View Full Version : 60lb injector idle quality


69-chvl
04-01-2012, 07:38 AM
I have a totally stock LQ4 and a s475. With a Holley HP system, best idle I can get with the Siemens injector is 650 rpm, about 19" of vac. The injec PW is 1.5 ms. I stuck the stock inj back in, and I can get the idle down to 500-550, which is probably stock. Their PW was around 2.5 ms.

Sort of a newby here with LS motors, and I havent done a bunch of tuning yet, but I changed the idle AFR to 14.0 from 14.7 and it idled slightly better. Taking the idle timing to 30* from a base of 22* also helped.

I saw some tech specs on the Siemens injectors, and I think I read that the min PW is about 1.5, which is were mine were operating at.

Is this about it as far as idle quality?

ajseburg
04-01-2012, 10:46 AM
I'm also running these injectors and have the same issues. I'm waiting to see if anyone has any tricks to remedy the semi-poor idle quality. I'm running Banish's data.

stangtrader
04-01-2012, 01:53 PM
My idle is nice and clean. I think maybe your trying to set the idle too low? My lq4 in my fbody I have idling around 800 rpms. 14.7 at idle and iirc 1.8ms pulse.

got-a-ls1
04-01-2012, 02:00 PM
i cant get my idle afr any higher then 11 at idle with mine on a 5.3. think i need an adjustable regulator. even if i command 18:1 it wont change... lol think the pulsewidths are around 1.5. wont go lower no matter what i try for the injector min pulse width and whatever. gonna try to mess with the offsets some more. dont know why offsets for these injectors so such a highly guarded secret unless you buy a 250 dollar banish dvd.

69-chvl
04-01-2012, 03:10 PM
My idle is nice and clean. I think maybe your trying to set the idle too low? My lq4 in my fbody I have idling around 800 rpms. 14.7 at idle and iirc 1.8ms pulse.


Possible.

I assumed the idle speed should be around 550, as my 01 Tahoe idles there with the same cam I believe. And again, I could get it to idle at 550 with the 28lb'ers.

I tried fattening it up, leaning it out, more/less timing. Best idle I could get was 650 with an AFR of about 13.7, and 30* of timing. Gives me a kpa of 31 = around 19-20" of vacuum.

stevieturbo
04-01-2012, 06:24 PM
You guys need to take it a tuner who knows what they are doing. There should be no difficulty whatsoever with those 60lb injectors.

69-chvl
04-01-2012, 06:40 PM
You guys need to take it a tuner who knows what they are doing. There should be no difficulty whatsoever with those 60lb injectors.

I can get it to idle pretty good, just not as good at the OE's.

Do you feel the 60's should be able to idle just as well as the OE 28 lbs'ers?

stevieturbo
04-01-2012, 06:59 PM
I can get it to idle pretty good, just not as good at the OE's.

Do you feel the 60's should be able to idle just as well as the OE 28 lbs'ers?

Yes, and thousands do.

Slowhawk
04-01-2012, 09:42 PM
Tuning Motron 60's is easy. We only go as low as 850rpm but never a problem to get 14-1 or even 16-1 A/F if wanted. That is with stock 60psi fuel pressure at the rail.

ajseburg
04-01-2012, 11:25 PM
After some research, I found that there is a table that sets a minimum transient pulsewidth (B9021- hidden until I added the .cax file) that will override the minimum pulsewidth defined in B4003. I am using EFI Live on a 0202003 OS. If you're using HP Tuners, I'm not sure what the equivalent table would be. My default value in this table was 1.27xxxx, and the new value has to be lower than that set in B4003 to force the computer to use B4003 instead of B9021. I set mine at .75. I plan on loading the new calibration tomorrow and taking the car for a drive. I'll report back with the results. I'm hoping this helps with lean tip-in and rich decel.

white01ss
04-02-2012, 02:19 PM
After some research, I found that there is a table that sets a minimum transient pulsewidth (B9021- hidden until I added the .cax file) that will override the minimum pulsewidth defined in B4003. I am using EFI Live on a 0202003 OS.

Had this same problem where the pulse width wouldn't go lower and the minimum transient pulse width solved that problem. Don't set it too low or some of the injectors won't open at all and the idle will be lean, but rough and a little erratic. I think minimum pulse width for this injector is around 1.2 ms.

