8 stack FI issues

[hercf16]

Roush 427R, Imagine 8 stack FI, MSD 6AL, MSD Blaster 2. All controlled by
Easy EFI 1.0.

Have AFR set at 14.2 idle, 14.5 cruise and 12.8 WOT as per Imagine FI in AZ.
Set up run but don't exactly know what to put for fuel pressure and flow.

Starts, but needs a bit of throttle even after the pre squirt, and idles ok, set at
1000 rpm as per Roush 427IR specs. Revs and runs fine with no load.

When driving the AFRs don't seem close to the set values but runs ok until
I give it a bit of throttle as if to pass, then it hesitates/bogs down. I was
watching the AFR today and it went from 13. 6 or so to 15.9 when giving
it that throttle amount. Also does it leaving a stop in first gear unless I rev
it a bit first.

Thoughts?

Herc

[twobjshelbys]

I had the same problem with my Roush 427IR. Mine was the Accel system. They had not done the high altitude compensation setup. I shipped the car back to them in Detroit and they said it ran great, got it back to 6000' and it didn't work. Finally took it to an Accel tuner (not Roush) that had been trained on high altitude setups. Ran great after that.

[philminotti]

Listen, i know there'll be plenty of people who will disagree with me, but you HAVE to have a professional dyno tune. Period. Even more so with an eight stack system. I'll go one inflammatory step further and say that an "EZ" type system may in fact be the wrong choice and that you'd be way better off with the real deal XFI system from FAST or other similar fully programmable system (bigstuff, megasquirt, etc..)
Jmho.

[Dimis]

Originally Posted by philminotti

Listen, i know there'll be plenty of people who will disagree with me,

No Sir... Not me..

[bobcowan]

The first thing to do is set your balance with a synchrometer. If it's even a little bit off, it won't run well.

With a carb, you have pump squirter's. When you step on the gas pedal, they give an extra squirt of fuel for the added load. EFI needs something similar. I have a separate map based on vacuum load and rpm. When the vacuum goes down, the computer adds extra fuel. Seems to work pretty well.

You'll need to look and see how the ECU manages air pressure changes. I'm not really familiar with that system, but it must be able so sense and adjust for ambient air pressure. If your AFR is correct during steady driving, it's probably fine, and probably not your problem.

[hercf16]

Originally Posted by bobcowan

The first thing to do is set your balance with a synchrometer. If it's even a little bit off, it won't run well.

With a carb, you have pump squirter's. When you step on the gas pedal, they give an extra squirt of fuel for the added load. EFI needs something similar. I have a separate map based on vacuum load and rpm. When the vacuum goes down, the computer adds extra fuel. Seems to work pretty well.

You'll need to look and see how the ECU manages air pressure changes. I'm not really familiar with that system, but it must be able so sense and adjust for ambient air pressure. If your AFR is correct during steady driving, it's probably fine, and probably not your problem.

I synced all the stacks. The Fast 1.0 has an accel setting to up the fuel for
acceleration, I have been slowly upping it, no change. The system is supposed
adjust and learn for altitude changes. I just bought the car, the 8 stack system
was set up by Imagine FI in AZ, I have talked with them a few times and was
told it should adjust for altitude.

What I don't understand right now, am about to call FAST, is why the AFR
settings I put in are not what is showing during operation and why it goes
to an AFR of 15.9 when I open the throttle under load.

[philminotti]

Not sure how your system works, but with the FAST XFI 2.0 system, changing the AFR table does not directly change the actual AFR. If O2 correction is on, the ECU will attempt to adjust the VE table on the fly to try to match the actual AFR to the setting in the table. If O2 correction isn't on, the actual AFR is strictly a function of the VE table, not the AFR table. The ratio of the actual AFR to the table value at that operating point is the lambda value. Now, if learning is enabled, the ECU will not only try to make the actual AFR agree with the table, it will reprogram the VE table, thus saving the on-the-fly O2 corrections. For self learning to occur, O2 correction must be enabled and certain other parameters must be met. Remember, if O2 correction is disabled, changing the AFR table does exactly nothing to the actual AFR. That's the job of the VE table.

[RICK LAKE]

hercf 16 Herc before you damage the motor, goto a dyno shop in your area and have the FI system setup for high altitude. These FI systems with self adjust are for fine tuning AFTER you get them into the correct settings. A have an Speed Pro system which was before they changed to F.A.S.T. There are 2 styles of running these system, one runs off the TPS signal. The other way is with a Baro and Map sensor. From the readings you have giving, You are out of range and getting limit readings.
Out side of synro of the throttlebodies, Let a pro do this. I have been a tech for over 30+ years. I figured I could do my own tuning at the start. I ran into the same problems. IF the camshaft doesn't give a good steady signal to the map sensor the whole system goes crazy. It will never correct itself. I ended going to a dyno shop and found that Speedpro had setup the ECM with a BBC softwear. It was amazing how a motor could run so far out of range. The guy said my motor was too far out with a rough camshaft and had to go to the "N" programming. 3 hours later, holy cow. Idles, hauls a$$. was slipping the tires on the dyno drums. Other thing you need to have correct are fuel pressures. I run over size injectors of 50 pounders instead of 38-42 pounders. I have a vacuum regulator on the system and with 13 HG of vacuum idle the car with 35-36 psi which is low but gives good control. The max duty cycle for my injectors at 6,200 rpms is only 56%. I built this motor for a supercharger and had blt problems and left it off. This is the reason for larger injectors. My fuel pressure does run at 46-48 rail pressure. I don't have any black puffs or hesitating when hitting the throttle. ( side note, with FI system learn to roll on and off the throttle and not stab it. You will see alot better drivability and responce this way).
I could go on for hours, but Jamo will limit my talk. Anyway Call around and find a dyno shop in the area and trailer the car over for setup. It will cost you 300-500 dollars. The car will be setup correctly for your high elavation. Make sure you get a Mstick of disc of the programming when the car is running right. This way if you should not want to leave well enough alone, you can always go back to the originial tune. This should be included in your dyno repair time. Don't be afraid to ask for it. Your the customer. I have mine for both motors. Good luck Rick L.