It's running but dont really know why???

[corvairnut]

I will make a long story bearable.... I have a Corvair (6 Cyl horizontal) w/ 2 TBI-700 (Approx 27 lbs per hour each @ 12 PSI), DIS running on a 16196395 OD mask and runs really well. I have tried to tweak the system a few times, but pretty much I got it where I want it. I have to use an off-set to make the computer run the DIS, but it also works without a hitch. Now..... I want to change the system to a center mounted Throttle body with a turbo tube that has the bungs welded close to intake pads and pretty much replaces the TBIs at the ports. Got everything plumbed up, wired, etc. Figured since the current EFI runs well and the new EFI uses about the exact same injectors (lbs per hour), everything should work with just some tweaking. Pic is attached so you kinda see where Im going on this.

To make the engine run, I have to move the TBI lbs per hour from 50 to 18 to get enough fuel into the system to make it run. I have been driving it around, but I don't want to start making fuel adjustments if something else is going on and end up changing it. I don't understand why 2 - 30 lbs injectors at 39 PSI does not put our as much as 2 - 27 lbs injectors at 12 PSI. Something tells me its more to do with pulse-width using the high-z injector and that is why lowering the TBI lbs per hour keeps the injectors open longer when gives me pretty close to the right amount of fuel.

Last time I tried CPI mode, but as I remember, it gave even less fuel and really ran bad on the upper end. Currently its in TBI mode and again, runs pretty good, but having to move it to 18lbs per hour to get enough fuel in it to run has got me.

So I'm calling on the EFI gods to tell me what is realty going on here?

[EagleMark]

Mark talked awhile back that using high-Z injectors in a Quazi TBI would yield some unexpected results and they have.

That was the Quazi closed loop run in some CPI calibrations, not injectors. Someone else will have to help with the injector swap you did...

[1project2many]

Something's not adding up. If you swapped injectors and did nothing else I'd expect rich running. Make sure the basics are right before trying to fix it in the cal.

If it was lean I'd look at the injector transition times in the cal vs actual. I'd ensure pressure and flow at injector matched expected and that there's sufficient power to supply the injectors. I'd probably use a scope to ensure the drivers weren't entering "hold" mode and reducing current to the injectors allowing them to close prematurely.

[corvairnut]

That was the Quazi closed loop run in some CPI calibrations, not injectors. Someone else will have to help with the injector swap you did...

My apologies for the paraphrasing error and corrected. I worked on this before my heart attack/surgery, so it's been awhile, and as of this past week, I'm back to 100% and going to put this puppy to bed. Yea... Theoretically its pretty much an injector swap with a single throttle body and that is why I don't understand why different amounts of fuel would flow if the injectors are rated about the same. Swapped out the TBI pump for a MPI pump and added MPI Regulator (Approx. 50 PSI at WOT and 43 PSI at idle), so I'm just a little stumped of why the BIG difference in fuel. Does the 16196395 ECM look at the injectors differently when they are high-z? From everything I've learned on this forum, the answer is "NO".

I am verifying the AFR with an Innovate LC-1 WideBand O2 and using my new Moates Ostrich which is a little better than my Romulator-II.

[corvairnut]

Something's not adding up. If you swapped injectors and did nothing else I'd expect rich running. Make sure the basics are right before trying to fix it in the cal.

If it was lean I'd look at the injector transition times in the cal vs actual. I'd ensure pressure and flow at injector matched expected and that there's sufficient power to supply the injectors. I'd probably use a scope to ensure the drivers weren't entering "hold" mode and reducing current to the injectors allowing them to close prematurely.

Thanks for putting it in good order for me. I have verified the fuel pressures/supply and worked on that first (started with 1/4" lines and replaced with 5/16 - same results), so I'm sure it down the electrical/signal side. I will take the harness out and verify I didn't make a mistake building it and then go deeper with a scope if that does not work. I will say that watching the injectors when I had them out and connected to the pump, it didn't look like they were putting out a ton of fuel like the TBI injectors did, so you may pointed me in the right direction. Just for edification, the injectors are 30 pph from a 6.1 Dodge Hemi , but had the same results from another set of 27 pph injectors.
Thanks for your post.

[1project2many]

The high impedance injectors should cause the injector driver to stay in "peak" mode and not transition to "hold."

Are the dodge injectors rated for 30 #/hr at 39 psi? That's quite high. I wonder if the Dodge injector ratings are somehow different from what we're used to, meaning they actually flow less than expected?

[corvairnut]

The high impedance injectors should cause the injector driver to stay in "peak" mode and not transition to "hold."

