems like you would have noticed, also depending on how you packaged them it could have happened in transit. With the way the ev1 connector is made its pretty hard to screw up the pins, not that its impossible.

Just have to wait and see what the logs say to determine if that was it.

The guys at fic are top notch and if they say its nuts on then it is.

 

Got the injectors back from FIC, they are dead perfect on the flow.

But they did notice something interesting. One electrical pin in one injector was bent down. It would seem obvious that one injector was not firing previously.

The injectors are now back in the motor and the splits of gone total opposite of before. Stock IFT's are showing 144/116 on the BLMs. Nothing else has been changed and the injectors were not worked in any way.

I raised the left trims .04 and lowered the right terms .04 and now I am getting 138/120 on the BLM's.

I still need to do some more driving to see what they do plus I want to adjust the TB buterflies too.

So now I have ruled out the injectors causing the split BLMs at idle. All that appears to be really left is the 107 LSA of the cam. The idle is really good and definitely seems smoother now most likely as a result of all injectors working. Should I just accept the 138/120 and call it a day?

Thoughts?

 

UPDATE


I pulled the intake off this weekend. Cleaned the Idle Air passages through the manifold. Unfortunately - none of them were dirty. I got minor amounts out of them.

However - I did notice one thing. Of the 8 idle air holes drilled into the runners (7) of them were significantly larger than the #1 cylinder. I think this may have had something to do with GM's research pertaining to idle air distribution corresponding to the firing order and such. With a big cam, could this be the reason many cars exhibit horrible split BLM's? It changes the idle airflow so much that the #1 cylinders idle air passage way (which is HALF the size) can't keep up? Something to question ...

In the meantime, I am soaking the pintle of my injectors in strong injector cleaner to remove any deposits. I will be putting the rail with injectors back on the car and testing for cone shaped even distribution while cranking the engine.

If the injectors test out OK (They all spec'ed out fine for Ohms and all have the 12V source. All have the ground signal pulsed by the PCM. All injectors are ticking when opening. None are leaking.) which I believe they will - then I will be going back to individual cylinder fuel trims to figure out my problems.

I really question the idle airflow distribution and the small #1 idle passageway - particularly the effects reversion from a tight LSA camshaft have on them.


I know which cylinder's individual fuel trims I will be playing with first to try to see the idle and closed throttle effects in relationship to my split BLM's.


*New O2's functioning fine
*No vacuum leaks
*No exhaust leaks
etc.

 

Enlarge the #1 cylinder Idle air hole and let me know what happens.

Larger cams and narrow LSA, I have never seen a cure for split blms at idle.

You are going to drive yourself insane. If it idles decent and pulls hard be happy,

 

It does idle decent but I know somehow this split is curable. As soon as I even give it 1 or 2% throttle the split starts to dissipate. It has to be a poor distribution of idle air.

I see two potential cures for this (assuming that a smaller #1 cylinder idle air passage way and a large cam with tight LSA are not jiving ...

1 - Enlarge the #1 intake runner's idle air passageway by removing the LARGE allen head plug from the intake and drilling it out to match size of the other (7) cylinders.

2 - Tweak the individual cylinder fuel trims for just the #1 cylinder and follow the BLM split via tuning software.



It is possible through the individual fuel trims - one can reasonably tweak the idle/closed throttle air starved cylinder down to provide a more in line value across the board.

I have a 2nd intake manifold so I decided to clean up and open the end of the orifice some for the #1 idle air passageway. It now flows more than before. The orifice end of it coming into the manifold seemed choked up. I did not drill the whole thing out yet. I will remove and redrill if necessary.

However, I am glad to finally find something that is not consistant, not symetrical with the rest of the system. I have a point to start from now. I hope that tweaking the individual cylinder fuel trims for #1 (and others if needed ... ) will help me out. At least I see something now that could serve as a problem. I intend to lower the closed throttle injector constant for #1 by .01 at a time to see if my hot idle split BLM condition improves.

It drives me crazy. I am not yet ready to give up and run a BLM locker though ... ****ing cars ... I think a Vic manifold is the way to go for a cam, big blower, turbo, etc.

 

I feel your pain, I love a tight LSA Wont go any other way on a naturally aspirated car, But your at idle blms will never agree.
If you can solve the issue please let me know!

 

I fixed my cell 16 split BLMs.
The root problem was on a pair of left bank plug wires at the spark plug end. I have MSD DIY super conductors that are several years old. When the spiral conductor was bent over backwards to put the crip on, it stresses the conductor in the bend. I determined the problem by doing an Ohms check on the wires. The good ones measured ~150 ohms while the bad one were 4K Ohms and up.

I found two wires that were broken and burned in the bend of the conductor:


So I essential had a couple of slight misfires. There was still spark getting to the two plugs but the sparks were not 100%. So on the left bank I had more O2 not being burned during the power stroke and the O2 sensor took note. The left BLM got higher and actually drug the right BLM down when this was occuring. Cant explain that one.

Now I have very consistant 128/129 or +/- 1 point when the motor is hot. Just fixing these wires made an immediate difference to the cell 16 BLMs.

BTW I am running the OEM individual fuel trims with NO corections to try to balance the BLM's.
Check your wires guys.

 

I just put new super conductors on. Old wires were coroded on. The opti side.

For. me all that's left is opti and fuel trims.

Joe

 

UPDATE - I noticed a slight misfire only really prevalent at idle. The plugs/wires have less than 200 miles on them. None are burned.

So ...

I replaced the Opti. It now runs stronger and smoother. My BLM Split is still getting worse. It no longer is a closed throttle thing and is now prevalent across all cells.

The only changes have been to replace the distributor, pull & inspect & replace intake gaskets & seal with The Right Stuff, and swap left injectors to right after soaking the pintle end in a quality jet and injector cleaner.

All injectors are ticking. All Ohm out the same.

FWIW - The car ran STRONG until it relearned its Split BLM's.

They are prevalent at all times now though. Idle, Part Throttle, Mid Throttle, WOT ... Its so ****ing frustrating.

To date I have done the following:

-Plugs
-Wires
-Opti
-Intake Manifold Gasket
-O2 Sensors
-Closed TB (stock TB) as far as screws allow before blades (clean) stick
-Tested Manifold, TB, and Elbow for vacuum leaks after the MAF

The exhaust gaskets, I can't hear, smell, or see a leak at the flange. At the collectors there are ZERO leaks.

I am absolutely out of ideas!


I may swap to the stock injectors, reflash, and see what happens...?


Can anyone help me? The car ran very strong until it learned its Fuel Trims ... At some points it is the full 108/160 split. Part throttle usually is a 20 split in BLM. The minimum split is at least 8.

 

Man I hate that you are still fighting this. Again my idle BLMs are equal +/- 3 points at the most but most of the time equal. It was the fixing of the wires and the 58mm idle circuit mod that fixed my problem.

Might pull the injectors and send them to FIC and have them flowmatched to rule that out. I think they charge me $40.00 to do this.