closed loop gain #'s for big injectors (XFI)

[Blazer406]

Update:

Evidently earlier in the week when the FP/wiring issue surfaced.... even though the test run seemed smooth.... AFR spiked to 13.75:1 under boost..... saw about 6-8 spikes all over 13:1..... I guess the pump was cutting off... then back on.... in the end the FAST was trying to save it with 25% positive O2 correction..... anyway...

With that fixed... we went to the track.... 1st pass off the trailer.... trans brake launch 12-16 psi launch... car spun a little with a 1.61 I think 60' time... ... 6.90 or so in the 1/8..... head gasket popped at 900-1000 ft..... coasted to a 11.0....

Run was at 20 psi.... just before the gasket let go.... 02 corrections were -1.6%, -1.3%, actual AFR was 11.0:1. Early in the run.... he went straight from first to 3rd..... then realized it... and went back to second.... when things settled out in second..... the AFR and 02 corrections looked great.... within a few percent on either side of 0....

Head will come off today... get fixed... and a new gasket will be installed hopefully before the end of the week....

These cars will definately try ones patience.

I really think that run could have been well into the 10's....

 

[Blazer406]

new logs

Here is a shot of the log at the track. The only two traces litup are actual AFR and O2 correction. Notice how the yo-yo is nearly non existant toward the end of the run. The first part it was pulling a bunch of fuel.... I had never tuned the spoolup fuel on the transbrake....so it still needs some work..... it was kinda fat.....he also accidently went from 1st to 3rd....then upon realizing it... went back to second....but the latter part of the run looked pretty good. The run was cut short.... because the HG let go somewhere past the 1/8.... notice the small spike in actual AFR just after the vertical white line.

The second datalog shows all the traces litup. He left on probably 12-15 psi... there is a slight dip in the TPS (100% to 97%) where I think he left the line.... I am betting his foot slipped off the gas slightly when he let the t-brake go at 15 lbs :biggrin:

Anyway... we are getting there.... slowly but surely. They got the head off, fixed, and back on with a new HG today....got it cranked about 6:00 tonight....

 

[TurboTR]

Another thing you can/should do to help the idle issues (if you're running gasoline) turn the 160's way down by lowering the base fuel pressure. I had mine down to about 30 psi static. This makes them about 135 lb/hr, roughly. Closer to appropriately sized. Then adjust the injector constant down same to compensate. I also had the opening time adjusted down to like 0.8ms to get close to a target of stocih a/f. After all that the best it could do was still about +1 a/f ratio off at idle (from a commanded ~ 14:1, cl), but still far better than it would have been otherwise. Extra important for a high hp streeter running around with colder plugs, C16, etc.

TurboTR

 

[Chuck Leeper]

Batt volts only 12.4. I wonder what it is at the pump??

 

[Blazer406]

Batt volts only 12.4. I wonder what it is at the pump??

He smoked his volt booster... and his 200 amp alternator.... I have attempted to sway him to stay away from another volt booster. I wonder if the voltage drop is because he is sucking all the amps the alternator can dish out... or if his wire size needs upgrading going from the back of the alternator to the rear mounted battery.....??

His new alternator is a Impala SS 140 amp alternator.... it ought to have plenty of balls to tote the car during a run w/o dropping back to battery voltage during the run...... IMHO....

I just cant see 140 amps worth of draw...

 

[Blazer406]

Another thing you can/should do to help the idle issues (if you're running gasoline) turn the 160's way down by lowering the base fuel pressure. I had mine down to about 30 psi static. This makes them about 135 lb/hr, roughly. Closer to appropriately sized. Then adjust the injector constant down same to compensate. I also had the opening time adjusted down to like 0.8ms to get close to a target of stocih a/f. After all that the best it could do was still about +1 a/f ratio off at idle (from a commanded ~ 14:1, cl), but still far better than it would have been otherwise. Extra important for a high hp streeter running around with colder plugs, C16, etc.

TurboTR

We really haven't ever had an idling problem.... it idles fairly nice..... even with the 160's......I believe the dips I was seeing in AFR and correction at the beginning of the post..... was from the compromised wiring being smashed by the rear end during a run.....

 

[Chuck Leeper]

Just my $.02..

He smoked his volt booster... and his 200 amp alternator.... I have attempted to sway him to stay away from another volt booster. I wonder if the voltage drop is because he is sucking all the amps the alternator can dish out... or if his wire size needs upgrading going from the back of the alternator to the rear mounted battery.....??

His new alternator is a Impala SS 140 amp alternator.... it ought to have plenty of balls to tote the car during a run w/o dropping back to battery voltage during the run...... IMHO....

I just cant see 140 amps worth of draw...

Nor can I.
I'm betting there's issues w/ the wiring to the batt.
A 140 alt should have at least a #6 back to the batt.
Does he have a disconnect at the rear? If so, check volt drop across that. Many of them are not rated for continous hi loading. It's not in the neg side, is it?
What does the alt show for charge volts? That should indicate the quality, [or lack of] of the charge wiring.
IE: 14vdc at the alt, and the 12.4 at the batt?? Sumptin wong!
The volt booster is an item that's FIRST on my list of trash can items.
Questionable ground cable quality at the batt is another place to look.
I use ONLY 1/0 welding cable for both the +, and - sides, with crimped ends.
What's the Fp volts?
You posted:
"The fuel pump hot wire kit was being smashed during a run by the torque arm..... it had compromised some of the wiring."
Perhaps the damage didn't stop at the place you repaired??
Tank grounded?

Just some more what if's!

 

[Blazer406]

You posted:
"The fuel pump hot wire kit was being smashed during a run by the torque arm..... it had compromised some of the wiring."
Perhaps the damage didn't stop at the place you repaired??
Tank grounded?

Just some more what if's!

Unfortunately I didn't repair it... 88ZNX fixed it himself after the run that smashed it. There is a little more to the story.... he carried the car many months ago to get the roll bar added and get the shocks moved inboard to allow more clearance for larger tires..... Evidently the suspension bumpers got sacrificed when the shocks got moved.... so now the rear end has little/nothing to keep it from traveling further than it used to.... to the point that the relay for the hot wire kit... that is bolted to the body in the vicinity where the stock wires for the FP come out...is too close at maximum travel...and smushed the wires to the point that they weren't cut... but copper could be seen through in several places and they were smashed fairly flat...

I have noticed voltage in the mid to upper 13's when cruising or idling...

I am going to bet since the battery was relocated to the trunk.... that we don't have large enough wire from the alternator going out.... probably needs .... like you said... #6.... #4 or even a little larger wouldn't hurt....IMHO...

 

[TurboDave]

I would recommend AT LEAST a #4. that's what I run from the alternator to my battery in the normal location. I don't think a #6 would be sufficient to run that far and still provide a good source during max draw (WOT).

 

[Blazer406]

The car had a caspers wiring harness to put the LC2 in the Iroc.... don't know what size they use.... but I doubt it is any larger than #8..... Now that the battery is in the rear of the car.... looks like we need to route a #4 or #2 either back to the battery.... or down to the starter... where the main battery wire connects to the starter....