Are the dodge injectors rated for 30 #/hr at 39 psi? That's quite high. I wonder if the Dodge injector ratings are somehow different from what we're used to, meaning they actually flow less than expected?

I needed big injectors as I was only planning on using 2. Here are the specs on the injector. Also I had a typo on the flow PSI, I stated 39.5, but its 43.5

Mfg Name: Chrysler
Injector No: 5037479AA
Description: Injector - Siemens Deka - Dodge 6.1L HEMI
Alternate No: Siemens Deka
Color Code: Yellow Tip
Cross Reference No: SMP FJ732
Application: 06-07 Dodge Charger, Magnum, Chrysler 300, 6.1L HEMI
cc/min @ 3 BAR: 324
lbs/hr @ 3 BAR: 30.8
Ohm: 12.5
Connector: USCAR / EV6

Update: I drove the car around yesterday before the rains and it runs pretty good until I put it in closed loop and appears to be adjusting the fuel the wrong way (crazy). I created a new bin file from BPJH (which is a 4..3 CPI Chip) and go down that road. Installed another Heated O2 sensor to see how it goes. The wideband was all over the place and didn't really do that good of a job on the BLMs, so I might need to recalibrate it and try later. Im going to give it a try with the Bosch sensor and try to adjust my fuel maps from there.

[corvairnut]

Latest Update: I think I have fuel pooling in the intakes and making my #1 and #2 (opposite sides) run heavy rich (according to the spark plugs) and the other 4 Cyls appear to be normal color (slightly rich). I may have the injectors too close to the floor of the intake and the injector may be spraying to the floor and pooling. Just what I think, but that might explain why I have crazy readings and why I cant get a tune out of it. I'm I washed up like cyls #1 and #2 ???

I'm thinking of maybe relocating the injectors farther up the tube intake for more of a mix, I just cant go to far as the intake tubes will ice over. If that is not it, I may have to abandon this project for awhile and get back to running with my dual throttle bodies.

Any thoughts???

[Six_Shooter]

Any reason you didn't want to make it true multiport and place an injector over each intake valve?

[EagleMark]

Those injectors are a pencil pattern meant to spray directly onto intake valve. So I think you found they are just dumping fuel on whatever it hits and spreading with the little airflow...

Unlike a TBI Injector which is a cone pattern to mix with air around the throttle blade.

[1project2many]

Generally, when you inject fuel into a manifold (vs at a valve) you need to supply some form of heat energy to aid in vaporization. If your manifold is icing it's the surrounding air that's providing the necessary heat, at least until the ice becomes thick enough to act as an insulator. With a liquid cooled engine the OEM would supply heat to the TB but things are a bit tougher in your case. If you can't orient fuel directly toward the valves, and even that may give issues, can you tap into forced air used to cool cylinders? Or can you build ducting so intake air is drawn over cylinders before entering the engine? How about using the heat from the engine oil to heat the TB?? There's always the option to route some exhaust heat around the intake but it really seems like a waste to skip using the cooling ability of fuel to try and help stabilize engine temperature.

And I agree with Mark... those injectors may not be best for your engine. Maybe, however, you could aim the injectors at a specific place in the manifold then heat that portion of the manifold with oil / exhaust?

Air cooled engines pose some interesting challenges. They also provide opportunities to get creative.

[corvairnut]

Any reason you didn't want to make it true multiport and place an injector over each intake valve?

The intake on a Corvair is integral intake and once you cut/drill/weld it belongs to the whole head. These things are also prone to drop valves, so if it had a bolt-on intake, no problem. I wanted to keep the system bolt-on to eliminate welding/welding mistakes.

[corvairnut]

Ya'll were right..... It appears fuel pooling in my intake was my problem, so it was my design that was flawed, not my computer settings. I could adjust around it and got it where it ran pretty good at higher RPMs, but then suffered at the lower (which all makes sense now). I have abandoned the tube injection project and think I will move toward a true MPFI using the stuff that I have already built (like the turbo tube with the 3.1 Throttle body). I learned a lot, was taught a lot and now it time to move on to the next project. I plan to use the 16196395 w/6 injectors which should work, but I'm going to put off any new projects until after summer (so I will be cutting ya'll some slack during that period).

[ony]

have you ever seen one of them corver corsairs, my cousin had one if I remember right it had 6 -1 barrel carbs on it,i don't remember how the manifolds where made if they where single manifolds it might be a starting point for multi port[6 injectors] system? 1967 model I think.

[Six_Shooter]

That's kinda what I was thinking after seeing this picture:



If you look closely, it is fuel injected. ;)