You may also need to visit the B4005 Small Pulse Adjust and B3701 Injector Pulse Width Voltage Adjustment as they will have an big impact at idle as well. I had mine set at 0.4103 ms @ 14V which is around stock.

denmah
04-02-2012, 04:22 PM
i run 80lb injectors @ 58psi fuel pressure on a stock cam/heads/intake turbo 4.8l

siemens decka USCAR 80lb injectors from lethal performance,

with a MS1 Ecu and i can make it start and idle beautifully.
the injectors are linear and have no problem flowing super low pulse widths, i am using about 1.2 % duty cycle at idle.

69-chvl
04-02-2012, 05:32 PM
This is the default specs in the Holley software. Does this look pretty good to you guys?

Again, motor idles good at 650, I just cant idle it at 550 like the stock injectors did.



Siemens Deka IV High Impedance "60 lb/hr"
Offtime curve at 60 psi

8.0 V 1.64
8.8 V 1.38
9.6 V 1.18
10.4 V 1.03
11.2 V .91
12.0 V .81
12.8 V .74
13.6 V .68
14.4 V .62
15.2 V .55
16.0 V .49
16.8 V .45
17.6 V .42
18.4 V .37
19.2 V .33
20.0 V .29

stevieturbo
04-02-2012, 06:13 PM
Never used Holley before, so cant comment there.

On my own ecu I calculated injector dead time at around 0.65ms at 14v so the numbers above seem ok in that respect. Cannot comment at other voltages as I dont have that info.

As to how the Holley is wired or configured I have no idea though and could affect how the system performs.
I'll at least assume the injectors are wired and fired sequentially ? And they are firing in the correct order and not at some ridiculous time ?

69-chvl
04-02-2012, 08:19 PM
Never used Holley before, so cant comment there.

On my own ecu I calculated injector dead time at around 0.65ms at 14v so the numbers above seem ok in that respect. Cannot comment at other voltages as I dont have that info.

As to how the Holley is wired or configured I have no idea though and could affect how the system performs.
I'll at least assume the injectors are wired and fired sequentially ? And they are firing in the correct order and not at some ridiculous time ?

Yes sequential, yes firing order is correct. "Some ridiculos time" - meaning regular engine timing?

got-a-ls1
04-02-2012, 11:47 PM
ha i knew there had to be a hidden table keeping my pulse widths high.. the transient fuel fixed all my idle problems. idles fine at 14.7 now. i missed it because of the label...

stevieturbo
04-03-2012, 02:18 AM
Yes sequential, yes firing order is correct. "Some ridiculos time" - meaning regular engine timing?

No, I mean injection timing.

ajseburg
04-03-2012, 08:49 PM
Sorry for taking so long for the update. I've driven around for the last 2 days with the B9021 table set at .75 and my minimum pulsewidth is dropping to 1.2 at times. I'm using Siemens Deka 60# with Banish's data. Street driving has improved 100%. I no longer have rich decel or lean tip in. It appears that my car is abiding by the b3647 table much better, but I have some more fine tuning to do. I can finally creep through a parking lot in 2nd gear off the gas without bucking. Also, my car has the hot cam, known for its awful... everything. This is the most driveable my car has been since I bought it. I also adjusted my impact factor table by +30%. I did pull some timing in the "in gear" cells that pertain to idle/off throttle creeping at 800-1200 rpm range (its a m6 car). As I continue to play around with the tune, I'll continue to report my findings.

69-chvl
04-03-2012, 10:02 PM
I guess I'm sorta on my own with the Holley ECU huh? Although, I have the ability to adjust all that stuff. Can you guys post whatever details/specs regarding these injectors? There really isnt any tuners around here that I would feel comfortable with.

stevieturbo
04-04-2012, 02:42 AM
I guess I'm sorta on my own with the Holley ECU huh? Although, I have the ability to adjust all that stuff. Can you guys post whatever details/specs regarding these injectors? There really isnt any tuners around here that I would feel comfortable with.

Just because the OEM table has multiple tables and menu's doesnt mean yours will.

Certainly any aftermarket ecu Ive ever tuned this should be very easy. Although Ive never used Holley or seen their software.